Engine Controls - Tests W/codes - Eec-Iv (2.0L): Diagnosis Ford Probe II

DIAGNOSTIC FORMATS

QUICK TEST and CIRCUIT TESTS are diagnostic formats used to test and service EEC-IV system. QUICK TEST allows technician to identify problems and retrieve diagnostic trouble codes. CIRCUIT TESTS check circuits, sensors and actuators.

Before starting any CIRCUIT TEST, follow all steps under QUICK TEST to find correct CIRCUIT TEST to perform. If vehicle passes QUICK TEST and no driveability symptoms or intermittent faults exist, EEC-IV system is okay.

DIAGNOSTIC TROUBLE CODES (DTC)

During QUICK TEST, 3 types of diagnostic trouble codes are retrieved: KOEO, KOER and Continuous Memory codes. See QUICK TEST for self-test procedures. Codes may be cleared from PCM memory after they have been recorded or repaired. See CLEARING CODES.

KOEO & KOER SELF-TEST Codes

PCM outputs codes one digit at a time. Record codes in order received. These codes indicate current faults in system and should be serviced in order of appearance. Use DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS to identify correct CIRCUIT TEST to perform.

If using VOM, pay careful attention to length of pauses in order to read codes correctly. A 1/2-second pause occurs between number of sweeps in a digit. A 2-second pause occurs between digits in a code. A 4-second pause occurs between each code. KOEO codes are separated from Continuous Memory codes by a 6-second delay, a 1/2-second sweep (separator) and another 6-second delay. see scheme 1

If using MIL/CHECK ENGINE light, diagnostic trouble codes are displayed as flashes.

Scan tester, if used, will count pulses and display them as a digital code. STAR tester cannot be used to read 3-digit codes. Super Star II or New Generation Star tester can be used to read 3-digit codes. If using Super Star II tester, 3-digit codes will only be displayed in fast code mode. If slow code mode is used, display will be blank.

Diagnostic Aids

After each service or repair procedure has been completed, repeat QUICK TEST to ensure all EEC-IV systems work properly and diagnostic trouble codes are no longer present.

KOEO SELF-TEST

Ensure engine is warmed to normal operating temperature. If engine does not start (or stalls after starting), continue KOEO SELF-TEST. DO NOT depress throttle. Turn ignition off. Ensure test equipment is properly attached. Turn ignition on (engine off). Record all KOEO and Continuous Memory Codes.

If a Code 111 (pass code) is not retrieved, service KOEO codes. See DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS. If PCM will not output codes, go to CIRCUIT TEST QA. If diagnostic trouble codes are retrieved

1. If MIL/CHECK ENGINE light is on, service diagnostic trouble codes in order retrieved. See DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS.
2. On distributorless ignition models, see IGNITION SYSTEM in «SYSTEM/COMPONENT TESTS - EEC-IV (2.0L)»(ref-22925) article in the ENGINE PERFORMANCE section if Continuous Memory Code 215, 216, 217, 218, 222, 223, 224, 232 or 238 is retrieved during KOEO SELF-TEST.
3. If vehicle has a no-start condition, go to CIRCUIT TEST AA (DI), CIRCUIT TEST AB (EI - low data rate) or CIRCUIT TEST AC (EI -high data rate).
4. If vehicle displays a Code 111 (pass code) and does not have any symptoms described in previous steps, go to KOER SELF -TEST.

DO NOT enter this test sequence until a Code 111 (pass code) has been retrieved in KOEO SELF-TEST. If system has not passed KOEO SELF-TEST, codes recorded in KOER SELF-TEST may not be valid.

Deactivate self-test by removing and reconnecting jumper wire or by procedure specified by test equipment in use. Start engine, and run it for 2 minutes at 2000 RPM to warm Heated Exhaust Gas Oxygen Sensor (HO2S). Turn engine off, and wait 10 seconds. Activate KOER SELF-TEST using a jumper wire or appropriate procedure for test equipment used. Start engine. Record all diagnostic trouble codes displayed. Check following items

1. If engine starts and stalls (or stalls during self-test), go to CIRCUIT TEST S.
2. If Code 998 is displayed, EEC-IV system is operating in Failure Management Effects Mode (FMEM) and vehicle has not passed KOEO SELF-TEST. Vehicle cannot be diagnosed while in FMEM mode.
3. If vehicle is equipped with a Brake On-Off (BOO) switch, brake pedal must be depressed and released after ID code portion of test.
4. On vehicles with Power Steering Pressure (PSP) switch, turn steering wheel at least 1/2 turn and release within 1-2 seconds after ID code portion of test.
5. If Dynamic Response Code appears, perform a brief Wide Open Throttle (WOT). DO NOT perform WOT unless requested.
6. If a Code 111 (pass code) is retrieved during KOER SELF-TEST, service Continuous Memory Codes retrieved in KOEO SELF-TEST. See DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS.
7. If KOER codes are present, see DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS. If system will not output codes, go to CIRCUIT TEST QA.
8. If a Code 111 (pass code) is retrieved during Continuous Memory Code portion of KOEO SELF-TEST and no driveability problem exists, EEC-IV testing is complete. If driveability problems still present, see the article «TESTS W/O CODES - EEC-IV (2.0L)»(ref-22923) in the ENGINE PERFORMANCE section.
9. If a Code 111 (pass code) is retrieved during KOER SELF-TEST and intermittent fault(s) continue, go to CONTINUOUS MONITOR MODE (WIGGLE TEST).

CONTINUOUS MONITOR MODE (WIGGLE TEST)

Continuous Monitor Mode allows technician to attempt to recreate an intermittent fault while monitoring system. This mode, also called wiggle test, may be used in both KOEO SELF-TEST and KOER SELF-TEST. CIRCUIT TESTS specify use of this procedure to identify intermittent faults in specific circuits or components.

KOEO Wiggle Test Procedure

Connect test equipment. see scheme 2 Turn ignition on. Activate self-test using jumper lead or diagnostic tester. Wait 10 seconds, and then deactivate and reactivate self-test. Wiggle test mode is now activated. Tap, move and wiggle suspect sensor and/or harness area. If a fault is detected, a diagnostic trouble code may be stored in memory and indicated at diagnostic tester or scan tester. Retrieve code, and perform appropriate test. See DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS.

KOER Wiggle Test Procedure

Connect test equipment. see scheme 2 Start engine. Activate self-test using jumper lead or diagnostic tester. Wait 10 seconds, and then deactivate and reactivate self-test. DO NOT turn engine off. KOER wiggle test mode is now activated. Tap, move and wiggle suspect sensor and/or harness area. If a fault is detected, a diagnostic trouble code may be stored in memory and indicated at diagnostic tester or scan tester. Retrieve code, and perform appropriate test. See DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS.

CYLINDER BALANCE TEST

This test helps identify a weak or non-contributing cylinder in engines with sequential PFI fuel systems. PCM shuts off fuel supply to each injector and measures RPM drop. It computes variation between cylinders and identifies weak ones. This test mode is entered from KOER SELF-TEST after all codes have been displayed. Within 2 minutes after codes have been displayed, lightly depress throttle (a 2-3 degree throttle angle is required, not a wide open throttle). After a brief stabilizing period, PCM will activate test procedure.

Test will be repeated if throttle is depressed within 2 minutes of final code output. During second and third test sequences, percentage of allowable variation between cylinders is reduced. Service codes displayed during this test identify weak or non-contributing cylinder. See CYLINDER BALANCE TEST DIAGNOSTIC TROUBLE CODES table.

If Code 90 is displayed during this test, system has passed test. If Code 77 is displayed, repeat cylinder balance test. If throttle is moved during this test, Code 77 will appear, indicating test is not complete. Repeat Cylinder Balance Test. Total test time is about 3 minutes.

CYLINDER BALANCE TEST DIAGNOSTIC TROUBLE CODES

3-DIGIT SERVICE CODE REFERENCE CHART (CODES 111-186). Scheme 1

3-DIGIT SERVICE CODE REFERENCE CHART (CODES 187-328). Scheme 2

3-DIGIT SERVICE CODE-TO-TEST MENU (CODES 332-529). Scheme 3

3-DIGIT SERVICE CODE-TO-TEST MENU (CODES 532-587). Scheme 4

3-DIGIT SERVICE CODE-TO-TEST MENU (CODES 617-998). Scheme 5

Scheme 6

Scheme 7

Scheme 8

Scheme 9

CIRCUIT TEST AA - NO-START - DI - DIST IGNITION SYSTEMS

Enter this CIRCUIT TEST only when steps in QUICK TEST have been successfully completed but engine still does not start or if directed here from another test or chart.

This test is only intended to diagnose the following EEC-IV ignition systems and circuits

1. Powertrain Control Module (PCM).
2. Spark (PCM-controlled).
3. Wiring harness circuits (PIP, SPOUT, IGN GND and VPWR).

Note. Vehicles are equipped with either a Closed Bowl Distributor (ICM remote mounted) or a standard (ICM distributor mounted).

To prevent replacement of good components, be aware the following non-EEC related areas and components may be cause of problem

1. Fuel quality and quantity.
2. Ignition (general system condition).
3. Engine mechanical components.
4. Starter and battery circuits.
5. Distributor.
6. Camshaft Position (CMP) sensor.
7. Ignition Control Module (ICM).
8. Ignition coil.

REMOTE MOUNTED ICM MODULE LOCATION

ICM Circuit & Connector Terminal ID (AA1- Distributor Mounted). Scheme 10

ICM Ckt. & Conn. Term. ID (AA2 - Remote Mounted - Probe 2.0L). Scheme 11

TEST PIN NO. 16 (IGN GND) WIRE COLOR IDENTIFICATION

TEST PIN NO. 36 (SPOUT) WIRE COLOR IDENTIFICATION

TEST PIN NO. 56 (PIP) WIRE COLOR IDENTIFICATION

1) Check No Start Condition Try to start engine. If engine does not start, go to next step. If engine starts, no-start condition is intermittent. Check and repair ignition system. See SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section for appropriate testing.

2) Attempt To Crank Engine Try to crank engine. If engine does not crank, check vehicle starting and charging systems. If engine cranks, verify inertia switch button is pushed in. If inertia switch button is pushed in, go to next step.

3) Check VREF Signal At TP Sensor Turn ignition off. Disconnect Throttle Position (TP) sensor. Turn ignition on (engine off). Measure voltage at TP sensor harness connector between VREF and SIG RTN. (Scheme 12) If voltage is 4-6 volts, reconnect TP sensor and go to next step. If voltage is not 4-6 volts, go to CIRCUIT TEST C.

TP Sensor Harness Connector Terminal ID (AA4). Scheme 12

4) Check For Spark At Plugs Disconnect any spark plug wire. Connect spark tester between spark plug wire and ground. Crank engine and check for spark. If spark is present and consistent, connect spark plug wire and go to step 14). If spark does not exist, connect spark plug wire and go to step 25).

5) Check For Spark At Coil Remove coil secondary wire from distributor. Install spark tester. Check for spark while cranking engine. If spark exists, connect coil wire, and service ignition secondary system. If no spark exists, connect coil wire and go to next step.

6) Check Ignition Circuit Ground Continuity Turn ignition off. Disconnect and inspect PCM 60-pin connector. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. On models with distributor mounted ICM, disconnect ICM connector. Disconnect ICM and Camshaft Position (CMP) sensor connectors. Measure resistance between test pin No. 16 at breakout box and IGN GND circuit of CMP sensor connector or ICM connector. If resistance is 5 ohms or more, repair open in IGN GND circuit. Remove breakout box, reconnect components and repeat QUICK TEST. If resistance is less than 5 ohms, go to next step.

7) Isolate SPOUT Circuit Fault Connect CMP and/or ICM connector. Connect PCM to breakout box. Set breakout box timing switch to DIST position. Try to start vehicle. If vehicle starts, go to step 12). If vehicle does not start, go to next step.

8) Check SPOUT Signal Turn ignition off. Set breakout box timing switch to DIST position. Set DVOM on 20-volt scale. Turn ignition on. Measure voltage between test pin No. 36 at breakout box and negative battery terminal while cranking engine. If voltage is 3-6 volts, EEC-IV system is not at fault. Diagnose ignition system. Proceed to IGNITION SYSTEM in SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section for appropriate testing. If voltage is not 3-6 volts, go to next step.

9) Check SPOUT & PIP Circuits For Short To Power Turn ignition off. With breakout box installed, move timing switch to COMPUTED position. Disconnect PCM. On models with distributor mounted ICM, disconnect ICM connector. On all other models, disconnect CMP and/or ICM connector. Turn ignition on. Measure voltage between test pin No. 36 (SPOUT) and negative battery terminal. Also, measure voltage between test pin No. 56 (PIP) and negative battery terminal. If either reading is more than 10.5 volts, repair short to power. Remove breakout box, reconnect components and repeat QUICK TEST. If both readings are 10.5 volts or less, go to next step.

10) Check SPOUT & PIP Circuits For Short To Ground Turn ignition off. Measure resistance between test pin No. 36 (SPOUT) and test pins No. 16, 20, 40, 46 and 60 for short to ground. Also, measure resistance between test pin No. 36 and test pin No. 56 for short to PIP. Also, measure resistance between test pin No. 56 (PIP) and test pins No. 16, 20, 40, 46 and 60. If all readings are 10,000 ohms or more, go to next step. If any reading is less than 10,000 ohms, repair short in wiring harness. Remove breakout box, reconnect components and repeat QUICK TEST. If engine still does not start, go to next step.

11) Isolate Shorts In PCM Turn ignition off. With breakout box installed, reconnect PCM. On models with distributor mounted ICM, disconnect ICM connector. On all other models, disconnect CMP and/or ICM connector. Measure resistance between test pin No. 36 (SPOUT) and test pins No. 37, 40, 57 and 60. Measure resistance between test pin No. 56 (PIP) and test pins No. 37, 40, 57 and 60. If any reading is less than 500 ohms, replace PCM. Remove breakout box, reconnect components and repeat QUICK TEST. If all readings are 500 ohms or more, reconnect components, and go to next step.

12) Check PIP Signal Turn ignition off. With breakout box installed and PCM connected, move timing switch to COMPUTED position. While cranking engine, measure voltage between test pin No. 56 (PIP) and test pins No. 40 and 60. If voltage is 3-7 volts, replace PCM. Remove breakout box, reconnect components and repeat QUICK TEST. If voltage is not 3-7 volts, go to next step.

13) Check Continuity Of PIP Circuit Turn ignition off. Disconnect PCM from breakout box. On models with distributor mounted ICM, disconnect ICM connector. On all other vehicles, disconnect CMP and/or ICM connector. Measure resistance between test pin No. 56 and PIP circuit of ICM or CMP sensor. If resistance is 5 ohms or more, repair open PIP circuit. Remove breakout box, reconnect components and repeat QUICK TEST. If resistance is less than 5 ohms, remove breakout box and diagnose ignition system. Proceed to IGNITION SYSTEM in SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

14) Verify SPOUT Signal If spark was present in step 4), turn ignition off. Disconnect PCM 60-pin connector, and inspect for damaged pins, corrosion and loose wires. Repair as necessary. Install breakout box, leaving PCM connected. Ensure breakout box timing switch is in COMPUTED position. Set DVOM on 20-volt scale. Measure voltage between test pin No. 36 and pins No. 40 and 60 while cranking engine. If voltage is 3-6 volts, go to step 21). If voltage is not 3-6 volts, return to step 9).

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 14) to step 21). No test procedures have been omitted.

21) Fuel Pump Check Connect pressure gauge to vehicle. Note initial pressure reading. Pressurize fuel system by turning ignition on for one second, and observe pressure gauge. Turn ignition off, and wait 10 seconds. Repeat sequence 5 times. If pressure increases, go to CIRCUIT TEST S. If pressure does not increase, repair fuel system as necessary. See FUEL SYSTEM in BASIC TESTING - 4-CYL article in the ENGINE PERFORMANCE section.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 21) to step 25). No test procedures have been omitted.

25) VPWR Circuit Check Turn ignition off. Disconnect CMP sensor. Turn ignition on. Measure voltage between VPWR circuit of CMP sensor connector and negative battery terminal. If voltage is more than 10.5 volts, go to step 5). If voltage is 10.5 volts or less, go to next step.

26) VPWR Continuity Check Turn ignition off. Disconnect PCM 60-pin connector, and inspect for damaged pins, corrosion and loose wires. Repair as necessary. Install breakout box, leaving PCM disconnected. Measure resistance between VPWR circuit of CMP sensor connector and test pin No. 37 or 57 at breakout box. If resistance is less than 5 ohms, go to CIRCUIT TEST B. If resistance is 5 ohms or more, repair open in VPWR circuit.

CIRCUIT TEST AC - NO-START - EI - DISTRIBUTORLESS

IGNITION SYSTEMS (HIGH DATA RATE)

Enter this CIRCUIT TEST only when all steps under QUICK TEST have been successfully completed and engine still does not start or if directed here from another test or chart. This test is only intended to diagnose

1. Powertrain Control Module (PCM).
2. Spark (PCM-controlled).
3. Wiring harness circuits (PIP, IGN GND and VPWR).

To prevent replacement of good components, be aware the following non-EEC related areas and components may be cause of problem

1. Fuel quality and quantity.
2. Ignition (general condition).
3. Engine mechanical components.
4. Starter and battery circuits.
5. Crankshaft Position (CKP) sensor.
6. Ignition Control Module (ICM).
7. Coil packs.

TEST PIN NO. 16 (IGN GND) WIRE COLOR IDENTIFICATION

TEST PIN NO. 36 (SPOUT) WIRE COLOR IDENTIFICATION

TEST PIN NO. 56 (PIP) WIRE COLOR IDENTIFICATION

1) Starting System Ensure fuel pump inertia switch is closed (button pushed in). Try to start engine. If engine does not crank, check vehicle starting and charging systems. If engine cranks, go to next step.

2) Check VREF Signal At TP Sensor Turn ignition off. Disconnect Throttle Position (TP) sensor. Turn ignition on (engine off). Measure voltage between VREF and SIG RTN at TP sensor harness connector. (Scheme 13) If voltage is not 4-6 volts, go to CIRCUIT TEST C. If voltage is 4-6 volts, reconnect TP sensor and go to next step.

TP Sensor Harness Connector Terminal ID (AC4). Scheme 13

3) Check For Spark At Plugs Disconnect any spark plug wire. Connect spark tester between plug wire and engine ground. Crank engine and check for spark. If spark is present, reconnect spark plug wire and go to next step. If spark is not present, check ignition system. Proceed to IGNITION SYSTEM in SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

4) Check IGN GND Continuity Turn ignition off. Disconnect PCM 60-pin connector, and inspect it for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Disconnect Ignition Control Module (ICM). Measure resistance between test pin No. 16 at breakout box and IGN GND terminal at ICM wiring harness connector. If resistance is 5 ohms or more, repair open in IGN GND circuit. Remove breakout box, reconnect components and repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

5) Check PIP For Short To Power Ensure ICM and PCM are disconnected. Turn ignition on. Measure voltage between test pin No. 56 at breakout box and negative battery terminal. If voltage is more than 7 volts, repair PIP circuit short to power. Remove breakout box, reconnect components and repeat QUICK TEST. If voltage is 7 volts or less, go to next step.

6) Check PIP Circuit Continuity Turn ignition off. Measure resistance between test pin No. 56 at breakout box and PIP terminal at ICM wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open PIP circuit. Remove breakout box, reconnect components and repeat QUICK TEST.

7) Check PIP Circuit For Shorts To Ground Ensure ICM and PCM are disconnected. Measure resistance between test pin No. 56 (PIP) and test pins No. 16, 40, 46 and 60 for short to ground. If any reading is less than 10,000 ohms, repair short in PIP circuit. Remove breakout box, reconnect components and repeat QUICK TEST. If engine still does not start, go to next step. If all readings are 10,000 ohms or more, go to next step.

8) Isolate Shorts In PCM Ensure ignition is turned off. With breakout box installed, connect PCM to breakout box. Leave ICM disconnected. Measure resistance between test pin No. 56 (PIP) and test pins No. 37 and 57 for short to power. Also, measure resistance between test pin No. 56 and test pins No. 40 and 60 for short to ground. If any resistance is not 15,000-180,000 ohms, replace PCM. Remove breakout box, reconnect components and repeat QUICK TEST. If all resistances are 15,000-180,000 ohms, go to next step.

9) Check PIP Signal Turn ignition off. Disconnect PCM from breakout box. Reconnect ICM module. Measure voltage between test pin No. 56 and test pin No. 16 at breakout box while cranking engine. Record voltage. If voltage is 3-7 volts, go to next step. If voltage is not 3-7 volts, replace ICM. Remove breakout box, and repeat QUICK TEST.

10) Isolate Short In PCM Turn ignition off. Reconnect PCM to breakout box leaving ICM disconnected. Measure voltage between test pin No. 56 and test pin No. 16 at breakout box while cranking engine. Record voltage. If voltage is 3-7 volts, go to next step. If voltage is not 3-7 volts, replace PCM. Remove breakout box, reconnect components and repeat QUICK TEST.

11) Fuel Pump Check Connect fuel pressure gauge to vehicle. Note initial fuel pressure reading. Pressurize fuel system by turning ignition on for one second, and observe pressure gauge. Turn ignition off, and wait 10 seconds. Repeat sequence 5 times. If pressure increases, go to CIRCUIT TEST S. If pressure does not increase, go to FUEL SYSTEM in SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

Enter this CIRCUIT TEST only when directed by CIRCUIT TEST C, CIRCUIT TEST J, CIRCUIT TEST PA, CIRCUIT TEST PB or CIRCUIT TEST PC.

This test is only intended to diagnose

1. Power Control Module (PCM).
2. EEC power relay.
3. Ignition switch.
4. Wiring harness circuits (SIG RTN, PWR GND, VPWR, KAPWR and VREF).

To prevent replacement of good components, be aware the following non-EEC related areas and components may be cause of problem

1. Battery cables and ground straps.
2. Voltage regulator.
3. Alternator.
4. Ignition switch.

Power Relay Circuit ID (B2 - 2.0L). Scheme 14

TEST PIN NO. 1 (KAPWR) WIRE COLOR IDENTIFICATION

TEST PIN NO. 17 (STO) WIRE COLOR IDENTIFICATION

TEST PIN NO. 37/57 (VPWR) WIRE COLOR IDENTIFICATION

TEST PIN NO. 46 (SIG RTN) WIRE COLOR IDENTIFICATION

TEST PIN NO. 48 (STI) WIRE COLOR IDENTIFICATION

1) Battery Voltage Check Turn ignition on (engine off). Measure battery voltage. If voltage is less than 10.5 volts, recharge or replace battery. If voltage is 10.5 volts or more, go to next step.

2) Check Continuity Of PWR GND Circuit Turn ignition off. Disconnect PCM, and inspect connector pins. If PCM connector pins are damaged, loose or corroded, repair as necessary. Install Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Measure resistance between test pins No. 40 and 60 at breakout box and negative battery terminal. If one or both readings are 5 ohms or more, repair open in PWR GND circuit. Remove breakout box, reconnect components and repeat QUICK TEST. If both readings are less than 5 ohms, go to next step.

3) Check For Open Between SIG RTN & PWR GND Circuits At PCM -Ensure ignition is turned off. With breakout box installed and PCM connected, set DVOM on 200-ohm scale. Measure resistance between test pin No. 46 and test pins No. 40 and 60 at breakout box. If one or both readings are 5 ohms or more, replace PCM. Remove breakout box, and repeat QUICK TEST. If both readings are less than 5 ohms, go to next step.

4) Check Continuity Of SIG RTN Circuit Ensure ignition is turned off. Measure resistance between test pin No. 46 at breakout box and SIG RTN terminal of Data Link Connector (DLC). If resistance is 5 ohms or more, repair open in SIG RTN circuit. Remove breakout box, reconnect components and repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

5) Check KAPWR Circuit Voltage At EEC Power Relay Turn ignition off. Locate relay block in engine compartment. Disconnect EEC power relay from relay block. Turn ignition on. Measure voltage between negative battery terminal and KAPWR terminal at EEC power relay connector. If voltage is 10.5 volts or less, check KAPWR circuit between EEC power relay and positive battery terminal for open circuit. If voltage is 10.5 volts or more, go to next step.

Note. Vehicles equipped with Power Distribution Boxes use a diode to provide electrical surge protection for the ignition switch and Ignition Control Module (ICM). If a no-start/no-code condition exists, ensure diode continuity in one direction only is present before going to step 6).

6) Check Ignition Circuit Voltage At EEC Power Relay Ensure PCM is connected to breakout box and EEC power relay is disconnected. Turn ignition on. Measure voltage between negative battery terminal and IGNITION terminal at EEC power relay connector. If voltage is less than 10.5 volts, repair open in ignition switch circuit. Remove breakout box, reconnect components and repeat QUICK TEST. If voltage is 10.5 volts or more, go to next step.

7) Check PWR GND Circuit Continuity Turn ignition off. With PCM connected to breakout box, measure resistance between negative battery terminal and PWR GND terminal at EEC power relay connector. If resistance is 10 ohms or more, repair open circuit. If reading is less than 10 ohms, go to next step.

8) Check VPWR Circuit Continuity Turn ignition off. Measure resistance between test pins No. 37 and 57 (VPWR) at breakout box and VPWR terminal of EEC power relay connector. If resistance is 5 ohms or more, repair VPWR open circuit between EEC power relay and PCM. Remove breakout box, reconnect components and repeat QUICK TEST. If resistance is less than 5 ohms, go to next step.

9) Check VPWR Circuit Voltage Turn ignition off. Install EEC power relay. Turn ignition on. With PCM connected, measure voltage between test pins No. 37 and 57 (VPWR) and test pins No. 40 and 60 (PWR GND) and 46 (SIG RTN) at breakout box. If voltage is 10.5 volts or more, repair circuit between PCM and EEC power relay. Remove breakout box, reconnect components and repeat QUICK TEST. If voltage is less than 10.5 volts, replace EEC power relay. Remove breakout box, reconnect components and repeat QUICK TEST.

10) Check Ground Circuit Continuity Between Power Relay & CCRM. Turn ignition off. Ensure EEC power relay is disconnected. Disconnect Constant Control Relay Module (CCRM). CCRM is mounted to upper radiator support in right front of engine compartment. Measure resistance between terminal No. 9 of CCRM connector and PWR GND terminal of EEC power relay. If resistance is 5 ohms or more, repair open PWR GND circuit between EEC power relay and CCRM. Remove breakout box, reconnect components and repeat QUICK TEST. If resistance is less than 5 ohms, go to next step.

11) Check CCRM Ground Circuit Continuity Ensure ignition is off and CCRM is disconnected. Probe terminal No. 9 of CCRM with positive lead of DVOM. Probe terminal No. 15 of CCRM with negative lead of DVOM. Note resistance reading. If resistance is 5 ohms or more, replace CCRM. Remove breakout box, reconnect components and repeat QUICK TEST. If resistance is less than 5 ohms, repair open in ground circuit between CCRM and negative battery terminal. Remove breakout box, reconnect components and repeat QUICK TEST.

Perform this test when a check for VREF signal has failed in sensor input CIRCUIT TESTS AA-AC, DA-DR or QA. SIG RTN is a dedicated ground used by most EEC-IV system sensors. VREF is a 5-volt reference voltage that is continuously output by PCM. This consistent voltage signal is used on all 3-wire sensors.

This circuit test is only intended to diagnose the following components and circuits

1. Powertrain Control Module (PCM).
2. Vehicle wiring harness circuits (SIG RTN and VREF).

Reference Voltage Circuits & Connector Terminal ID (C1). Scheme 15

TEST PIN NO. 26 (VREF) WIRE COLOR IDENTIFICATION

TEST PIN NO. 46 (SIG RTN) WIRE COLOR IDENTIFICATION

1) Check Battery Power Circuit Turn ignition off. Disconnect PCM 60-pin connector, and inspect it for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Turn ignition on. Measure and record voltage between breakout box test pin No. 37 and SIG RTN terminal of Data Link Connector (DLC). Also, measure and record voltage across battery terminals. If both readings are less than 10.5 volts or if they differ by more than 1.0 volt, reconnect sensor (if applicable). Go to CIRCUIT TEST B. If voltages are 10.5 volts or more and do not differ from one another by more than 1.0 volt, go to next step.

2) Check VREF Voltage With breakout box installed and PCM connected, set DVOM on 20-volt scale. Turn ignition on. Measure voltage between test pins No. 26 and 46 at breakout box. If voltage is 4-6 volts, go to next step. If voltage is more than 6 volts, go to step 4). If voltage is less than 4 volts, go to step 5).

3) Check VREF & SIG RTN Circuit Continuity Turn ignition off. Disconnect PCM. If directed here by a sensor test, ensure sensor is disconnected. Measure resistance between test pin No. 26 and VREF terminal at wiring harness connector of applicable sensor. Also, measure resistance between test pin No. 46 and SIG RTN circuit terminal at wiring harness connector of applicable sensor. If both readings are less than 5 ohms, VREF circuit is okay. Remove breakout box, reconnect components and repeat QUICK TEST. If either reading is 5 ohms or more, repair open in VREF or SIG RTN circuit. Remove breakout box, reconnect components and repeat QUICK TEST.

4) Check For Excess VREF Circuit Voltage Turn ignition off. Ensure PCM is disconnected. With breakout box installed, disconnect scan tester or STAR tester (if applicable). Turn ignition on. Measure voltage between test pin No. 26 and battery ground. If voltage is less than 0.5 volt, replace PCM. Remove breakout box, reconnect components and repeat QUICK TEST. If voltage is 0.5 volt or more, repair short to battery power in wiring harness. Remove breakout box, reconnect components and repeat QUICK TEST.

5) Check For Shorted TP Sensor Turn ignition off. Connect PCM to breakout box. Disconnect Throttle Position (TP) sensor connector from wiring harness. Turn ignition on. Measure voltage between test pins No. 26 and 46 at breakout box. If voltage is 4 volts or more, replace TP sensor. Remove breakout box, reconnect components and repeat QUICK TEST. If voltage is less than 4 volts on models with EVP, PFE or DPFE sensor, go to next step. If voltage is less than 4 volts on all other models, go to step 7).

6) Check For Shorted EVP/PFE/DPFE Sensor Turn ignition off. Disconnect EVP/PFE/DPFE sensor. Turn ignition on. Measure voltage between test pins No. 26 and 46. If voltage is 4 volts or more, replace EVP/PFE/DPFE sensor. Remove breakout box, reconnect components and repeat QUICK TEST. If voltage is less than 4 volts, reconnect EVP/PFE/DPFE sensor and go to next step.

7) Check For Shorted MAP/BARO Sensor On models not equipped with a MAP/BARO sensor, go to next step. On all other vehicles, turn ignition off. Ensure PCM is connected to breakout box. Disconnect MAP/BARO sensor. Turn ignition on. Measure voltage between test pins No. 26 and 46. If voltage is 4 volts or more, replace MAP/BARO sensor. Remove breakout box, reconnect components and repeat QUICK TEST. If voltage is less than 4 volts, reconnect MAP/BARO sensor and to next step.

8) Check VREF Circuit For Short To Ground Turn ignition off. Disconnect PCM. Disconnect TP sensor, MAP/BARO sensor and EVP/PFE/DPFE sensor (if equipped). Measure resistance between test pin No. 26 and test pins No. 20, 40, 46 and 60. If any resistance is less than 1000 ohms, repair short to ground. Remove breakout box, reconnect components and repeat QUICK TEST. If original problem still exists, replace PCM and repeat QUICK TEST. If readings are 1000 ohms or more, replace PCM. Remove breakout box, reconnect components and repeat QUICK TEST.

Perform this test only when directed by QUICK TEST. Ambient air temperature must be at least 50°F (10°C) to receive valid input from IAT sensor. Engine coolant temperature must be more than 50°F (10°C) to pass KOEO SELF-TEST and more than 180°F (82°C) to pass KOER SELF-TEST. Voltage values in this test are based on a 5-volt VREF signal. Values may vary up to 15 percent due to sensor and VREF variations.

This circuit test is intended to diagnose the following components and circuits

1. Intake Air Temperature (IAT) sensor.
2. Engine Coolant Temperature (ECT) sensor.
3. Wiring harness circuits (IAT, ECT and SIG RTN).
4. Powertrain Control Module (PCM).

To prevent replacing good components, ensure the following non-EEC areas or components are not cause of problem

1. Coolant level low.
2. Cooling system, water pump or fan.
3. Engine operating temperature.
4. Engine oil level low.
5. Thermostat.
6. Air cleaner duct.
7. Ambient temperature.

Temperature Sensor Circuits & Connector Terminal ID (DA1). Scheme 16

TEST PIN NO. 7 (ECT) WIRE COLOR IDENTIFICATION

TEST PIN NO. 25 (IAT) WIRE COLOR IDENTIFICATION

TEST PIN NO. 46 (SIG RTN) WIRE COLOR IDENTIFICATION

1) Code 114 Or 116 Code 114 (IAT) or 116 (ECT) indicates corresponding sensor is out of self-test range. Correct range for measurement is .3-3.7 volts. Check for following possible causes

1. Ambient temperature less than 50°F (10°C).
2. Low coolant level.
3. Faulty harness connector.
4. Faulty sensor.

Start engine and run until engine is at normal operating temperature. If vehicle cannot be started, go to step 3). If vehicle stalls, go to CIRCUIT TEST S. Ensure upper radiator hose is hot and pressurized. Repeat QUICK TEST. If Code 114 or 116 is present, go to next step. If none of these codes are present, service other codes as necessary.

2) Check VREF Circuit Voltage At TP Sensor Turn ignition off. Disconnect Throttle Position (TP) sensor. With ignition on and engine off, measure voltage at TP sensor wiring harness connector between VREF and SIG RTN. see scheme 19 If voltage is 4-6 volts, reconnect TP sensor and go to next step. If voltage is not 4-6 volts, go to CIRCUIT TEST C.

3) Check Temperature Sensor Resistance Turn ignition off. Disconnect suspect sensor. Measure resistance between sensor terminals. See ACT & ECT SENSOR SPECIFICATIONS table. If resistance is not within specification, replace suspected sensor and repeat QUICK TEST. If resistance is within specification, perform following step as applicable.

1. For diagnosing vehicles with ECT sensor and a no-start condition, DO NOT service Code 116 at this time. Go to CIRCUIT TEST AA for models equipped with Distributor Ignition, or CIRCUIT TEST AC for models equipped with High Data Rate Electronic Ignition system (formally Electronic Distributorless Ignition - EDIS).
2. For diagnosing vehicles with ECT sensor, without a no-start condition, go to next step.

4) Check Temperature Sensor Resistance Warm engine to normal operating temperature. Turn ignition off. Disconnect suspect sensor. Run engine at 2000 RPM for 2 minutes. Measure resistance between sensor terminals. See ACT & ECT SENSOR SPECIFICATIONS table. If resistance is within specification, replace PCM and repeat QUICK TEST. If sensor is not within specification, replace sensor and repeat QUICK TEST.

ACT & ECT SENSOR SPECIFICATIONS

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 4) to step 10). No test procedures have been omitted.

10) Code 118 Or 113: Induce Opposite Code (Code 112 Or 117) Code 118 (ECT) or 113 (IAT) indicate corresponding sensor signal is more than self-test maximum. Maximum signal voltage for ECT and IAT sensor is 4.6 volts. Possible causes for excess voltage signals are

1. Open circuit in wiring harness (IAT or ECT).
2. Faulty connection.
3. Faulty sensor.
4. Faulty PCM.

Turn ignition off. Disconnect suspect temperature sensor. Connect a jumper wire between SIG RTN terminal at sensor and SIG RTN terminal at sensor wiring harness connector. Repeat KOEO SELF-TEST. If Code 112 or 117 is displayed, replace suspect sensor, remove jumper wire, and repeat QUICK TEST. If Code 112 or 117 is not displayed, remove jumper wire and go to next step.

11) Check Continuity Of Sensor Signal & SIG RTN Circuits Turn ignition off. Ensure suspect temperature sensor is disconnected. Disconnect PCM 60-pin connector. Check for damaged wiring, and repair as necessary. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance of sensor signal circuit between test pin No. 7 (ECT sensor) or test pin No. 25 (IAT sensor) at breakout box and sensor signal circuit terminal at sensor wiring harness connector. Also, measure resistance between test pin No. 46 and SIG RTN circuit at sensor wiring harness connector. If both readings are less than 5 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If either reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 11) to step 20). No test procedures have been omitted.

20) Code 112 or 117: Induce Opposite Code (113 or 118) Code 117 (ECT) or 112 (IAT) indicates sensor signal is less than self-test minimum. Minimum signal for IAT and ECT sensor is 0.2 volt. Possible causes for this fault are

1. Circuit grounded in wiring harness.
2. Faulty sensor.
3. Faulty PCM.
4. Faulty connection.

Turn ignition off. Disconnect wiring harness connector from suspect sensor. Check for damaged wiring, and repair as necessary. Repeat KOEO SELF-TEST. If Code 113 or 118 is displayed, replace sensor and connect harness. Repeat QUICK TEST. If Codes 113 or 118 is not displayed, go to next step.

21) Check VREF Circuit Voltage At TP Sensor Turn ignition off. Disconnect wiring harness connector from suspect sensor. Disconnect TP sensor. Turn ignition on. Measure voltage between VREF and SIG RTN at TP sensor wiring harness connector. If voltage is not 4-6 volts, go to CIRCUIT TEST C. If voltage is 4-6 volts, connect TP sensor and go to next step.

22) Check Temperature Sensor Signal For Shorts To Ground Turn ignition off. Disconnect suspect sensor. Disconnect PCM 60-pin connector. Check for damaged wiring, and repair as necessary. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 7 (ECT) or 25 (IAT) and test pins No. 40, 46 and 60. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 90). No test procedures have been omitted.

90) Continuous Memory Code 112, 113, 117 Or 118: Check Sensor A Continuous Memory Code 113 or 118 indicates sensor signal is more than self-test maximum of 4.6 volts. Code is set during normal driving conditions. Continuous Memory Code 112 or 117 indicates sensor signal is less than self-test minimum of 0.2 volt. Code is set during normal driving conditions. Possible causes for these faults are

1. Faulty sensor.
2. Open or grounded circuit in harness.
3. Faulty PCM.

SENSOR CODES

Enter KOEO wiggle test mode. See CONTINUOUS MONITOR MODE (WIGGLE TEST) under QUICK TEST. Observe analog voltmeter or scan tester for indication of fault while tapping sensor lightly and wiggling sensor connector. If fault is indicated, disconnect and inspect connector and terminals. If connector and terminals are okay, replace sensor, clear continuous memory and repeat QUICK TEST. If fault is not indicated, go to next step.

91) Check EEC-IV Wiring Harness While in CONTINUOUS MONITOR MODE (WIGGLE TEST), observe analog voltmeter or scan tester while wiggling and bending wiring harness, a small section at a time, from sensor to cowl. Also, check harness from cowl to PCM. If fault is indicated, isolate fault and repair as necessary. Clear continuous memory, and repeat QUICK TEST. If no fault is found, go to next step.

92) Inspect PCM & Wiring Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. If connectors and terminals are damaged, repair as necessary and repeat QUICK TEST. If connectors and terminals are okay and fault cannot be duplicated at this time, see INTERMITTENTS in TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 92) to step 100). No test procedures have been omitted.

100) Continuous Memory Code 338 A Continuous Memory Code 338 indicates cooling system has not reached normal operating temperature. Possible causes for this fault are

1. Thermostat stuck open.
2. Coolant outlet gasket leak.
3. Water pump gasket leak.
4. Heater hose leak.

Repair cooling system as necessary. Clear continuous memory, and repeat QUICK TEST.

101) Continuous Memory Code 339 A Continuous Memory Code 339 indicates cooling system has overheated. Possible causes for this fault are

1. Coolant level low.
2. Thermostat stuck closed.
3. Coolant system clogged.
4. Water pump damaged or worn.
5. Radiator cap damaged or worn.
6. Cooling fan damaged or worn.

Repair cooling system as necessary. Clear continuous memory, and repeat QUICK TEST.

Perform this test when instructed by QUICK TEST or if directed by other test procedures.

To prevent replacement of good components, be aware the following non-EEC related areas may be cause of problem

1. Damaged EGR valve.
2. Damaged EGR transducer.
3. Stuck throttle plate.
4. Exhaust system restriction.
5. Damaged canister, reservoir and/or vacuum hoses.

This CIRCUIT TEST is intended to diagnose the following

1. EGRT sensor.
2. EGRT and SIG RTN wiring harness circuits.
3. Powertrain Control Module (PCM).

EGR Temperature (EGRT) Sensor Ckts. & Conn. Terminal ID (DB). Scheme 17

TEST PIN NO. 43 (EGRT) WIRE COLOR IDENTIFICATION

TEST PIN NO. 46 (SIG RTN) WIRE COLOR IDENTIFICATION

1) Continuous Memory Code 327: Verification Code 327 indicates that at least once within previous 40 warm-up cycles, EGRT sensor signal was less than self-test minimum. Possible causes for this fault are

1. Faulty EGRT sensor.
2. Open or grounded wiring harness.
3. Faulty PCM.

Turn ignition off. Clear codes from PCM memory. Start engine, and let it run for at least 2 minutes. Repeat KOEO SELF-TEST. If Code 327 is not displayed, go to step 90). If Code 327 is displayed, go to next step.

2) Induce Opposite Code Clear codes from PCM memory. Disconnect EGRT sensor. Start engine, and let it run for at least 2 minutes. Repeat KOEO SELF-TEST. If Code 337 is not displayed, go to next step. If Code 337 is displayed, replace EGRT sensor. Clear continuous memory, and repeat QUICK TEST.

3) Check EGRT Circuit For Short To Ground Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Disconnect EGRT sensor wiring harness connector. Measure resistance between test pin No. 43 and pins No. 40, 46 and 60 at breakout box. If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 3) to step 5). No test procedures have been omitted.

5) Continuous Memory Code 337: Verification Code 337 indicates that at least once within previous 40 warm-up cycles, EGRT sensor signal was more than self-test maximum. Possible causes for this fault are

1. Faulty EGRT sensor.
2. Open wiring harness circuit.
3. Faulty PCM.

Clear codes from PCM memory. Start engine, and let it run for at least 2 minutes. Repeat KOEO SELF-TEST. If Code 337 is not displayed, go to step 90). If Code 337 is displayed, go to next step.

6) Check EGRT Circuit For Short To Power Turn ignition off. Disconnect EGRT sensor. Turn ignition on. Measure voltage between EGRT terminal at EGRT sensor wiring harness connector and negative battery terminal. If voltage is 1.0 volt or more, repair short and repeat QUICK TEST. If voltage is less than 1.0 volt, go to next step.

7) Induce Opposite Code Clear codes from PCM memory. Connect jumper wire between EGRT terminal and SIG RTN terminal at EGRT sensor wiring harness connector. Start engine, and let it run for at least 2 minutes. Repeat KOEO SELF-TEST. If Code 327 is displayed, replace EGRT sensor. Clear continuous memory, and repeat QUICK TEST. If Code 327 is not displayed, go to next step.

8) Check Continuity Of Circuits Turn ignition off. Disconnect PCM 60-pin connector. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM and EGRT sensor disconnected. Measure resistance between EGRT terminal at EGRT wiring harness connector and test pin No. 43 at breakout box. Also, measure resistance between SIG RTN terminal at EGRT wiring harness connector and test pin No. 46 at breakout box. If either reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If both readings are less than 5 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 8) to step 10). No test procedures have been omitted.

10) Continuous Memory Code 326 Code 326 indicates that within previous 40 warm-up cycles, PCM detected EGR flow at idle. Possible causes for this fault are

1. EGR valve stuck open.
2. Faulty EGRT sensor.
3. Open or shorted wiring harness circuit.

Clear codes from PCM memory. Start engine, and let it run for at least 2 minutes. If engine idles rough or stalls, clean or replace EGR valve. If engine does not stall or idle rough, go to next step.

11) Verify Condition Repeat KOEO SELF-TEST. If Continuous Memory Code 326 is not present, go to step 90). If Continuous Memory Code 326 is present, go to next step.

12) Check Continuity Of Harness Circuits Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Disconnect EGRT sensor connector. Measure resistance between EGRT terminal at EGRT wiring harness connector and test pin No. 43 at breakout box. Also, measure resistance between SIG RTN terminal at EGRT wiring harness connector and test pin No. 46 at breakout box. If either resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If either resistance is less than 5 ohms, replace EGRT sensor. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 20). No test procedures have been omitted.

20) Continuous Memory Code 332 Code 332 indicates that within previous 80 warm-up cycles, PCM did not detect EGR flow at part throttle. Possible causes for this fault are

1. Damaged or plugged vacuum line.
2. EGR valve stuck closed.
3. Damaged EGR pressure transducer.
4. Damaged or plugged exhaust tube.
5. Faulty EGRT sensor.
6. Open or shorted wiring harness circuit.

Turn ignition off. Disconnect vacuum hose at EGR valve. Connect vacuum pump to EGR valve. Apply 10 in. Hg to EGR valve. If vacuum is not held, repair or replace EGR valve. If vacuum is held, go to next step.

21) Release vacuum from EGR valve. Clear codes from PCM memory. Start engine. Apply 10 in. Hg to EGR valve, and hold 2 minutes. If engine idles rough or stalls, go to next step. If engine does not idle rough or stall, clean or replace EGR valve.

22) Repeat KOEO SELF-TEST. If Continuous Memory Code 326 is present, clean or repair EGR system as necessary. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If Continuous Memory Code 326 is not present, replace EGRT sensor and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 90). No test procedures have been omitted.

90) Check EEC-IV Wiring Harness Enter wiggle test. See CONTINUOUS MONITOR MODE (WIGGLE TEST) under QUICK TEST. Bend, wiggle and shake small sections of EEC-IV harness from TP sensor wiring harness connector to firewall and from firewall to PCM while observing analog voltmeter or scan tester. If fault is indicated, isolate fault in wiring and repair as necessary. Clear codes, and repeat QUICK TEST. If no fault is indicated, go to next step.

91) Check PCM & Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Clear codes from PCM memory, and repeat QUICK TEST. If connectors and terminals are okay, fault cannot be duplicated at this time. Testing is complete.

Perform this test when directed by QUICK TEST. This CIRCUIT TEST is intended to diagnose the following

1. MAF sensor.
2. Wiring harness circuits (VPWR, PWR GND, MAF and MAF RTN).
3. Powertrain Control Module (PCM).

To prevent replacement of good components, be aware the following non-EEC related areas may be cause of problem

1. Air cleaner element.
2. Inlet air duct.
3. Throttle body.

Code 159, retrieved during KOEO SELF-TEST, indicates voltage exceeded .7-volt test range. Code 159, retrieved during KOER SELF-TEST, indicates voltage is not within .2-1.5 volts operating range.

MAF Sensor Circuits & Connector Terminal ID (DC1). Scheme 18

TEST PIN NO. 9 OR 15 (MAF RTN) WIRE COLOR ID

TEST PIN NO. 14 OR 50 (MAF) WIRE COLOR ID

TEST PINS NO. 37 & 57 (VPWR) WIRE COLOR IDENTIFICATION

TEST PINS NO. 40 & 60 (PWR GND) WIRE COLOR ID

MAF SIGNAL VOLTAGE (1)

Note. Code 159 may be caused by use of a garage exhaust ventilation system. Ensure vehicle is vented to outside atmosphere before repeating QUICK TEST.

1) Code 159: Check VPWR Circuit Voltage Code 159 indicates that MAF sensor was out of range during KOEO or KOER SELF-TEST. Possible causes for this fault are

1. Air leak before or after MAF sensor.
2. Faulty MAF sensor.
3. Faulty IAC solenoid.
4. Open or grounded wiring harness.
5. Faulty PCM.

Repeat QUICK TEST. If Code 412 is present, go to CIRCUIT TEST KE, step 1). If Code 411 is present, go to CIRCUIT TEST KE, step 15). If Code 411 or 412 is not present, go to next step.

2) VPWR Circuit Voltage Check Turn ignition off. Disconnect MAF sensor connector. Set DVOM on 20-volt scale. Turn ignition on. Measure voltage between VPWR terminal at MAF sensor wiring harness connector and negative battery terminal. If voltage is less than 10.5 volts, repair open in VPWR circuit and repeat QUICK TEST. If voltage is 10.5 volts or more, go to next step.

3) Check MAF Sensor Ground Turn ignition on. With MAF sensor disconnected, measure voltage between VPWR terminal and PWR GND terminal at MAF sensor connector. If voltage is less than 10.5 volts, repair open PWR GND circuit. Connect MAF sensor, and repeat QUICK TEST. If voltage is 10.5 volts or more, go to step 13).

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 3) to step 10). No test procedures have been omitted.

10) Continuous Memory Code 157: Check For Intermittent Sensor Failure Continuous Memory Code 157 indicates MAF signal was less than 0.4 volt sometime during last 80 warm-up cycles. Possible causes for this fault are

1. Open MAF circuit.
2. MAF circuit shorted to ground.
3. Faulty MAF sensor.
4. MAF sensor disconnected.

Clear continuous memory. Start engine and allow to idle for 5-10 minutes. Increase engine speed to 1500 RPM for 5 seconds. Perform KOEO SELF-TEST. If Code 157 is present, go to step 13). If Code 157 is not present, go to next step.

11) Monitor MAF Circuit Under Simulated Road Shock Turn ignition off. Disconnect and inspect 60-pin connector at PCM. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Connect DVOM between MAF test pin and MAF RTN test pin. See appropriate table at beginning of this CIRCUIT TEST. DVOM should read about 0.4 volt. Start engine and allow to idle. Lightly tap on MAF sensor and wiggle wiring harness to simulate road conditions. If sudden change in DVOM reading occurs, fault is indicated. If fault is indicated, replace MAF sensor and repeat QUICK TEST. If no fault is indicated, leave DVOM connected and go to next step.

12) Check Wiring Harness For Open Or Short Circuit Turn ignition on. Shake and bend small sections of wiring harness starting at MAF sensor and working toward dash panel. Shake and bend small sections of wiring harness starting at dash panel and working toward PCM. If fault is indicated, isolate and repair as necessary. If fault is not indicated, problem is intermittent and cannot be duplicated at this time.

13) Codes 129 Or 157: Check For Air Leak At MAF Sensor Check for broken or loose air outlet tube clamps at throttle body and air cleaner assembly. Repair or replace as necessary. If no faults are found, go to next step.

14) Check Continuity Of MAF & VPWR Circuit Turn ignition off. Disconnect MAF sensor and PCM wiring harness connector. Inspect for damaged pins, corrosion, etc. Service connector ends as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between MAF terminal of MAF sensor wiring harness connector and test pins No. 37 and 57. On SFI vehicles, measure resistance between MAF terminal of MAF sensor wiring harness connector and test pin No. 50. On MFI vehicles, measure resistance between MAF terminal of MAF sensor wiring harness connector and test pin No. 14. If resistance is more than 5 ohms, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If resistance is 5 ohms or more, go to next step.

15) Check MAF Signal For Short To Ground Turn ignition off. Ensure MAF sensor and PCM wiring harness are disconnected. Measure resistance between test pin No. 50 and test pins No. 9, 40 and 60. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are 10,000 ohms or more, go to next step.

16) Turn ignition off. Ensure MAP sensor and PCM wiring harness connectors are disconnected. Measure resistance between PWR GND terminal at MAF sensor wiring harness connector and negative battery terminal. If resistance is 10 ohms or more, repair open PWR GND circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If resistance is less than 10 ohms, go to next next step.

17) Check Continuity Of MAF RTN Circuit Ensure ignition is turned off. Measure resistance between MAF RTN terminal of MAF sensor wiring harness connector and test pin No. 9. If resistance is more than 5 ohms, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If resistance is 5 ohms or more, go to next step.

18) Check MAF Circuit For Short To Ground Turn ignition off. Ensure MAF sensor is disconnected. Connect PCM to breakout box. Measure resistance between test pin No. 50 and test pins No. 9, 40 and 60. If any reading is less than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are 10,000 ohms or more, go to next step.

19) Check MAF Circuit Output Turn ignition off. Connect MAF sensor wiring harness connector. Start engine. Measure voltage between test pin No. 50 and negative battery terminal. If voltage is .36-1.50 volts, go to next step. If voltage is not .36-1.50 volts, replace MAF sensor. Remove breakout box, reconnect all components, and repeat QUICK TEST.

20) With engine running, measure voltage between test pin No. 9 and test pin No. 50. If voltage is .36-1.50 volts, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If voltage is not .36-1.50 volts, replace MAF sensor. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. Code 158 may be caused by foreign material blocking MAF sensor screen creating an airflow restriction. If contaminates are found on screen, check air filter installation in air cleaner tray, and proper sealing or air cleaner/tube before proceeding.

21) Code 158: Repeat KOEO SELF-TEST Turn ignition off. Disconnect MAF sensor wiring harness connector. Start engine, and allow it to idle for one minute. Turn ignition off. Repeat KOEO SELF-TEST. If Code 157 is present, replace MAF sensor and repeat QUICK TEST. If Code 157 is not present, go to next step.

22) Check MAF Circuit For Short To VPWR Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Measure resistance between MAF and VPWR terminals at MAF sensor wiring harness connector. If resistance is 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If resistance is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. Remove breakout box, reconnect all components, and repeat QUICK TEST.

CIRCUIT TEST DD - EGR POSITION (EGRP) SENSOR, EGR VACUUM

(EGRV) SOLENOID & EGR ATMOSPHERIC (EGRA) SOLENOID

Perform this test only when directed by QUICK TEST. This circuit test is intended to diagnose the following components and circuits

1. EGRP sensor.
2. Wiring harness circuits (EGRP, SIG RTN, VREF, EGRV, EGRA and VPWR.
3. Powertrain Control Module (PCM).
4. Vacuum lines (EGRV, EGRA and EGR.

EGRP Sensor Connector Terminal ID (DD1). Scheme 19

EGRV & EGRA Solenoid Connector Terminal ID (DD2). Scheme 20

1) Code 327: Attempt To Generate Code 337 Code 327 indicates EGR Position (EGRP) sensor signal is less than self-test minimum. Possible causes for this fault are

1. Faulty EGRP sensor/EGR valve assembly.
2. Open sensor VREF or SIG RTN circuits.
3. Open sensor VREF circuit.
4. Short to ground in sensor EGRP circuit.
5. Faulty Powertrain Control Module (PCM).

Turn ignition off. Disconnect EGRP sensor connector. Connect jumper wire between terminals VREF and EGRP of EGRP sensor wiring harness connector. Repeat KOEO and KOER SELF-TEST. If Code 337 is displayed, replace EGRP sensor/EGR valve assembly. Remove jumper wire, and repeat QUICK TEST. Disregard any other codes that are set at this time. If Code 337 is not displayed, remove jumper wire, and go to next step.

2) Check EGRP VREF Voltage Turn ignition on. Ensure EGRP sensor is disconnected. Measure voltage between VREF and SIG RTN terminals at EGRP sensor connector. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to CIRCUIT TEST C.

3) Check EGRP Sensor SIG RTN Circuit Continuity Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between SIG RTN terminal of EGRP sensor connector and test pin No. 46 at breakout box. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

4) Check For Short To Ground In EGRP SIG RTN Circuit Measure resistance between test pin No. 27 and test pins No. 40, 46 and 60 at breakout box. If all readings are more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If any reading is 10,000 ohms or less, repair short to ground. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 4) to step 10). No test procedures have been omitted.

10) Code 337: Attempt To Generate Code 327 Code 337 indicates EGR Position (EGRP) sensor signal is more than self-test minimum. Possible causes for this fault are

1. Open or short in EGRP circuit.
2. Faulty EGRP sensor/EGR valve assembly.
3. Faulty EGR Vacuum (EGRV) solenoid valve.
4. Faulty Powertrain Control Module (PCM).
5. Improper EGR valve vacuum hose routing.

Turn ignition off. Disconnect EGRP sensor connector. Connect jumper wire between EGRP and SIG RTN terminals of EGRP sensor wiring harness connector. Repeat KOEO and KOER SELF-TEST. If Code 327 is displayed, remove jumper wire, and go to step 13). Disregard any other codes that are set at this time. If Code 327 is not displayed, remove jumper wire, and go to next step.

11) Check EGRP Circuit Continuity Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair connector as necessary. Ensure EGRP sensor is disconnected. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between EGRP terminal at EGRP sensor connector and test pin No. 27 at breakout box. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

12) Check For Short To Power In EGRP Circuit Measure resistance between test pin No. 27 and test pins No. 26, 37 and 57 at breakout box. If all readings are more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

13) Check Vacuum At EGRV Solenoid Valve Turn ignition off. Disconnect EGRV solenoid vacuum line at EGRV solenoid output port. Install vacuum gauge at output port of EGRV solenoid. Start engine and allow it to idle. Observe vacuum gauge. If vacuum is present, replace EGRV solenoid. Remove vacuum gauge. Reconnect all components and repeat QUICK TEST. If vacuum is not present, check EGR valve vacuum hose routing. Repair as necessary. If hose routing is okay, replace EGRP sensor/EGR valve assembly. Remove vacuum gauge. Reconnect all components and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 20). No test procedures have been omitted.

20) Code 571 & 572: Check EGRA/EGRV Solenoid Resistance Code 571 indicates failure in EGRA solenoid circuit. Code 572 indicates failure in EGRV solenoid circuit. Possible causes for this fault are

1. Open or short in wiring harness.
2. Faulty EGRA/EGRV solenoid.
3. Faulty Powertrain Control Module (PCM).

Turn ignition off. Disconnect EGRA (Code 571) or EGRV (Code 572) solenoid connector. Measure resistance between solenoid connector terminals. If resistance is 30-70 ohms, go to next step. If resistance is not 30-70 ohms, replace solenoid, and repeat QUICK TEST.

21) Check Solenoid VPWR Circuit Turn ignition on. Ensure solenoid to be tested is disconnected. Measure voltage between negative battery terminal and VPWR terminal at solenoid connector. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open circuit. Repeat QUICK TEST.

22) Check Solenoid Circuit Continuity Turn ignition off. Ensure solenoid to be tested is disconnected. Disconnect PCM 60-pin connector. Inspect for damage, and repair if necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. If testing EGRA solenoid, measure resistance between test pin No. 12 at breakout box and EGRA terminal at solenoid connector. If testing EGRV solenoid, measure resistance between test pin No. 33 at breakout box and EGRV terminal at solenoid connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

23) Check For Solenoid Circuit Short If testing EGRA solenoid, measure resistance between test pin No. 12 and test pins No. 37, 40, 57 and 60 at breakout box. If testing EGRV solenoid, measure resistance between test pin No. 33 and test pins No. 37, 40, 57 and 60 at breakout box. If all readings are more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 23) to step 30). No test procedures have been omitted.

30) Code 332: Check Vacuum To EGR Valve Code 332 indicates EGRP sensor input did not change after PCM commanded EGR valve to open. Possible causes for this fault are

1. Faulty vacuum lines.
2. Faulty EGRP/sensor/EGR valve assembly.
3. Faulty EGRA solenoid.
4. Faulty EGRV solenoid.

Turn ignition off. Disconnect EGR vacuum hose at EGR valve, and connect vacuum gauge to disconnected vacuum hose. Repeat KOEO SELF-TEST, while observing vacuum gauge. If vacuum is less than 1.0 in. Hg throughout KOEO SELF-TEST, go to next step. If vacuum is 1.0 in. Hg or more throughout KOEO SELF-TEST, replace EGRP sensor/EGR valve. Reconnect all components and repeat QUICK TEST.

31) Check EGR Vacuum Hose Ensure EGR valve vacuum hose is disconnected. Insect vacuum hose between EGR valve and EGRV/EGRA solenoids. Replace hose as necessary. Repeat QUICK TEST. If vacuum hose is okay, reconnect vacuum hose, and go to next step.

32) Check Vacuum To EGRV Solenoid Turn ignition off. Disconnect vacuum hose from EGRV solenoid input port. Install vacuum gauge to disconnected hose. Start engine and allow it to idle. If vacuum is more than 10 in. Hg, remove vacuum gauge. Reconnect vacuum hose, and go to next step. If vacuum is 10 in. Hg or less, check vacuum hose to EGRV solenoid. Replace hose as necessary. If vacuum hose is okay, check vacuum source for solenoid. Repair as necessary. Repeat QUICK TEST.

33) Check EGRV Solenoid Valve Turn ignition off. Disconnect vacuum hose from EGRV solenoid output port. Install vacuum gauge to output port of EGRV solenoid. Repeat KOEO SELF-TEST and observe vacuum gauge. If vacuum signal decreases then increases, remove vacuum gauge, and go to next step. If vacuum signal does not decrease then increase, replace EGRV solenoid. Remove vacuum gauge. Reconnect all components and repeat QUICK TEST.

34) Check EGRV Solenoid Output Port Vacuum Hose Disconnect vacuum hose from EGRV solenoid output port. Inspect vacuum hose for obstructions, cracks and kinks. Replace vacuum hose as necessary, and repeat QUICK TEST. If vacuum hose is okay, reconnect vacuum hose and go to next step.

35) Check EGRA Solenoid Vacuum Hose Disconnect EGRA vacuum hose. Inspect vacuum hose for obstructions, cracks and kinks. Replace vacuum hose as necessary, and repeat QUICK TEST. If vacuum hose is okay, replace EGRA solenoid. Reconnect vacuum hose, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 35) to step 90). No test procedures have been omitted.

90) Continuous Memory Code 327 Or 337: Check for Intermittent Continuous Memory Code 327 indicates EGRP sensor input to PCM was below minimum acceptable voltage sometime during vehicle operation. Continuous Memory Code 337 indicates EGRP sensor input to PCM was more than the maximum acceptable voltage sometime during vehicle operation. Possible causes for this fault are

1. Faulty EGRP/sensor/EGR valve assembly.
2. Intermittent open in EGRP sensor SIG RTN circuit.
3. Intermittent open in EGRP circuit.
4. Intermittent open in EGRP sensor VREF circuit.
5. Intermittent short to power in EGRP circuit.

Enter CONTINUOUS MONITOR MODE (WIGGLE TEST). Observe test equipment and perform the following

1. Lightly tap on EGRP sensor (to simulate road shock).
2. Wiggle sensor wiring harness connector.

If a fault is indicated, inspect EGRP sensor connector and terminals. Repair as necessary. If connector and terminals are okay, replace EGRP sensor/EGR valve assembly. Clear codes, and repeat QUICK TEST. If a fault is not indicated, go to next step.

91) Check For Intermittent Harness Damage: Check For Intermittent Sensor Damage While still in CONTINUOUS MONITOR MODE (WIGGLE TEST), observe test equipment and perform the following. Shake and bend small sections of wiring harness starting at EGRP sensor and working toward dash panel. Also, shake and bend small sections of wiring harness starting at dash panel and working toward PCM. If a fault is indicated, isolate fault and repair as necessary. Clear codes and repeat QUICK TEST. If a fault is not indicated, go to next step.

92) Check PCM Connector Turn ignition off. Disconnect PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Clear codes and repeat QUICK TEST. If connector and wiring are okay, fault cannot be duplicated at this time. Testing is complete.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 92) to step 100). No test procedures have been omitted.

100) Continuous Memory Code 332: Check EGR Valve Function Continuous Memory Code 332 indicates EGR valve did not open when engine load and requested conditions had been met sometime during vehicle operation. Possible causes for this fault are

1. Faulty EGRP/sensor/EGR valve assembly.
2. Faulty EGR valve vacuum hose.
3. Faulty EGRV or EGRA solenoid vacuum lines.

Turn ignition off. Disconnect and plug EGR valve vacuum line at EGR valve. Connect vacuum pump to EGR valve. Apply 10 in. Hg to EGR valve. Observe EGR valve and release vacuum. If EGR valve functions properly, remove vacuum pump. Unplug vacuum hose, and go to next step. If EGR valve does not function properly, remove EGRP sensor/EGR valve assembly. Inspect EGR valve for blockage, binding, contamination and leakage. Repair or replace EGR valve assembly as necessary. Clear codes and repeat QUICK TEST.

101) Check EGR Valve Vacuum Hose Disconnect EGR vacuum hose at vacuum source and EGR valve. Inspect vacuum hose for obstructions, cracks and kinks. Replace vacuum hose as necessary. Clear codes and repeat QUICK TEST. If vacuum hose is okay, reconnect vacuum hose and go to next step.

102) Check EGRA & EGRV Solenoid Vacuum Hoses Disconnect solenoid vacuum hose to be checked. Inspect vacuum hose for obstructions, cracks and kinks. Replace vacuum hose as necessary. Clear codes and repeat QUICK TEST. If vacuum hose is okay, reconnect vacuum hoses and go to next step.

103) Check EGRV/EGRA Solenoids & Circuits For Intermittent Fault Turn ignition off. Disconnect vacuum hose at EGR valve and connect vacuum pump to disconnected hose. Start engine and allow it to idle. Observe vacuum pump for increased vacuum while performing the following

1. Lightly tap on EGRV and EGRA solenoids (to simulate road shock).
2. Wiggle EGRV and EGRA solenoid wiring harness connectors.

If vacuum reading increased, isolate fault and repair as necessary. Clear codes and repeat QUICK TEST. If vacuum reading did not increase, fault cannot be duplicated at this time. Testing is complete.

Perform this test when directed by QUICK TEST. Barometric pressure sensor output is digital and must be measured using an oscilloscope or MAP/BARO tester. To prevent replacement of good components, be aware the following non-EEC related areas may be cause of problem

1. Unusually high or low atmospheric barometric pressure.
2. Kinked or blocked vacuum lines.
3. Engine mechanical condition (valves, vacuum leaks, timing, EGR valve, etc.).

This test is intended to diagnose the following

1. MAP/BARO sensor.
2. Wiring harness circuits (VREF, MAP/BARO SIG and SIG RTN).
3. MAP vacuum line.
4. Powertrain Control Module (PCM).

MAP/BARO Sensor Ckts., Conn. Terminal ID & Tester Hookup (DF1). Scheme 21

TEST PIN NO. 26 (VREF) WIRE COLOR ID

TEST PIN NO. 46 (SIG RTN) WIRE COLOR ID

MAP SENSOR SPECIFICATIONS

MAP/BARO SENSOR SPECIFICATIONS

1) Code 126: Check Power To MAP/BARO Sensor Code 126 indicates MAP/BARO sensor is out of self-test voltage range (1.4-1.6 volts). Following are possible causes of this code

1. Vacuum trapped at MAP/BARO sensor.
2. High atmospheric pressure.
3. MAP/BARO signal circuit open between sensor and PCM.
4. MAP/BARO signal circuit shorted to VREF, SIG RTN or GND.
5. VREF circuit open at sensor.
6. SIG RTN circuit open at sensor.
7. Faulty MAP/BARO sensor.
8. Faulty PCM.

Turn ignition off. Disconnect MAP/BARO sensor from wiring harness.Connect MAP/BARO tester between wiring harness and MAP/BARO sensor. Connect banana plugs of tester into DVOM. Set DVOM on 20-volt scale. Turn ignition on. If Red light or no light is on, VREF is out of range. Go to next step. If Green light is on, VREF is okay. Go to step 3).

2) Check Power At Sensor Wiring Harness Connector Disconnect MAP/BARO sensor. Turn ignition on. If tester Green light is on, replace MAP/BARO sensor and repeat QUICK TEST. If Green light is off, remove MAP/BARO tester. Connect MAP/BARO sensor, and go to CIRCUIT TEST C.

3) Check MAP/BARO Sensor Output With MAP/BARO tester connected and ignition on, measure sensor output voltage. If output voltage is within range for altitude in which vehicle is being tested, remove MAP/BARO tester and go to next step. If output reading is not within range, remove MAP/BARO tester and go to step 5).

If possible, measure output voltage of several known good MAP/BARO sensors on available vehicles. Average voltage reading will be typical for location and time of testing.

MAP SENSOR VOLTAGE OUTPUT

4) Check MAP/BARO SIG Circuit Continuity Turn ignition off. Disconnect MAP/BARO sensor wiring harness connector. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair connector as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between MAP/BARO SIG terminal at sensor wiring harness connector and test pin No. 45. If reading is less than 5 ohms, replace PCM and repeat QUICK TEST. If reading is 5 ohms or more, repair open MAP/BARO SIG circuit and repeat QUICK TEST.

5) Check MAP/BARO SIG Circuit For Short To VREF, SIG RTN & Ground Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Disconnect wiring harness at MAP/BARO sensor. Measure resistance between test pin No. 45 and test pins No. 26, 40, 46 and 60. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are 10,000 ohms or more, replace MAP/BARO sensor. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 5) to step 7). No test procedures have been omitted.

7) KOER Code 126: Check For EGR-Related Codes Code 126 indicates MAP/BARO signal is out of self-test range during KOER SELF-TEST. Possible causes for this code are

1. Excess EGR flow.
2. Damaged or misrouted MAP/BARO sensor vacuum hose.
3. Faulty MAP/BARO sensor.

If Code 326, 327, 328, 332, 334, 336 or 337 is present, perform applicable CIRCUIT TEST. See DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS. If codes are not present, go to next step.

8) Check MAP Sensor Operation Turn ignition off. Disconnect vacuum hose from MAP sensor. Connect vacuum pump to MAP sensor, and apply 18 in. Hg. If vacuum does not hold, replace sensor and repeat QUICK TEST. If MAP sensor holds vacuum, release vacuum and go to next step.

9) Attempt To Eliminate Code 126 Plug MAP sensor vacuum supply hose. Start engine, and run it at 1400-1600 RPM. Slowly apply 15 in. Hg to MAP sensor. Perform KOER SELF-TEST. Check for Code 126, disregarding any other codes at this time. If Code 126 is still present, replace MAP sensor. If Code 126 is not present, inspect MAP sensor vacuum supply hose. If hose is okay, service other codes at this time. If no other code is present, check engine mechanical condition for cause of low vacuum.

10) Code 129: Repeat Dynamic Response Test Code 129 indicates MAP sensor output did not change enough during dynamic response test. Possible causes for this code are

1. System failed to detect Wide Open Throttle (WOT).
2. Damaged or misrouted MAP/BARO sensor vacuum hose.
3. Faulty MAP sensor.

Repeat KOER SELF-TEST. Ensure complete WOT is performed during dynamic response portion of test. If KOER Code 129 is still present, go to next step. If code is not present, service any other codes as necessary.

11) Continuous Memory Code 128: Check Vacuum Hoses Continuous Memory Code 128 indicates MAP sensor vacuum has not changed more than 2 in. Hg during normal vehicle operation. Possible causes for this code are

1. MAP sensor vacuum hose is improperly routed, blocked or is leaking.
2. MAP sensor is leaking.

Check vacuum lines for correct routing. Refer to Vehicle Emission Control Identification (VECI) decal. Check for loose connections, kinks and blockage. Repair vacuum lines as necessary. If vacuum lines are okay, go to next step.

12) Check MAP Sensor Operation Turn ignition off. Disconnect vacuum supply hose from MAP sensor. Attach vacuum pump to MAP sensor. Apply 18 in. Hg to MAP sensor. If MAP sensor holds vacuum, release vacuum and go to next step. If sensor does not hold vacuum, replace MAP sensor and repeat QUICK TEST.

13) Verify Vacuum To MAP Sensor Decreases During Dynamic Response Test. Turn ignition off. Use a "T" fitting to install a vacuum gauge in MAP sensor vacuum hose. Perform KOER SELF-TEST while observing vacuum gauge. If vacuum decreases by more than 10 in. Hg during dynamic response test, replace MAP sensor and repeat QUICK TEST. If vacuum does not decrease by more than 10 in. Hg, EEC-IV system is okay. Check for engine mechanical problems affecting engine vacuum.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 90). No test procedures have been omitted.

90) Continuous Memory Code 126 Code 126 indicates MAP/BARO sensor was out of self-test range (1.4-1.6 volts) during normal driving conditions. Possible causes for this code are

1. Faulty MAP/BARO sensor.
2. Faulty wiring harness or connectors.
3. Unusually high or low barometric pressure.

Enter CONTINUOUS MONITOR MODE (WIGGLE TEST). Observe test equipment while performing following

1. Connect a vacuum pump to MAP/BARO sensor.
2. Slowly apply 25 in. Hg to sensor.
3. Slowly bleed off vacuum from sensor.
4. Lightly tap on sensor (to simulate road shock).
5. Wiggle sensor connector.

If a fault is indicated, disconnect sensor and inspect connectors. Repair if necessary. If connectors are okay, replace MAP/BARO sensor. Repeat QUICK TEST. If a fault is not indicated, go to next step.

91) Check EEC-IV Wiring Harness Stay in wiggle test. Observe analog VOM or scan tester for indication of fault while bending or wiggling small sections of harness from sensor connector to firewall, and from firewall to PCM. If fault is indicated, isolate fault in harness and repair as necessary. Repeat QUICK TEST. If no fault is indicated, go to next step.

92) Check PCM & Wiring Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector. Inspect connectors and terminals for damage. Repair if necessary. If connectors and terminals are okay, fault cannot be duplicated at this time. Testing is complete. Refer to INTERMITTENTS in TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

Perform this test when during QUICK TEST procedure or if directed by other diagnostic tests. This test is intended to diagnose

1. Knock sensor.
2. Wiring harness circuits (KS and SIG RTN).
3. Powertrain Control Module (PCM).

To prevent replacement of good components, be aware the following non-EEC related areas may be cause of problem

1. Poor fuel quality.
2. Engine mechanical condition.
3. Ignition timing.

Knock Sensor Ckts. & Conn. Terminal ID (DG1). Scheme 22

TEST PIN NO. 23 (KS) WIRE COLOR IDENTIFICATION

TEST PIN NO. 46 (SIG RTN) WIRE COLOR IDENTIFICATION

1) Code 225: Generate Knock Signal Manually Code 225 indicates Knock Sensor (KS) signal was not received by PCM during dynamic response (goose) check in KOER SELF-TEST. Possible causes for this fault are

1. Faulty Knock Sensor (KS).
2. Open or shorted harness.
3. Faulty PCM.

Disconnect PCM 60-pin connector. Inspect connector terminals for damage and repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Turn ignition on. Measure DC voltage between test pins No. 23 and No. 46 at breakout box. If DC voltage is 2.4-2.6 volts, go to next step. If DC voltage is less than 2.4 volts, go to step 4). If DC voltage is more than 2.6 volts, go to step 5).

2) Check KS Voltage Increase Start engine. Leave DVOM test leads connected to test pins No. 23 and No. 46. Monitor AC voltage at idle and at 3000 RPM. If AC voltage increases, replace PCM and repeat QUICK TEST. If AC voltage does not increase, go to next step.

3) Check Continuity Of KS & SIG RTN Circuits Turn ignition off. Disconnect knock sensor(s) wiring harness connector. Measure resistance between SIG RTN terminal at KS wiring harness connector and test pin No. 46 at breakout box. Also, measure resistance between KS terminal at wiring harness connector and test pin No. 23 at breakout box. If either reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If both readings are less than 5 ohms, go to next step.

4) Check KS Circuit For Short To Ground Turn ignition off. Measure resistance between test pin No. 23 and test pins No. 40, 46 and 60 at breakout box. If all readings are 10,000 ohms or more, replace knock sensor. Remove breakout box, reconnect all components, and repeat QUICK TEST. If Code 225 is still present, replace PCM. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

5) Check KS Circuit For Short To Voltage Ensure PCM and KS are disconnected. Turn ignition on. Measure voltage between test pins No. 23 and 40. If reading is 0.5 volt or more, repair short circuit in wiring harness. Remove breakout box, reconnect all components, and repeat QUICK TEST. If reading is less than 0.5 volt, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Perform this test only when directed by QUICK TEST. This test is intended to diagnose the following

1. TP sensor.
2. Wiring harness circuits (TP, SIG RTN and VREF).
3. Powertrain Control Module (PCM).

Normal range of throttle angle measurement for TP sensor is 0-85 degrees. To pass QUICK TEST procedure, range of throttle rotation (in degrees) must be within 3 percent of specification. (Scheme 23)

To prevent replacement of good components, be aware the following non-EEC related areas may be at fault

1. Idle speed.
2. Binding throttle shaft or linkage.
3. TP sensor not seated.

TEST PIN NO. 26 (VREF) WIRE COLOR IDENTIFICATION

TEST PIN NO. 46 (SIG RTN) WIRE COLOR IDENTIFICATION

TEST PIN NO. 47 (TP) WIRE COLOR IDENTIFICATION

TP Sensor Specification Chart (DH2). Scheme 23

1) KOER Code 121: Check For Other Codes KOER Code 121 indicates TP sensor rotational setting may be out of self-test range. Possible causes for this fault are

1. Binding throttle linkage.
2. TP sensor not seated correctly.
3. Faulty TP sensor.
4. Faulty Powertrain Control Module (PCM).

Perform KOER SELF-TEST. Check for Code 327. If Code 327 is present with Code 121, service Code 327 and repeat QUICK TEST. If Code 327 is not present with Code 121, go to next step.

2) Code 121: Check For Binding Throttle Plate Inspect throttle body for binding. If throttle body is binding, check for binding throttle or cruise control linkage, vacuum line or harness interference. Repair as necessary, and repeat QUICK TEST. If no mechanical problem is found, go to next step.

3) Code 123: Attempt To Generate Code 122 Code 123 indicates TP sensor signal is more than self-test maximum value. Possible causes for this fault are

1. TP sensor not seated properly.
2. Faulty TP sensor.
3. Short circuit to power.
4. Faulty PCM.

Turn ignition off. Disconnect TP sensor wiring harness connector. Inspect and repair connector pins if damaged. Repeat KOEO SELF-TEST. Disregard all other codes at this time. If Code 122 is not displayed, go to step 5). If Code 122 is displayed, go to next step.

4) Check VREF Circuit Voltage Turn ignition on. Measure voltage between VREF and SIG RTN terminals at TP sensor wiring harness connector. If reading is 4-6 volts, replace TP sensor and repeat QUICK TEST. If reading is not 4-6 volts, reconnect sensor and go to CIRCUIT TEST C.

5) Check TP Circuit For Short To Power Turn ignition off. Leave TP sensor disconnected. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 47 and test pins No. 26 and 57 at breakout box. If any resistance is less than 10,000 ohms, repair short circuit in wiring harness. Remove breakout box, reconnect all components, and repeat QUICK TEST. If both resistances are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 5) to step 10). No test procedures have been omitted.

10) Code 122: Attempt To Generate Code 123 Or 121 Code 122 indicates TP signal is less than minimum self-test value. (Scheme 23) Possible causes for this fault are

1. TP sensor not seated correctly.
2. Faulty TP sensor.
3. Open circuit in wiring harness.
4. Grounded circuit in wiring harness.
5. Faulty PCM.

Turn ignition off. Disconnect TP sensor from harness. Install a jumper wire between VREF and TP terminals at TP sensor wiring harness connector. Perform KOEO SELF-TEST. If no codes are generated, remove jumper wire and go to step 13). If Codes 123 and 121 are not present, remove jumper wire and go to next step. If either Code 123 or 121 is displayed, replace TP sensor and repeat QUICK TEST.

11) Check VREF Circuit Voltage Turn ignition on. Measure voltage between VREF and SIG RTN terminals at TP sensor wiring harness connector. If voltage is not 4-6 volts, turn ignition off. Reconnect all components and go to CIRCUIT TEST C. If voltage is 4-6 volts, go to next step.

12) Check TP Sensor Circuit Continuity Turn ignition off. Leave TP sensor disconnected. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between TP terminal at TP sensor wiring harness connector and test pin No. 47. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If resistance is less than 5 ohms, go to next step.

13) Check TP Circuit For Shorts To Ground Turn ignition off. Leave TP sensor disconnected. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. With breakout box installed and PCM disconnected, measure resistance between test pin No. 47 and test pins No. 40, 46 and 60 at breakout box. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 20). No test procedures have been omitted.

20) Code 167: Repeat Dynamic Response Test KOER Code 167 indicates TP sensor did not exceed 25 percent rotation during dynamic response portion of KOER SELF-TEST. A complete Wide Open Throttle (WOT) must be performed during dynamic response portion of test. Perform KOER SELF-TEST. Ensure a WOT is performed during dynamic response portion of test. If Code 167 is still present, go to next step. If Code 167 is not present, system is unable to duplicate Code 167 at this time. Service any other KOER codes. If no other service codes are present, testing is complete.

21) Check TP Sensor Movement During Dynamic Response Test Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Set DVOM on 20-volt scale. Connect DVOM between test pins No. 46 and 47 at breakout box. Perform KOER SELF-TEST and ensure proper WOT is completed during dynamic response test. If DVOM reading exceeds 3.5 volts during dynamic response test, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If reading does not exceed 3.5 volts, ensure TP sensor is correctly installed and adjusted. If TP sensor is correctly installed and adjusted, replace TP sensor. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 21) to step 90). No test procedures have been omitted.

90) Continuous Memory Code 123 This test monitors TP sensor under simulated road conditions. Enter wiggle test. See CONTINUOUS MONITOR MODE (WIGGLE TEST) under QUICK TEST. Connect DVOM or diagnostic tester to STO terminal of Data Link Connector (DLC). While slowly opening throttle to WOT, observe DVOM or diagnostic tester for indication of fault. Slowly bring throttle to closed position. Lightly tap TP sensor and wiggle harness connector. This test checks for open or short in TP sensor and wiring harness. If no fault is indicated, go to step 92). If fault is indicated, go to next step.

91) Measure TP Circuit Voltage While Exercising TP Sensor Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Stay in wiggle test (as in previous step). Connect DVOM between test pins No. 47 and 46. Set DVOM on 20-volt scale. With ignition on and engine off, observe DVOM and repeat step 90). If fault occurs at less than 4.25 volts, inspect TP sensor connectors and terminals. If connectors and terminals are okay, replace TP sensor, clear codes and repeat QUICK TEST. If fault does not occur at less than 4.25 volts, TP sensor over-travel may have caused Continuous Memory Code 123. TP sensor is okay. Go to step 92) to check wiring harness.

92) Check EEC-IV Wiring Harness While in wiggle test, bend and shake small sections of EEC-IV harness from TP sensor wiring harness connector to firewall and from firewall to PCM while observing analog voltmeter or scan tester. If fault is indicated, isolate fault in wiring and repair as necessary. Clear codes, and repeat QUICK TEST. If no fault is indicated, go to next step.

93) Check PCM & Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector from breakout box. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Clear codes from PCM memory, and repeat QUICK TEST. If connectors and terminals are okay, fault cannot be duplicated at this time. Continuous Memory Code 123 testing is complete.

94) Continuous Memory Code 122 Enter wiggle test. See CONTINUOUS MONITOR MODE (WIGGLE TEST) under QUICK TEST. Connect DVOM or diagnostic tester to STO terminal of Data Link Connector (DLC). Observe DVOM or diagnostic tester for indication of fault while performing the following

1. Slowly open throttle to WOT.
2. Slowly bring throttle to closed position.
3. Lightly tap TP sensor and wiggle connector.

If fault is indicated, disconnect TP sensor. Inspect connectors and terminals. If connectors and terminals are okay, replace TP sensor. Clear codes from PCM memory, and repeat QUICK TEST. If no fault is indicated, go to next step.

95) Check EEC-IV Wiring Harness Stay in wiggle test (as in previous step). Bend, wiggle and shake small sections of EEC-IV harness from TP sensor wiring harness connector to firewall and from firewall to PCM while observing analog voltmeter or scan tester. If fault is indicated, isolate fault in wiring and repair as necessary. Clear codes from PCM memory, and repeat QUICK TEST. If no fault is indicated, go to next step.

96) Check PCM & Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Clear codes from PCM memory, and repeat QUICK TEST. If connectors and terminals are okay, fault cannot be duplicated at this time. Continuous Memory Code 122 testing is complete.

CIRCUIT TEST DL - PRESSURE FEEDBACK EGR (PFE) VALVE, DELTA

PFE (DPFE) SENSOR & EGR VACUUM REGULATOR (EVR) SOLENOID

Perform this test only when instructed during QUICK TEST or if directed by other test procedures. This CIRCUIT TEST is intended to diagnose

1. VREF, DPFE, PFE, SIG RTN, EVR and VPWR harness circuits.
2. DPFE sensor.
3. PFE sensor.
4. EVR solenoid.
5. EGR valve assembly.
6. EVR and PFE/DPFE vacuum lines.
7. Powertrain Control Module (PCM).

To prevent replacement of good components, be aware the following non-EEC components may be at fault

1. Faulty or damaged EGR valve.
2. Restricted exhaust system.
3. Damaged vacuum reservoir or canister.

PFE Sensor & EVR Sol. Conn. Term. ID (DL2). Scheme 24

TEST PIN NO. 26 (VREF) WIRE COLOR IDENTIFICATION

TEST PIN NO. 27 (PFE/DPFE) WIRE COLOR IDENTIFICATION

TEST PINS NO. 37 & 57 WIRE COLOR IDENTIFICATION

TEST PIN NO. 46 (SIG RTN) WIRE COLOR IDENTIFICATION

PFE SENSOR SPECIFICATIONS

DPFE SENSOR SPECIFICATIONS

1) Code 327: Generate Code 337 Code 327 indicates PFE/DPFE sensor signal is less than self-test minimum of 0.2 volt. Possible causes for this fault are

1. Faulty PFE/DPFE sensor.
2. Open or shorted wiring harness circuits.
3. Faulty PCM.

Turn ignition off. Disconnect PFE/DPFE wiring harness connector at sensor. Install a jumper wire between VREF circuit and PFE or DPFE circuit at sensor wiring harness connector. Perform KOEO SELF-TEST. If no codes are present, remove jumper wire and go to step 4). If Code 337 is present, ignore all other codes and replace PFE/DPFE sensor. Remove jumper wire, and repeat QUICK TEST. If Code 337 is not present, remove jumper wire and go to next step.

2) Measure VREF Circuit Voltage With PFE/DPFE sensor disconnected, turn ignition on. Measure voltage between sensor wiring harness connector VREF and SIG RTN terminals. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to CIRCUIT TEST C.

3) Check PFE/DPFE Circuit Continuity Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between PFE/DPFE terminal at sensor wiring harness connector and test pin No. 27 at breakout box. If resistance is more than 5 ohms, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If reading is 5 ohms or less, go to next step.

4) Check PFE/DPFE Circuit For Shorts To Ground & SIG RTN Turn ignition off. Measure resistance between test pin No. 27 and test pins No. 40, 46 and 60 at breakout box. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

5) Code 337: Generate Code 327 Code 337 indicates PFE/DPFE sensor signal is more than self-test maximum of 4.8 volts. Possible causes for this code are

1. Faulty PFE/DPFE sensor.
2. Shorted vehicle harness circuits.
3. Open SIG RTN circuit.
4. Faulty Powertrain Control Module (PCM).

Turn ignition off. Disconnect PFE/DPFE sensor. Repeat KOEO SELF-TEST. Check for Code 327. Ignore all other codes at this time. If Code 327 is not present, go to step 7). If Code 327 is present, go to next step.

6) Measure VREF Circuit Voltage With PFE/DPFE sensor disconnected, turn ignition on. Measure voltage between VREF and SIG RTN terminals at PFE/DPFE sensor wiring harness connector. If voltage is 4-6 volts, replace PFE/DPFE sensor. Repeat QUICK TEST. If voltage is not 4-6 volts, go to CIRCUIT TEST C.

7) Check PFE/DPFE Circuit For Shorts To Power With ignition off, disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 27 and test pins No. 26, 37 and 57. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

8) Code 335: Verify KOER Codes Code 335 indicates PFE/DPFE sensor is out of self-test range (2.6-4.2 volts) and may be faulty. PFE/DPFE system can detect lack of pressure in exhaust system. A garage exhaust ventilation system, installed during KOEO SELF-TEST, may cause PFE/DPFE sensor to generate Code 335. Remove exhaust ventilation system. Repeat KOEO SELF-TEST. Service codes as necessary. If no codes are present during KOEO SELF-TEST, complete QUICK TEST. If Code 335 is present during KOEO SELF-TEST, go to next step.

9) Check PFE/DPFE Sensor Pressure Input Hose Remove pressure feed tube from PFE/DPFE sensor. Inspect tube, including PFE/DPFE inlet, for blockage. Repair if necessary, and repeat QUICK TEST. If no blockage is found, go to next step.

10) Measure VREF Circuit Voltage With ignition off, disconnect PFE/DPFE sensor wiring harness connector. Turn ignition on. Measure voltage between VREF and SIG RTN terminals at PFE/DPFE sensor wiring harness connector. If voltage is 4-6 volts, replace PFE/DPFE sensor and repeat QUICK TEST. If voltage is not 4-6 volts, go to CIRCUIT TEST C.

11) Code 558: Measure EVR Solenoid Resistance Code 558 indicates failure in EVR solenoid or circuit. Possible causes for this code are

1. Faulty EVR solenoid.
2. Faulty Powertrain Control Module (PCM).
3. Open or shorted wiring harness circuit.

Turn ignition off. Disconnect EVR solenoid connector. Measure resistance between EVR solenoid terminals. If resistance is 25-70 ohms, go to next step. If resistance is not 25-70 ohms, replace EVR solenoid. Repeat QUICK TEST.

12) Check VPWR Circuit Voltage Set DVOM on 20-volt scale. Turn ignition on. Measure voltage between VPWR terminal at EVR solenoid wiring harness connector and negative battery terminal. If voltage is less than 10.5 volts, repair open circuit and repeat QUICK TEST. If voltage is 10.5 volts or more, go to next step.

13) Check EVR Circuit Continuity Turn ignition off. Leave EVR solenoid connector disconnected. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between EVR terminal at EVR solenoid wiring harness connector and test pin No. 33 at breakout box. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

14) Check EVR Circuit For Shorts To Power Or Ground Turn ignition off. Measure resistance between test pin No. 33 and pins No. 37, 40, 57 and 60 at breakout box. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If Code 558 is repeated, replace PCM. If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 14) to step 20). No test procedures have been omitted.

20) Code 326: Verify KOER Codes Code 326 indicates PFE circuit voltage is low during zero EVR duty cycle. Possible causes for this fault are

1. Obstructed vacuum line.
2. Contaminated EVR filter.
3. Faulty EVR solenoid.
4. Faulty EGR valve.

PFE/DPFE system can detect lack of pressure in exhaust system. A garage exhaust ventilation system, installed during KOER SELF-TEST, may cause PFE/DPFE sensor to generate Code 326. Temporarily remove exhaust ventilation system, and retest. If Code 326 is not present, service other codes present during KOER SELF-TEST. If no code is present, testing is complete. If Code 326 is present, go to next step.

21) Code 327 Code 327 indicates PFE/DPFE sensor signal is less than self-test minimum. Disconnect and plug EGR valve vacuum hose. Perform KOER SELF-TEST. If Codes 327 or 326 are present, go to next step. If codes are not present, check EVR vent and vacuum hose to EGR valve for blockage. Repair as necessary. If vent and vacuum hose are okay, replace EVR solenoid and repeat QUICK TEST.

22) Code 326 Or 327: Check PFE/DPFE Input Hoses With ignition off, check PFE/DPFE sensor pressure input hose for blockage and leaks. Repair as necessary. Connect all lines, and repeat QUICK TEST. If no fault is found, go to next step.

23) Check PFE/DPFE Voltage With Engine At Idle Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Start engine and allow to idle with transmission in Park or Neutral. Measure voltage between test pins No. 27 and 46 at breakout box. On DPFE sensor, if voltage is less than 2.9 volts, replace sensor. Remove breakout box, reconnect all components, and repeat QUICK TEST. On PFE sensor, if voltage is less then 0.2 volt, go to next step. On either sensor, if voltage is more than specified, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

24) Check EGR Valve For Binding Fault has been isolated to either EGR valve or PFE sensor. If engine runs rough at idle, EGR valve may not be fully seated. Remove EGR valve. Inspect EGR valve for signs of contamination, wear, carbon deposits, binding and other damage. Repair or replace as necessary. If EGR valve is okay, install EGR valve. Perform KOER SELF-TEST. If Codes 327 or 326 are present, replace EGR valve. Remove breakout box, reconnect all components, and repeat QUICK TEST. If either codes is still present, replace PFE sensor. If codes are not present, original Code 327 or 326 was result of EGR valve not fully seating. Testing is complete.

25) Codes 336 & 337: Check For Exhaust Restriction Code 336 indicates PFE circuit voltage is higher than expected at zero duty cycle. Code 337 indicates PFE circuit voltage is higher than self-test maximum. Possible causes for these codes are

1. Exhaust system restricted.
2. PFE sensor faulty.
3. Faulty PCM.
4. Shorted harness circuits.

Attach vacuum gauge to intake manifold. Connect tachometer to engine. Start engine and allow to idle. Observe vacuum gauge as engine speed is increased to 2000 RPM. Vacuum gauge needle should drop to zero and then quickly return to 16 in. Hg. If vacuum gauge needle movement is slow, check for restriction in exhaust system. Repair exhaust system as necessary. If vacuum gauge needle is quick, go to next step.

26) Check PFE Sensor Output With Engine Idling Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Start engine and allow to idle with transmission in Park or Neutral. Measure voltage between test pins No. 27 and 46 at breakout box. If voltage is 3.0-3.5 volts, replace PCM and repeat QUICK TEST. If voltage is not 3.0-3.5 volts, go to next step.

27) Check PFE & SIG RTN Harness Continuity Turn ignition off. Ensure PFE sensor is disconnected. Disconnect PCM 60-pin connector. Measure resistance between PFE terminal at PFE sensor wiring harness connector and test pin No. 27. Measure resistance between PFE SIG RTN terminal at PFE sensor wiring harness connector and test pin No. 46. If each resistance is less than 5 ohms, go to next step. If any resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

28) Check PFE Harness Circuit For Short To Power Ensure ignition is off. With PFE sensor and PCM disconnected, measure resistance between test pin No. 27 and test pins No. 26, 37 and 57 at breakout box. If all readings are more than 10,000 ohms, replace PFE sensor. Remove breakout box, reconnect all components, and repeat QUICK TEST. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 28) to step 30). No test procedures have been omitted.

30) Code 332: Verify Vacuum At EGR Valve Code 332 indicates PFE/DPFE sensor input to PCM did not change after EVR solenoid received signal from PCM to open EGR valve. Possible causes for this fault are

1. Vacuum hose leaks or restrictions.
2. Faulty PFE/DPFE sensor.
3. Faulty EVR solenoid.
4. Faulty EGR valve.
5. Faulty Powertrain Control Module (PCM).

Turn ignition off. Using a vacuum "T", connect vacuum gauge at EGR valve. Perform KOER SELF-TEST while observing vacuum gauge. Disregard code output at this time. If vacuum reading is more than 1.0 in. Hg, go to step 34). If vacuum reading is 1.0 in. Hg or less, remove vacuum gauge and go to next step.

31) Check Vacuum Input To EVR Solenoid Turn ignition off. Disconnect EVR vacuum hose. Connect EVR vacuum hose to vacuum gauge. Start engine and allow it to idle while observing vacuum gauge. If 15 in. Hg or more is present, replace EVR solenoid and repeat QUICK TEST. If less than 15 in. Hg is present, repair vacuum source and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 31) to step 34). No test procedures have been omitted.

34) Check Vacuum At PFE/DPFE Inlet Hose(s) Turn ignition off. Inspect vacuum hose for damage and repair if necessary. Using a vacuum "T", connect vacuum gauge at PFE/DPFE inlet hose(s). Perform KOER SELF-TEST while observing vacuum gauge. If vacuum momentarily increases, go to next step. If momentary increases in vacuum do not occur, service EGR valve.

35) Attempt To Generate KOEO Code 337 Turn ignition off. Disconnect PFE/DPFE sensor. Install jumper wire between PFE/DPFE terminal and VREF terminal at PFE/DPFE sensor wiring harness connector. Perform KOEO SELF-TEST. If Code 337 is present, ignore all other codes and replace PFE/DPFE sensor. Repeat QUICK TEST. If Code 337 is not present, remove jumper wire and go to next step.

36) Measure VREF Circuit Voltage With PFE/DPFE sensor disconnected, turn ignition on. Measure voltage between VREF terminal and SIG RTN terminal at PFE/DPFE sensor wiring harness connector. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to CIRCUIT TEST C.

37) Check PFE/DPFE Circuit Resistance Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between PFE/DPFE terminal at PFE/DPFE sensor wiring harness connector and test pin No. 27 at breakout box. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

38) Check PFE/DPFE Circuit For Short To SIG RTN & Ground Turn ignition off. Measure resistance between PFE/DPFE terminal at PFE/DPFE sensor wiring harness connector and test pins No. 40, 46 and 60 at breakout box. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 38) to step 50). No test procedures have been omitted.

50) Codes 336 & 337: Check EVR Malfunction Code 336 indicates DPFE voltage is too high at zero duty cycle. Possible causes for these codes are

1. Vacuum hose routing.
2. EGR valve faulty.
3. EVR solenoid faulty.
4. DPFE sensor faulty.
5. Faulty PCM.

Disconnect and plug EGR vacuum hose. Perform KOER SELF-TEST. If Code 336 or 337 is present, go to next step. If Code 336 or 337 is not present, ensure vacuum hose routing is correct and EVR filter is clean. If okay, replace EVR solenoid. Reconnect all vacuum lines, and repeat QUICK TEST.

51) Check DPFE Sensor Output With Engine Idling Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Start engine and allow to idle with transmission in Park or Neutral. Measure voltage between test pins No. 27 and 46 at breakout box. If voltage is less than 0.7 volt at idle, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If voltage is 0.7 volt or more, go to next step.

52) Check EGR Valve Remove EGR valve. Check EGR valve for carbon deposits, binding or other damage. Repair as necessary. Install EGR valve and repeat KOER SELF-TEST. If Code 336 or 337 is still present, replace EGR valve and repeat KOER SELF-TEST. If Code 336 or 337 is still present, replace DPFE sensor. Repeat QUICK TEST. If Code 336 or 337 is not present, fault is intermittent and cannot be duplicated at this time. Testing is complete.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 52) to step 90). No test procedures have been omitted.

90) EGR Fault Code(s) In Continuous Memory Repeat QUICK TEST. If fault code(s) are present in KOEO SELF-TEST or KOER SELF-TEST, go to appropriate circuit test. If fault codes are present in continuous memory only, go to next step. If vehicle will not start or idle, go to step 101).

91) PFE/DPFE System Inspection Check for damaged or loose connectors. Check for loose or corroded connector pins. Inspect wiring harness for proper routing and insulation. Ensure component mounting and vacuum hose routing is correct. Ensure EVR solenoid filter is clean. Repair or replace as necessary. Clear codes and repeat QUICK TEST. If no faults are present, reconnect all components and go to next step.

92) EGR Fault Code(s) In Continuous Memory Repeat QUICK TEST. If fault code(s) are present in KOEO SELF-TEST or KOER SELF-TEST, go to appropriate circuit test. If fault Code 326, 327, 336 or 337 is present in continuous memory only, go to next step. If fault Code 332 is present in continuous memory only, go to step 105).

93) Continuous Memory Code 326, 327, 336 Or 337 If code is present, possible causes are

1. Damaged connectors or terminals.
2. Open or shorted wiring harness.
3. Faulty EGR valve operation.
4. Faulty EVR solenoid operation.
5. Circuit fault can be in wiring harness, component or PCM.

Enter wiggle test. See CONTINUOUS MONITOR MODE (WIGGLE TEST) under QUICK TEST. Observe analog VOM or diagnostic tester for indication of fault while performing following steps. Grasp wiring harness near sensor connector while observing VOM or diagnostic tester for fault indication. Shake and bend small sections of harness, working from sensor toward firewall. Shake and bend harness from firewall to PCM. If fault is indicated, inspect connectors and terminals. Repair as necessary. If connectors and terminals are okay, replace PFE/DPFE sensor. Clear codes and repeat QUICK TEST. If no fault is indicated, go to next step.

94) Stay in wiggle test. Observe analog VOM or scan tester for indication of fault while bending or wiggling small sections of harness from sensor connector to firewall, and from firewall to PCM. If fault is indicated, isolate fault in harness and repair as necessary. Repeat QUICK TEST. If no fault is indicated, go to next step.

95) Check PCM Wiring Harness Connector Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Clear codes, and repeat QUICK TEST. If connector and terminals are okay but fault code is present, go to appropriate step as follows

1. Code 326 or 327 on models equipped with PFE; go to next step.
2. Code 336 on models equipped with PFE; go to step 100).
3. Code 336 or 337 on models equipped with DPFE; go to next step.

If no codes are present, unable to duplicated and/or identify fault at this time. Testing is complete.

96) Check EGR Valve Operation Turn ignition off. Disconnect vacuum hose from EGR valve. Connect vacuum pump to EGR valve. While observing EGR valve, slowly apply 10 in. Hg and release. If EGR valve does not operate smoothly, service or replace EGR valve. Repeat QUICK TEST. If EGR valve operation is smooth, go to next step.

97) Check EVR Solenoid & Hoses Turn ignition off. Inspect EVR solenoid vacuum hoses for contamination, moisture or restriction. Ensure EVR solenoid filter is clean. Repair or replace as necessary and repeat QUICK TEST. If no faults are found, reconnect all components and go to next step.

98) Check EVR Solenoid For Short Circuit Turn ignition off. Disconnect vacuum hose from EGR valve. Connect vacuum pump to vacuum hose. Start engine and operate at idle. While observing vacuum gauge, tap on EVR solenoid and wiggle wiring harness connector. If vacuum gauge does not remain less than 1.0 in. Hg and has erratic increases, replace EVR solenoid and repeat QUICK TEST. If vacuum gauge remains less than 1.0 in. Hg with no erratic increases, leave vacuum gauge connected and go to next step.

99) Check Wiring Harness Between EVR Solenoid & PCM With engine running, observe vacuum gauge while wiggling wiring harness connector between EVR solenoid and dash panel. Wiggle wiring harness between dash panel and PCM. If EGR vacuum increases, isolate short and repair as necessary. Repeat QUICK TEST. If EGR vacuum does not increase, fault is intermittent and cannot be duplicated at this time. Testing is complete.

100) Continuous Memory Code 336 (PFE) With ignition off, remove PFE sensor. Inspect PFE sensor inlet for liquids and/or blockage. Inspect PFE supply host to EGR valve base for liquids and/or blockage. Repair as necessary. Clear codes and repeat QUICK TEST. If PFE sensor and EGR supply hose are okay, fault is intermittent and cannot be duplicated at this time. Testing is complete.

101) Check EGR Vacuum At Start-Up Disconnect and plug EGR vacuum hose. Start engine and allow to idle (if possible). If engine idle is correct, ensure EVR hoses are correctly routed. If hoses are okay, replace EVR solenoid. Clear codes and repeat QUICK TEST. If engine does not idle correctly, go to next step.

102) Check EGR Valve Operation Turn ignition off. Disconnect vacuum hose from EGR valve. Connect vacuum pump to EGR valve. While observing EGR valve, slowly apply 10 in. Hg and release. If EGR valve does not operate smoothly or close completely, service or replace EGR valve. If EGR valve operation is okay, problem is not EGR related. Connect all components and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 102) to step 105). No test procedures have been omitted.

105) Continuous Memory Code 332: Check EGR Valve Operation If code is present, possible causes are

1. EGR valve sticking closed.
2. EGR valve diaphragm leaks.
3. Faulty EVR solenoid operation.
4. Loss of vacuum to or from EVR solenoid.
5. Open in EVR VWPR or driver circuits.
6. Leak or restriction in PFE/DPFE signal hoses.

Turn ignition off. Disconnect vacuum hose from EGR valve. Connect vacuum pump to EGR valve. While observing EGR valve, apply 1.0-1.5 in. Hg. EGR valve should begin to open. Increase vacuum pump application to 4 in. Hg. EGR valve should be fully open. Increase vacuum pump application to 10 in. Hg. EGR valve should hold and maintain vacuum. If EGR valve does not perform as specified, repair or replace EGR valve as necessary. Clear codes and repeat QUICK TEST. If EGR valve is okay, go to next step.

106) With ignition off, remove EVR vacuum hoses. Inspect vacuum hose for damage or restrictions. Repair as necessary. Clear codes and repeat QUICK TEST. If EVR vacuum hoses are okay, go to next step.

107) Inspect PFE/DPFE Hoses With ignition off, remove PFE/DPFE hoses from sensor. Inspect hoses for contamination, leaks or restrictions. Repair as necessary. Clear codes and repeat QUICK TEST. If PFE/DPFE hoses are okay, go to next step.

108) Check EVR Solenoid Ground Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Disconnect vacuum hose from EGR valve. Connect EGR vacuum hose to vacuum pump. Start engine and allow to idle. Connect jumper wire between test pins No. 33 and 40 at breakout box. EVR solenoid should turn on. Observe vacuum gauge while tapping on EVR solenoid. Wiggle wiring harness and connector. A sudden drop in vacuum indicates a fault in the system. If a sudden drop in vacuum occurs, isolate fault and repair as necessary. Clear codes and repeat QUICK TEST. If no drop in vacuum occurs, problem cannot be identified at this time. Testing is complete.

CIRCUIT TEST DN - EGR VALVE POSITION (EVP) SENSOR &

EGR VALVE REGULATOR (EVR) SOLENOID

EVR solenoid receives variable input from PCM, which allows it to control vacuum level to EGR valve. Vacuum not used by EGR is routed to EVR solenoid and vented to atmosphere.

Perform this test when instructed by QUICK TEST or if directed by other test procedures. To prevent replacement of good components, be aware a damaged EGR valve may be cause of problem. This CIRCUIT TEST is intended to diagnose the following

Scheme 25

1. EVP sensor.
2. EVR solenoid.
3. EGR valve assembly.
4. Powertrain Control Module (PCM).
5. EGR and EVR vacuum lines.
6. Wiring harness circuits (VREF, EVP, SIG RTN, EVR and VPWR). (Scheme 25): EVP Sensor & EVR Solenoid Connector Terminal ID (DN1) TEST PIN NO. 26 (VREF) WIRE COLOR IDENTIFICATION Application Wire Color All Models Brown/White TEST PIN NO. 27 (EVP) WIRE COLOR IDENTIFICATION Application Wire Color All Models Brown/Light Green TEST PIN NO. 33 (EVR) WIRE COLOR IDENTIFICATION Application Wire Color All Models Brown/Pink TEST PIN NO. 46 (SIG RTN) WIRE COLOR IDENTIFICATION Application Wire Color All Models Gray/Red NOTE: EVR sensor is preloaded when attached to EGR valve. Valve failure causing EVR sensor to lose preload may set Code 327. Step 1) Code 327: Attempt To Generate Code 337 - Code 327 indicates EVP sensor signal is less than self-test minimum of 0.2 volt. Possible causes for this fault are
7. Faulty EVP sensor.
8. Faulty EGR valve.
9. Open or grounded harness.
10. Faulty PCM.

Turn ignition off. Disconnect EVP sensor wiring harness connector. Install a jumper wire between VREF terminal and EVP terminal at EVP sensor wiring harness connector. Repeat KOEO SELF-TEST and KOER SELF-TEST. Check for Code 337. Ignore all other codes at this time. If Code 337 is present, replace EVP sensor. Remove jumper wire and repeat QUICK TEST. If Code 337 is not present, remove jumper wire and go to next step. If no codes are present, remove jumper wire and go to step 4).

2) Check VREF Circuit Voltage Disconnect EVP sensor. Turn ignition on. Measure voltage between VREF terminal and SIG RTN terminal at EVP sensor wiring harness connector. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to CIRCUIT TEST C.

3) Check EVP Circuit Resistance Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving ECA disconnected. Measure resistance between EVP terminal at EVP sensor wiring harness connector and test pin No. 27. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If resistance is less than 5 ohms, go to next step.

4) Check EVP Circuit For Shorts To Ground Ensure ignition is off and EVP sensor is disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 27 and test pins No. 40, 46 and 60. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

5) Code 337: Attempt To Generate Code 327 Code 337 indicates EVP sensor signal is more than self-test maximum of 4.81 volts. Possible causes for this fault are

1. Faulty EVP sensor.
2. Faulty PCM.
3. Short to power in vehicle harness.
4. Open in SIG RTN circuit.

Turn ignition off. Disconnect EVP sensor. Perform KOEO SELF-TEST and KOER SELF-TEST. Check for Code 327. Ignore all other codes at this time. If Code 327 is present, go to next step. If Code 327 is not present, go to step 7).

6) Check VREF Circuit Voltage Turn ignition on. Measure voltage between VREF terminal and SIG RTN terminal at EVP sensor wiring harness connector. If voltage is 4-6 volts, replace EVP sensor. Repeat QUICK TEST. If voltage is not 4-6 volts, go to CIRCUIT TEST C.

7) Check EVP Circuit For Short To Power Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 27 and test pins No. 26 and 57 at breakout box. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 7) to step 10). No test procedures have been omitted.

10) Code 558: Check EVR Solenoid Resistance Code 558 indicates fault in EVR solenoid circuit. Possible causes for this fault are

1. Faulty EVR solenoid.
2. Faulty PCM.
3. Shorted or open harness.

Turn ignition off. Disconnect EVR solenoid connector. Measure resistance between EVR solenoid terminals. If resistance is not 20-70 ohms, replace EVR solenoid assembly and repeat QUICK TEST. If resistance is 20-70 ohms, go to next step.

11) Check VPWR Circuit Voltage Disconnect EVR solenoid. Turn ignition on. Measure voltage between negative battery terminal and VPWR terminal at EVR solenoid wiring harness connector. If reading is less than 10.5 volts, repair open in VPWR circuit and repeat QUICK TEST. If reading is 10.5 volts or more, go to next step.

12) Check EVR Circuit Continuity Turn ignition off. Disconnect EVR solenoid. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between EVR terminal at EVR solenoid wiring harness connector and test pin No. 33. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open. Remove breakout box, reconnect all components, and repeat QUICK TEST.

13) Check EVR Circuit For Shorts To Power Or Ground Turn ignition off. Measure resistance between test pin No. 33 and test pins No. 37, 40, 46, 57 and 60 at breakout box. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If code is repeated, replace EVR solenoid. If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 20). No test procedures have been omitted.

20) Code 334: Check For Code 558 Code 334 indicates EGR valve and/or EVP is not fully seated in closed position. EVP voltage signal, in closed position, is more than self-test maximum of 0.67 volt. Because of EVP sensor preload, determining whether EGR valve is seated or EVP sensor contacts EGR valve stem is difficult. Because of EVP sensor preload, determining whether EGR valve is seated or EVP sensor contacts EGR valve stem is difficult. Possible causes for this fault are

1. Poor contact in EVP sensor circuit.
2. EGR valve not seated.
3. Faulty EGR valve.
4. Faulty EVP sensor.
5. Faulty EVP solenoid.
6. Faulty PCM.

Turn ignition off. Perform KOEO SELF-TEST. If Code 558 is present, return to step 10). If Code 558 is not present, go to next step.

21) Perform SELF-TEST Without EGR Remove and plug vacuum line to EGR valve. Perform KOEO SELF-TEST and KOER SELF-TEST. If Code 334 is still present, go to next step. If Code 334 is not present, check EVR solenoid for obstructions. If no obstructions are present, replace EVR solenoid. Repeat QUICK TEST.

22) Check EGR Valve & EVP Sensor Operation Turn ignition off. Disconnect EVP sensor. Inspect harness and connector, and service as necessary. Remove and plug vacuum hose to EGR valve. Install vacuum gauge at EGR valve vacuum port. Operate EGR valve by applying and releasing vacuum. Install vacuum hose to EGR valve and wiring harness connector to EVP sensor. Repeat KOEO SELF-TEST and KOER SELF-TEST. If Code 334 is present, go to next step. If Code 334 is not present, original fault was caused by poor continuity at EVP sensor connector or binding/sticking of EGR valve stem.

23) Check EVP Signal Voltage Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Turn ignition on. Measure voltage between test pins No. 27 and 46 at breakout box. If voltage is less than 0.67 volt, replace PCM. Remove breakout box and repeat QUICK TEST. If voltage is more than 0.67 volt, go to next step.

24) EGR Valve/EVP Sensor Fault Isolation Remove EGR valve and EVP sensor. Inspect valve and sensor for binding, carbon deposits, excessive wear and damage. Repair or replace EGR valve as necessary. Install EGR valve and EVP sensor. Perform KOEO SELF-TEST and KOER SELF-TEST. If Code 334 is still present, replace EGR valve. Remove breakout box and repeat QUICK TEST. If Code 334 is not present, original code was a result of EGR valve contamination, binding or a faulty EVP sensor. Testing is complete.

25) Code 328: Check EVP Sensor & EGR Valve Operation Code 328 indicates EVP sensor is lower than normal (0.24 volt) in closed position. Because of EVP sensor preload, determining whether EGR valve has malfunctioned or EVP sensor has an abnormally high resistance is difficult. Possible causes for this fault are

1. Faulty EGR valve.
2. Faulty EVP sensor.
3. Faulty PCM.
4. Poor continuity in EVP sensor circuit.

Turn ignition off. Disconnect EVP sensor wiring harness connector. Inspect harness and connector, and service as necessary. Remove EGR valve vacuum hose. Attach vacuum pump to EGR valve. Operate EGR valve by applying and releasing vacuum. Install vacuum hose to EGR valve and wiring harness connector to EVP sensor. Repeat KOEO SELF-TEST and KOER SELF-TEST. If Code 328 is not present, original fault was caused by poor continuity at EVP sensor connector or binding/sticking of EGR valve stem. If Code 328 is present, go to next step.

26) Check EVP Signal Voltage Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Remove and plug EGR valve vacuum hose. Connect vacuum pump to EGR valve vacuum hose. Turn ignition on. Measure voltage between test pins No. 27 and 46 at breakout box while performing following: apply 6 in. Hg to EGR valve and then slowly bleed vacuum completely off. If voltage does not drop to less than 0.24 volt, replace PCM. Remove breakout box and repeat QUICK TEST. If voltage drops to less than 0.24 volt, go to next step.

27) Substitute EVP Sensor On Original EGR Valve Turn ignition off. Install a known good EVP sensor on original EGR valve. Ensure all hoses and electrical connectors are attached. Perform KOEO SELF-TEST and KOER SELF-TEST. If Code 328 is present, replace EGR valve. Remove breakout box and repeat QUICK TEST. If Code 328 is not present, replace original EVP sensor. Testing is complete.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 27) to step 40). No test procedures have been omitted.

40) KOER Code 332: Check Vacuum At EGR KOER Code 332 indicates EVP sensor input did not change after PCM signaled operation of EGR. Because Code 558 was not retrieved in KOEO SELF-TEST, EVR solenoid electrical function is okay. Lack of Code 328 or 334 indicates EVP sensor is within closed position specification. Possible causes for this fault are

1. Leaking vacuum hose.
2. Restricted vacuum hose.
3. Restricted EVR solenoid filter.
4. Faulty EVR solenoid.
5. Faulty EVP sensor.
6. Faulty EGR valve.

Turn ignition off. Disconnect vacuum hose from EGR valve. Connect a vacuum gauge at open end of hose. Perform KOER SELF-TEST while observing vacuum gauge. If vacuum reading is more than 1.0 in. Hg, remove vacuum gauge and go to step 43). If reading is 1.0 in. Hg or less, remove vacuum gauge and reconnect EGR vacuum hose. Go to next step.

41) Verify Vacuum Supply To EVR Solenoid Turn ignition off. Disconnect EVR solenoid vacuum hose. Install vacuum gauge at vacuum hose. Start engine and check vacuum. If reading is 10 in. Hg or more, go to next step. If reading is less than 10 in. Hg, check vacuum line to EVR solenoid. Repair if necessary. Repeat QUICK TEST.

42) Check Vacuum Between EVR Solenoid & EGR Valve Check vacuum hose for cracks, loose connections, blockage and kinks. Repair or replace vacuum hose as necessary, and repeat QUICK TEST. If vacuum hose is okay, check EVR solenoid filter for obstructions. Replace if necessary. If filter is okay, replace EVR solenoid. Repeat QUICK TEST.

43) Check EVP Sensor & EGR Valve Operation Turn ignition off. Disconnect EVP sensor. Inspect connector and harness for damage, and service as necessary. Remove vacuum hose from EGR valve. Connect vacuum pump to EGR valve. Operate EGR valve operation by applying and releasing vacuum. Connect vacuum line to EGR valve. Connect wiring harness connector to EVP sensor. Repeat KOER SELF-TEST. If Code 332 is still present, go to next step. If Code 332 is not present, original code was set either by poor continuity at EVP sensor connector or sticking EGR valve. Testing is complete.

44) Check EGR Valve Function Turn ignition off. Install tachometer. Remove Idle Air Control (IAC) wiring harness connector. Remove and plug vacuum hose to EGR valve. Start engine, and allow it to idle with transmission in Neutral. Ensure idle speed is adjusted correctly. Connect vacuum pump to EGR valve. Slowly apply 5-10 in. Hg. If engine idle decreases more than 100 RPM with vacuum applied and returns to correct idle with vacuum released, EGR valve is okay. Replace EVP sensor. Repeat QUICK TEST. If vacuum does not drop more than 100 RPM with vacuum applied, repair or replace EGR valve. Repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 44) to step 90). No test procedures have been omitted.

90) Continuous Memory Code 327, 328 Or 337 Continuous Memory Code 327 or 328 indicates EGR valve closed further than normal or EVP circuit failed with intermittent low voltage sometime during engine operation. Code 337 indicates EVP signal to PCM was above maximum self-test limit sometime during engine operation. Possible causes for these faults are

1. Poor continuity in EVP wiring harness or connectors.
2. Intermittent open or short in EVP sensor or wiring harness.
3. Faulty EVP sensor.

Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Turn ignition on. Connect DVOM between test pins No. 27 and 46 at breakout box. Wiggle wiring harness and lightly tap on EVP sensor. If voltage remains steady at .24-.67 volt, go to next step. If voltage is erratic or not within .24-.67 volt range, remove and inspect EVP sensor wiring harness connector. Repair or replace as necessary. Repeat QUICK TEST. If sensor connector is okay, replace EVP sensor. Repeat QUICK TEST.

91) Check Wiring Harness Connect DVOM between test pins No. 27 and 46 at breakout box. Turn ignition on. Observe DVOM for fault indication while wiggling and bending small sections of wiring harness near sensor, working from sensor toward dash panel. Wiggle and bend wiring harness from firewall to PCM. If fault is indicated, isolate fault and repair wiring harness. Clear codes, and repeat QUICK TEST. If fault is not found, go to next step.

92) Measure EVP Signal Voltage While Exercising EGR Valve Remove and plug vacuum hose to EGR valve. Install vacuum gauge at EGR valve vacuum hose. Turn ignition on. Measure voltage between test pins No. 27 and 46 at breakout box while performing following: apply 5-10 in. Hg to EGR valve and slowly bleed vacuum completely off. If voltage steadily fluctuates between 0.24-4.81 volts, problem is intermittent and cannot be duplicated at this time. If voltage does not fluctuate between 0.24-4.81 volts, replace EVP sensor. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 92) to step 110). No test procedures have been omitted.

110) Continuous Memory Code 332 Code 332 indicates EGR valve did not open with engine at normal operating temperature and with EVR solenoid signal present sometime during engine operation. Possible causes of this fault are

1. Fault in vacuum line.
2. Faulty EGR valve.
3. Open or shorted EVR circuit.

Turn ignition off. Disconnect vacuum hose at EGR valve. Connect vacuum pump to valve. Apply 10-20 in. Hg to EGR valve. If EGR valve opens and holds vacuum, go to next step. If EGR valve does not open and hold vacuum, service or replace EGR valve as necessary. Clear codes and repeat QUICK TEST.

111) Check EVR Solenoid Vacuum Hoses Disconnect and vacuum hose from EGR valve to EVR solenoid, and vacuum hose from EVR solenoid to vacuum source. Check hoses for obstructions, cracks, kinks and leaks. Replace hoses as necessary. Clear codes and repeat QUICK TEST. If vacuum hoses are okay, go to next step.

112) Check EVR Solenoid & Wiring Harness For Intermittent Turn ignition off. Disconnect vacuum hose from EGR valve. Connect EGR valve hose to vacuum gauge. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Start engine, and allow it to idle. Connect jumper wire between test pins No. 33 and 40. Tap on EVR sensor and wiggle wiring harness while observing vacuum gauge. If vacuum gauge shows a sudden drop in vacuum, isolate cause and repair as necessary. Remove breakout box, reconnect all components, and repeat QUICK TEST. If vacuum gauge does not show a drop in vacuum, problem is intermittent and cannot be duplicated at this time.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 112) to step 115). No test procedures have been omitted.

115) Continuous Memory Code 334: Code 334 indicates EGR valve was open with engine idling at normal operating temperature. Possible causes for this fault are

1. Faulty EVP sensor.
2. Faulty EVR solenoid.
3. Faulty EGR valve.

Turn ignition off. Disconnect vacuum hose from EGR valve. Connect EGR valve hose to vacuum gauge. Start engine, and allow it to idle. Tap on EVR sensor and wiggle wiring harness while observing vacuum gauge. If vacuum gauge reading does not remain less than 1.0 in. Hg and/or has sudden vacuum increase, check for shorts in EVR solenoid connector. Repair as necessary. If connector is okay, service or replace EVR solenoid. Clear codes and repeat QUICK TEST. If vacuum gauge reading remains less than 1.0 in. Hg with no sudden increase, go to next step.

116) EVR Solenoid Check Leave engine idling and vacuum gauge connected to EGR valve hose. Observe vacuum gauge while wiggling and bending small sections of wiring harness near EVR sensor, working from sensor toward dash panel. Wiggle and bend wiring harness from firewall to PCM. If vacuum gauge shows an increase in vacuum, isolate cause and repair as necessary. Remove breakout box, reconnect all components, and repeat QUICK TEST. If vacuum gauge does not show an increase in vacuum, reconnect vacuum hose to EGR valve and go to next step.

117) Check EVR Signal At PCM Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Start engine, and allow it to idle. Connect DVOM between test pins No. 27 and 46 at breakout box. Wiggle wiring harness and lightly tap on EVP sensor. If voltage increases to more than 0.67 volt, remove and service EGR valve. If EGR valve is okay, replace EVP sensor and repeat QUICK TEST. If voltage is 0.67 volt or less, problem is intermittent and cannot be duplicated at this time. Testing is complete.

Perform this test when directed by QUICK TEST. This CIRCUIT TEST is intended to diagnose

1. Vehicle Speed Sensor (VSS).
2. VSS wiring harness circuits.
3. Powertrain Control Module (PCM).

Vehicle Speed Sensor Circuit (DP1). Scheme 26

TEST PIN NO. 3 (VSS +) WIRE COLOR IDENTIFICATION

TEST PIN NO. 6 (VSS -) WIRE COLOR IDENTIFICATION

CID signal provides PCM information for fuel injector synchronization. The CID signal originates from Camshaft Position (CMP) sensor.

Enter this CIRCUIT TEST only when instructed during QUICK TEST. This test is only intended to diagnose

1. CID +, CID -, CID, SIG RTN and VREF wiring harness circuits.
2. Camshaft Position (CMP) sensor.
3. Crankshaft Position (CKP) sensor.
4. Powertrain Control Module (PCM).

CID Wiring Harness Circuits (DR2 - 2.0L). Scheme 27

1) Continuous Memory Code 214 Code 214 indicates error has been detected in CID sensor input signal. Error could be due to a hard fault or an intermittent fault. Possible causes for this fault are

1. Open or shorted wiring harness.
2. Faulty CMP sensor.
3. Faulty ICM.
4. Faulty PCM.

Start engine. If engine starts, go to next step. If engine does not start, go to step 10) for 2.0L.

2) Attempt To Generate Code 214 Clear continuous memory codes. Start engine. Raise engine speed to 1500 RPM for 10 seconds. Return to idle speed. Raise speed to 1500 RPM for 10 seconds again. Turn ignition off. Perform KOEO SELF-TEST. If Continuous Memory Code 214 is not present, go to step 20). If Continuous Memory Code 214 is present, go to next step.

3) Check Continuity Of CID Circuits Disconnect CMP sensor. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between CID or CID (+) test pin at breakout box and CID or CID (+) terminal at sensor wiring harness connector.

4) Check CID Circuit For Short To Power Turn ignition off. Ensure PCM and CMP sensor are disconnected. Ensure scan tester is not connected to vehicle. Turn ignition on. Measure voltage between CID or CID (+) test pin and test pin No. 40 at breakout box. If voltage is less than 1.0 volt, go to next step. If voltage is 1.0 volt or more, repair short to power in CID circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

5) Check CID Circuit For Short To Ground Turn ignition off. Ensure PCM and CMP sensor are disconnected. Measure resistance between CID or CID (+) test pin and pins No. 16, 40 and 46 at breakout box. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are more than 10,000 ohms, proceed to step 7).

6) Check VPWR Circuit Voltage Ensure PCM and CMP are disconnected. Turn ignition on. Measure voltage between VPWR terminal at CMP sensor and negative battery terminal. If voltage is less than 10.5 volts, repair open in VREF circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If voltage is 10.5 volts or more, go to next step.

7) Check For Shorts In PCM Turn ignition off. Ensure CMP is disconnected. Connect PCM to breakout box. Measure resistance between test pin No. 24 and test pins No. 16, 37, 40, 46, 57 and 60 at breakout box. On all models, if all readings are more than 500 ohms, go to next step. If any reading is 500 ohms or less, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

8) Check CMP Sensor Output Turn ignition off. Reconnect CMP sensor wiring harness connector. Set DVOM on AC scale. Start engine. Measure voltage between test pins No. 24 and 40 while varying engine RPM. On all models, if voltage varies more than 0.1 volt, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If voltage does not vary more than 0.1 volt, replace CMP sensor. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 8) to step 10). No test procedures have been omitted.

10) Check VPWR At CMP Sensor Turn ignition off. Disconnect CMP sensor. Turn ignition on. Measure voltage between VPWR terminal at CMP sensor wiring harness connector and negative battery terminal. If voltage is less than 10.5 volts, repair open in VREF circuit and repeat QUICK TEST. If voltage is 10.5 volts or more, VPWR circuit is okay.Go to IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING -EEC-IV.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 10) to step 20). No test procedures have been omitted.

20) Check CID Circuit Enter wiggle test. See CONTINUOUS MONITOR MODE (WIGGLE TEST) under QUICK TEST. Observe analog VOM or diagnostic tester for indication of fault while performing following: grasp wiring harness near PCM wiring harness connector while observing VOM or diagnostic tester for fault indication. Shake and bend small sections of harness, working from PCM toward sensor. If fault is indicated, isolate fault and repair as necessary. Repeat QUICK TEST. If no fault is indicated, problem cannot be duplicated at this time. Proceed to SYMPTOMS in TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

Perform this test when directed by QUICK TEST. This test is intended to diagnose a faulty BOO switch circuit or PCM. To prevent replacement of good components, be aware following non-EEC related areas may be at fault

1. Brakelight bulb.
2. Brakelight switch or brakelight fuse.

BOO Switch Circuit (FD1). Scheme 28

TEST PIN NO. 2 OR 5 (BOO) WIRE COLOR IDENTIFICATION

TEST PIN NO. IDENTIFICATION

1) Code 536: Verify Brake Pedal Was Depressed Code 536 indicates that when brake pedal is applied during KOER SELF-TEST, BOO signal did not cycle high and low. Possible causes for this fault are

1. Brake pedal not applied during self-test.
2. Brake pedal applied during entire self-test.
3. Open brakelight circuit.
4. Short to ground or power.
5. Faulty brakelight switch.
6. Faulty Powertrain Control Module (PCM).

If brake was not applied during KOER SELF-TEST, repeat test. Depress and release brake pedal only once during test. If pedal was depressed, go to next step.

2) Check Operation Of Brakelights With ignition on, check operation of brakelights. If brakelights operate normally, go to next step. If brakelights do not operate, go to step 4). If brakelights are always on,go to step 5).

3) Check For BOO Switch Circuit Cycling Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure voltage between BOO test pin (No. 2 or 5) and test pin No. 40 while applying and releasing brake. If voltage cycles, replace PCM and repeat QUICK TEST. If voltage does not cycle, repair open circuit in BOO switch circuit between PCM and BOO switch connection to brakelight circuit. Repeat QUICK TEST.

4) Check For Power To Brakelight Switch Ensure related fuses and brakelight bulbs are in good condition. Turn ignition off. Disconnect brakelight switch (located on brake pedal). Measure voltage between BATT (+) input to brakelight switch and ground. If voltage is more than 10 volts, check condition of brakelight switch. If brakelight switch is okay, repair open circuit between brakelight switch and brakelight ground. Repeat QUICK TEST. If voltage is less than 10 volts, repair open BATT (+) circuit to brakelight switch and repeat QUICK TEST.

5) Verify Brake Switch Is Not Always Closed Turn ignition off. Disconnect brakelight switch (located on brake pedal). Turn ignition on. If brakelights are still on, go to next step. If brakelights are not on, verify correct installation of brakelight switch. If installation is okay, replace brakelight switch and repeat QUICK TEST.

6) Check For Short To Power In PCM Turn ignition off. Disconnect PCM. Turn ignition on. Check brakelights. If brakelights are on, go to next step. If brakelights are off, replace PCM and repeat QUICK TEST.

7) Check For Short To Power In Shift Lock Actuator Turn ignition off. Ensure PCM and brakelight switch are disconnected. Disconnect shift lock actuator, cruise control module and ABS module (if equipped). Turn ignition on. If brakelights are still on, repair short to power in BOO or STOPLAMP circuit and repeat QUICK TEST. If brakelights are off, repair short circuit in shift lock actuator circuit, cruise control system circuit or ABS circuit. Reconnect all components and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 7) to step 90). No test procedures have been omitted.

90) Continuous Memory Code 536: Check For Proper Brakelight Switch Installation Code 536 indicates a BOO circuit failure. Possible causes for this fault are

1. Brakelight switch installed improperly.
2. Open brakelight circuit.
3. Short to ground or power.
4. Faulty brakelight switch.
5. Faulty brakelight switch ground connection.

Check brakelight switch for proper installation (alignment with brake pedal, corrosion or frayed wires). If brakelight switch is okay, go to next step. If brakelight switch is not okay, repair as necessary. Clear codes and repeat QUICK TEST.

91) Check Brakelight Switch Ground Check brakelight switch ground connection. Also, check brakelight connector wires for corrosion or damage. Repair as necessary. Clear codes and repeat QUICK TEST. If connector and wires are okay, go to next step.

92) Check Brakelight BOO Circuits For Short To Power Turn ignition on. Observe brakelights. With brake pedal released, wiggle brakelight BOO circuit wires and connectors. If brakelights flash, isolate short to power and repair as necessary. Clear codes and repeat QUICK TEST. If brakelights do not flash, go to next step.

93) Check Brakelight Circuit Continuity Turn ignition off. Depress and hold-down brake pedal. Observe brakelights and wiggle brakelight circuit wires and connectors. Also, lightly tap on brakelight switch (to simulate road shock). If brakelights flash or go off, isolate open in brakelight circuit and repair as necessary. Clear codes and repeat QUICK TEST. If brakelights stay on (normal operation), go to next step.

94) Check BOO Circuit Continuity Turn ignition off. Release brake pedal. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Connect DVOM between BOO test pin (No. 2 or 5) at breakout box and BOO terminal at brakelight switch. Observe DVOM and wiggle BOO circuit wires and connectors. If resistance at anytime was more than 5 ohms, isolate open in BOO circuit and repair as necessary. Remove breakout box, reconnect all components, and repeat QUICK TEST. If resistance was 5 ohms or less at all times, fault is intermittent and cannot be duplicated at this time. Testing is complete.

Electrical load inputs are used for idle speed control strategy so correct idle can be maintained regardless of electrical demands on engine. PCM uses 4 accessories to determine electrical load status: blower motor, headlights, rear window defroster, and daytime running lights (if equipped).

Perform this test when directed by QUICK TEST or CIRCUIT TEST S. This CIRCUIT TEST is intended to diagnose

1. Blower (BLR) motor input circuit.
2. Daytime Running Lights (DRL) input circuit.
3. Headlight (HDL) input circuit.
4. Rear window Defroster (DEF) input circuit.
5. Powertrain Control Module (PCM).

SWITCH CIRCUIT LOGIC

Electrical Load Input Circuit (FE1 - Probe A/T & M/T Calif.). Scheme 29

1) Isolate Faulty System If idle speed fault occurs when blower motor is on, go to step 10). If idle speed fault occurs when daytime running lights are on, go to step 20). If idle speed fault occurs when headlights are on, go to step 30). If idle speed fault occurs when rear window defroster is on, go to step 40).

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 1) to step 10). No test procedures have been omitted.

10) Check Blower Motor Switch (Low Speed) Turn ignition and all accessories off. Remove PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Turn climate control motor switch to low-speed position "1" or "2". Measure voltage between chassis ground and test pin No. 29 at breakout box. If voltage is not 10-17 volts, go to step 13). If voltage is 10-17 volts, go to next step.

11) Check Blower Motor Switch (High Speed) Turn ignition and all accessories off. Turn climate control motor switch to high-speed position "3" or "4". Turn ignition on. Measure voltage between chassis ground and test pin No. 29 at breakout box. If voltage is less than 1.5 volts, replace PCM and confirm idle speed fault has been corrected. If voltage is 1.5 volts or more, go to next step.

12) Check Blower Circuit For Short To Power Turn ignition off. Disconnect blower motor relay. Measure resistance between test pin No. 29 and test pins No. 37 and 57 at breakout box. If all readings are more than 10,000 ohms, check for damaged blower motor or relay. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected.

13) Check Blower Circuit Continuity Turn ignition off. Disconnect blower motor relay. Measure resistance between BLR terminal at power distributor box and test pin No. 29 at breakout box. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected. If resistance is less than 5 ohms, go to next step.

14) Check Blower Circuit For Short To Ground Turn ignition off. Disconnect blower motor relay. Measure resistance between test pin No. 29 and test pins No. 40, 46 and 60 at breakout box. If all readings are more than 10,000 ohms, check for damaged blower motor switch or relay. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 14) to step 20). No test procedures have been omitted.

20) Check DRL Circuit Voltage (Headlights On) Turn ignition and all accessories off. Remove PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Apply parking brake. Turn ignition on. Turn headlights on. Turn accessories off. Measure voltage between chassis ground and test pin No. 14 at breakout box. If voltage is not 10-17 volts, go to step 23). If voltage is 10-17 volts, go to next step.

21) Check DRL Circuit Voltage (Headlights Off) Turn headlights off. Release parking brake. Turn ignition on. Measure voltage between chassis ground and test pin No. 14 at breakout box. If voltage is less than 1.5 volts, replace PCM. Remove breakout box and confirm idle speed fault has been corrected. If voltage is 1.5 volts or more, go to next step.

22) Check DRL Circuit For Short To Power Turn ignition off. Ensure PCM is disconnected. Disconnect daytime running lights relay. Measure resistance between test pin No. 14 and pins No. 37 and 57 at breakout box. If all readings are more than 10,000 ohms, check daytime running lights module for malfunction. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected.

23) Check DRL Circuit Continuity Turn ignition off. Disconnect daytime running lights relay. Measure resistance between DRL relay connector and test pin No. 14 at breakout box. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected. If resistance is less than 5 ohms, go to next step.

24) Check DRL Circuit For Short To Ground Turn ignition off. Measure resistance between test pin No. 14 and test pins No. 40, 46 and 60 at breakout box. If all readings are more than 10,000 ohms, check daytime running lights module for malfunction. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 24) to step 30). No test procedures have been omitted.

30) Check Headlight Circuit Voltage (Headlights Off) Turn ignition off. Remove PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn all accessories off. Turn ignition on. Measure voltage between chassis ground and test pin No. 42 at breakout box. If voltage is 1.5 volts or more, go to step 34). If voltage is less than 1.5 volts, go to next step.

31) Check Headlight Circuit Voltage (Headlights On) Turn all accessories off. Turn ignition on. Turn headlights on. Measure voltage between chassis ground and test pin No. 42 at breakout box. If voltage is 10-17 volts, replace PCM. Remove breakout box and confirm idle speed fault has been corrected. If voltage is not 10-17 volts, go to next step.

32) Check HDL Circuit Continuity Turn ignition off. Disconnect headlight relay. Measure resistance between HDL terminal at power distribution box and test pin No. 42 at breakout box. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected. If resistance is less than 5 ohms, go to next step.

33) Check HDL Circuit For Short To Ground Turn ignition off. Disconnect headlight relay. Measure resistance between test pin No. 42 and test pins No. 40, 46 and 60 at breakout box. If all readings are more than 10,000 ohms, check headlight switch for malfunction. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected.

34) Check HDL Circuit For Short To Power Turn ignition off. Disconnect headlight relay. Measure resistance between test pin No. 42 and test pins No. 37 and 57 at breakout box. If all readings are more than 10,000 ohms, check headlight switch for malfunction. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 34) to step 40). No test procedures have been omitted.

40) Check DEF Circuit Voltage (Defrost Off) Turn ignition off. Turn all accessories off. Remove PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Measure voltage between chassis ground and test pin No. 23 at breakout box. If voltage is 10-17 volts, go to next step. If voltage is not 10-17 volts, go to step 43).

41) Check DEF Circuit Voltage (Defrost On) Turn ignition on. Turn rear window defroster on. Measure voltage between chassis ground and test pin No. 23 at breakout box. If voltage is less than 3 volts, replace PCM. Remove breakout box and confirm idle speed fault has been corrected. If voltage is 3 volts or more, go to next step.

42) Check DEF Circuit For Short To Power Turn ignition off. Disconnect rear window defroster relay. Measure resistance between test pin No. 23 and test pins No. 37 and 57 at breakout box. If all readings are more than 10,000 ohms, check DEF switch or relay for malfunction. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected.

43) Check DEF Circuit Continuity Turn ignition off. Disconnect rear window defroster switch. Measure resistance between DEF terminal at power distribution box and test pin No. 23 at breakout box. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected.

44) Check DEF Circuit For Short To Ground Turn ignition off. Disconnect rear window defroster relay. Measure resistance between test pin No. 23 and test pins No. 40, 46 and 60 at breakout box. If all readings are more than 10,000 ohms, check DEF switch and relay circuit for malfunction. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and confirm idle speed fault has been corrected.

The PSP switch, on 2.0L, is a normally open switch that closes as pressure in the power steering system increases.

Perform this test when instructed during QUICK TEST or if directed by other test procedures. Some vehicles may not have power steering, but PCM may be equipped with PSP switch software strategy. If a KOEO Code 519 is displayed, check if vehicle is equipped with power steering. If vehicle is not equipped with power steering, disregard Code 519. This test is only intended to diagnose

1. Power Steering Pressure (PSP) switch.
2. PSP and SIG RTN wiring harness circuits.
3. Powertrain Control Module (PCM).

To prevent replacement of good components, be aware the following non-EEC related areas may be at fault

1. Idle speed/throttle stop adjustment.
2. Binding throttle shaft/linkage.
3. Cruise control linkage.
4. Power steering hydraulic system.

Power Steering Pressure (PSP) Switch Circuit (FF1 - Probe). Scheme 30

PSP SWITCH TEST PIN NUMBER IDENTIFICATION

TEST PIN NO. 2 OR 28 (PSP) WIRE COLOR IDENTIFICATION

TEST PIN NO. 46 (SIG RTN) WIRE COLOR IDENTIFICATION

1) KOEO Code 519: Attempt To Eliminate Code Code 519 indicates PSP switch circuit is open. Possible causes for this fault are

1. Damaged PSP switch.
2. Open circuit in wiring harness.
3. Faulty PCM.

Turn ignition off. Disconnect PSP switch. Install jumper wire between PSP terminal and SIG RTN terminal at wiring harness connector. Repeat KOEO SELF-TEST. If Code 519 is not displayed, replace PSP switch and repeat QUICK TEST. If Code 519 is displayed, remove jumper wire and go to next step.

2) Check Continuity Of PSP Circuits Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 46 and SIG RTN terminal at PSP switch wiring harness connector. Also measure resistance between PSP test pin at breakout box and PSP terminal at switch wiring harness connector. If both readings are less than 5 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If readings are 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

3) Check PSP Switch Operation Turn ignition off. Connect tachometer, and start engine. Allow engine to idle in Park or Neutral. Disconnect PSP switch wiring harness connector. If RPM increases, replace PSP switch and recheck system. If RPM does not increase, go to next step.

4) Check PSP Switch Circuits For Shorts Turn ignition off. Disconnect PSP switch wiring harness connector. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between PSP test pin at breakout box and test pin No. 46 at breakout box. If resistance is 10,000 ohms or less, repair short in harness and recheck symptom. If resistance is more than 10,000 ohms, replace PCM and recheck symptom.

5) KOER Code 521 Disregard this code if vehicle does not have power steering. Code 521 indicates PSP switch did not change states due to open or closed switch. Possible causes for this fault are

1. Damaged PSP switch.
2. Open or shorted circuit in wiring harness.
3. Front wheels turned but not centered.
4. Faulty PCM.

If steering wheel was turned 1/2 turn within 2 seconds after engine ID code and then returned to center, go to next step. If steering wheel was not turned, repeat QUICK TEST.

6) Check PCM Open Circuit Identifying Capabilities Turn ignition off. Disconnect PSP switch. Perform KOEO SELF-TEST. If Code 519 is present, go to step 8). If Code 519 is not present, go to next step.

7) Check PSP Switch Circuits For Shorts Turn ignition off. Disconnect PSP switch. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between PSP test pin and test pin No. 46 at breakout box. If resistance is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If resistance is more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

8) Check PSP Switch Position Comparison Turn ignition off. Connect PCM connector to breakout box. With PSP switch connected, turn ignition on. Measure and record resistance between PSP test pin and test pin No. 46 at breakout box. Start engine. Measure and record resistance between PSP test pin and test pin No. 46 at breakout box. If reading shows less than 10 ohms difference between key on engine off and key on engine running, go to next step. If reading is not as described, replace PSP switch and repeat QUICK TEST.

9) Check PSP Switch With Engine Running (Load & No Load) Connect PSP switch. Start engine, and allow it to idle. Measure resistance between PSP test pin and test pin No. 46 at breakout box. Turn steering wheel 1/2 turn and return to center position. If resistance changes from less than 10 ohms to infinity and then returns to 10 ohms or less (when steering wheel is centered), PSP switch system is okay. Testing is complete. If reading does not change as indicated, replace PSP switch. Repeat QUICK TEST.

10) Code 519: Attempt To Eliminate Code 519 Disregard this code if vehicle does not have power steering. Code 519 indicates PSP switch circuit is closed. Possible causes for this fault are

1. Damaged PSP switch.
2. Open or shorted circuit in wiring harness.
3. Faulty PCM.

Turn ignition off. Disconnect PSP switch connector. Repeat KOEO SELF-TEST. Measure resistance between PSP test pin and test pin No. 46 at breakout box. If Code 519 is not present, replace PSP switch. Repeat QUICK TEST. If Code 519 is present, go to next step.

11) Check PSP Circuit For Short Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between PSP test pin and test pin No. 46 at breakout box. If reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and recheck symptom. If reading is more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and recheck symptom.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 11) to step 15). No test procedures have been omitted.

15) Check PSP Switch Operation Connect tachometer, and start engine. Allow engine to idle in Park or Neutral. Disconnect PSP switch connector. Using jumper wire, connect PSP switch wiring harness connector terminals. If RPM increases, replace PSP switch and recheck symptom. If RPM does not increase, go to next step.

16) Check Continuity Of PSP Switch Circuits Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Measure resistance between test pin No. 46 and SIG RTN terminal at PSP switch wiring harness connector. Also, measure resistance between PSP switch test pin at breakout box and PSP terminal at PSP switch wiring harness connector. If both readings are less than 5 ohms, replace PCM. Remove breakout box, reconnect all components, and recheck symptom. If any reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 16) to step 20). No test procedures have been omitted.

20) KOER Code 521 Disregard this code if vehicle does not have power steering. Code 521 indicates PSP switch did not change states due to open or closed switch. Possible causes for this fault are

1. Damaged PSP switch.
2. Open or shorted circuit in wiring harness.
3. Front wheels turned but not centered.
4. Faulty PCM.

If steering wheel was turned 1/2 turn within 2 seconds after engine ID code and then returned to center, go to next step. If steering wheel was not turned, repeat QUICK TEST.

21) Check PCM Closed Circuit Identifying Capabilities Turn ignition off. Disconnect PSP switch. Connect jumper wire between PSP terminal and SIG RTN terminal at PSP switch wiring harness connector. Perform KOEO SELF-TEST. If Code 519 is present, remove jumper wire and go to step 23). If Code 519 is not present, go to next step.

22) Check Continuity Of PSP Switch Circuits Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between PSP test pin at breakout box and PSP terminal at PSP switch wiring harness connector. Also, measure resistance between test pin No. 46 at breakout box and SIG RTN terminal at PSP switch wiring harness connector. If both readings are less than 5 ohms, replace PCM and repeat QUICK TEST. If any reading is 5 ohms or more, repair open circuit and repeat QUICK TEST.

23) Check PSP Switch Position Comparison Turn ignition off. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Reconnect PSP switch. Turn ignition on. Measure resistance between PSP switch test pin and test pin No. 46 at breakout box. Start engine. If reading remains less than 10 ohms difference between key on engine off and key on engine running, go to next step. If reading is not as described, replace PSP switch and repeat QUICK TEST.

24) Check PSP Switch With Engine Running (Load & No Load) Start engine, and allow it to idle. Measure resistance between PSP switch test pin and test pin No. 46 at breakout box. Turn steering wheel 1/2 turn and return to center position. If resistance changes from less than 30 ohms to infinity and then returns to 30 ohms or less (when steering wheel is centered), PSP switch system is okay. Testing is complete. If reading does not change as indicated, replace PSP switch. Repeat QUICK TEST.

Perform this test when instructed during QUICK TEST or if directed by other test procedures. To prevent replacement of good components, be aware the following non-EEC related areas may be at fault

1. Excessive blow-by.
2. PCV malfunction.
3. Vacuum leaks.
4. Incorrect fuel pressure.
5. Throttle binding.
6. Improper fuel pressure.
7. Idle air control solenoid.

This test is only intended to diagnose

1. MAP/BARO sensor.
2. Throttle Position Sensor (TPS).
3. Mass Airflow (MAF) sensor.
4. Intake Air Temperature (IAT) sensor.
5. Fuel injectors.

1) Check For Idle Air Codes Code 121 indicates TPS is inconsistent with MAF value. Code 124 indicates TPS value is higher than expected. Code 125 indicates TPS value is lower than expected. Turn ignition on. Repeat KOEO SELF-TEST. If Code 411 or 412 is present, perform appropriate circuit test. See DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS. If Code 411 or 412 is not present, go to next step.

2) Throttle Position (TP) Sensor: TP Sensor Integrity Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Connect DVOM to test pins No. 46 and 47 at breakout box. Turn ignition on. Slowly apply throttle to WOT, and release to closed position. Voltage should change smoothly from 0.4-4.5 volts. See CIRCUIT TEST DH for schematics and specific engine values. If voltage change is incorrect or erratic, ensure TP sensor is properly installed. If TP sensor is properly installed, replace TP sensor. Remove breakout box, reconnect all components, and repeat QUICK TEST. If voltage is okay, go to step 8) for Code 121 or next step for all other codes.

3) Check Idle Ensure idle is correct. If idle is correct, go to next step. If idle is incorrect, see IDLE SPEED in ADJUSTMENTS - 4-CYL article in the ENGINE PERFORMANCE section.

4) Check Throttle Body Ensure idle is correct. Check throttle and/or cruise control linkage for binding and rough operation. Inspect throttle body for sludge build-up. Check engine vacuum hoses. Refer to Vehicle Emission Control Information (VECI) decal for proper vacuum hose routing. Check for air leak between ISC solenoid and MAF sensor. If problems are found, repair as necessary. Remove breakout box, reconnect all components, and repeat QUICK TEST. If no problems are found, go to next step.

5) Check MAP/BARO Sensor Output On vehicles without MAP/BARO go to next step. On vehicles with MAP/BARO, see DIAGNOSTIC AIDS, then continue with this test. With tester connected and ignition on, measure sensor output voltage. If output voltage is within range for specified altitude, remove MAP/BARO tester and go to next step. See MAP SENSOR VOLTAGE OUTPUT table for specification. If output voltage is not within range, replace MAP/BARO sensor. Remove breakout box, reconnect all components, and repeat QUICK TEST.

If possible, measure several known good MAP/BARO sensors. Average voltage reading will be typical for location and day of testing. Also, refer to CIRCUIT TEST DF for MAP/BARO sensor output check. (Scheme 21)for connector terminal identification and MAP/BARO tester hookup.

MAP SENSOR VOLTAGE OUTPUT

6) Check IAT Sensor Ensure ambient temperature is more than 50°F (10°C) before performing this test. Also, check and repair any air leaks in front of IAT sensor. Turn ignition off. Connect breakout box to PCM. Set DVOM to 20-volt scale. Connect DVOM to test pins No. 25 and 46. Start engine, and let it idle. Observe voltage as engine warms up. See CIRCUIT TEST DA for voltage specifications. If voltage decreases smoothly and stabilizes when engine reaches operating conditions, system is operating properly at this time. Testing is complete. If voltage does not decrease smoothly and stabilize after engine reaches operating conditions, replace IAT sensor and repeat QUICK TEST.

7) Continuous Memory Code 184 & 185: Inspect MAF Sensor Code 184 indicates MAF sensor signal is higher than expected. Code 185 indicates MAF sensor signal is lower than expected. Turn ignition off. Check for air leaks between Idle Air Control (IAC) solenoid and MAF sensor. Inspect MAF sensor for oil contamination caused by excessive blow-by or malfunctioning PCV. If problems are found, repair as necessary. Clear codes and repeat QUICK TEST. If no problems are found, go to step 10).

8) Check MAF Sensor Circuit Voltage Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Start engine, and warm it to normal operating temperature. Measure voltage between test pin No. 50 and test pin No. 40 or 60 at breakout box. If voltage is not within specification, replace MAF sensor. Remove breakout box, reconnect all components, and repeat QUICK TEST. See MAF SENSOR DATA table. If voltage is within acceptable range, system is operating normally at this time. Sometime during the last 80 warm-up cycles, MAF sensor signal was out of range. See SYMPTOMS in TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

MAF SENSOR DATA

9) Continuous Memory Code 186 & 187: Visual Vacuum Checks Code 186 indicates pulse width is longer than expected (rich). Code 187 indicates pulse width is shorter than expected (lean). Inspect air cleaner and air inlet duct. Replace or repair an necessary. Check for unmetered air leaks between MAF sensor and IAC solenoid. Check all engine vacuum hoses for damage, blockage and improper routing. Repair as necessary, and repeat QUICK TEST. If all checks are okay, go to next step.

10) Check Fuel Pressure Turn ignition off. Install fuel pressure gauge. Ensure vacuum hose is connected to fuel pressure regulator (if applicable). Start engine, and run it at idle. If fuel pressure is within specification, go to next step. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. If fuel pressure is not within specifications, repair as necessary. See FUEL SYSTEM in SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

11) Verify Fuel Pressure Retention Ability Turn ignition on. If fuel pressure remains at specification for 60 seconds, go to next step. If fuel pressure does not remain at specification, repair fuel delivery system as necessary. Proceed to FUEL SYSTEM in SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

12) Cylinder Balance Test Perform KOER SELF-TEST. After last code, wait 5-10 seconds, and then goose throttle lightly (not wide open throttle). This will activate cylinder balance test. If Code 90 is present after test, go back to step 7). If Code 90 is not present after test, go to CIRCUIT TEST H, step 4).

CIRCUIT TEST H - FUEL CONTROL

Note. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article.

Perform this test when instructed during QUICK TEST or if directed by other test procedures. (Fuel-contaminated engine oil may affect Codes 136, 137, 139, 144, 171, 172, 173, 175, 176 and 177. If fuel-contaminated engine oil is suspected, remove PCV valve from valve cover and repeat QUICK TEST). If problem is corrected, change engine oil and filter. Only use this test to diagnose

1. HO2S and sensor connection.
2. Vacuum systems.
3. Fuel injector and/or fuel injector circuitry.
4. Powertrain Control Module (PCM).
5. Electrical circuits (HO2S, HO2S GND, INJ 1-8, VPWR and SIG RTN).

To prevent replacement of good components, be aware the following non-EEC areas may be cause of driveability concerns

1. Ignition system.
2. Faulty evaporative emission system.
3. EGR and/or PCV system.
4. Air intake system.
5. Engine oil contamination.
6. Fuel system.
7. Intake, supercharger, or charge air cooler leaks.
8. Exhaust system leaks or restriction.
9. Electrical system.
10. Secondary air injection system.
11. Engine cooling system.

INDIVIDUAL INJECTOR RESISTANCE

Test Schematic (H2 - 2.0L Federal M/T). Scheme 31

Test Schematic (H3 - 2.0L Except Federal M/T). Scheme 32

1) Check For Contaminated Engine Oil Turn ignition off. Remove PCV valve from valve cover. Inspect PCV system for damage. Inspect valve for blockage and movement of valve plunger. Repair as necessary. Perform KOEO and KOER SELF-TEST. Service ignition continuous memory code (if present) before servicing KOER codes. If vehicle is a no-start, install PCV valve and go to next step. If Code 139, 144, 171, 176 or 177 is present, go to next step. If no codes are set, change engine oil and filter. Install PCV valve, and drive vehicle for 5 miles at 55 MPH. Repeat QUICK TEST.

2) Check Fuel Pressure Turn ignition off. Release fuel pressure. Install fuel pressure gauge. Ensure manifold vacuum supply is connected to fuel pressure regulator (if equipped). Run engine at idle and check fuel pressure. If vehicle will not start, cycle ignition on and off several times. Check fuel pressure. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. If fuel pressure is within specification, go to next step. If pressure is not within specification, proceed to FUEL SYSTEM in appropriate SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

3) Check System Ability To Hold Fuel Pressure Turn ignition on. Check fuel system for leaks. Repair or replace as necessary. If fuel system does not leak and pressure remains at specification for 60 seconds, go to next step (no-starts), step 5) (MFI) or step 6) (SFI).

4) Fuel Delivery Test Release fuel system pressure. With fuel pressure gauge installed, pressurize fuel system as in step 1). Disconnect inertia switch. Crank engine for 5 seconds. If fuel pressure drop is greater than 5 psi after 5 seconds of cranking, EEC-IV system is not causing no-start condition. Check additional no-start tests in TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If fuel pressure drop is less than 5 psi, remove fuel pressure gauge. Connect inertia switch. Go to step 7) for MFI or step 8) for SFI.

5) Cylinder Balance Test (MFI) Connect a tachometer to engine. Start engine, and run it at idle. Disconnect and reconnect injectors individually, noting RPM drop as each injector is disconnected. IAC motor will attempt to re-establish RPM. If each injector does not produce a momentary drop in RPM, go to step 7). If each injector produces a momentary drop in RPM, perform the following. For Codes 172, 136 or 176, go to step 13). For Codes 173, 137 or 177, go to step 24). For all others, go to step 14).

6) Cylinder Balance Test (SFI) Perform KOER SELF-TEST. After last code is displayed, wait 5-10 seconds. Enter CYLINDER BALANCE TEST by lightly goosing throttle (not WOT). Test time is about 2-3 minutes. To interpret codes retrieved from test, refer to CYLINDER BALANCE TEST SERVICE CODES table. If KOEO Code 244 is output, cylinder balance test has been aborted. Go to CIRCUIT TEST DR. Code 77/538 indicates throttle was touched when test was run and test is not completed. Code 538 could also be output if Continuous Memory Code 214 (CID) is present. If Continuous Memory Code 214 is present, see appropriate chart under DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS for instruction. For Code 172, 136 or 176, go to step 13). For Code 173, 137 or 177, go to step 24). For all other codes, go to step 14).

CYLINDER BALANCE TEST SERVICE CODES

7) Check Injector & Harness Resistance (MFI) Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance of injector bank No. 1 between test pins No. 37 and 58 at breakout box. Also, measure resistance of injector bank No. 2 between test pins No. 37 and 59 at breakout box. Record resistances. Refer to INJECTOR BANK RESISTANCE table in this circuit test. If each resistance is within specification, go to step 12). If resistance is not as specified, repair open circuit on VPWR circuit for no-start or go to step 9) for all other conditions.

8) Check Injector & Harness Resistance (SFI) Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure and record resistance between suspected injector circuit test pin and test pin No. 37. For no-start, measure and record resistance between injector circuit test pin and test pin No. 37. (Scheme 31)and (Scheme 32). Refer to INDIVIDUAL INJECTOR RESISTANCE table in this circuit test. If each resistance is within specification, go to step 12). If resistance is not as specified, repair open circuit on VPWR circuit for no-start or go to next step for all other conditions.

9) Check Continuity Of Fuel Injector Harness Turn ignition off. Disconnect injector wiring harness connector at injectors. Set DVOM to 200-ohm scale. Measure resistance between test pins No. 37 and 57 at breakout box and each injector VPWR terminal at wiring harness connector. (Scheme 31)and (Scheme 32). Measure resistance between injector test pin(s) at breakout box and same injector circuit terminal at each injector wiring harness connector. If each reading is less than 5 ohms, go to next step. If each reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components and drive vehicle for 5 miles at 55 MPH. Repeat QUICK TEST.

10) Check Injector Harness Circuit For Short To Power Or Ground Turn ignition off. With breakout box installed and PCM disconnected, disconnect fuel injector wiring harness connector. (Scheme 31)and (Scheme 32). Measure resistance between injector test pin(s) and test pins No. 37, 40, 46, 57 and 60. Also, measure resistance between injector test pin(s) at breakout box and chassis ground. If each resistance is 10,000 ohms or more, replace injector per cylinder balance test service code and repeat QUICK TEST (SFI) or go to next step (MFI). If each resistance is less than 10,000 ohms, repair short. Remove breakout box, reconnect all components and drive vehicle for 5 miles at 55 MPH. Repeat QUICK TEST.

11) Isolate Faulty Injector Circuit Turn ignition off. Install breakout box and disconnect PCM. Disconnect all injectors on suspect bank. With DVOM set on 200-ohm scale, connect one injector and measure resistance between test pins No. 37 and 58 (injector bank No. 1) or 59 (injector bank No. 2). Disconnect injector, and repeat process for all other injectors. See INDIVIDUAL INJECTOR RESISTANCE table. If all injectors are within specification, go to next step. If injectors are not as specified, replace injector. Remove breakout box, and reconnect components. Drive vehicle for 5 miles at 55 MPH. Repeat QUICK TEST.

12) Check Injector Drive Signal With ignition off and breakout box installed, connect PCM to breakout box. Use a non-powered 12-volt test light, and connect as follows

1. MFI Connect test light between test pins No. 37 and 58 at breakout box. Connect light between test pins No. 37 and 59 at breakout box.
2. SFI Connect test light between test pin No. 37 and suspect injector test pin at breakout box.

Crank or start engine. If test light glows dimly, system is operating correctly. Clean injectors, and drive vehicle for 5 miles at 55 MPH. Repeat QUICK TEST and CYLINDER BALANCE TEST. If test light does not glow dimly (no light/bright light), replace PCM. Reconnect all components, and drive vehicle for 5 miles at 55 MPH. Repeat QUICK TEST.

13) Check Thermactor Operation If vehicle is equipped with pulse-air or does not have secondary air injection system, go to next step. A HO2S which is always lean could be caused by thermactor air being diverted upstream from HO2S. With dual HO2S, Code 172 applies to right or rear HO2S and Code 136 or 176 applies to left or front HO2S. Turn ignition off. Disconnect secondary air hose(s) from pump and vent to atmosphere. Perform KOER SELF-TEST. If Code 172, 136 or 176 is present, reconnect air hose(s) and go next step. If Continuous Memory Code 139, 144, 171, 176 or 177 is present, go to step 90). If code(s) is not present, repair air injection system as necessary.

14) Check HO2S Integrity A HO2S which is always lean, slow to switch or does not switch could be caused by

1. Moisture inside HO2S or connector causing a short to ground.
2. HO2S coated with contaminants.
3. HO2S circuit open.
4. HO2S circuit shorted to ground.

Turn ignition off. Inspect HO2S wiring harness for damage. Inspect HO2S and connector for signs of fluid entry. Repair or replace as necessary. Start engine, and run it at 2000 RPM for 2 minutes. Turn ignition off. Run KOER SELF-TEST. If fault codes are present, go to next step (MAP sensor-equipped models) or step 16) (MAF sensor-equipped models). If no codes are present, go to step 21).

15) Check HO2S (Engines With MAP Sensors) Vacuum or air leaks in non-EEC-IV areas could cause Code 136, 172 or 176. Check following possibilities before continuing

1. Leaking vacuum actuated motor.
2. Leaking intake gasket.
3. EGR system.
4. PCV system.
5. Lead-contaminated HO2S.

Turn ignition off. Ensure MAP sensor output voltage is correct. See CIRCUIT TEST DF, step 3). Disconnect appropriate HO2S from wiring harness connector. On 3-wire HO2S, connect DVOM to HO2S terminal at sensor wiring harness connector and negative battery terminal. On 4-wire HO2S, connect DVOM to HO2S and HO2S GND or SIG RTN terminal at sensor wiring harness connector. On all models, disconnect and plug vacuum line at MAP sensor. Start engine, and apply 10-14 in. Hg to MAP sensor. Run engine at 2000 RPM for 2 minutes. If reading is 0.5 volt or more, go to step 17). If reading is less than 0.5 volt, replace HO2S and repeat QUICK TEST.

16) Check HO2S (Engines With MAF Sensor) Purpose of this test is to verify HO2S can generate a voltage signal of greater than 0.5 volt during KOER SELF-TEST. Vacuum or air leaks in non-EEC-IV areas could cause Code 136, 172 or 176. Check following possibilities before continuing

1. Leaking vacuum actuated motor.
2. Leaking intake gasket.
3. EGR system.
4. PCV system.
5. Unmetered air between MAF sensor and throttle body.
6. Lead-contaminated HO2S.

Turn ignition off. Disconnect appropriate HO2S from harness. On 3-wire HO2S, connect DVOM to HO2S terminal at sensor wiring harness connector and negative battery terminal. On 4-wire HO2S, connect DVOM between HO2S terminal and HO2S GND or HO2S GND terminal at HO2S wiring harness connector. On all models, run engine at 2000 RPM for 2 minutes. Repeat KOER SELF-TEST and monitor HO2S voltage. If voltage is 0.5 volt or more at end of self-test, go to next step. If voltage is less than 0.5 volt, replace HO2S and repeat QUICK TEST.

17) Check Continuity Of HO2S Ground Circuits Turn ignition off. Install breakout box, leaving PCM disconnected. Disconnect suspect HO2S wiring harness connector. Inspect connector for damage, moisture and corrosion. Repair as necessary. Measure resistance between HO2S test pin at breakout box and HO2S terminal at sensor wiring harness connector. On 3-wire HO2S, measure resistance between HO2S GND test pin at breakout box and negative battery terminal. On 4-wire HO2S, measure resistance between SIG RTN test pin at breakout box and SIG RTN terminal at sensor wiring harness connector. Where applicable, measure resistance between HO2S GND and SIG RTN at breakout box. On all models, go to next step if each resistance is less than 5 ohms. If any resistance is 5 ohms or more, repair open circuit. Remove breakout box, and reconnect all components. Drive vehicle for 5 minutes at 55 MPH. Repeat QUICK TEST.

18) Check HO2S Circuit For Short To Ground Turn ignition off. Leave breakout box installed and PCM disconnected. Disconnect HO2S. Measure resistance between HO2S circuit test pin and test pins No. 40, 46 and 49 at breakout box. If any reading is less than 10,000 ohms, repair short to ground. Drive vehicle at 55 MPH for 5 minutes and repeat QUICK TEST. If reading is 10,000 ohms or more, go to next step.

19) Check HO2S For Short To Ground Ensure ignition is off and PCM is disconnected. With HO2S disconnected, measure resistance between PWR GND and HO2S terminal at HO2S connector. On 4-wire HO2S, also measure resistance between HO2S GND and/or SIG RTN terminal at sensor wiring harness connector. If resistance is less than 10,000 ohms, replace HO2S. Drive vehicle for 5 miles at 55 MPH and repeat QUICK TEST. If resistance is 10,000 ohms or more, perform following procedure as applicable.

1. For Codes 139, 144, 171, 174, 175 and 178, go to step 90).
2. For all other codes, go to next step if engine is equipped with MAP sensor. If engine is equipped with MAF sensor, replace PCM. Drive vehicle for 5 miles at 55 MPH, and repeat QUICK TEST.

20) Attempt To Eliminate Code 136, 172 Or 176 (Engines With MAP Sensor) Turn ignition off. Connect PCM to breakout box. Connect HO2S. Disconnect and plug MAP sensor vacuum hose. Start engine and apply 10-14 in. Hg to MAP sensor. Increase engine speed to 2000 RPM for 2 minutes. Allow engine to return to idle. Perform KOER SELF-TEST. If diagnosing continuous memory codes, drive vehicle 5 miles at 55 MPH. If Code 136, 172, or 176 is still present, remove breakout box. Connect all components. If engine runs rough, go to CIRCUIT TEST S, step 2). If engine does not run rough, replace PCM, drive vehicle 5 miles at 55 MPH and repeat QUICK TEST. If code is not present, remove breakout box and connect all components. HO2S input circuit and fuel delivery are okay; fault is in area common to all cylinders (vacuum leak, fuel contamination, EGR, ignition system, etc.). Proceed to TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

21) Check Resistance Of HO2S Heating Element Turn ignition off. Disconnect suspect HO2S. Inspect both ends of connector for damage, moisture and corrosion. Repair as necessary. Measure resistance between IGNITION RUN circuit and PWR GND circuit at HO2S connector. Hot to warm engine resistance should be 5-30 ohms. Cold engine temperature resistance is 2-5 ohms. If resistance is within specification, go to next step. If resistance is not as specified, replace HO2S and repeat QUICK TEST.

22) Check For Power At HO2S Harness Connector Disconnect HO2S. Turn ignition on. Measure voltage between IGNITION RUN and PWR GND circuits at HO2S wiring harness connector. If voltage is 10.5 volts or more, HO2S system and fuel delivery are okay. HO2S may have cooled before KOER SELF-TEST. If driveability symptom continues, fault is in area common to all cylinders (vacuum leak, fuel contamination, EGR, ignition system, etc.). Refer to the TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If voltage is less than 10.5 volts, go to next step.

23) Check Continuity Of Power Ground Circuit Turn ignition off. Measure resistance between PWR GND circuit at HO2S wiring harness connector and negative battery terminal. If resistance is less than 5 ohms, repair open in IGNITION RUN circuit and repeat QUICK TEST. If resistance is 5 ohms or more, repair open in PWR GND circuit and repeat QUICK TEST.

24) Diagnostic Test Code 173, 137 Or 177: Check HO2S SIGNAL For Short To Power On dual HO2S systems, Code 173 applies to right or rear sensor. Codes 137 and 177 applies to left or front sensor. HO2S continuously rich could be caused by

1. Moisture inside wiring harness causing short to power.
2. HO2S shorted to power.

Turn ignition off. Disconnect appropriate HO2S. Inspect connector for damage and repair as necessary. Turn ignition on. Measure voltage between HO2S and PWR GND terminal at HO2S wiring harness connector. If reading is less than 0.5 volt, go to step 26). If reading is 0.5 volt or more, go to next step.

25) Check For Short To Power Turn ignition off. Disconnect HO2S. Inspect wiring harness for damage and repair as necessary. Disconnect PCM 60-pin connector. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Disconnect suspect HO2S. Measure resistance between VPWR test pin and HO2S SIG test pin at breakout box. If reading is 10,000 ohms or more, replace PCM. Remove breakout box, and reconnect all components. Drive vehicle 5 miles at 55 MPH. Repeat QUICK TEST. If reading is less than 10,000 ohms, repair short circuit. Remove breakout box, and reconnect all components. Drive vehicle 5 miles at 55 MPH. Repeat QUICK TEST.

26) Check HO2S For Short To IGNITION RUN Circuit Turn ignition off. Disconnect HO2S. Measure resistance between IGNITION RUN terminal and HO2S terminal at HO2S wiring harness connector. If resistance is 10,000 ohms or more, go to next step for Codes 173, 137 and 177 or step 28) for Codes 171, 174, 175 and 178 (MAP sensor) or step 30) on models with MAF sensor. If resistance is less than 10,000 ohms, replace HO2S. Drive vehicle for 5 miles at 55 MPH, and repeat QUICK TEST.

27) Attempt To Generate Code 172, 136 Or 176 Turn ignition off. Disconnect appropriate HO2S. Using jumper wire, connect HO2S terminal at HO2S wiring harness connector to negative battery terminal. Repeat KOER SELF-TEST. If Code 172, 136 or 176 is present, remove jumper wire and go to next step for engines with MAP sensor or step 30) for engines with MAF sensor. If Codes 172, 136 and 176 are not present, remove jumper wire. Disconnect PCM connector, and inspect it for damage. If connector is okay, replace PCM. Drive vehicle for 5 miles at 55 MPH. Repeat QUICK TEST.

Because MAP sensor greatly influences fuel control, MAP sensor may malfunction without setting Code 126. Next 2 steps test MAP vacuum circuit.

28) Check MAP Sensor For Vacuum Leaks Turn ignition off. Disconnect vacuum hose from MAP sensor. Inspect hose for damage and repair as necessary. Connect vacuum pump to sensor. Apply 18 in. Hg to MAP sensor. If sensor does not hold vacuum, replace MAP sensor. Drive vehicle for 5 miles at 55 MPH. Repeat QUICK TEST. If sensor holds vacuum, release vacuum and go to next step.

29) Check For Loss Of Vacuum To MAP Sensor Using vacuum "T", connect vacuum gauge in MAP sensor vacuum circuit. Start engine. Note vacuum reading after idle stabilizes. Turn ignition off. Remove "T" and vacuum gauge. Reconnect hose to MAP sensor. Connect vacuum gauge at a different manifold vacuum location. Start engine, and note vacuum reading. If readings do not differ by more than one in. Hg, go to next step. If readings differ by more than 1 in. Hg, inspect vacuum hoses for leaks, kinks and blockage. Repair as necessary. Connect all components, and drive vehicle for 5 miles at 55 MPH. Repeat QUICK TEST.

30) HO2S Check Turn ignition off. Disconnect HO2S. For 4-wire HO2S, connect DVOM to HO2S terminal and HO2S GND or SIG RTN terminal at HO2S connector. For 3-wire HO2S, connect DVOM to HO2S terminal at HO2S connector and negative battery terminal. On all models, cause a vacuum leak to force HO2S to go lean. Remove PCV valve hose. Start engine. Raise engine speed to about 2000 RPM. DVOM should indicate less than 0.4 volt within 30 seconds. If voltage is not as specified, replace HO2S. Reconnect vacuum hoses, and drive vehicle for 5 miles at 55 MPH. Repeat QUICK TEST. If voltage is as specified, go to step 90).

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 30) to step 90). No test procedures have been omitted.

90) Check Continuous Monitor Mode Start engine, and warm it to normal operating temperature. Raise engine speed to 2000 RPM for 2 minutes and then return to idle. Enter KOER wiggle test. See CONTINUOUS MONITOR MODE (WIGGLE TEST) under QUICK TEST. While observing DVOM or scan tester, shake or bend small sections of wiring harness from HO2S to PCM. Wiggle, shake or bend small sections of wiring harness from HO2S GND to PCM. If no fault is indicated, remain in CONTINUOUS MONITOR MODE and go to next step. If fault is indicated, isolate and repair fault as necessary. Clear codes. Repeat QUICK TEST.

91) Continuous Monitor Test Drive Check While still in KOER wiggle test, test drive vehicle for 5 miles at 55 MPH over smooth roads. Drive an additional 5 miles at 55 MPH over rough roads. If possible, drive vehicle through a pool of water to wet HO2S and connector. If fault is indicated, isolate fault and repair as necessary. Clear codes, and remove breakout box. Repeat QUICK TEST. If no codes are indicated, exit KOER wiggle test and go to next step.

92) Check HO2S Switching Turn ignition off. Inspect wiring harness for proper routing and insulation. Check for burnt, chaffed or open wires. Repair as necessary. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install breakout box. Connect PCM to breakout box. Connect analog voltmeter to suspect HO2S test pin and HO2S GND at breakout box. Test drive vehicle for 5 miles at 55 MPH while observing voltmeter. HO2S should switch from .3 volt to .9 volt within 3 seconds. If HO2S does not switch as described, replace HO2S. Connect all components, and repeat QUICK TEST. If HO2S switches as described, fault cannot be identified or duplicated at this time. Proceed to INTERMITTENTS in the TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

CIRCUIT TEST HA - ADAPTIVE FUEL STRATEGY

Note. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article.

Perform this test when directed by QUICK TEST. PCM uses adaptive fuel logic to compensate for normal variances in fuel system components. If fuel system appears to be too rich or too lean, adaptive fuel will make appropriate shift in fuel delivery calculations to compensate.

If possible, measure several known good MAP/BARO sensors. Average voltage reading will be typical for location and day of testing.

MAP SENSOR VOLTAGE OUTPUT

CIRCUIT TEST HA ACRONYMS

1) Continuous Memory Codes 181, 183, 189 & 192 These codes identify a lean fuel condition resulting in adaptive fuel strategy enriching fuel system to compensate.

1. Code 181 Indicates single right or rear HO2S detected a problem and adaptive fuel rich limit has been reached.
2. Code 183 Indicates single right or rear HO2S detected a problem and adaptive fuel rich limit has been reached at idle.
3. Code 189 Indicates left or front HO2S detected a problem and adaptive fuel rich limit has been reached.
4. Code 192 Indicates left or front HO2S detected a problem and adaptive fuel rich limit has been reached at idle.

1a) Continuous Memory Codes 179, 182, 188 & 191 These codes identify a rich fuel condition resulting in adaptive fuel strategy leaning fuel system to compensate.

1. Code 179 Indicates right or rear HO2S detected a problem and adaptive fuel lean limit has been reached at idle.
2. Code 182 Indicates right or rear HO2S detected a problem and adaptive fuel lean limit has been reached at idle.
3. Code 188 Indicates left or front HO2S detected a problem and adaptive fuel lean limit has been reached.
4. Code 191 Indicates left or front HO2S detected a problem and adaptive fuel lean limit has been reached. Possible causes for these codes are
5. Incorrect fuel pressure.
6. Faulty fuel injector or circuit.
7. Leaking or restricted air intake.
8. Faulty MAP sensor.
9. Restricted air or fuel filter.

If other codes are present, repair as necessary. If no other codes are present, go to next step.

2) Check Fuel Pressure Release fuel system pressure. With ignition off, install fuel pressure gauge. Ensure manifold vacuum is connected to fuel pressure regulator. Start engine and allow to idle. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. If fuel system pressure is not within specification, repair as necessary. See FUEL SYSTEM in SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If fuel system pressure is within specification, go to next step.

3) Check System Ability To Hold Fuel Pressure With fuel pressure gauge installed, cycle ignition from OFF to ON position 3-4 times to pressurize fuel system (DO NOT start engine). If fuel pressure remains at specification for 60 seconds, go to next step (MAP/BARO equipped vehicles) or step 6) (all other vehicles). If fuel pressure does not remain at specification for 60 seconds, repair fuel system as necessary. Proceed to FUEL SYSTEM in SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

4) Check MAP/BARO Frequency Turn ignition off. Connect MAP/BARO tester to MAP/BARO sensor. (Scheme 21)in CIRCUIT TEST DF. Turn ignition on. If MAP/BARO voltage is within specification, go to next step (MFI) or step 6) (SFI). See MAP SENSOR VOLTAGE OUTPUT table. If voltage is not within specification, check wiring to MAP/BARO sensor for corrosion and other damage. Repair as necessary. Clear KAM, and repeat QUICK TEST. If wiring is okay, replace MAP/BARO sensor. Clear KAM, and repeat QUICK TEST.

5) Cylinder Balance Test (MFI) Connect a tachometer to engine. Start engine, and run it at idle. Disconnect and reconnect injectors individually, noting RPM drop as each injector is disconnected. IAC motor will attempt to re-establish RPM. If each injector produces a momentary drop in RPM, original fault is in ignition system. If each injector does not produce a momentary drop in RPM, go to step 7).

6) Cylinder Balance Test (SFI) Perform KOER SELF-TEST. After last code is displayed, wait 5-10 seconds. Enter CYLINDER BALANCE TEST by lightly goosing throttle (not WOT). Test time is about 2-3 minutes. To interpret codes retrieved from test, refer to CYLINDER BALANCE TEST SERVICE CODES table. If Code 90 is present, original fault is in ignition system. If Code 90 is not present, go to step 8).

CYLINDER BALANCE TEST SERVICE CODES

7) Check Injector & Circuit Resistance (MFI) Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance of injector bank No. 1 between test pins No. 37 and 58 at breakout box. Also, measure resistance of injector bank No. 2 between test pins No. 37 and 59 at breakout box. Record resistances. Refer to INJECTOR BANK RESISTANCE (MFI) table in this circuit test. If each resistance is within specification, go to step 12). If resistance is not as specified, go to step 9).

8) Check Injector & Circuit Resistance (SFI) Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure and record resistance between suspected injector circuit test pin and test pin No. 37. (Scheme 31)and (Scheme 32). Refer to INDIVIDUAL INJECTOR RESISTANCE table in this circuit test. If each resistance is within specification, go to step 12). If resistance is not as specified, go to next step.

INDIVIDUAL INJECTOR RESISTANCE

9) Check Continuity Of Fuel Injector Circuit Turn ignition off. Disconnect suspect injector wiring harness connector at injector. Measure resistance between test pins No. 37 and 57 at breakout box and each injector VPWR terminal at wiring harness connector. (Scheme 31)and (Scheme 32). Measure resistance between injector test pin(s) at breakout box and same injector circuit terminal at each injector wiring harness connector. If each resistance is less than 5 ohms, go to next step. If each resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components and drive vehicle for 5 miles at 55 MPH. Repeat QUICK TEST.

10) Check Injector Circuit For Short To Power Or Ground Turn ignition off. With breakout box installed and PCM disconnected, disconnect suspect fuel injector wiring harness connector. Measure resistance between injector test pin(s) and test pins No. 37, 40, 46, 57 and 60. Also, measure resistance between injector test pin(s) at breakout box and chassis ground. If each resistance is 10,000 ohms or more, replace injector per cylinder balance test service code and repeat QUICK TEST (SFI) or go to next step (MFI). If each resistance is less than 10,000 ohms, repair short. Remove breakout box, reconnect all components and drive vehicle for 5 miles at 55 MPH. Repeat QUICK TEST.

11) Isolate Faulty Injector Circuit (MFI) Turn ignition off. With PCM disconnected, disconnect all injectors on suspect bank. Connect one injector and measure resistance between test pins No. 37 and 58 (injector bank No. 1) or 59 (injector bank No. 2). Disconnect injector, and repeat process for all other injectors. See INDIVIDUAL INJECTOR RESISTANCE table. If all injectors are within specification, go to next step. If injectors are not as specified, replace injector. Remove breakout box, and reconnect components. Drive vehicle for 5 miles at 55 MPH. Repeat QUICK TEST.

12) Check Injector Drive Signal With ignition off, connect PCM to breakout box. Use a non-powered 12-volt test light, and connect as follows

1. MFI Connect test light between test pins No. 37 and 58 at breakout box. Connect light between test pins No. 37 and 59 at breakout box.
2. SFI Connect test light between test pin No. 37 and suspect injector test pin at breakout box.

On all models, crank or start engine. If test light glows dimly, system is operating correctly. Clean injectors, and drive vehicle for 5 miles at 55 MPH. Repeat QUICK TEST and CYLINDER BALANCE TEST. If test light does not glow dimly (no light/bright light), replace PCM. Reconnect all components, and drive vehicle for 5 miles at 55 MPH. Repeat QUICK TEST.

When ignition switch is in the ON or START position, the PCM connects FUEL PUMP circuit (PCM terminal No. 22) to ground. The fuel pump relay is energized and electrical current flows to the fuel pump. If PCM does not receive ignition PIP signal within 2 seconds, FUEL PUMP circuit is opened and fuel pump operation is terminated. Perform this test when instructed by QUICK TEST or CIRCUIT TEST AA. This test is only intended to diagnose

1. Fuel pump relay.
2. Inertia Fuel Shutoff (IFS) switch.
3. Wiring harness circuits (B+, VPWR, FUEL PUMP, GND and POWER-TO-PUMP).
4. Faulty Powertrain Control Module (PCM).

Fuel Pump Monitor Circuit Diagram (J3 - Probe). Scheme 33

1) Code 556: Check VPWR To Fuel Pump Relay Code 556 indicates a fuel pump primary circuit failure. Possible causes for this fault are

1. IFS switch not reset or circuit open.
2. Open or shorted circuit.
3. Faulty fuel pump relay.
4. Faulty PCM.

Disconnect fuel pump relay. Turn ignition on. Measure voltage between chassis ground and VPWR circuit at fuel pump relay wiring harness connector. If reading is 10.5 volts or more, go to next step. If reading is less than 10.5 volts, verify IFS switch is in ON position. If switch is okay, repair open in VPWR circuit between EEC power relay and fuel pump relay. Connect fuel pump relay and repeat QUICK TEST.

2) Check Fuel Pump Relay Turn ignition off. Disconnect fuel pump relay. Set DVOM on 200-ohm scale. On ISO relays, measure resistance between terminals No. 85 and 86. (Scheme 34) On all other relays, measure resistance between VPWR pin and FUEL PUMP circuit pin at fuel pump relay. On all relays, both readings should be 40-85 ohms. Set DVOM to 10-k/ohm scale. On ISO relays, measure resistance between terminal No. 85 and terminals No. 30 and 87. On all other relays, measure resistance between FUEL PUMP circuit terminal and both POWER-TO-PUMP and B+ pins at fuel pump relay. On all relays, if all readings are more than 10,000 ohms, go to next step. If any reading is 10,000 ohms or less, replace fuel pump relay and repeat QUICK TEST.

Fuel Pump Relay Connector Terminal ID (J4). Scheme 34

3) Check For Short To Power Turn ignition off. Disconnect fuel pump relay. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Measure voltage between test pin No. 22 and negative battery terminal. If voltage is less than 1.0 volt, go to next step. If voltage is 1.0 volt or more, repair short circuit. Remove breakout box and reconnect all components. Attempt to start vehicle. If vehicle fails to start, replace PCM and repeat QUICK TEST.

4) Check For Shorts To Ground Turn ignition off. Leave fuel pump relay and PCM disconnected. Measure resistance between test pin No. 22 and test pins No. 40 and 60 at breakout box. If resistance is 10,000 ohms or less, repair short circuit and repeat QUICK TEST. If resistance is 10,000 ohms or more, go to next step.

5) Check Fuel Pump Circuit Continuity Turn ignition off. Leave fuel pump relay and PCM disconnected. Measure resistance between FUEL PUMP circuit at fuel pump relay vehicle wiring harness connector and test pin No. 22 at breakout box. If resistance is less than 5 ohms, replace PCM. Reconnect fuel pump relay and repeat QUICK TEST. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 5) to step 10). No test procedures have been omitted.

10) Code 542 A KOEO Code 542 indicates one of the following conditions

Due to internal circuitry of PCM, a left/front HO2S signal short to power could produce a Code 542 or 543.

25) Check Left/Front HO2S Sensor For Short To Power Turn ignition off. Disconnect left or front HO2S sensor. Measure resistance between HO2S SIGNAL terminal and KEY POWER terminal at HO2S sensor wiring harness connector. If resistance is more than 10,000, go to next step. If resistance is 10,000 ohms or less, replace HO2S sensor. Clear KAM, and repeat QUICK TEST.

HO2S Sensor Connector (J6). Scheme 35

HO2S Sensor Wiring Harness Connector (J7). Scheme 36

26) Check HO2S Circuit For Short To Power Turn ignition off. Leave left or front HO2S sensor disconnected. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Turn ignition on. Measure voltage between HO2S SIGNAL at HO2S wiring harness connector and chassis ground. If voltage is less than 2 volts, replace PCM. Reconnect HO2S and repeat QUICK TEST. If voltage is 2 volts or more, repair short circuit. Reconnect components, clear KAM, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 26) to step 90). No test procedures have been omitted.

90) Continuous Memory Code 542 Code 542 indicates one of the following conditions

1. Faulty ground circuit at fuel pump.
2. FPM or POWER-TO-PUMP circuit short to power.
3. IFS switch not reset.
4. Fuel pump relay contacts stuck closed.
5. Open circuit in or between fuel pump and FPM circuit at PCM.
6. Left or front HO2S circuit short to power (dual HO2S system).
7. FUEL PUMP circuit is activated at a time that is not programmed into PCM strategy.
8. Engine stall due to excessive load.

Start engine. Check for engine miss or intermittent fuel pump deactivation while performing following

1. Shake and bend POWER-TO-PUMP circuit wiring harness connector between fuel pump relay and fuel pump.
2. Shake and bend fuel pump ground circuit between fuel pump and ground.
3. Lightly tap fuel pump to simulate road shock.
4. Lightly tap IFS switch to simulate road shock.

Turn ignition off. Check fuel pump harness connector and fuel pump ground for corrosion and damage. Isolate and repair any faults. Clear continuous memory, and repeat QUICK TEST. If no faults are found, go to next step.

91) Check FPM Circuit Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Connect test light between test pin No. 8 and test pin No. 37 at breakout box. With test light lit, perform wiggle test on FPM circuit between fuel pump and PCM. Light will go out if fault is found, indicating an open circuit. If a fault is found, repair as necessary. Remove breakout box, reconnect all components, and repeat QUICK TEST. If no fault is found, go to next step.

92) Check For Shorts To Power Connect a test light between breakout box test pin No. 8 and test pin No. 40. Test light should be off. Observe test light while bending and shaking FPM circuit and POWER-TO-PUMP circuit. Lightly tap fuel pump relay to simulate road shock. Fault is indicated if test light comes on. Isolate and repair fault as necessary, and repeat QUICK TEST. If no fault is found, go to step 96) (dual HO2S) or step 99) (single HO2S).

93) Continuous Memory Code 543: Check For Continuous Memory Code 556 If Code 556 is present, go to step 95). If Code 556 is not present, go to next step.

94) Check EEC-IV Harness A Continuous Memory Code 543, without an accompanying Continuous Memory Code 556, indicates one of the following conditions has occurred during vehicle operation

1. An open in B+ circuit between B+ and fuel pump relay.
2. Fuel pump relay contacts open.
3. Open in POWER-TO-PUMP circuit between fuel pump relay to FPM splice (if applicable).
4. Left/front HO2S circuit short to power (dual HO2S).

Start engine. Check for engine miss or intermittent fuel pump deactivation while performing the following

1. Shake and bend B+ circuit wiring harness between power source and fuel pump relay.
2. Shake and bend POWER-TO-PUMP circuit wiring harness connector between fuel pump relay and FPM splice (if applicable).
3. Lightly tap fuel pump relay to simulate road shock.

Turn ignition off. Inspect all fuel pump relay and B+ connectors for damage and corrosion. If fault is found, repair as necessary. Clear continuous memory and repeat QUICK TEST. If no fault is found, a Continuous Memory Code 543 may have been set without a Continuous Memory Code 556, even though a fault has occurred in fuel pump primary circuit. Go to next step for fuel pump primary circuit check.

95) Continuous Memory Code 556: Check EEC-IV Harness Continuous Memory Code 556 indicates primary fuel pump circuit has failed during vehicle operation. Possible causes for this fault are

1. Open in VPWR circuit between EEC power relay and fuel pump relay.
2. Open coil in fuel pump relay.
3. Open in fuel pump circuit (pin No. 22).
4. Faulty IFS switch.

Start engine. Check for engine miss or intermittent fuel pump deactivation while performing the following

1. Shake and bend VPWR circuit wiring harness between EEC and fuel pump relay.
2. Shake and bend FP circuit wiring harness connector between fuel pump relay and PCM.
3. Lightly tap fuel pump relay to simulate road shock.
4. Lightly tap IFS switch to simulate road shock (if equipped).

Turn ignition off. Inspect PCM connector and fuel pump relay connectors for damaged pins, corrosion and loose wires. Repair as necessary. Clear continuous memory and repeat QUICK TEST. If connectors and wires are okay, but Code 543 is found, go to next step (dual HO2S). If fault cannot be duplicated at this time, go to step 99) (all others).

Due to internal circuitry of PCM, an intermittent left/front HO2S signal short to power could produce a Continuous Memory Code 542 or 543.

96) Check Left/Front HO2S Circuit For Short To Power Turn ignition off. Breakout box should be installed with PCM disconnected. Connect test light between left/front HO2S test pin and pin No. 40 at breakout box. See CIRCUIT TEST H for left/front HO2S test pin identification. Test light should be off. Observe test light while bending and shaking left/front HO2S circuit from HO2S sensor to PCM. Lightly tap HO2S SENSOR to simulate road shock. Fault is indicated if test light comes on. Isolate and repair as necessary. Remove breakout box, reconnect all components, and repeat QUICK TEST. If no fault is indicated, go to step 99).

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 96) to step 99). No test procedures have been omitted.

99) Road Test Vehicle Purpose of this test is to identify faults by monitoring certain controlled parameters while trying to recreate a drive-ability or MIL symptom. To prepare for road test

1. Install fuel pressure gauge and if available, a MAP/BARO tester.
2. Disconnect PCM 60-pin connector, install breakout box and reconnect PCM to breakout box.
3. Connect "T" vacuum gauge into manifold vacuum line.
4. Have DVOM, writing materials and appropriate schematics and pin voltage charts available.

With ignition on and negative lead of DVOM connected to negative battery terminal, ensure following signals are correct

1. POWERS: KAPWR (pin No. 1) is greater than 10.5 volts, VPWR (pins No. 37 and 57) is greater than 10.5 volts and VREF (pin No. 26) is 4-6 volts.
2. GROUNDS: PWR GND (pins No. 40 and 60), SIG RTN (pin No. 46) and IGN GND (pin No. 16) are 0.0-0.5 volt.
3. OPTIONAL GROUNDS: HO2S GND (pin No. 49), CSE GND (pin No. 20) and MAF RTN (pin No. 9 or 15) are 0.0-0.5 volt.

Test lights and DVOM are useful during diagnosis. For example: with Continuous Memory Code 556 (fuel pump primary circuit failure) and a surge or stall symptom, connect a test light to fuel pump relay between VPWR and ground. Connect DVOM between FP circuit at fuel pump relay and breakout box test pin No. 1. Under normal driving conditions, test light will be on and DVOM will read battery voltage. If vehicle stalls, PCM will open FP circuit and DVOM voltage will be low. If fault is in fuel pump circuit, test light and DVOM status will change as fault occurs. If test light at VPWR circuit goes out, fault is in VPWR circuit to fuel pump relay. If test light and DVOM status do not change and Continuous Memory Code 556 is set again, replace fuel pump relay. If only FP voltage goes low, fault is in FP circuit or PCM. To diagnose FP circuit and PCM, connect DVOM between breakout box test pin No. 1 and 22. If voltage goes low as symptom occurs, replace PCM. If voltage stays high as symptom occurs, fault is in FP circuit. For fuel pump secondary circuit Codes 542 and 543, circuits B+, POWER-TO-PUMP and FPM can be diagnosed using same procedure. Drive vehicle and attempt to induce symptom.

Information provided by vehicle operator may help when trying to recreate symptom. When symptom occurs, assistant should observe and record changes in voltage signals. Information about symptom and operating condition value of voltage signal and any other information available should be recorded for analysis. If unable to duplicate symptom during road test, verify EEC-IV values are within acceptable range. After test is completed, analyze results to locate and repair fault causing symptom. If problem cannot be identified, proceed to TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section for other possible causes of symptom.

Perform this test when instructed by QUICK TEST. To prevent replacement of good components, be aware the following non-EEC related areas may be at fault

1. Damaged vacuum hoses.
2. Damaged EGR Pressure Transducer (EPT).
3. EGR valve.

This test is only intended to diagnose

1. EGR Vacuum Regulator (EVR) solenoid.
2. PCM.
3. Wiring harness circuits (EVR and VPWR).

EVR solenoid regulates vacuum to EGR valve by way of EPT. When energized, EVR opens a port between manifold vacuum and EGR valve. When not energized, EVR closes port to EGR and vacuum is vented to atmosphere.

EGR Valve Regulator (EVR) Sol. Ckts. & Conn. Term. ID (KA1). Scheme 37

1) KOEO Code 558 Code 558 indicates failure in EVR solenoid circuit. Possible causes for this fault are

1. Faulty EVR solenoid.
2. Faulty vacuum hoses.
3. Open or short circuit in wiring harness.
4. Faulty Powertrain Control Module (PCM).

Turn ignition off. Remove scan tester (if applicable). Disconnect cruise control servo wiring harness connector. Connect DVOM negative lead to STO terminal at Data Link Connector (DLC). Connect positive lead to positive battery terminal. Connect a jumper wire between STI terminal and SIG RTN terminal at DLC. (Scheme 14) Perform KOEO SELF-TEST until continuous memory test is complete. DVOM will read less than 1.0 volt when test is complete to indicate PCM has entered OUTPUT STATE CHECK. Depress and release throttle. If voltage does not increase, fully apply throttle and release. If STO voltage remains low, go to CIRCUIT TEST QC. If voltage increases, remain in OUTPUT STATE CHECK and go to next step.

2) Check EVR Solenoid Electrical Turn ignition off. Disconnect EVR solenoid wiring harness connector. Connect DVOM positive lead to VPWR terminal and negative test lead to EVR terminal at EVR solenoid vehicle wiring harness connector. Depress and release throttle 3-5 times to cycle solenoid output. If EVR solenoid voltage output change is 0.5 volt or more, go to next step. If EVR solenoid voltage output change is less than 0.5 volt, go to step 5).

3) Check EVR Solenoid Vacuum Turn ignition on. Disconnect EVR solenoid vacuum hoses. Install vacuum pump on EVR solenoid vacuum input port. Install vacuum gauge on solenoid output port. Apply 6 in. Hg, and hold. Depress and release throttle 3-5 times to cycle solenoid output. Turn ignition off. If vacuum gauge shows vacuum cycling at output port, go to next step. If vacuum gauge does not show vacuum cycling at output port, replace EVR solenoid. Remove jumper wire, vacuum pump and gauge. Repeat QUICK TEST.

4) Check EVR Vacuum Hoses Remove jumper wire, vacuum pump and gauge. Remove vacuum hoses individually. Plug one end of hose. Connect vacuum pump at opposite end. Apply vacuum and observe gauge. If vacuum is not held, replace hose and repeat QUICK TEST. If vacuum is held, ensure vacuum port between EPT and EGR is not restricted. If vacuum port is clear, go to next step.

5) Check EVR Solenoid VPWR Turn ignition off. Disconnect EVR solenoid wiring harness connector. Turn ignition on. Measure voltage between negative battery terminal and VPWR terminal at EVR solenoid vehicle wiring harness connector. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open VPWR circuit and repeat QUICK TEST.

6) Check EVR Solenoid Circuit Continuity Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between EVR terminal at EVR solenoid wiring harness connector and test pin No. 31. If reading is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

7) Check EVR Solenoid Circuit For Short Turn ignition off. Leave EVR solenoid disconnected. Measure resistance between test pin No. 31 and test pins No. 37 and 57 at breakout box. Also, measure resistance between test pin No. 31 and test pins No. 40, 46 and 60 at breakout box. If each resistance is more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

CANP valve is controlled by the PCM. CANP valve is used to regulate the flow of fuel vapors from the EVAP canister to the fuel system. The CANP valve operates on manifold vacuum and a duty cycle from the PCM.

Perform this test when instructed by QUICK TEST. This test is only intended to diagnose

1. CANP valve.
2. Faulty Powertrain Control Module (PCM).
3. Wiring harness circuits (CANP and VPWR).

CANP Valve Schematic (KB1). Scheme 38

CANP Valve Circuit & Connector Terminal ID (KB2). Scheme 39

1) Code 565 Code 565 indicates failure in CANP valve. Possible causes for this fault are

1. Faulty CANP valve.
2. Faulty vacuum hoses.
3. Open or short circuit in wiring harness.
4. Faulty Powertrain Control Module (PCM).

Turn ignition off. Remove scan tester (if applicable). Disconnect cruise control servo wiring harness connector (if equipped). Connect DVOM negative lead to STO terminal at Data Link Connector (DLC). Connect positive lead to positive battery terminal. Install a jumper wire between STI terminal and SIG RTN terminal at DLC. (Scheme 14) Perform KOEO SELF-TEST until continuous memory test is complete. DVOM will read less than 1.0 volt when test is complete to indicate PCM has entered OUTPUT STATE CHECK. Fully apply and release throttle. If voltage does not increase, fully apply throttle and release. If voltage remains low, fully apply and release throttle. If voltage does not increase, go to CIRCUIT TEST QC. If voltage increases, remain in OUTPUT STATE CHECK and go to next.

2) Check CANP Valve Electrical Turn ignition off. Remove CANP valve wiring harness connector. Connect DVOM positive lead to VPWR terminal and negative test lead to CANP terminal at CANP valve vehicle wiring harness connector. Depress and release throttle 3-5 times to cycle voltage output. If voltage output change is 0.5 volt or more, go to next step. If EVR solenoid voltage output change is less than 0.5 volt, go to step 7).

3) Measure CANP Valve Resistance Leave ignition off and CANP valve connector disconnected. Measure resistance between connector terminals. If resistance is not 30-36 ohms, replace CANP valve and repeat QUICK TEST. If resistance is 30-36 ohms, go to next step.

4) Check CANP Valve For Vacuum Leaks Leave CANP valve connector disconnected. Remove vacuum hose from input port of CANP valve. Using a vacuum pump, apply 16 in. Hg to input port. Replace valve if it does not hold vacuum for 20 seconds. If valve holds vacuum for 20 seconds, go to next step.

5) Check CANP Valve Electrical/Mechanical Reconnect CANP valve connector. Ensure 16 in. Hg is applied to input port. Fully apply and release throttle. If vacuum is not released, replace CANP valve and repeat QUICK TEST. If vacuum is released, remove jumper wire between SIG RTN and STI terminals of DLC. Go to next step.

6) Check Vacuum At CANP Valve Input Port Leave CANP valve wiring harness connected. Start engine and allow to idle. Remove CANP valve vacuum input hose. If vacuum is not present at hose, check hose for blockage, leaking or incorrect routing. If vacuum is present at hose, EEC system is okay. Testing is complete.

7) Check VPWR Circuit Voltage Leave CANP valve wiring harness disconnected. Turn ignition on. Measure voltage between negative battery terminal and terminal VPWR at CANP valve vehicle wiring harness connector. If more than 10.5 volts is present, go to next step. If 10.5 or less volts is present, repair open circuit. Repeat QUICK TEST.

8) Check CANP Circuit Continuity Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 11 and CANP terminal of CANP valve vehicle wiring harness connector. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If resistance is less than 5 ohms, go to next step.

9) Check For CANP Circuit Short To Power Leave ignition off and CANP valve connector disconnected. Measure resistance between breakout box test pin No. 11 and pins No. 37 and 57. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are 10,000 ohms or more, go to next step.

10) Check For Short To Ground Leave ignition off and CANP valve connector disconnected. Measure resistance between breakout box test pin No. 11 and pins No. 40, 46 and 60. If any reading is less than 10,000 ohms, repair short to ground. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are 10,000 ohms or more, replace PCM and repeat QUICK TEST.

PCM uses secondary air injection solenoids to control Air Injection By-pass (AIRB) and Air Injection Diverter (AIRD) valves. AIRB and AIRD are used to direct air to either engine or exhaust system.

Perform this test when instructed by QUICK TEST or if directed by other test procedures. This test is only intended to diagnose

1. AIRB/AIRD solenoid valve assembly.
2. Wiring harness circuits (AIRB, AIRD and VPWR).
3. Vacuum supply.
4. Powertrain Control Module (PCM).

To prevent replacement of good components, be aware the following non-EEC related areas may be at fault

1. Secondary air injection system (belt, pump, valve or reservoir).
2. Blocked or restricted secondary air passages in engine.

1) Codes 311 & 314 Code 311 or 314 indicates that secondary air injection system is inoperative. Code 312 indicates that secondary air is incorrectly routed. Code 313 indicates that secondary air is not by-passed when directed. Possible causes for these faults are

1. Vacuum hoses leaking, blocked or kinked.
2. AIRB/AIRD valve inoperative.
3. Defective AIRB/AIRD solenoids.
4. Defective air pump.

Check for correct vacuum hose routing to AIRB/AIRD solenoids and by-pass diverter valve. See Vehicle Emission Control Information (VECI) label. Check for kinked or blocked vacuum hoses. Check for kinked or blocked air hoses. Check for disconnected vacuum hoses. Also, check for loose or broken air pump belt (if equipped). If faults are detected, repair as necessary and repeat QUICK TEST. If no faults are detected and Code 311 or 314 is present, go to step 4). If Code 313 is present, go to step 3). If Code 312 is present, go to next step.

2) Attempt To Eliminate Code 312 Disconnect and plug vacuum hose at AIRD valve. Repeat KOER SELF-TEST. If Code 312 is present, EEC-IV system is okay. Inspect diverter valve and check valve for faults. If Code 312 is not present, go to step 4).

3) Attempt To Eliminate Code 313 Disconnect and plug vacuum hose at by-pass valve. Repeat KOER SELF-TEST. If Code 313 is present, EEC-IV system is okay. Check by-pass valve for problem. If Code 313 is not present, go to next step.

4) OUTPUT STATE CHECK Use only a VOM or DVOM for this step. DO NOT use scan tester. Turn ignition off. Disconnect cruise control servo (if equipped). With DVOM on 20-volt scale, connect DVOM negative lead to STO terminal at Data Link Connector (DLC). Connect positive lead to positive battery terminal. Using jumper wire, connect STI to SIG RTN at DLC. (Scheme 14) Perform KOEO SELF-TEST until continuous memory test is complete. DVOM will read less than 1.0 volt when test is complete. Depress and release throttle. If voltage increases, OUTPUT STATE CHECK has been entered. Go to next step. If voltage does not increase, depress throttle to WOT and release. If STO voltage does not increase, go to CIRCUIT TEST QC.

5) Check Solenoid Electrical Operation Set DVOM on 20-volt scale. Disconnect AIRB/AIRD solenoids. Connect DVOM positive lead to VPWR terminal and negative lead to AIRB terminal at AIRB solenoid wiring harness connector. While observing DVOM, depress and release throttle several times to cycle output on and off. Repeat test for AIRD solenoid. Connect DVOM positive lead to VPWR terminal and negative test lead to AIRD terminal on AIRD solenoid wiring harness connector. Cycle AIRD solenoid on and off. If either solenoid does not cycle more than 0.5 volt, remove jumper and go to step 9). If both solenoids cycle more than 0.5 volt, stay in OUTPUT STATE CHECK. Reconnect solenoids and go to next step .

6) Check Solenoids For Vacuum Cycling Connect vacuum pump to solenoid vacuum supply port. Connect vacuum gauge to output port. Maintain 15 in. Hg at vacuum source while depressing and releasing throttle to cycle output on and off. Observe vacuum gauge. Repeat for other solenoid. If either output does not cycle on and off, replace solenoid assembly and repeat QUICK TEST. If both outputs cycle on and off, go to next step.

7) Check Solenoids For Internal Vacuum Leaks Connect a vacuum pump to AIRB solenoid input port. Connect a vacuum gauge to AIRB solenoid output port. Apply 15 in. Hg at vacuum source. Observe gauge while depressing and releasing throttle to cycle output on and off. Repeat test for AIRD solenoid. If solenoids cycle on and off, fault is in secondary air injection system (belt, pump, valve or reservoir). If solenoids do not cycle on and off, replace solenoid assembly and repeat QUICK TEST.

8) Codes 552 & 553 Codes 552 and 553 indicate voltage output for secondary air injection solenoid did not change when activated. Possible causes for this fault are

1. AIRB/AIRD circuit(s) shorted or open.
2. Fault in solenoid or PCM.

Disconnect both solenoid connectors. Turn ignition on. Measure voltage between VPWR terminal of wiring harness connector and negative battery terminal for both solenoids. If either voltage reading is less than 10.5 volts, repair wiring harness open circuit, and repeat QUICK TEST. If both readings are 10.5 volts or more, go to next step.

9) Measure Solenoid Resistance Turn ignition off. Leave solenoid connectors disconnected. Measure resistance of both solenoids. If either reading is not 50-100 ohms, replace solenoid assembly and repeat QUICK TEST. If both readings are 50-100 ohms, go to next step.

10) Check Circuit Continuity Leave ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 31 and AIRB terminal at wiring harness connector. If either reading is 5 ohms or more, repair open circuit and repeat QUICK TEST. If both readings are less than 5 ohms, go to next step.

11) Check For Short To Ground Leave ignition off and solenoids disconnected. Measure resistance between breakout box test pin No. 31 and pins No. 40, 46 and 60. If any reading is less than 10,000 ohms, repair short to ground. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are 10,000 ohms or more, go to next step.

12) Check For Shorts To Power Circuit Turn ignition off. Measure resistance between breakout box pin No. 31 and test pins No. 37 and 57. If any resistance is less than 10,000 ohms, repair short to power. Remove breakout box, reconnect all components, and repeat QUICK TEST. If code is repeated, replace PCM. If all resistances are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Perform this test when instructed by QUICK TEST or if directed by other test procedures. This test is only intended to diagnose

1. CANP solenoid.
2. Harness circuits (CANP and VPWR).
3. Powertrain Control Module (PCM).

Canister Purge (CANP) Circuit (KD1 - 2.0L). Scheme 40

TEST PIN NO. 11, 15 OR 31 (CANP) WIRE COLOR ID

TEST PINS NO. 37 & 57 (VPWR) WIRE COLOR ID

1) Enter OUTPUT STATE CHECK Use only VOM or DVOM for this step. DO NOT use scan tester. Turn ignition off. Disconnect cruise control servo wiring harness connector. Connect DVOM negative lead to STO terminal at Data Link Connector (DLC). Connect positive lead to positive battery terminal. Install a jumper wire between STI terminal and SIG RTN terminal at DLC. (Scheme 14) Perform KOEO SELF-TEST until continuous memory test is complete. DVOM will read less than 1.0 volt when test is complete to indicate PCM has entered OUTPUT STATE CHECK. Depress and release throttle. If voltage increases, remain in OUTPUT STATE CHECK and go to next step. If voltage does not increase, depress throttle to WOT and release. If STO voltage does not increase, leave test equipment hooked up and go to CIRCUIT TEST QC.

2) Check CANP Solenoid Electrical Function Turn ignition on. Disconnect CANP solenoid. Connect DVOM positive test lead to VPWR terminal and negative test lead to CANP terminal at solenoid wiring harness connector. While observing DVOM, depress and release throttle several times to cycle output on and off. If CANP circuit voltage does not cycle 0.5 volt or more, remove jumper wire and go to step 7). If CANP circuit voltage cycles, remain in OUTPUT STATE CHECK and go to next step.

3) Check Solenoid For Vacuum Leaks Turn ignition on. Leave CANP solenoid disconnected. Disconnect vacuum hose at CANP solenoid from manifold vacuum side of solenoid. Apply 16 in. Hg vacuum to manifold vacuum side of CANP solenoid. If CANP solenoid does not hold vacuum for 20 seconds, replace solenoid and repeat QUICK TEST. If fault is still present, service fuel evaporation canister or hoses. If CANP holds vacuum for 20 seconds, remain in OUTPUT STATE CHECK, leave vacuum pump attached and go to next step.

4) Check Solenoid Mechanical Operation Connect CANP solenoid connector. Apply 16 in. Hg vacuum to manifold vacuum side of CANP solenoid. Depress and release throttle. If vacuum is released, check hose from CANP solenoid to canister for leaks and cracks. If hose is okay, remove jumper wire from STI to SIG RTN and go to next step. If vacuum is not released, check hose from CANP solenoid to canister for blockage or kinks. If hose is okay, replace CANP solenoid and repeat QUICK TEST.

5) Check Vacuum Supply To CANP Solenoid Disconnect vacuum hose from CANP solenoid on manifold vacuum side. Start engine. If vacuum is present at vacuum hose, engine control system is okay. Check evaporative canister. If vacuum is not present at hose, check vacuum hose for improper routing, kinks and blockage. If hose is okay, check engine for mechanical cause of low vacuum.

6) Code 565 Or 569: Check CANP Solenoid Resistance Code 565 or 569 indicates fault in CANP solenoid circuit. Possible causes for this fault are

1. Faulty CANP solenoid.
2. Open or short circuit in wiring harness circuit.
3. Faulty PCM.

Turn ignition off. Disconnect CANP solenoid connector. Measure CANP solenoid resistance. If resistance is 30-90 ohms, go to next step. If resistance is not 30-90 ohms, replace CANP solenoid and repeat QUICK TEST.

7) Check Voltage Of VPWR Circuit With CANP solenoid disconnected, turn ignition on. Measure voltage between VPWR terminal at CANP solenoid vehicle harness connector and negative battery terminal. If reading is more than 10.5 volts, go to next step. If reading is 10.5 volts or less, repair open circuit and repeat QUICK TEST.

8) Check Continuity Of CANP Circuit Turn ignition off. Disconnect CANP solenoid. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between CANP circuit breakout box test pin (No. 11, 15 or 31) and CANP harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

9) Check CANP Circuit For Short To Ground Turn ignition off. Disconnect scan tester from DLC, if applicable. With CANP solenoid disconnected, measure resistance between CANP circuit breakout box test pin (No. 11, 15 or 31) and pins No. 40, 46 and 60. If all readings are more than 10,000 ohms, go to next step. If any reading is 10,000 ohms or less, repair short to ground. Remove breakout box, reconnect all components, and repeat QUICK TEST.

10) Check CANP Circuit For Short To Power Turn ignition off. With CANP solenoid and PCM disconnected, measure resistance between CANP circuit breakout box test pin (No. 11, 15 or 31) and test pins No. 37 and 57. If all readings are more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If any reading is 10,000 ohms or less, repair short to power. Remove breakout box, reconnect all components, and repeat QUICK TEST.

The IAC solenoid controls engine idle speed and dashpot functions by regulating the volume of air by-passing the throttle plate. IAC solenoid positioning is determined by signals sent from the PCM. A thermowax material is built into the unit to aid operation of IAC solenoid.

Perform this test when instructed by QUICK TEST or if directed by other test procedures. This test is intended to diagnose

1. RPM during SELF-TEST mode.
2. IAC solenoid.
3. Wiring harness circuits (IAC and VPWR).
4. Powertrain Control Module (PCM).

To prevent replacement of good components, be aware the following non-EEC related areas may be at fault

1. Engine temperature outside correct operating range.
2. A/C input (electrical problem).
3. Incorrect throttle stop adjustment.
4. Faulty throttle or cruise control linkage.

Idle Air Control Circuit (KE1 - 2.0L). Scheme 41

TEST PIN NO. 21 (IAC) WIRE COLOR IDENTIFICATION

TEST PINS NO. 37 & 57 (VPWR) WIRE COLOR IDENTIFICATION

1) Code 412: Check For RPM Drop Code 412 indicates engine RPM could not be controlled within upper RPM limit during KOER SELF-TEST. Possible causes for this fault are

1. Open or shorted circuit.
2. Sticking or binding throttle linkage.
3. Incorrect idle airflow setting.
4. Throttle body or IAC solenoid contaminated.
5. Faulty IAC solenoid.
6. Faulty PCM.
7. Mechanical faults unrelated to EEC-IV which could affect RPM.

Turn ignition off. Connect tachometer to engine. Start engine. Disconnect Idle Air Control (IAC) harness. If RPM drops or engine stalls, go to next step. If RPM does not drop or engine does not stall, go to step 3).

2) Check For EGR Codes If EGR service Code 213, 232, 326, 327, 328, 332, 334 or 336 is displayed, reconnect IAC solenoid. Go to appropriate KOER SELF-TEST. See DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS. If these codes are not displayed, go to next step.

3) Check For Other Diagnostic Test Codes If Code 126, 136, 137, 172 or 173 is displayed, reconnect IAC solenoid. Go to appropriate KOER SELF-TEST. See DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS. If these codes are not displayed, go to next step.

4) Measure IAC Solenoid Resistance Turn ignition off. Disconnect IAC solenoid. Connect DVOM positive lead to VPWR terminal and negative lead to IAC terminal. (Scheme 42) Measure resistance of IAC solenoid. If resistance is not 6-13 ohms, replace IAC solenoid and repeat QUICK TEST. If resistance is 6-13 ohms, go to next step.

IAC Solenoid Connector (KE3). Scheme 42

5) Check For Internal Short To IAC Solenoid Case Turn ignition off. With IAC solenoid disconnected, measure resistance from either IAC terminal pin to IAC solenoid housing. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, replace IAC solenoid. Repeat QUICK TEST.

6) Check VPWR Circuit Voltage Leave IAC harness disconnected. Turn ignition on. Measure voltage between VPWR terminal at IAC vehicle harness connector and negative battery terminal. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in circuit and repeat QUICK TEST.

7) Check IAC Circuit Continuity Turn ignition off. Leave IAC solenoid disconnected. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 21 and IAC terminal at IAC vehicle wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST.

8) Check IAC Circuit For Short To Ground Turn ignition off. Leave IAC solenoid and PCM disconnected. Measure resistance between test pin No. 21 and test pins No. 40, 46 and 60. If any reading is 10,000 ohms or less, repair short to ground. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are more than 10,000 ohms, go to next step.

9) Check IAC Circuit For Short To Power Leave IAC solenoid and PCM disconnected. Turn ignition on. Measure voltage between breakout box test pin No. 21 and chassis ground. If voltage is 1.0 volt or more, repair short circuit and repeat QUICK TEST. If code or symptom is still present, replace PCM. If voltage is lee than 1.0 volt, go to next step.

10) Check IAC Signal From PCM Turn ignition off. Reconnect IAC solenoid. Connect PCM to breakout box. Connect DVOM between test pins No. 21 and 40 at breakout box. Start engine. Observe DVOM while slowly increasing engine speed to 3000 RPM. If voltage is 3.0-11.5 volts, go to next step. If voltage is not 3.0-11.5 volts, remove IAC solenoid to confirm that it is not stuck open. If IAC is okay, replace PCM and repeat QUICK TEST.

11) Check Base Idle Verify base idle speed is correct. See appropriate ADJUSTMENTS - 4-CYL article in the ENGINE PERFORMANCE section. If base idle speed is within specification, remove IAC solenoid and inspect for contamination. Clean or replace solenoid as necessary. Repeat QUICK TEST. If code or symptom is still present, replace IAC solenoid. If base idle speed is not correct, reset idle speed to specification. Repeat QUICK TEST. If unable to set idle to specification, go to next step.

12) Check For Faults Affecting Idle Speed Check following mechanical items for faults

1. Throttle linkage and/or cruise control linkage (sticking or binding).
2. Throttle body (contamination).
3. Vacuum hoses. Check Vehicle Emission Control Information (VECI) label.
4. Check for leaks around IAC solenoid (gaskets, etc.).

If any of these items are faulty, service as necessary, and repeat QUICK TEST. If all of these items are okay, remove IAC solenoid and inspect for contamination. Clean or replace solenoid as necessary. Repeat QUICK TEST. If code or symptom is still present, replace IAC solenoid. Repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 15). No test procedures have been omitted.

15) Code 411 Code 411 indicates engine RPM could not be controlled within lower RPM limit during KOER SELF-TEST. Possible causes for this fault are

1. Incorrect idle airflow setting.
2. Vacuum leaks.
3. Sticking or binding throttle linkage.
4. Throttle plates open.
5. Incorrect ignition timing (distributor ignition only).
6. Throttle body or IAC solenoid contamination.
7. IAC circuit shorted to ground.
8. Faulty IAC solenoid.

If above items are okay and idle is set to specification, remove IAC solenoid and inspect for contamination. Repair or replace as necessary. Repeat QUICK TEST. If code or symptom is still present, replace IAC solenoid. If idle speed is not within specification, adjust as necessary and repeat QUICK TEST. If idle speed cannot be set to specification, go to next step.

16) Check For Conditions Affecting Idle Speed Check the following mechanical components

1. Vacuum hoses. Check Vehicle Emission Control Information (VECI).
2. Throttle linkage and/or cruise control linkage (sticking or binding).
3. Ensure throttle plates are fully closed.
4. Induction system (vacuum leaks).
5. Throttle body (contamination).
6. Ensure CANP solenoid is not stuck open.
7. Ensure base ignition timing is to specification on emission decal (distributor ignition only.

If everything checks okay, go to next step. If fault is found, service as necessary and repeat QUICK TEST.

17) Check For Internal Short To IAC Solenoid Case Turn ignition off. Disconnect IAC solenoid wiring harness connector. Measure resistance from either IAC terminal pin to IAC solenoid housing. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, replace IAC solenoid. Repeat QUICK TEST.

18) Check IAC Circuit For Short To Ground Turn ignition off. Leave IAC solenoid disconnected. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 21 and test pins No. 40, 46 and 60. If any reading is 10,000 ohms or less, repair short to ground. Reconnect components, and repeat QUICK TEST. If all readings are more than 10,000 ohms, go to next step.

19) Check IAC Signal From PCM Turn ignition off. Connect PCM to breakout box. Reconnect IAC solenoid. Set DVOM on 20-volt scale. Connect DVOM between test pins No. 21 and 40. Start engine. Observe DVOM while slowly increasing engine speed to 3000 RPM. If voltage is 3.0-11.5 volts, go to next step. Clean or replace IAC solenoid as necessary, and repeat QUICK TEST. If code or symptom is still present, replace IAC solenoid. If voltage is not 3.0-11.5 volts, replace PCM and repeat QUICK TEST.

20) Check For Proper Engine Coolant Flow To Idle Air Control Bypass Air (IAC-BPA) valve. Check the following

1. Verify engine coolant is warming up properly.
2. Check engine coolant level.
3. Check coolant hoses to and from IAC-BPA valve for leaks, blockage and kinks.

If any check is not okay, repair as necessary. Remove breakout box and reconnect PCM. If all checks are okay, remove IAC-BPA valve and inspect it for contamination. Clean or replace IAC-BPA valve as necessary, and repeat QUICK TEST. If code or symptom is still present, replace IAC-BPA valve.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 20) to step 25). No test procedures have been omitted.

25) Lack Of High Idle With Engine Cold: Verify IAC-BPA Valve Is Not Stuck Closed Turn ignition off. Remove IAC-BPA valve from engine. With IAC-BPA valve at room temperature, blow through air passage. Air should flow freely. If air does not flow freely, replace IAC-BPA valve and check system operation. If air flows freely, no problem is indicated at this time. See SYMPTOMS in H - EEC-IV TESTS W/O CODES in the ENGINE PERFORMANCE section.

The PCM controls cooling fan operation through High Fan Control (HFC) and Low Fan Control (LFC) outputs. HFC relay is normally open. LFC is normally open for 2.0L. Perform this test only when directed here by QUICK TEST or a driveability symptom. This test is only intended to diagnose

1. Wiring harness circuits (LFC, HFC, LFC POWER-TO-FAN, HFC POWER-TO-FAN, IGN START/RUN and GND).
2. LFC and HFC relays.
3. Cooling fan.
4. Powertrain Control Module (PCM).

LFC/HFC Circuit (KF2 - 2.0L). Scheme 43

TEST PIN NO. 13 OR 32 (LFC) WIRE COLOR ID

LFC/HFC Circuit Connector Terminal ID (KF3 - 2.0L). Scheme 44

1) Code 563 Or Code 564: Check For Voltage At LFC/HFC Relay Code 563 indicates faulty HFC circuit. Code 564 indicates faulty LFC circuit. Possible causes for these faults are

1. Open or shorted circuit.
2. Faulty fan relay.
3. Faulty PCM.

Turn ignition off. Disconnect LFC and HFC relays. Turn ignition on. Measure voltage between IGNITION START/RUN circuit at LFC/HFC relay vehicle wiring harness connector and chassis ground. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, check fuse/fuse link and circuit to LFC/HFC. Repair as necessary. If fuse/fuse link and circuit are okay, repair open circuit and repeat QUICK TEST.

2) Enter OUTPUT STATE CHECK Use only VOM or DVOM for this step. Turn ignition off. Disconnect cruise control servo wiring harness connector. Connect DVOM negative lead to STO terminal at Data Link Connector (DLC). Connect positive lead to positive battery terminal. Install a jumper wire between STI terminal and SIG RTN terminal at DLC. (Scheme 14) Perform KOEO SELF-TEST until continuous memory test is complete. DVOM will read less than 1.0 volt when test is complete to indicate PCM has entered OUTPUT STATE CHECK. Depress and release throttle. If voltage increases to more than 10.5 volts, stay in OUTPUT STATE CHECK and go to next step. If voltage does not increase to at least 10.5 volts, depress throttle to wide open throttle and release. If STO voltage does not increase to at least 10.5 volts, leave equipment connected and go to CIRCUIT TEST QC, step 2).

3) Check For LFC/HFC Circuit Cycling With vehicle still in OUTPUT STATE CHECK, disconnect LFC or HFC relay. Connect DVOM positive lead to IGNITION START/RUN circuit. Connect negative test lead to LFC or HFC terminal at relay vehicle wiring harness connector. Depress throttle to cycle outputs off. Observe DVOM and depress throttle again. For LFC, wait until CHECK ENGINE light flashes once (about 10 seconds). For HFC, wait until CHECK ENGINE light flashes twice (about 15 seconds). Release throttle. LFC/HFC output is now on. To cycle off output, depress and release throttle. If voltage cycles (about a 1-volt change), replace LFC or HFC relay. Remove jumper wire and repeat QUICK TEST. If voltage does not cycle, remove jumper wire and go to step 5).

Note. A/C Pressure Switch (ACPSW) is also known as A/C high pressure cut-off switch.

4) Verify A/C Pressure Switch Medium Pressure Contacts Are Not Closed While still in OUTPUT STATE CHECK and with HFC relay disconnected, disconnect A/C Pressure Switch (ACPSW). Connect DVOM positive lead to IGNITION START/RUN circuit. Connect negative test lead to HFC terminal at HFC relay vehicle wiring harness connector. Depress throttle to cycle outputs off. Observe DVOM and depress throttle again. Wait until CHECK ENGINE light flashes twice (about 15 seconds). Release throttle. HFC output is now on. To cycle off output, depress and release throttle. If voltage cycles (about a 1-volt change), check ACPSW for closed medium pressure contacts. Replace switch as necessary. If voltage does not cycle, reconnect ACPSW, remove jumper wire and go to next step.

Note. ACPSW switch controls operation of both A/C clutch and engine cooling fan. Contacts for cooling fan portion of ACPSW are normally open. When high side pressure reaches 325 psi (22.9 kg/cm 2 ), switch contacts close. For more information, see A/C-HEATER SYSTEM - MANUAL in the AIR CONDITIONING & HEAT section.

5) Check Continuity Of LFC/HFC Circuit Turn ignition off. Disconnect LFC or HFC relay. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Set DVOM on 200-ohm scale. Perform appropriate following check

1. Code 563 Measure resistance between breakout box HFC test pin and HFC terminal at HFC relay vehicle wiring harness connector.
2. Code 564 Measure resistance between breakout box LFC test pin and LFC terminal at LFC relay vehicle wiring harness connector.

For either code, if resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

6) Check LFC/HFC Circuit For Short To Power Disconnect LFC or HFC relay. Turn ignition on. Measure voltage between breakout box LFC or HFC test pin and negative battery terminal. If voltage is less than 1.0 volt, go to next step. If voltage is 1.0 volt or more, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If code is still present, replace PCM.

7) Check LFC/HFC Circuit For Short To Ground Turn ignition off. Leave PCM and LFC or HFC relay disconnected. Measure resistance between breakout box LFC or HFC test pin and test pins No. 40 and 60. If resistance is more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If resistance is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 7) to step 10). No test procedures have been omitted.

10) Low-Speed (LFC) And/Or High-Speed (HFC) Cooling Fan Does Not Operate Turn ignition off. Disconnect LFC relay. Set DVOM on 20-volt scale. Turn ignition on. Measure voltage between HFC relay terminal at LFC relay vehicle wiring harness connector and negative battery terminal. If voltage is more than 10.5 volts, go to step 13). If voltage is 10.5 volts or less, go to next step.

11) Check For Voltage To HFC Relay Turn ignition off. Disconnect LFC and HFC relays. Turn ignition on. Measure voltage between IGNITION RELAY (BATT + for 2.0L) terminal at HFC relay vehicle wiring harness connector and negative battery terminal. If voltage is more than 10.5 volts, go to next step. If fuse/fuse link and/or relay are okay, repair open circuit and check system operation.

12) Check Continuity Between LFC & HFC Relays Turn ignition off. Disconnect LFC and HFC relays. Measure resistance between HFC terminal at LFC relay wiring harness connector and output to LFC terminal at HFC relay wiring harness connector. If resistance is less than 5 ohms, replace HFC relay and check system operation. If resistance is 5 ohms or more, repair open circuit and check system operation.

13) Check Circuits From LFC Relay To Fan Turn ignition off. Disconnect LFC relay. Install a jumper wire between HFC terminal and POWER-TO-FAN terminal at LFC relay wiring harness connector. Turn ignition on. If fan operates, remove jumper and go to step 16). If fan does not operate, remove jumper wire and go to next step.

14) Check LFC POWER-TO-FAN Circuit Continuity Turn ignition off. Disconnect LFC relay and cooling fan. Measure resistance between POWER-TO-FAN terminal at LFC wiring harness connector and POWER-TO-FAN input terminal at cooling fan wiring harness connector. If resistance is less than 5 ohms, go to step 15). If resistance is 5 ohms or more, repair open circuit. Reconnect all components and check system operation.

15) Check Cooling Fan Ground Circuit Turn ignition off. Leave LFC relay and cooling fan disconnected. Measure resistance between GND terminal at cooling fan vehicle wiring harness connector and negative battery terminal. If resistance is less than 5 ohms, replace cooling fan. Reconnect all components and check system operation. If resistance is 5 ohms or more, repair open circuit. Reconnect all components and check system operation.

16) Check Circuits From HFC Relay To Fan Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Install a jumper wire between test pins No. 40 and 33 (Federal M/T) or No. 31 (except Federal M/T) at breakout box. Turn ignition on. If fan runs at high speed, replace LFC relay and check system operation. If fan does not run at high speed, remove jumper wire and go to next step.

17) Check HFC Power-To-Fan Voltage At Fan Turn ignition off.Leave LFC relay disconnected. Disconnect cooling fan connector. Install a jumper wire between test pins No. 33 and 40 at breakout box. Turn ignition on. Measure voltage between HFC POWER-TO-FAN circuit at cooling fan vehicle wiring harness connector and negative battery terminal. If voltage is more than 10.5 volts, replace cooling fan and check system operation. If voltage is 10.5 volts or less, remove jumper wire and go to next step.

18) Check HFC POWER-TO-FAN Circuit Continuity Turn ignition off. Leave PCM, cooling fan, HFC and LFC relays disconnected. Measure resistance between HFC POWER-TO-FAN terminal at HFC relay vehicle wiring harness connector and HFC POWER-TO-FAN terminal at cooling fan vehicle wiring harness connector. If resistance is less than 5 ohms, replace HFC relay and check system operation. If resistance is 5 ohms or more, repair open circuit and check system operation.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 18) to step 25). No test procedures have been omitted.

25) Low-Speed (LFC) Or High-Speed (HFC) Cooling Fan Always On For 2.0L models, go to step 26).

26) Check For Relay Always Closed Turn ignition off. Disconnect LFC relay. Turn ignition on. If fan continues to run, go to next step. If fan does not continue to run, replace LFC relay and check system operation.

27) Check HFC Relay Turn ignition off. Disconnect HFC relay. Turn ignition on. If fan continues to run, go to next step. If fan does not continue to run, go to step 30) (A/C equipped with R134a refrigerant) or replace HFC relay and check system operation (all others).

28) Check LFC POWER-TO-FAN Circuit For Short to Power Turn ignition off. Leave cooling fan, LFC and HFC relays disconnected. Turn ignition on. Measure voltage between LFC POWER-TO-FAN terminal cooling fan vehicle wiring harness connector and negative battery terminal. If voltage is more than 1.0 volt, repair short to power in LFC POWER-TO-FAN circuit. Reconnect all components and check system operation. If voltage is 1.0 volt or less, repair short to power in HFC POWER-TO-FAN circuit. Reconnect all components and check system operation.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 28) to step 30). No test procedures have been omitted.

30) Check A/C Pressure Switch (ACPSW) Operation Turn ignition off. Leave LFC relay disconnected. Reconnect HFC relay. Disconnect ACPSW connector. Start engine. If fan runs, go to next step. If fan does not run, check ACPSW. Replace switch as necessary.

Note. ACPSW controls operation of both A/C clutch and engine cooling fan. Contacts for cooling fan portion of ACPSW are normally open. When high side pressure reaches 325 psi (22.9 kg/cm 2 ), switch contacts close. For more information, see the A/C-HEATER SYSTEM article.

31) Check PCM Turn ignition off. Disconnect 60-pin PCM connector. Turn ignition on. If fan does not run, go to next step. If fan runs, turn ignition off and replace HFC relay. Reconnect all components and check system operation.

32) Check ACPSW For Short To Ground Turn ignition off. Leave PCM and ACPSW disconnected. Measure resistance between ACPSW terminal at ACPSW vehicle wiring harness connector and negative battery terminal. (Scheme 45) If resistance is more than 10,000 ohms, replace PCM. Reconnect all components and check system operation. If resistance is 10,000 ohms or less, repair short to ground in ACPSW circuit. Reconnect all components and check system operation.

A/C Pressure Switch (ACPSW) Connector (KF12). Scheme 45

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 32) to step 35). No test procedures have been omitted.

35) Check A/C Pressure Switch (ACPSW) Medium Pressure Circuits Turn ignition off. Disconnect ACPSW connector. Ensure A/C is off. Connect a jumper wire between ACPSW terminal and GND terminal at ACPSW vehicle wiring harness connector. (Scheme 45) If high speed fan does not run, go to next step. If high speed fan runs, ACPSW medium pressure circuits are okay, check ACPSW operation. Replace ACPSW as necessary. If ACPSW is okay, no problem is indicated at this time. See SYMPTOMS in TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

Note. ACPSW controls operation of both A/C clutch and engine cooling fan. Contacts for cooling fan portion of ACPSW are normally open. When high side pressure reaches 325 psi (22.9 kg/cm 2 ), switch contacts close. For more information, see A/C-HEATER SYSTEM - MANUAL in the AIR CONDITIONING & HEAT section.

36) Check ACPSW Ground (GND) Circuit Turn ignition on. Connect a jumper wire between negative battery terminal and ACPSW terminal at ACPSW vehicle wiring harness connector. (Scheme 45) If high speed fan runs, repair open in ground circuit to ACPSW. Remove jumper wire, reconnect all components and check system operation. If fan does not run, remove jumper wire and go to next step (A/C equipped with R134a refrigerant) or repair open in ACPSW circuit between ACPSW and splice (A/C equipped with R-12 refrigerant). Remove jumper wire, reconnect all components and check system operation.

37) Check ACPSW Circuit Continuity To PCM Turn ignition off. Leave ACPSW disconnected. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Leave PCM disconnected. Measure resistance between test pin No. 14 at breakout box and ACPSW circuit at ACPSW vehicle wiring harness connector. (Scheme 45) If resistance is less than 5 ohms, replace PCM. Remove breakout box, reconnect all components and check system operation. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components and check system operation.

CIRCUIT TEST KM - WIDE OPEN THROTTLE A/C CUT-OUT (WAC)

& A/C DEMAND SWITCH

Perform this test when instructed by QUICK TEST or if directed by CIRCUIT TEST TA. To prevent replacing good components, check the following non-EEC components and systems

1. Refrigerant charge.
2. Low ambient temperature (less than 45°F).

This test is only intended to diagnose

1. Wiring harness circuits (WAC, VPWR, GND, POWER-TO-CLUTCH and ACD).
2. WAC relay.
3. Faulty PCM.

WOT A/C Cut-Out Circuit (KM3 - Probe). Scheme 46

TEST PIN NO. 10 OR 23 (ACD) WIRE COLOR IDENTIFICATION

TEST PIN NO. 54 (WAC) WIRE COLOR IDENTIFICATION

Note. A/C switch is also referred to as A/C demand switch in this circuit test.

1) Low/No Voltage To A/C Clutch Check all A/C-related fuses in fuse panel before proceeding with this test. On 2.0L, go to step 50).

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 1) to step 50). No test procedures have been omitted.

50) No A/C (2.0L): Attempt To Generate KOEO 539 Turn ignition off. Turn A/C switch on. Perform KOEO Self-Test. If Code 539 is not present, go to step 55). If Code 539 is present, go to next step.

51) Check For Power To A/C Relay Turn ignition off. Disconnect A/C relay. Turn ignition on. Measure voltage between B(+) terminal at relay wiring harness connector and chassis ground. If voltage is 10.5 volts or less, repair open circuit and check system operation. If voltage is more than 10.5 volts, go to next step.

52) Check For POWER-TO-CLUTCH Circuit Continuity Turn ignition off. Leave A/C relay disconnected. Disconnect A/C clutch. Measure resistance at POWER-TO-CLUTCH terminal of the A/C clutch connector and A/C relay connector. If resistance is 5onnector. If resistance is 5 or more ohms, repair open circuit and check system operation. If resistance is less than 5 ohms, go to next step.

53) Check For A/C Relay Turn ignition off. Leave A/C clutch disconnected. Reconnect A/C relay. Connect jumper wire between ACON terminal of the A/C relay wiring harness connector to chassis ground. Measure voltage between POWER-TO-CLUTCH terminal of the A/C clutch connector and chassis ground. If voltage is more than 10.5 volts, EEC system is okay. Check for problem in A/C system. If voltage is 10.5 volts or less, replace A/C relay and check system operation.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 53) to step 55). No test procedures have been omitted.

55) Check For ACD Circuit Continuity Turn ignition off. Turn A/C demand switch on. Disconnect A/C low pressure switch. Measure resistance between chassis ground and A/C demand switch side (White wire) of low pressure switch wiring harness connector. If resistance is 5 ohms or more, check for defective A/C demand switch. Replace switch as necessary. If switch is okay, repair open circuit. Reconnect all components and check system operation. If resistance is less than 5 ohms, go to next step.

56) Check Low Pressure Switch Resistance Turn ignition off. Leave low pressure switch disconnected. Measure resistance between low pressure switch terminals. If resistance is 5 ohms or more, EEC system is okay. Check for problem in A/C system. If resistance is less than 5 ohms, go to next step.

57) Check PCM-To-Low Pressure Switch Circuit Continuity Turn ignition off. Leave low pressure switch disconnected. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 23 (Federal M/T) or No. 10 (except Federal M/T) and ACD terminal of low pressure switch wiring harness connector. If resistance is 5 ohms or more, repair open circuit and check system operation. If resistance is less than 5 ohms, replace PCM. Remove breakout box, reconnect all components, and check system operation.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 57) to step 60). No test procedures have been omitted.

60) Code 559: Check Power To A/C Relay Code 559 indicates A/C relay input circuit fault. Possible causes are as follows

1. Open or shorted circuit.
2. Damaged A/C relay.
3. Damaged PCM.

Turn ignition off. Disconnect A/C relay. Turn ignition on. Measure voltage between IGN RUN terminal at A/C relay wiring harness connector and chassis ground. If voltage is 10.5 volts or less, repair open circuit and repeat QUICK TEST. If voltage is more than 10.5 volts, go to next step.

A/C Relay Wiring Harness Connector Terminal ID (KM5). Scheme 47

61) Check A/C Relay Turn ignition off. Leave A/C relay disconnected. Measure resistance between IGN RUN and ACON terminal at A/C relay. Resistance should be 50-100 ohms. Also, measure resistance between ACON and the following A/C relay terminals; B(+), POWER-TO-CLUTCH and ground. Resistance should be more than 10,000 ohms. If resistance is not as specified, replace A/C relay. Reconnect all components and repeat QUICK TEST. If resistance is as specified, go to next step.

A/C Relay Terminal ID (KM6). Scheme 48

62) Check ACON Circuit For Short To Power Turn ignition off. Leave A/C relay disconnected. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Measure voltage between test pin No. 54 and chassis ground. If voltage is 1.0 volt or more, repair short to power. Remove breakout box, reconnect all components, and repeat QUICK TEST. If voltage is less than 1.0 volt, go to next step.

63) Check ACON Circuit For Short To Ground Leave ignition off and A/C relay disconnected. Measure resistance between test pin No. 54 and chassis ground. If resistance is 10,000 ohms or less, repair short circuit to ground. If resistance is more than 10,000 ohms, go to next step.

64) Check ACON Circuit Continuity Leave ignition off and A/C relay disconnected. Measure resistance between test pin No. 54 and ACON terminal at A/C relay wiring harness connector. If resistance is less than 5 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 64) to step 70). No test procedures have been omitted.

70) Code 539: Check A/C Input Code 539 indicates A/C demand input to PCM was low, indicating A/C on, during KOEO SELF-TEST. Verify A/C is off. If A/C was on, repeat KOEO SELF-TEST. If Code 539 is repeated, turn ignition off. Disconnect low pressure switch. Measure resistance between chassis ground and A/C demand switch (White wire) side of low pressure switch wiring harness connector. If resistance is 10,000 ohms or less, check for defective A/C demand switch. If switch is okay, repair short to ground. Reconnect all components and check system operation. If resistance is more than 10,000 ohms, go to next step.

71) Check Low Pressure Switch Turn ignition off. Leave low pressure switch disconnected. Measure resistance between each terminal of switch and chassis ground. If either resistance is 10,000 ohms or less, replace switch and check system operation. If each resistance is more than 10,000 ohms, go to next step.

72) Check PCM-To-Low Pressure Switch Circuit For Short To Ground Leave ignition off and low pressure switch disconnected. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Measure resistance between chassis ground and PCM side of low pressure switch wiring harness connector. If resistance is 10,000 ohms or less, repair short circuit to ground. Reconnect all components and check system operation. If resistance is more than 10,000 ohms, replace PCM. Reconnect all components and check system operation.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 72) to step 80). No test procedures have been omitted.

80) A/C Always On: Check For Short To Power Perform KOEO SELF-TEST. If any code(s) is present, service as necessary. If no code(s) is present, turn ignition off. Disconnect A/C relay and A/C clutch. Turn ignition on. Measure voltage between power side of A/C clutch wiring harness connector and negative battery terminal. If voltage is 1.0 volt or more, repair short to power. Reconnect all components and check system operation. If voltage is less than 1.0 volt, go to next step.

81) Check A/C Relay Turn ignition off. Leave A/C relay disconnected. Measure resistance between POWER-TO-CLUTCH and terminals B(+) and IGN RUN at A/C relay. If both readings are more than 10,000 ohms, EEC system is okay. Check for fault in A/C system. If any reading is 10,000 ohms or less, replace A/C relay. Reconnect all components and check system operation.

Perform this test when instructed during QUICK TEST. Use this test only to diagnose

1. FPRC solenoid.
2. Wiring harness circuits (FPRC and VPWR).
3. Faulty Powertrain Control Module (PCM).

To prevent replacement of good components, be aware the following non-EEC areas may be cause of driveability concerns

1. Fuel pressure regulator.
2. Engine not obtaining correct operating temperature.
3. Vacuum hoses leaking or misrouted.
4. Excessive internal engine wear or damage.

Fuel Pressure Regulator Control (FPRC) Solenoid Ckt. (KN1). Scheme 49

TEST PIN NO. 13 OR 32 (FPRC) WIRE COLOR IDENTIFICATION

1) Code 554: Enter OUTPUT STATE CHECK Code 554 indicates fault in FPRC circuit. Possible causes are

1. Faulty FRPC solenoid.
2. Vacuum hoses leaking or misrouted.
3. Open or shorted circuit.
4. Faulty PCM.

Use only VOM or DVOM for this step. DO NOT use scan tester. Turn ignition off. Disconnect cruise control servo wiring harness connector. Connect DVOM negative lead to STO terminal at Data Link Connector (DLC). Connect positive lead to positive battery terminal. Install a jumper wire between STI terminal and SIG RTN terminal at DLC. (Scheme 14) Perform KOEO SELF-TEST until continuous memory test is complete. DVOM will read less than 1.0 volt when test is complete to indicate PCM has entered OUTPUT STATE CHECK. Depress and release throttle. If voltage increases, remain in OUTPUT STATE CHECK and go to next step. If voltage does not increase, depress throttle to WOT and release. If voltage increases, remain in OUTPUT STATE CHECK and go to next step. If voltage does not increase, leave test equipment connected and go to CIRCUIT TEST QC.

DLC Terminal (KN2). Scheme 50

2) Check FPRC Solenoid Operation Disconnect FPRC solenoid. Turn ignition on. Connect DVOM positive lead to VPWR terminal and negative lead to FPRC terminal at FPRC solenoid wiring harness connector. Observe DVOM while depressing and releasing throttle 3-5 times. If FPRC solenoid output voltage varies 1.0 volt or less, go to step 7). If FPRC solenoid output voltage varies more than 1.0 volt, go to next step.

3) Check Vacuum Hose Turn ignition off. Disconnect vacuum hose between manifold vacuum source and FPRC solenoid input port. Inspect vacuum hose for kinks, blockage and cracks. Replace hose as necessary. Repeat QUICK TEST. If hose is okay, go to next step.

4) Check FPRC Vacuum Signal Turn ignition off. Using a vacuum tee, connect vacuum gauge between manifold vacuum source and FPRC solenoid input port. Start engine and observe vacuum gauge. If vacuum is present, remove vacuum gauge and go to next step. If vacuum is not present, check engine mechanical condition (valves, vacuum leaks, timing, EGR valve, etc.).

5) Check Vacuum Hose Turn ignition off. Disconnect vacuum hose between FPRC solenoid output port and fuel pressure regulator. Inspect vacuum hose for kinks, cracks and blockage. Replace hose as necessary. Repeat QUICK TEST. If hose is okay, reconnect hose and go to next step.

6) Check FPRC Solenoid Operation Turn ignition off. Install vacuum gauge between FPRC solenoid output port and fuel pressure regulator. Perform road test as follows

1. Warm engine to normal operating temperature.
2. Observe vacuum gauge and accelerate heavily to 40 MPH.
3. Observe vacuum gauge and decelerate to a steady cruise below 20 MPH.

Vacuum gauge should indicate a low vacuum (FPRC solenoid closed) during heavy acceleration and a higher vacuum (FPRC solenoid open) during steady cruise if FPRC solenoid is functioning properly. Repeat test as necessary to confirm test results. If vacuum signal is as specified, remove vacuum gauge and check for fuel system malfunction. Proceed to FUEL SYSTEM in the appropriate SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If vacuum signal is not as specified, replace FPRC solenoid. Repeat QUICK TEST.

7) Check FPRC Solenoid VPWR Turn ignition off. Remove FPRC solenoid wiring harness connector. Turn ignition on. Measure voltage between VPWR terminal at FPRC wiring harness connector and negative battery terminal. If voltage is 10.5 volts or less, repair open circuit and repeat QUICK TEST. If voltage is more than 10.5 volts, go to next step.

8) Check Continuity Of FPRC Circuit Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Disconnect FPRC solenoid wiring harness connector. Measure resistance between test pin No. 13 (pin No. 32 on 2.0L Federal M/T) and FPRC terminal at solenoid wiring harness connector. If resistance is 5 ohms or more, repair open circuit. Repeat QUICK TEST. If resistance is less than 5 ohms, go to next step.

9) Check FPRC Circuit For Short Leave ignition off and FPRC solenoid disconnected. Measure resistance between test pin No. 13 (pin No. 32 on 2.0L Federal M/T) and test pins No. 37 and 57. Also, measure resistance between test pin No. 13 (pin No. 32 on 2.0L Federal M/T) and test No. 40, 46 and 60. If any resistance is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If each resistance is more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Enter this test when directed by QUICK TEST. This test is only intended to diagnose

1. Harness circuits (SIG RTN and OCT ADJ).
2. Octane adjust shorting bar connector.

Purpose of Octane Adjust Shorting Bar is to provide optimum spark advance for fuel used. If engine detonates (spark knock), remove Octane Shorting Bar. This retards spark advance about 3-4 degrees. If engine continues to detonate, use fuel with a higher octane rating.

Octane Adjust Circuit (KP1). Scheme 51

TEST PIN NO. 46 (SIG RTN) WIRE COLOR IDENTIFICATION

Octane Adjust (OCT ADJ) shorting bar is similar in shape to SPOUT in-line connector and on some models the Power Steering Pressure (PSP) circuit will also have a similar shorting bar connector. DO NOT remove OCT ADJ shorting bar unless instructed to do so.

1) Code 341 Code 431 indicates Octane Adjust (OCT ADJ) shorting bar is not in place or OCT ADJ circuit is open. Turn ignition off. Inspect Octane Adjust in-line connector. If shorting bar has been removed, go to next step. If shorting bar is in place, go to step 4).

2) Check For Modification Decal If vehicle has modification decal indicating OCT ADJ shorting bar was removed as a factory authorized procedure, testing is complete. If engine is detonating, proceed to the appropriate TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If vehicle does not have modification decal, go to next step.

3) Check For Code 341 Replace OCT ADJ shorting bar. Perform KOEO SELF-TEST. If Code 341 is present, go to next step. If Code 341 is not present, testing is complete. If driveability faults are present, go to TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

4) Check Octane Adjust Circuit Continuity Continuity should exist from OCT ADJ circuit, through in-line connector and shorting bar, to SIG RTN circuit. Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 46 and OCT ADJ test pin at breakout box. If resistance is 5 ohms or more, repair open OCT ADJ circuit, shorting bar or SIG RTN circuit. Repeat QUICK TEST. If resistance is less than 5 ohms, replace PCM and repeat QUICK TEST.

5) Check For Code 111 Start engine. Warm it to normal operating temperature. Turn ignition off. Perform KOEO SELF-TEST. If Code 111 is present, go to next step. If Code 341 is present, return to step 1). For all other codes, return to QUICK TEST.

6) Verify In-Line Shorting Bar Is Installed Turn ignition off. Inspect OCT ADJ in-line connector. If shorting bar is installed, go to step 8). If shorting bar is not installed, go to next step.

7) Check For Modification Decal If vehicle has modification decal indicating OCT ADJ shorting bar was removed as a factory authorized procedure, go to step 10. If vehicle does not have a modification decal, replace shorting bar. If engine is detonating, go to TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

8) Check For Technical Service Bulletin (TSB) If a TSB authorizing removal of OCT ADJ shorting bar exists, go to next step. If a TSB authorizing removal of OCT ADJ shorting bar does not exist, testing is complete. If engine is detonating, proceed to TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

9) Remove OCT ADJ Shorting Bar Turn ignition off. Remove OCT ADJ shorting bar. Test drive vehicle to verify complaint. If detonation is present, go to next step. If detonation is not present, EEC-IV is okay. Testing is complete.

10) Check Octane Adjust Circuit For Short To Ground Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between OCT ADJ terminal at in-line connector and test pins No. 40 and 60 at breakout box. If resistance is 10,000 ohms or less, repair short circuit. If engine is detonating, go to TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If each resistance is more than 10,000 ohms, go to next step.

11) Check PCM Turn ignition off. Disconnect OCT ADJ shorting bar. Connect PCM to breakout box. Turn ignition on. Measure voltage between breakout box OCT ADJ test pin terminal and test pins No. 40 or 60. If voltage is 4 volts or less, replace PCM. If engine is detonating, go to TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If voltage is more than 4 volts, remove breakout box. If engine is detonating, go to the article TESTS W/O CODES - EEC-IV (2.0L) in the ENGINE PERFORMANCE section.

Perform this test only when instructed by QUICK TEST or directed here by a driveability symptom. This test is only intended to diagnose

1. Wiring harness circuits (VPWR and IMRC).
2. Intake Manifold Runner Control (IMRC) solenoid.
3. Faulty Powertrain Control Module (PCM).

To prevent replacing good components, check the following non-EEC areas for faults

1. Vacuum tank leaks.
2. Vacuum hose leaks.

IMRC Circuit (KT1). Scheme 52

1) Code 551: Check IMRC Solenoid Resistance Code 551 indicates IMRC solenoid output voltage did not change when IMRC was activated during KOEO SELF-TEST. Possible causes for this fault are

1. IMRC circuit open or shorted.
2. Faulty IMRC solenoid.
3. PCM output driver open or grounded.

Turn ignition off. Disconnect IMRC solenoid wiring harness connector. Measure resistance between IMRC solenoid terminals. If resistance is not 50-100 ohms, replace solenoid and repeat QUICK TEST. If resistance is 50-100 ohms, go to next step.

2) Check Voltage Of VPWR Circuit Turn ignition on. Measure voltage between VPWR terminal of IMRC solenoid wiring harness connector and negative battery terminal. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open circuit and repeat QUICK TEST.

3) Check Continuity Of IMRC Solenoid Circuit Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 32 at breakout box and IMRC terminal of IMRC solenoid wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. and repeat QUICK TEST.

4) Check IMRC Circuit For Short To Ground Turn ignition off. Measure resistance between test pin No. 32 and test pins No. 40, 46 and 60. If all readings are more than 100,000 ohms, go to next step. If any reading is 100,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

5) Check IMRC Circuit For Short To Power Turn ignition off. Measure resistance between test pin No. 32 and test pins No. 37 and 57 at breakout box. If all readings are 100,000 ohms or more, replace PCM and repeat QUICK TEST. If any reading is less than 100,000 ohms, repair short circuit and repeat QUICK TEST. If fault is still present, replace PCM. Repeat QUICK TEST.

6) Check IMRC Valves Turn ignition off. Disconnect vacuum lines from both IMRC valves. Use vacuum pump to apply 10 in. Hg vacuum to each IMRC valve. If both valves hold vacuum, go to next step. If valve(s) do not hold vacuum, replace valve as necessary and repeat QUICK TEST.

7) Check Operation Of IMRC Valves Apply 10 in. Hg to each air valve. If both valves and mechanical linkage move in response to applied vacuum, go to next step. If valves and/or linkage do not move, repair as necessary and repeat QUICK TEST.

8) Check Vacuum IMRC Valves Check vacuum lines from IMRC valves to solenoids. Inspect vacuum lines for damage and blockage. If vacuum lines are damaged or blocked, repair as necessary. If vacuum lines are okay, go to next step.

9) Enter OUTPUT STATE CHECK Use only VOM or DVOM for this step. DO NOT use scan tester. Turn ignition off. Disconnect cruise control servo wiring harness connector. Connect DVOM negative lead to STO terminal at Data Link Connector (DLC). (Scheme 14) Connect positive lead to positive battery terminal. Install a jumper wire between STI terminal and SIG RTN terminal at DLC. Perform KOEO SELF-TEST until continuous memory test is complete. DVOM will read less than 1.0 volt when test is complete to indicate PCM has entered OUTPUT STATE CHECK. Depress and release throttle. If voltage increases, remain in OUTPUT STATE CHECK and go to next step. If voltage does not increase, depress throttle to WOT and release. If voltage does not go high, go to CIRCUIT TEST QC.

10) Check IMRC Solenoid Electrical Operation Turn ignition off. Disconnect IMRC solenoid wiring harness connector. Connect DVOM positive lead to connector VPWR terminal. Connect negative lead terminal IMRC at IMRC connector. Observe DVOM while cycling throttle open and closed. If DVOM does not cycle 0.5 volt or more, return to step 1). If DVOM does cycle 0.5 volt or more, go to next step.

11) Check IMRC Solenoid Vacuum Disconnect IMRC solenoid vacuum hose and wiring harness connector. Turn ignition on. Use vacuum pump to apply 16 in. Hg vacuum to each IMRC valve. If vacuum is not held for 20 seconds, replace solenoid and repeat QUICK TEST. If vacuum is held, go to next step.

12) Check IMRC Solenoid Mechanical Operation Remain in OUTPUT STATE CHECK. Using vacuum pump, apply 16 in. Hg vacuum to each IMRC valve. Depress and release throttle. If vacuum is not released, replace solenoid and repeat QUICK TEST. If vacuum is released, go to next step.

13) Disconnect IMRC solenoid vacuum hose. Start engine. Check vacuum at disconnected hose. If vacuum is present at hose, system is okay. If vacuum is not present, check supply hose to IMRC solenoid. Repair as necessary, and repeat QUICK TEST.

To prevent replacing good components, be aware the following non-EEC related areas may be cause of problem

1. Technician did not perform brief Wide Open Throttle (WOT) after Dynamic Response Code.
2. Engine did not go over 2000 RPM during WOT.

This test is only intended to diagnose

1. Throttle movement (minimum 3/4 throttle).
2. RPM increase is more than 2000 RPM.

If throttle is snapped open briefly, it may not pass WOT test. Ensure throttle is depressed fully to WOT and engine speed exceeds 2000 RPM.

Code 538 Displayed: System Failed To Recognize WOT Test

Repeat KOER SELF-TEST as follows

1. Activate SELF-TEST.
2. Start engine.
3. Observe ID Code start of test.
4. Observe Dynamic Response Code 1 (Code 0 with STAR tester).
5. Perform brief WOT.
6. Testing is complete; Diagnostic Test Code (DTC) output begins.

Ensure vehicle speed reached 2000 RPM during WOT. If Code 538 is present, replace PCM. Repeat QUICK TEST. If Code 538 is not present, vehicle has passed dynamic response test. Service other codes if necessary.

CKT TEST ML - SELF-TEST OUTPUT (STO) OR MALFUNCTION

INDICATOR LT (MIL)

The MIL is turned on when PCM detects a fault in EEC circuit(s). The light will remain on as long as fault remains in system.

Perform this test only when instructed by QUICK TEST or if directed by CIRCUIT TEST QA. This test does not include procedure for models with electronic instrument panel. To prevent replacing good components, be aware that fuse, bulb or bulb socket may be cause of problem. This test is only intended to diagnose

1. STO/MIL circuit.
2. Faulty PCM.

TEST PIN NO. 17 (STO/MIL) WIRE COLOR IDENTIFICATION

1) Malfunction Indicator Light (MIL) Always On If vehicle will not start, go to appropriate circuit test

1. For distributor ignition systems, CIRCUIT TEST AA.
2. For distributorless ignition systems (low data rate), CIRCUIT TEST AB.
3. For distributorless ignition systems (high data rate), CIRCUIT TEST AC.

Service all KOEO and Continuous Memory Codes before proceeding with this test. Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pins No. 17 and 40 at breakout box. If resistance is 5 ohms or more, replace PCM and repeat QUICK TEST. If reading is less than 5 ohms, repair short between test pin No. 17 and Diagnostic Link Connector (DLC) or MIL. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 1) to step 4). No test procedures have been omitted.

4) Malfunction Indicator Light (MIL) Does Not Light If vehicle will not start, go to step 1). Turn ignition on. Measure voltage between negative battery terminal and ground side of MIL fuse. If voltage is more than 10.5 volts, go to step 6). If voltage is 10.5 volts or less, go to next step.

5) Check For Voltage At Fuse Turn ignition on. Measure voltage from negative battery terminal to power side of MIL fuse. If voltage is more than 10.5 volts, replace fuse. Verify repair by turning ignition switch to RUN position. If voltage is 10.5 volts or less, repair open MIL/B+ circuit. Verify repair by turning ignition switch to RUN position.

6) Check Voltage At B+ Circuit Turn ignition on. Measure voltage between B+ side of MIL bulb socket and negative battery terminal. If voltage is 10.5 volts or less, repair open in MIL circuit between fuse and bulb. Verify repair by turning ignition switch to RUN position. If voltage is more than 10.5 volts, go to next step.

7) Check MIL Bulb Response To Grounding Turn ignition off. Attach jumper wire between ground side of MIL bulb socket and chassis ground. Turn ignition on. If MIL light comes on, remove jumper wire, and go to next step. If MIL light does not come on, remove jumper wire. Replace MIL bulb socket. Turn ignition on to verify correct MIL operation.

8) Check Continuity Of MIL Circuit Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 17 at breakout box and MIL wiring harness connector terminal. If resistance is less than 5 ohms, replace PCM. Turn ignition on to verify correct MIL operation. If resistance is 5 ohms or more, repair open in ground side of MIL circuit. Turn ignition on to verify correct MIL operation.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 8) to step 10). No test procedures have been omitted.

10) MIL On Intermittently, Check For Intermittent Short From STO To Ground If vehicle does not start, go to step 1). MIL comes on when a fault code is present. Service all fault codes before proceeding. If no codes are output, proceed with this test. Enter KOEO wiggle test. See CONTINUOUS MONITOR MODE (WIGGLE TEST) under QUICK TEST. Check DVOM for indication of fault while performing wiggle test on harness in the following areas

1. From Diagnostic Link Connector (DLC) to dash panel.
2. Dash panel to PCM.
3. Dash panel to Malfunction Indicator Light (MIL).

If a fault is indicated, repair short to ground and repeat QUICK TEST. If a fault is not indicated, fault cannot be duplicated at this time. Testing is complete.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 10) to step 15). No test procedures have been omitted.

15) MIL Flashes With Erratic Idle Symptoms indicate STI is grounded and PCM is performing self-test without tester installed. Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between STI connector and engine ground. If resistance is less than 10,000 ohms, repair short circuit. Reconnect PCM, and turn ignition on to verify correct MIL operation. If resistance is 10,000 ohms or more, MIL circuit is okay. Verify symptom, and test for other rough idle symptoms.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 15) to step 20). No test procedures have been omitted.

20) CHECK ENGINE Message Displayed If vehicle will not start, go to step 1). Perform KOEO SELF-TEST. If result is Code 111-10-111 (pass code), fault is in instrument cluster. If pass code is not displayed, service codes as necessary.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 20) to step 25). No test procedures have been omitted.

25) Continuous Memory Code 529 Or 533: CHECK ENGINE Or CHECK DCL Message Displayed Codes 529 and 533 indicate circuit fault has occurred on Data Communications Link (DCL). These codes can occur alone or with another code. Fault will occur under following conditions

1. Code 529 indicates PCM or DCL circuit failure.
2. Code 533 indicates DCL to electronic instrument cluster circuit failure.

If vehicle does not start, go to step 1). If vehicle starts, clear continuous memory codes. Wait 5 minutes, and repeat KOEO SELF-TEST. If result is pass code (Code 111-10-111), fault is in instrument cluster. If pass code is not displayed, service codes as necessary.

CIRCUIT TEST NA - DISTRIBUTOR IGNITION SYSTEM IGNITION

DIAGNOSTIC MONITOR (IDM)

The IDM is an input signal to the PCM that verifies spark plug fire based on ignition coil primary discharge. IDM signal consists of a single pulse for each engine RPM. No IDM pulse indicates secondary ignition misfire.

Perform this test when directed by QUICK TEST. This test is only intended to diagnose EEC-IV portion of ignition system. For additional information on ignition system and component testing, proceed to SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. To prevent replacing good components, be aware the following non-EEC related areas may be cause of problem

1. Ignition Control Module (ICM).
2. Ignition coil.
3. Spark plugs and/or wires.
4. Distributor.
5. Secondary ignition short to ground.

This test is intended to diagnose

1. IDM circuit.
2. Faulty PCM.

IDM Circuit Schematic (NA1 - 2.0L). Scheme 53

TEST PIN NO. 4 (IDM) WIRE COLOR IDENTIFICATION

TEST PIN NO. 36 (SPOUT) WIRE COLOR IDENTIFICATION

1) Continuous Memory Code 211 Code 211 indicates 2 successive erratic Profile Ignition Pick-Up (PIP) pulses occurred, resulting in a possible engine miss or stall. Check for the following possible causes of fault

1. Loose wires or connectors.
2. Arcing secondary ignition components.
3. On-board transmitter equipment (2-way radio).

If any of the above possible causes are present, repair as necessary. Clear code, and repeat QUICK TEST. If problem is not found, go to next step. If vehicle does not start, go to CIRCUIT TEST AA for 2.0L.

2) Continuous Memory Code 212: Check IDM Circuit Continuity Continuous Memory Code 212 indicates loss of IDM input to PCM. Possible causes for this fault are

1. Open or shorted circuit in wiring harness.
2. Faulty ICM.
3. Faulty PCM.

If vehicle is a no-start, see IGNITION SYSTEMS in I - SYS/COMP TESTS - EEC-IV in the ENGINE PERFORMANCE section. If vehicle starts, go to next step.

3) Check IDM Circuit Continuity Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Disconnect ICM. Measure resistance between test pin No. 4 at breakout box and IDM terminal at ICM wiring harness connector. If resistance is less than 5 ohms, go to step 5). If resistance is 5 ohms or more, repair open circuit, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 3) to step 5). No test procedures have been omitted.

5) Check IDM Circuit For Short To Power (Except VREF) Turn ignition off. Leave ICM and PCM disconnected. Measure voltage between breakout box test pin No. 4 and negative battery terminal. Turn ignition on. Measure voltage between test pin No. 4 and test pins No. 40 and 60 at breakout box. If any reading is more than 10.5 volts, repair short circuit. Clear codes, and repeat QUICK TEST. If both readings are 10.5 volts or less, go to next step.

6) Check IDM Circuit For Short To PIP & VREF Turn ignition off. Leave PCM and ICM disconnected. Remove scan tool (if applicable). For shorts to PIP, measure resistance between test pins No. 4 and No. 56 at breakout box. For shorts to VREF, measure resistance between test pins No. 4 and No. 26 at breakout box. If each resistance is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If each resistance is more than 10,000 ohms, go to next step.

During this test, a short to SIG RTN (pin No. 46) may be indicated along with an actual short to PWR GND when 4-wire HO2S is connected to vehicle wiring harness.

7) Check IDM Circuit For Short To Ground Turn ignition off. Leave ICM and PCM disconnected. Measure resistance between test pin No. 4 and test pins No. 20, 40, 46 and 60 at breakout box. If each resistance is more than 10,000 ohms, go to next step. If any resistance is 10,000 ohms or less, repair short to ground in IDM circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

8) Check ICM Turn ignition off. Connect PCM to breakout box. Reconnect ICM to wiring harness connector. Connect DVOM between test pins No. 4 and 16 at breakout box. Start engine. Observe DVOM for voltage surge while lightly tapping on ICM and Camshaft Position (CMP) sensor (if equipped) to simulate road shock. Wiggle all ICM and CMP sensor wiring and harness connectors. If fault (voltage surge) is not indicated, go to next step. If fault (voltage surge) is indicated, disconnect and inspect wiring harness connectors and terminals for damage. Repair as necessary. If connectors and terminals are okay, check ignition system. See SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

9) Check PCM & Harness Connectors Ensure engine is still running and DVOM is still connected between test pins No. 4 and 16 at breakout box. While observing DVOM, wiggle and bend wiring harness, a small section at a time, from ICM and CMP sensor (if equipped) to cowl. Also, check harness from cowl to PCM. If fault is indicated, isolate fault and repair as necessary. Remove breakout box, reconnect all components, and repeat QUICK TEST. If no fault is found, go to next step.

10) Check PCM & Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. If connector is damaged, repair as necessary. Remove breakout box, reconnect all components, and repeat QUICK TEST. If connector is okay, go to next step.

11) Check PCM For Short To Power Turn ignition off. Connect PCM to breakout box. Disconnect the following sensors as applicable.

1. On 2.0L, disconnect ICM wiring harness connector.
2. On vehicles with remote mount ICM and CMP, disconnect ICM and CMP wiring harness connector.
3. On all other models, disconnect ICM wiring harness connector.

On all models, measure voltage between test pin No. 4 at breakout box and chassis ground. Turn ignition on. Measure voltage between test pin No. 4 and test pins No. 40 and 60 at breakout box. If any reading is more than 10.5 volts, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If both readings are 10.5 volts or less, go to next step.

12) Check PCM For Short To Ground Turn ignition off. Leave PCM connected to breakout box. Disconnect ICM and CMP. Measure resistance between test pin No. 4 and test pins No. 40, 46 and 60 at breakout box. If all readings are more than 10,000 ohms, check ignition system. Proceed to the SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If any reading is 10,000 ohms or less, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

CIRCUIT TEST NB - IGNITION DIAGNOSTIC MONITOR (IDM)

DISTRIBUTORLESS IGNITION SYSTEM (LOW DATA RATE)

The IDM is an input signal to the PCM that verifies spark plug firing based on ignition coil primary discharge. IDM signal consists of a single pulse for each engine RPM. No IDM pulse indicates secondary ignition misfire.

Perform this test when directed by QUICK TEST. This test is only intended to diagnose EEC-IV portion of ignition system. For additional information on ignition system and component testing, proceed to SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. To prevent replacing good components, be aware the following non-EEC related areas may be cause of problem

1. Ignition Control Module (ICM).
2. Ignition coil pack(s).
3. Spark plugs and/or wires.
4. Crankshaft sensor.
5. Camshaft sensor (if equipped).
6. Secondary ignition short to ground.

This test is intended to diagnose

1. Wiring harness circuits (IDM and DPI).
2. Faulty Powertrain Control Module (PCM).

1) Continuous Memory Code 211: Erratic Ignition Code 211 indicates 2 successive erratic Profile Ignition Pick-Up (PIP) pulses occurred. Possible causes for this fault are

1. Loose wires or connectors.
2. Secondary ignition short to ground.
3. On-board transmitter equipment (2-way radio).

If any of the above possible causes are found, repair as necessary. Clear code, and repeat QUICK TEST. If no problem is found, go to step 4). If vehicle does not start, go to CIRCUIT TEST AB.

2) Continuous Memory Code 212: Check For Other Codes Continuous Memory Code 212 indicates loss of IDM input signal to PCM. Possible causes for this fault are

1. Open or shorted harness.
2. Faulty ICM.
3. Faulty PCM.

If vehicle is a Continuous Memory Code 214, go to CIRCUIT TEST DR. If vehicle is a no-start or Continuous Memory Code 215, 216 or 217 is present, proceed to IGNITION SYSTEMS in appropriate SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If vehicle starts and Code 214, 215, 216 or 217 is not present, go to next step.

3) Continuous Memory Code 212, 218 Or 222 Code 212 indicates loss of IDM input signal. Possible causes are

1. Open or shorted wiring harness circuit.
2. Faulty ICM.
3. Faulty PCM.

Code 222 indicates IDM input signal is always low. Possible causes are

1. Open or shorted wiring harness circuit.
2. Faulty Camshaft Position (CMP) sensor.
3. Faulty Crankshaft Position (CKP) sensor.
4. B+ (battery voltage) low at ICM.
5. Faulty ICM.
6. Faulty PCM.

Code 218 indicates IDM input signal is always high. Possible causes are

1. Open circuit in wiring harness.
2. B+ open or low at secondary coil.
3. VBAT low at secondary coil.

Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Disconnect ICM connector (pins No. 7-12). Measure resistance between test pin No. 4 at breakout box and ICM wiring harness connector pin No. 12. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Clear codes and repeat QUICK TEST.

4) Check IDM Circuit For Short To Power Turn ignition off. Disconnect ICM connector (pins No. 1-6). Leave PCM disconnected from breakout box. Turn ignition on. Measure voltage between test pin No. 4 and test pins No. 40 or 60 at breakout box. If voltage is 10.5 volts or less, go to next step. If voltage is more than 10.5 volts, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

5) Check IDM Circuit For Short To VREF & PIP Turn ignition off. Ensure scan tool is disconnected (if applicable). Ensure ICM (pins No. 1-6) and CMP sensor (if equipped) are disconnected. Check VREF circuit by measuring resistance between test pins No. 4 and 26. Check PIP circuit by measuring resistance between test pins No. 4 and 56. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If each resistance is more than 10,000 ohms, go to next step.

6) Check IDM Circuit For Short To Ground Turn ignition off. Leave ICM and PCM disconnected. Measure resistance between test pin No. 4 and test pins No. 16, 20, 40, 46 and 60 at breakout box. If any reading is 10,000 ohms or less, repair ICM circuit short to ground. Remove breakout box, reconnect all components, and repeat QUICK TEST. If each reading is more 10,000 ohms, go to next step.

During this test, a short to SIG RTN (pin No. 46) may be indicated along with an actual short to PWR GND when 4-wire HO2S is connected to vehicle wiring harness.

7) Check ICM Turn ignition off. Connect ICM to wiring harness connectors. Connect PCM to breakout box. Start engine, and allow it to idle. Connect DVOM to test pin No. 4 and No. 16. Observe DVOM for voltage surge (fault) while lightly tapping on ignition components to simulate road shock. Wiggle all ICM harness connectors. If fault is indicated, turn ignition off. Disconnect and inspect ICM wiring harness connectors and terminals for damage. Repair as necessary. If connectors and terminals are okay, check ignition system. Refer to SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If no fault is indicated, leave DVOM connected to breakout box and go to next.

8) Check EEC Harness Ensure engine is idling at correct RPM. Wiggle, shake or bend small sections of harness, working from ICM connectors to firewall. Observe DVOM for indication of fault. Repeat process from firewall to PCM. If fault is indicated, isolate and repair as necessary. Clear codes and repeat QUICK TEST. If no fault is indicated, go to next step.

9) Check PCM & Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Clear codes and repeat QUICK TEST. If connector is okay, go to next step.

10) Check PCM For Short To Power Turn ignition off. Disconnect ICM connector (pins No. 7-12). Connect PCM to breakout box. Measure voltage between test pin No. 4 and chassis ground. Turn ignition on. Measure voltage between test pin No. 4 and pins No. 40 and 60. If any reading is more than 10.5 volts, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If each reading is 10.5 volts or less, go to next step.

11) Check PCM For Short To Ground Turn ignition off. Leave ICM connector (pins No. 7-12) disconnected. Connect PCM to breakout box. Measure resistance between test pin No. 4 and pins No. 40, 46 and 60. If all readings are more than 10,000 ohms, check ignition system. Proceed to appropriate SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If any reading is 10,000 ohms or less, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

CIRCUIT TEST NC - IGNITION DIAGNOSTIC MONITOR (IDM)

DISTRIBUTORLESS IGNITION SYSTEM (HIGH DATA RATE)

The IDM is an input signal to the PCM that verifies spark plug fire based on ignition coil primary discharge. IDM signal consists of a single pulse for each engine RPM. No IDM pulse indicates secondary ignition misfire.

Perform this test when directed by QUICK TEST. This test is only intended to diagnose EEC-IV portion of ignition system. For additional information on ignition system and component testing, proceed to SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. To prevent replacing good components, be aware following non-EEC related areas may be at fault

1. Ignition Control Module (ICM).
2. Ignition coil packs.
3. Spark plugs and/or wires.
4. Crankshaft Position (CKP) sensor.
5. Secondary ignition short to ground.

This test is intended to diagnose

1. Wiring harness circuits (IDM and SPOUT).
2. Powertrain Control Module (PCM).

1) Continuous Memory Code 211: Erratic Ignition Code 211 indicates 2 successive erratic Profile Ignition Pick-Up (PIP) pulses occurred. Possible causes for this fault are

1. Loose wires or connectors.
2. Secondary ignition short to ground.
3. On-board transmitter equipment (2-way radio).

Repair any problems found as necessary. Clear codes and repeat QUICK TEST. If problem is not found, go to step 4) If vehicle does not start, go to CIRCUIT TEST AC.

2) Code 226: IDM Circuit Failure Code 226 indicates PCM did not receive IDM signal from ICM in KOEO SELF-TEST. Possible causes for this problem are

1. Open or short in IDM or IGN GND circuit wiring harness.
2. Faulty ICM.

If engine does not start, refer to IGNITION SYSTEMS in SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If engine starts go to step 4).

3) Continuous Memory Code 212: Check For Other Codes Code 212 indicates loss of IDM input signal to PCM. Possible causes for this fault are

1. Open or short circuit in wiring harness.
2. Faulty ICM.
3. Faulty PCM.

If vehicle is a no-start or Continuous Memory Code 215, 216, 217 or 232 is present, proceed to IGNITION SYSTEMS in SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If vehicle starts and Code 215, 216 or 217 is not present, go to next step.

4) Code 212: Check IDM Circuit Continuity Turn ignition off. Disconnect ICM. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 4 at breakout box and pin No. 2 at ICM wiring harness connector. If resistance is 5 ohms or more, repair open circuit. Clear codes and repeat QUICK TEST. If resistance is less than 5 ohms, go to next step.

5) Check IDM Circuit For Short To Power (Except VREF) Leave PCM and ICM disconnected. Monitor circuit voltage by connecting DVOM between test pin No. 4 and test pins No. 40 or 60. To check VBAT circuit, turn ignition off. To check VPWR circuit, turn ignition on. If any reading is more than 10.5 volts, repair short to power. Remove breakout box, reconnect all components, and repeat QUICK TEST. If voltage is 10.5 volts or less, go to next step.

6) Check IDM Circuit For Short To VREF & PIP Turn ignition off. Ensure PCM and ICM are disconnected. Disconnect scan tool (if applicable). To check for shorts to VREF, use DVOM to measure resistance between test pins No. 4 and 26 at breakout box. To test for shorts to PIP, measure resistance between test pins No. 4 and 56 at breakout box. If resistance is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If resistance is more than 10,000 ohms, go to next step.

During this test, a short to SIG RTN (pin No. 46) may be indicated along with an actual short to PWR GND when 4-wire HO2S is connected to vehicle wiring harness.

7) Check IDM Circuit For Short To Ground Leave PCM and ICM disconnected. Measure resistance between test pin No. 4 and test pins No. 40, 46 and 60 at breakout box. If any reading is 10,000 ohms or less, repair short to ground in IDM circuit. Clear codes and repeat QUICK TEST. If all resistances are more than 10,000 ohms, go to next step.

8) Check ICM Leave ignition off. Connect ICM to wiring harness connector. Connect PCM to breakout box. Start engine, and allow it to idle. Connect DVOM to test pin No. 4 and No. 16. Start engine. Observe DVOM for voltage surge (fault) while lightly tapping on ignition components to simulate road shock. Wiggle both ICM wiring harness connectors. If fault is indicated, disconnect and inspect ICM wiring harness connectors and terminals for damage. If connectors and terminals are okay, check ignition system. Proceed to the appropriate SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If fault is not indicated, leave DVOM connected to breakout box and go to step 9).

9) Check EEC-IV Harness Ensure engine is idling at correct RPM. Wiggle, shake or bend small sections of harness, working from ICM connectors to firewall. Observe DVOM for indication of fault. Repeat process from firewall to PCM. If fault is indicated, isolate fault and repair wiring harness. Repeat QUICK TEST. If no fault is indicated, go to next step.

10) Check PCM & Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Clear codes, and repeat QUICK TEST. If connector is okay, go to next step.

11) Check PCM For Short To Power Turn ignition off. Disconnect ICM connectors. Connect PCM to breakout box. Measure voltage between test pin No. 4 and chassis ground. Turn ignition on. Measure voltage between test pin No. 4 and pins No. 40 and 60. If any reading is more than 10.5 volts, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If each reading is 10.5 volts or less, go to next step.

12) Check PCM For Short To Ground Turn ignition off. Leave ICM connectors disconnected. Ensure PCM is connected to breakout box. Measure resistance between test pin No. 4 and pins No. 16, 20, 40, 46 and 60. If all readings are more than 10,000 ohms, EEC system is okay. Check ignition system. Refer to SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If any reading is 10,000 ohms or less, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Perform this test when checking computed timing or if directed by QUICK TEST. This test is intended to diagnose

1. SPOUT wiring harness circuit.
2. Base timing.
3. Powertrain Control Module (PCM).

To prevent replacing good components, be aware the following non-EEC related areas may be at fault

1. Basic engine condition (compression, valve timing, etc.).
2. Distributor.
3. Ignition Control Module (ICM).

Spark Timing Check Ckt. (PA1 - 2.0L W/ Dist. Mounted ICM). Scheme 54

Sprk. Timing Chck. Ckt. (PA2 - Exc. 2.0L W/ Dist. Mounted ICM). Scheme 55

1) Check For Power To PCM Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Measure voltage between test pins No. 37 and 40 and between test pins No. 57 and 60 at breakout box. If either reading is 10.5 volts or less volts, go to CIRCUIT TEST B. If both voltage readings are more than 10.5 volts, go to next step.

2) Check SPOUT Circuit For Continuity Turn ignition off. Disconnect ICM wiring harness connector. Measure resistance between test pin No. 36 at breakout box and SPOUT terminal at ICM wiring harness connector. If resistance is 5 ohms or more, repair open circuit. Reconnect all components, and check ignition timing. If resistance is less than 5 ohms, go to next step.

3) Check SPOUT Circuit For Short To B+ Turn ignition off. Leave PCM and ICM disconnected. Turn ignition on. Measure voltage between test pin No. 36 and test pins No 40 or 60. If voltage is more than 10.5 volts, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If voltage is 10.5 volts or less, go to next step.

4) Check SPOUT Circuit For Short To PIP, VREF & Ground Turn ignition off. Leave PCM and ICM disconnected. To check for shorts to VREF, use DVOM to measure resistance between test pins No. 26 and 36 at breakout box. To check for shorts to PIP, measure resistance between test pins No. 36 and 56 at breakout box. To check for shorts to ground, measure resistance between test pin No. 36 and test pins 16, 20, 40, 46 and 60 at breakout box. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are more than 10,000 ohms, EEC system is okay. Check ignition system. See IGNITION SYSTEMS in SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

CKT TEST PB - SPARK TIMING CHECK DISTRIBUTORLESS IGN

SYSTEM (LOW DATA RATE)

Perform this test when checking computed timing or if directed by QUICK TEST. This test is intended to diagnose

1. SPOUT wiring harness circuit.
2. Base timing.
3. Faulty PCM.

To prevent replacing good components, be aware the following non-EEC related areas may be at fault

1. Basic engine condition (compression, valve timing, etc.).
2. Ignition Control Module (ICM).
3. Camshaft Position (CMP) sensor.
4. Crankshaft Position (CKP) sensor.

1) Check For Power To PCM Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Measure voltage between test pins No. 37 and 40 and between test pins No. 57 and 60 at breakout box. If either reading is 10.5 volts or less, go to CIRCUIT TEST X. If both readings more than 10.5 volts or more, go to next step.

2) Check SPOUT Circuit For Continuity Turn ignition off. Disconnect ICM wiring harness connector (pins No. 1-6). Measure resistance between test pin No. 36 at breakout box and SPOUT terminal at ICM module wiring harness connector. If resistance is 5 ohms or more, repair open circuit and check ignition timing. If resistance is less than 5 ohms, go to next step.

3) Check SPOUT Circuit For Short To B+ Turn ignition off. Leave PCM and ICM disconnected. Turn ignition on. Measure voltage between test pin No. 36 and test pins No 40 or 60. If voltage is more than 10.5 volts, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. and repeat QUICK TEST. If voltage is 10.5 volts or less, go to next step.

4) Check SPOUT Circuit For Short To PIP, VREF & Ground Turn ignition off. Leave PCM and ICM disconnected. To check for shorts to VREF, use DVOM to measure resistance between test pins No. 26 and 36 at breakout box. To check for shorts to PIP, measure resistance between test pins No. 36 and 56 at breakout box. To check for shorts to ground, measure resistance between test pin No. 36 and test pins No. 16, 20, 40, 46 and 60. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are more than 10,000 ohms, EEC system is okay. Check ignition system. See IGNITION in SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 4) to step 10). No test procedures have been omitted.

10) Continuous Memory Code 219: Check SPOUT Circuit Continuity Code 219 indicates ignition timing has defaulted to 10 degrees BTDC. SPOUT signal has a variable duty cycle, with voltage varying from 0.4 volt to battery voltage. In event of a SPOUT failure, ICM will generate a fixed dwell and constant spark angle, based on CID and PIP signals (FMEM mode). Possible causes for this fault are

1. Faulty ICM.
2. Faulty SPOUT circuit.

Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Disconnect ICM (pins No. 1-6). Measure resistance between test pin No. 36 at breakout box and SPOUT terminal at ICM harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, check SPOUT in-line connector. If connector is okay, repair open circuit and repeat QUICK TEST.

11) Check SPOUT For Short To Power & Ground Turn ignition off. Leave PCM and ICM disconnected. Measure resistance between test pin No. 36 and test pins No. 16 and 40 at breakout box. Also, measure resistance between test pin No. 36 and positive battery terminal. If resistance is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If each resistance is more than 10,000 ohms, replace ICM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

CIRCUIT TEST PC - SPARK TIMING CHECK DISTRIBUTORLESS

IGNITION SYSTEM (HIGH DATA RATE)

Perform this test when checking computed timing or if directed by QUICK TEST. This test is intended to diagnose

1. SPOUT wiring harness circuit.
2. Base timing.
3. Powertrain Control Module (PCM).

To prevent replacing good components, be aware the following non-EEC related areas may be at fault

1. Basic engine condition (valves, vacuum leaks, valve timing, etc.).
2. ICM.
3. Crankshaft Position Sensor (CKP).

1) Check For Power To PCM Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Measure voltage between test pins No. 37 and 40 at breakout box. Also, measure voltage between test pins No. 57 and 60 at breakout box. If both readings are more than 10.5 volts, go to next step. If any reading is 10.5 volts or less, go to CIRCUIT TEST B.

2) Check SPOUT Circuit For Continuity Turn ignition off. Disconnect ICM. Measure resistance between test pin No. 36 at breakout box and SPOUT terminal at ICM wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit and check ignition timing.

3) Check SPOUT Circuit For Shorts To Power (Except VREF) Turn ignition off. Leave PCM and ICM disconnected. Measure voltage between test pin No. 36 and test pin No. 40 or 60 at breakout box. To check for short to VBAT, turn ignition off. To check for short to VPWR, turn ignition on. If any reading is more than 10.5 volts, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If voltage is 10.5 volts or less, go to next step.

During this test, a short to SIG RTN (pin No. 46) may be indicated along with an actual short to PWR GND when 4-wire HO2S is connected to vehicle wiring harness.

4) Check SPOUT Circuit For Shorts To VREF, Ground & PIP Turn ignition off. Leave PCM and ICM disconnected. To check for shorts to ground, measure resistance between test pin No. 36 and test pins No. 16, 20, 40, 46 and 60. To check for shorts to VREF, measure resistance between test pins No. 26 and 36. To check for shorts to PIP circuit, measure resistance between test pins No. 36 and 56. If all readings are more than 10,000 ohms, check ignition system. See IGNITION SYSTEM in SYSTEM/COMPONENT TESTS - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section. If any reading is 10,000 ohms or less, repair short circuit and repeat QUICK TEST.

Aftermarket devices, such as alarm system, may cause SELF-TEST to abort if wiring is connected to certain EEC components. If a device is installed, disconnect it completely from EEC system. Before continuing with this circuit test, restore EEC circuits to original state and repeat QUICK TEST.

Perform this test when directed by QUICK TEST or other test procedures. This test is intended to diagnose

1. Powertrain Control Module (PCM).
2. EEC power relay.
3. Constant Control Relay Module (CCRM).
4. Wiring harness circuits (HO2S, SIG RTN, STO, STI, VPWR and VREF).

No Codes/Codes Not Listed Circuits (QA1). Scheme 56

TEST PIN NO. 17 (STO/MIL) WIRE COLOR IDENTIFICATION

TEST PINS NO. 37 & 57 (VPWR) WIRE COLOR IDENTIFICATION

TEST PIN NO. 46 (SIG RTN) WIRE COLOR IDENTIFICATION

TEST PIN NO. 48 (STI) WIRE COLOR IDENTIFICATION

1) Check VREF Voltage At Data Link Connector (DLC) Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Turn ignition on. Measure voltage between test pin No. 26 at breakout box and SIG RTN terminal at DLC. If reading is 4-6 volts, go to step 3). If reading is not 4-6 volts, go to next step.

2) Check SIG RTN Circuit Continuity Turn ignition off. Disconnect PCM from breakout box. Measure resistance between test pin No. 46 at breakout box and SIG RTN terminal at DLC. If reading is less than 5 ohms, go to CIRCUIT TEST C. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST.

3) Check STI Circuit Continuity Turn ignition off. Disconnect PCM from breakout box. Measure resistance between test pin No. 48 at breakout box and Self-Test Input (STI) terminal at pigtail connector. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

4) Check STO Circuit Continuity Leave ignition off and PCM disconnected. Measure resistance between test pin No. 17 at breakout box and STO terminal at DLC. If resistance is less than 5 ohms, go to step 5). If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Diagnostic Aid

A right/rear HO2S short to power could prevent EEC system from entering self-diagnostics.

5) Check HO2S Signal For Short To Power Leave PCM disconnected. Turn ignition on. Measure voltage between test pin No. 40 or 60 and HO2S SIGNAL test pin No. 29 or 44 at breakout box. For HO2S circuit schematics, see CIRCUIT TEST H. If voltage is more than 2 volts, go to step 6). If voltage is 2 volts or less, go to step 7).

6) Isolate Short To Harness Or HO2S Sensor Turn ignition off. Leave PCM disconnected. Disconnect right/rear HO2S sensor connector. Turn ignition on. Measure voltage between HO2S SIGNAL test pin No. 29 or 44 and test pin No. 40 or 60 at breakout box. If any reading is more than 2 volts, repair short to power in HO2S SIGNAL circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If voltage is 2 volts or less, replace right/rear HO2S sensor. Remove breakout box, reconnect all components, and repeat QUICK TEST.

7) Check STO Circuit For Short To Ground Turn ignition off. Leave PCM disconnected. Measure resistance between STO at DLC and engine ground. If reading is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair STO or MIL circuit for short to ground. Remove breakout box, reconnect all components, and repeat QUICK TEST.

8) Check If Power Relay Is Always On Leave ignition off and PCM disconnected. Connect DVOM between test pin No. 37 or 57 and test pin No. 40 or 60 at breakout box. Turn ignition on and then off. Wait 10 seconds. If voltage changes from more than 10.5 volts to less than 1.0 volt, go to step 10). If voltage does not change from more than 10.5 volts to less than 1.0 volt, go to next step.

9) Check VPWR Circuit For Short To Power Turn ignition off. Leave PCM disconnected. Disconnect EEC power relay or Constant Control Relay Module (CCRM). Connect DVOM to test pin No. 37 or 57 and test pin No. 40 or 60 at breakout box. If voltage is more than 1.0 volt, repair VPWR circuit short to power. Remove breakout box, reconnect all components, and repeat QUICK TEST. If voltage is 1.0 volt or less, replace EEC power relay or CCRM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

10) Check Malfunction Indicator Light (MIL) Function If MIL is always on, go to CIRCUIT TEST ML, step 1). If MIL is always off, go to CIRCUIT TEST ML, step 4). If MIL is working normally, replace PCM and repeat QUICK TEST.

Perform this test when directed by QUICK TEST. This test is intended to diagnose

1. Faulty Powertrain Control Module (PCM).
2. KAPWR wiring harness circuits.

KAPWR Circuit Schematic (QB1). Scheme 57

TEST PIN NO. 1 (KAPWR) WIRE COLOR IDENTIFICATION

Continuous Memory Code 512 may be displayed when power between PCM and KAPWR is interrupted. This code may be set when a breakout box is installed or battery is disconnected.

1) Continuous Memory Code 512: Check KAPWR Circuit Voltage Code 512 indicates PCM power interruption in Keep-Alive Memory (KAM). Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure voltage between test pin No. 1 and test pin No. 40 or 60 at breakout box. Observe DVOM while wiggling small sections of EEC wiring harness from PCM to dash. If voltage is less than 10.5 volts, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If reading is 10.5 volts or more, go to next step.

2) Inspect Wiring Harness Routing Ensure EEC wiring is not routed close to ignition components and secondary ignition wires. If necessary, reroute EEC wiring. Clear codes, and wait 5 minutes. Repeat KOEO SELF-TEST. If Continuous Memory Code 512 is not repeated, service other codes as necessary. If no other codes are present, testing is complete. If Continuous Memory Code 512 is still present, replace PCM and repeat QUICK TEST.

Perform this circuit test when directed by other CIRCUIT TESTS. This test is only intended to diagnose

1. Throttle plate linkage.

1) Check For Codes 23, 53, 63, 121, 122 & 123 Disconnect cruise control servo wiring harness connector (if equipped). Perform KOEO SELF-TEST. If Code 23, 53, 63, 121, 122 or 123 is present, go to appropriate CIRCUIT TEST. See DIAGNOSTIC TROUBLE CODE REFERENCE CHARTS, and service codes as necessary. If Code 111 (pass code) is displayed, go to next step. If no code is displayed, go to CIRCUIT TEST QA.

2) Check Throttle Linkage Check throttle and linkage for sticking and binding. If throttle and linkage are okay, replace Throttle Position (TP) sensor and repeat QUICK TEST. If throttle and linkage are binding, repair as necessary and repeat QUICK TEST.

Perform this test only when directed by CIRCUIT TEST AA, CIRCUIT TEST AB or CIRCUIT TEST AC. This test is intended to diagnose

1. IAC system.
2. MAP/BARO system.
3. EGR system.

1) IAC Check Try to start engine at part throttle. If engine starts and runs smoothly at part throttle, go to CIRCUIT TEST KE, step 4). If engine does not run as described, go to step 3). If engine starts and idles smoothly, go to next step.

2) Check For RPM Drop Turn ignition off. Connect a tachometer to engine. Start engine. Disconnect IAC solenoid. If RPM drops or engine stalls, reconnect IAC solenoid and go to next step. If RPM does not drop, CIRCUIT TEST KE, step 4).

3) Power To MAP/BARO Sensor If vehicle is not equipped with a MAP/BARO sensor, go to step 8). If vehicle is equipped with a MAP/BARO sensor, turn ignition off. Disconnect MAP/BARO sensor. Connect MAP/BARO tester between wiring harness and MAP/BARO sensor. (Scheme 58) Connect banana plugs of tester into DVOM. Turn ignition on. If Green light is on, go to next step. If Green light is not on, repair open in VREF circuit. Remove tester and reconnect connectors. Check system operation.

MAP/BARO Tester & Circuit (S1). Scheme 58

4) MAP/BARO Tester Output Reading Measure several known good MAP/BARO sensors to obtain average voltage for location and date of testing. With MAP/BARO tester and DVOM connected, turn ignition on. Measure MAP/BARO voltage at MAP sensor. If voltage is not within specification for specific altitude, replace MAP/BARO sensor. See MAP VOLTAGE OUTPUT table. If voltage is in within specification for specific altitude, go to step 8) (MAF vehicles) or next step (except MAF vehicles).

MAP VOLTAGE OUTPUT

5) Check Vacuum Lines Check vacuum hoses for correct routing. Refer to VECI decal. Check MAP sensor vacuum hose for leaks and blockage. If vacuum hoses are okay, go to next step. If vacuum hoses are not okay, repair as necessary. Repeat QUICK TEST.

6) Check MAP Sensor Turn ignition off. Disconnect vacuum hose from manifold vacuum source. Connect vacuum pump to MAP sensor hose. Apply 18 in. Hg vacuum to MAP sensor. If MAP sensor holds vacuum, go to next step. If MAP sensor does not hold vacuum, replace MAP sensor or hose and repeat QUICK TEST.

7) Check Vacuum Manifold Source Install vacuum gauge at manifold vacuum source. Start engine and observe vacuum gauge. If manifold vacuum is present, remove vacuum gauge. Reconnect MAP sensor vacuum hose, and go to next step. If vacuum is not present, remove obstruction and repeat QUICK TEST.

8) Check EGR Vacuum If vehicle is not equipped with EGR system, go to CIRCUIT TEST H, step 2). If vehicle is equipped with EGR, disconnect and plug vacuum line at EGR valve. Attempt to start engine. If vehicle could not start previously and still does not start or if vehicle driveability fault is still present, go to next step. If vehicle did not start previously but starts now or if driveability symptoms are eliminated, go to one of the following

1. Models with Differential Pressure Feedback EGR (DPFE), go to CIRCUIT TEST DL, step 50).
2. Models with Pressure Feedback EGR (PFE), go to CIRCUIT TEST DL, step 21).
3. On Probe Federal M/T, check EGR system. See EMISSION SYSTEMS & SUB-SYSTEMS in «SYSTEM/COMPONENT TESTS - EEC-IV (2.0L)»(ref-22925) article in the ENGINE PERFORMANCE section.
4. On Probe except Federal M/T, go to CIRCUIT TEST DD, step 31).

9) Check EGR Valve Inspect EGR valve for leaks. If valve is fully closed, go to CIRCUIT TEST H. If EGR valve is leaking or is not fully seated, repair or replace valve as necessary.

CIRCUIT TEST TA - CLUTCH PEDAL POSITION (CCP) SWITCH/

PARK/NEUTRAL POSITION (PNP) SWITCH

Perform this test only when directed by QUICK TEST. This test is intended to diagnose

1. Clutch Pedal Position (CCP) switch.
2. Park/Neutral Position (PNP) switch.
3. Powertrain Control Module (PCM).
4. Wiring harness circuits (CPP, PNP and SIG RTN).

CCP Switch Circuit Schematic (TA5). Scheme 59

TEST PIN NO. 30 (CPP/PNP) WIRE COLOR IDENTIFICATION

TEST PIN NO. 46 (SIG RTN) WIRE COLOR IDENTIFICATION

1) Code 522, 525 Or 528 Code 522, 525 or 528 is a result of voltage being high at pin No. 10 (A/C input) or pin No. 30 (CPP/PNP input) while cranking engine or during KOEO SELF-TEST. Possible causes for these faults are

1. A/C circuit shorted to power.
2. CPP or PNP circuit open.
3. Faulty Powertrain Control Module (PCM).
4. Starter relay disconnected during self-test.

On A/T models, go to step 8). On M/T models, go to step 2).

2) Check CPP/PNP Input Turn ignition off. Turn A/C off (if equipped). Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pins No. 30 and 46 with transmission in Neutral and clutch pedal up. Also, measure resistance between test pins No. 30 and 46 with transmission in gear and clutch pedal down. If each resistance is less than 5 ohms, go to next step. If any resistance is 5 ohms or more, go to step 5).

3) Check CCP/PNP Switch Integrity Leave ignition off and PCM disconnected. Measure resistance between test pins No. 30 and 46 with transmission in any gear and clutch pedal up. If resistance is less than 5 ohms, go to CIRCUIT TEST KM, step 40) (models with A/C) or replace PCM and repeat QUICK TEST (all others). If resistance is 5 ohms or more, go to next step.

Neutral Gear/Clutch Input Circuit ID (TA6). Scheme 60

4) Check For CPP Short To Ground Leave ignition off and PCM disconnected. Disconnect CPP switch. Measure resistance between test pins No. 30 and 46. If resistance is more than 10,000 ohms, go to CIRCUIT TEST KM, step 40) (models with A/C) or replace PCM and repeat QUICK TEST (all others). If resistance is 10,000 ohms or less, repair short circuit. Reconnect all components, and repeat QUICK TEST.

5) Check Neutral Gear/Clutch Engage Switch Leave ignition off and PCM disconnected. Locate PNP switch (on transmission) and CPP switch (at clutch pedal linkage). Disconnect wiring harness at both switches. Measure resistance across PNP switch terminals with transmission in Neutral. Also, measure resistance across CPP switch with clutch pedal down. If each resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, replace switch. Remove breakout box, reconnect all components, and repeat QUICK TEST.

6) Check Neutral Gear/Clutch Harness Leave ignition off and PCM disconnected. Measure resistance between test pin No. 30 and the following terminals

1. PNP switch wiring harness connector terminal CPP and/or PNP.
2. CPP switch wiring harness connector terminal CPP and/or PNP.

Measure resistance between test pin No. 46 and the following terminals

1. PNP switch wiring harness connector terminal SIG RTN.
2. CPP switch wiring harness connector terminal SIG RTN.

If any resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If each resistance is less than 5 ohms, go to CIRCUIT TEST KM, step 40) (models with A/C) or replace PCM and repeat QUICK TEST (all others).

7) Check CCP Switch Turn ignition and A/C off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pins No. 30 and 46 at breakout box. If resistance is less than 5 ohms, go to CIRCUIT TEST KM, step 40) (models with A/C) or replace PCM and repeat QUICK TEST (all others). If each resistance is 5 ohms or more, repair open circuit. Reconnect all components, and repeat QUICK TEST.

8) Check PNP Input Turn ignition and A/C off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Ensure transmission is in Neutral or Park. Turn ignition on. Measure voltage between test pin No. 30 and chassis ground. If voltage is less than 1.0 volt, go to CIRCUIT TEST KM, step 40) (models with A/C) or replace PCM and repeat QUICK TEST (all others). If voltage is 1.0 volt or more, go to next step.

9) Check PNP Switch Resistance Turn ignition off. Disconnect PCM from breakout box. Disconnect PNP wiring harness connector. Measure resistance across switch terminals. If resistance is less than 5 ohms, repair open in PNP circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If resistance is 5 ohms or more, replace PNP switch. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 9) to step 15). No test procedures have been omitted.

15) Code 522: Check If Engine Starts KOEO Code 522 indicates that high voltage was sensed at test pin No. 30 during SELF-TEST. Possible causes for this fault are

CIRCUIT TEST TB - TRANSMISSION CNTRL SW (TCS), TRANSMISSION

CNTRL SW MODULE (TCSM) & TRANS CNTRL INDICATOR LIGHT (TCIL)

Perform this test only when directed by QUICK TEST. This test is intended to diagnose

1. Powertrain Control Module (PCM).
2. Wiring harness circuits (TCIL, TCS and TCSM).

To prevent replacing good components, be aware the following non-EEC related areas may be at fault

1. Basic engine condition (valves, vacuum leaks, valve timing, etc.).
2. Charging system.
3. Transmission (fluid, friction elements and cooling).

TEST PIN NO. 41 (TCS) WIRE COLOR IDENTIFICATION

TEST PIN NO. 37 OR 57 (VPWR) WIRE COLOR ID

Note. Procedure starts at step 2). No test procedures have been omitted.

2) Code 632 Or 653 Code 632 or 653 indicates that the TCS was not cycled between engine ID Code and WOT check during KOER SELF-TEST. Possible causes for this fault are

1. Faulty TCS or switch was not cycled during SELF-TEST.
2. Shorted wiring harness.
3. Faulty Powertrain Control Module (PCM).
4. Open in wiring harness or fuse.

If TCS cycled during KOER SELF-TEST, go to step 4). If TCS did not cycle during KOER SELF-TEST, repeat KOER SELF-TEST while cycling TCS.

3) Code 623 Or 631 Code 623 or 631 indicates transmission control indicator light circuit fault during KOEO SELF-TEST. Possible causes for this fault are

1. Burned out bulb.
2. Open or shorted wiring harness.

If TCS cycled during KOEO SELF-TEST, go to step 5). If TCS did not cycle during KOEO SELF-TEST, repeat KOER SELF-TEST while cycling TCS.

4) Check TCS Circuit Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Measure voltage between test pin No. 41 and test pin No. 40 or 60 while cycling TCS several times. If voltage cycles replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If voltage does not cycle, go to next step if diagnosing a trouble code or step 7) if diagnosing a driveability symptom.

5) Check Circuits For Short To Ground Turn ignition off. Leave PCM disconnected from breakout box. Disconnect TCS connector. Inspect connector for damage and repair as necessary. Measure resistance between test pin No. 41 and test pin 40 or 60. Also, measure resistance between test pin No. 55 and test pin No. 40 or 60. If each reading is more than 10,000 ohms, go to next step (Code 623 or 631) or step 8) (Code 632 or 653). If any reading is 10,000 ohms or less, repair short circuit. Repeat QUICK TEST. If code is still present, go to step 7).

6) Check Power Through TCIL Circuit Turn ignition off. Leave PCM disconnected from breakout box. Measure voltage between test pin No. 55 and test pin No. 40 or 60. If voltage is more than 10.5 volts, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If voltage is 10.5 volts or less, go to next step.

7) Check Output Driver Voltage Signal Leave PCM disconnected from breakout box. Turn ignition on. Measure voltage between test pin No. 55 and test pin No. 40 or 60. If voltage is 2 volts or more, go to next step. If voltage is less than 2 volts, check bulb and fuse. Replace as necessary. If bulb and fuse are okay, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

8) Check TCS & TCIL Circuits Turn ignition off. Leave PCM disconnected from breakout box. Ensure TCS is disconnected. Measure resistance of Purple/Orange wire between KEY POWER terminal of fuse No. 1 at instrument panel fuse block and TCS wiring harness connector. Also, measure resistance between test pin No. 41 at breakout box and Purple/Orange wire at TCS wiring harness connector. If any reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If each reading is less than 5 ohms, go to next step.

9) Check For Short To Power Turn ignition off. Leave PCM disconnected from breakout box. Ensure TCS is disconnected. Measure resistance between test pin No. 41 and test pin No. 37 or 57. Also, measure resistance between test pin No. 55 and test pin No. 37 or 57. If each reading is more than 10,000 ohms, replace TCS switch. Remove breakout box, reconnect all components, and repeat QUICK TEST. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 9) to step 20). No test procedures have been omitted.

Perform this test only when directed by QUICK TEST. To prevent replacing good components, be aware the following non-EEC areas may be at fault

1. Engine condition (compression, cam timing, valves, etc.).
2. Charging system or battery.
3. Transmission linkage, internal components or cooling.

This test is not intended to diagnose transmission. This test is intended to diagnose

1. Wiring harness circuits TCC, CCS, EPC, SS3/4, SS1, SS2, SS3, SIG RTN, EPC PWR and VPWR.
2. Faulty Powertrain Control Module (PCM).

CIRCUIT TEST TC ACRONYMS

AX4S & AODE DIAGNOSTIC TROUBLE CODE IDENTIFICATION

AODE DIAGNOSTIC TROUBLE CODE IDENTIFICATION

CD4E Solenoid Circuits (TC4 - Probe - Calif.). Scheme 61

CD4E DIAGNOSTIC TROUBLE CODE IDENTIFICATION

1) OUTPUT STATE CHECK Codes 621, 622, 626, 629, 641 and 652 indicates shift solenoid did not respond to PCM command. Possible causes for these faults are

1. Faulty solenoid assembly.
2. Circuit open or grounded.
3. Faulty Powertrain Control Module (PCM).

To enter OUTPUT STATE CHECK, use only VOM or DVOM. DO NOT use scan tester. Turn ignition off. Disconnect cruise control servo wiring harness connector. Connect DVOM negative lead to STO terminal at Data Link Connector (DLC). Connect positive lead to positive battery terminal. Install a jumper wire between SIG RTN terminal and STI terminal at DLC. (Scheme 56) Perform KOEO SELF-TEST until continuous memory test is complete. DVOM will read less than 1.0 volt when test is complete to indicate PCM has entered OUTPUT STATE CHECK. Depress and release throttle. If voltage increases, remain in OUTPUT STATE CHECK and go to next step. If voltage does not increase, depress throttle to WOT and release. If STO voltage goes high, go to next step. If STO voltage does not go high, leave test equipment connected and go to CIRCUIT TEST QC.

2) Check Solenoid Electrical Condition Turn ignition off. Disconnect transmission wiring harness connector. Inspect terminals, and repair if damaged. Connect VOM or DVOM positive test lead to solenoid wiring harness connector VPWR terminal. Connect negative test lead to appropriate shift solenoid terminal at transmission wiring harness connector. Turn ignition on. Cycle solenoid output on and off by depressing and releasing throttle 3-5 times. If voltage output changes 0.5 volt or more, fault is in transmission. If voltage output does not change 0.5 volt or more, remove jumper wire between SIG RTN terminal and STI terminal at DLC. Go to next step.

3) Check Solenoid & VPWR Circuit Continuity Turn ignition off. Leave transmission wiring harness disconnected. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between suspect signal output terminal at transmission wiring harness connector terminal and corresponding test terminal at breakout box. See appropriate wiring schematic at beginning of this circuit test. Also, measure resistance between breakout box test pins No. 37 and 57 and VPWR terminal at transmission wiring harness connector. If each resistance is less than 5 ohms, go to next step. If any resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

4) Check Solenoid Circuit For Short To Power Or Ground Leave ignition off and PCM disconnected. Leave transmission wiring harness disconnected. Measure resistance between PCM output signal test pin and test pins No. 37 and 57 at breakout box. Also, measure resistance between PCM output signal test pin and pins No. 40, 46 and 60 at breakout box and chassis ground. Measure resistance between PCM output signal test pin and chassis ground. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are 10,000 ohms or more, check solenoids. If solenoids are okay, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 4) to step 10). No test procedures have been omitted.

10) Code 624 Or 625: Check VPWR To Solenoid Code 624 indicates failure of EPC circuit. Code 625 indicates EPC driver failure. Possible causes for these faults are

1. Faulty solenoid.
2. Circuit open or grounded.

Turn ignition off. Disconnect transmission wiring harness connector. Turn ignition on. Measure voltage between VPWR and EPC PWR terminal at transmission wiring harness connector and chassis/battery ground. If voltage is less 10.5 volts or less, repair open circuit. Reconnect all components and repeat QUICK TEST. If voltage is more than 10.5 volts, go to next step.

11) Check Solenoid Signal & VPWR Circuit Continuity Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between VPWR/EPC PWR terminal at transmission wiring harness connector breakout box test pins No. 37 and 57. Also, measure resistance between test pin No. 38 at breakout box and EPC terminal at transmission wiring harness connector. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If resistance is less than 5 ohms, go to next step.

12) Check Circuit For Short To Power Or Ground Leave ignition off and PCM disconnected. Leave transmission wiring harness connector disconnected. Measure resistance between test pins No. 37 and 57 and suspect solenoid test pin at breakout box. Also, measure resistance between test pins No. 40, 46 and 60 and suspect solenoid test pin at breakout box. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are more than 10,000, check solenoids. If solenoids are okay, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 20). No test procedures have been omitted.

20) Code 621, 622, 641 Or 643: Check Solenoid Resistance KOEO Code 621 (SS1), 622 (SS2), 641 (SS3) or 643 (TCC) indicate failure in shift solenoid circuit. Possible causes for these faults are

1. Faulty shift solenoid.
2. Circuit open or grounded.
3. Faulty PCM.

Turn ignition off. Disconnect transmission wiring harness connector. Measure resistance between suspect shift solenoid at transmission wiring harness connector and chassis ground. If resistance is 13-27 ohms, go to next step. If resistance is not 13-27 ohms, go to step 25).

21) Check Shift Solenoid For Short To Power Leave ignition off and transmission wiring harness connector disconnected. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Turn ignition on. Measure voltage between suspect shift solenoid at transmission wiring harness connector and chassis ground. If voltage is 0.5 volt or more, repair short to power and repeat QUICK TEST. If voltage is less than 0.5 volt, go to next step.

22) Check Shift Solenoid For Short To Ground Turn ignition off. Leave transmission wiring harness connector disconnected. Measure resistance between suspect shift solenoid at transmission wiring harness connector and chassis ground. Also, measure resistance between suspect shift solenoid and other circuits at transmission wiring harness connector. If any reading is 10,000 ohms or less, repair short circuit. Reconnect all components and repeat QUICK TEST. If all readings are more than 10,000 ohms, go to next step.

23) Check Shift Solenoid Circuit Continuity Turn ignition off. Leave transmission wiring harness connector disconnected. Install EEC-IV Breakout Box (T83L-50-EEC-IV) or 4EAT tester, leaving PCM disconnected. Measure resistance between suspect shift solenoid test pin at breakout box and suspect shift solenoid terminal at transmission wiring harness connector. If resistance is 5 ohms or more, repair open circuit. Reconnect all components and repeat QUICK TEST. If resistance is less than 5 ohms, go to next step.

24) Check Shift Solenoid For Short To Power In Transmission Leave ignition off and PCM disconnected. Reconnect transmission wiring harness connector. Measure voltage between test pin No. 60 and suspect shift solenoid test pin at breakout box. If voltage is 0.5 volt or more, replace or repair solenoid short to power. Remove breakout box, reconnect all components, and repeat QUICK TEST. If voltage is less than 0.5 volt, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST.

25) Check Transmission Wiring Leave ignition off. Check transmission wiring harness circuits and connectors breaks or corrosion in insulation. Check for open or grounded circuits. Repair or replace as necessary. If connectors and circuits are okay, replace suspect solenoid and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 25) to step 30). No test procedures have been omitted.

30) Continuous Memory Codes 621, 622, 641 & 643 Continuous Memory Code 621 (SS1), 622 (SS2), 641 (SS3) or 643 (TCC) indicates a failure was detected in shift solenoid circuit during last 80 warm-up cycles. Possible causes for these faults are

1. Faulty shift solenoid.
2. Circuit open or grounded.

Turn ignition off. Check shift solenoid circuit between PCM and transmission. Repair or replace wiring as necessary. If circuits are okay, go to next step.

31) Check For Intermittent Short Or Open Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV) or 4EAT tester, leaving PCM disconnected. Turn ignition on. Connect test light between test pin No. 37 and suspect shift solenoid test pin at breakout box. See IDENTIFYING SHIFT SOLENOID TEST CIRCUITS table. Test light should be at partial brightness. Observe test light while wiggling and bending shift solenoid circuit between transmission and PCM. An open or short to power will be indicated by light going off. A short to ground will be indicated by light getting brighter. Repeat procedure for all solenoids. If fault is indicated, isolate and repair as necessary. If no fault is indicated, go to next step.

IDENTIFYING SHIFT SOLENOID TEST CIRCUITS

32) Check For Intermittent Short To Ground Leave ignition off and PCM disconnected. Disconnect transmission wiring harness connector. Turn ignition on. Connect test light between test pin No. 37 and suspect shift solenoid test pin at breakout box. Test light should be off. Observe test light while wiggling and bending shift solenoid circuit between transmission and PCM. A short to ground will be indicated by light turning on. Repeat procedure for all solenoids. If fault is indicated, isolate and repair as necessary. Remove breakout box, reconnect all components, and repeat QUICK TEST. If no fault is indicated, problem is intermittent and cannot be duplicated at this time.

Perform this test only when directed by QUICK TEST. To prevent replacing good components, be aware the following non-EEC areas may be at fault

1. Transmission linkage and internal components.
2. Electrical (alternator, battery, add-on devices, etc.).

This test is not intended to diagnose transmission. This test is intended to diagnose

1. Wiring harness circuits MLP, TRD, TRL, TRR, TROD and SIG RTN.
2. Powertrain Control Module (PCM).

MLP Sensor Circuit ID - (TD4, CD4E - Probe). Scheme 62

1) Codes 522, 634 & 654: Check MLP Sensor Alignment KOEO Code 634 indicates MLP sensor is out of self-test range (3770-4607 ohms) when gear selector is in Park position. KOEO Codes 522 and 654 indicate gear selector was not in Park position during self-test. Possible causes for these faults are

1. Linkage not adjusted correctly.
2. Faulty Manual Lever Position (MLP) sensor.
3. Circuit open or grounded.
4. Faulty Powertrain Control Module (PCM).

Turn ignition off. Apply parking brake. Place transmission gear selector in Neutral position. Place MLP Sensor Gauge (T91P-7010-AHT) in sensor slot. If gauge does not fit, loosen MLP mounting bolts and adjust sensor as necessary. If gauge fits, remove gauge and go to next step.

2) Check MLP Sensor Circuit Continuity Turn ignition off. Disconnect MLP sensor wiring harness connector. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between MLP terminal at MLP sensor wiring harness connector and test pin No. 30 at breakout box. Also, measure resistance between SIG RTN terminal at MLP sensor wiring harness connector and test pin No. 46 at breakout box. If any reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If both readings are less than 5 ohms, go to next step.

3) Check MLP Sensor For Short To Power & Ground Turn ignition off. Leave PCM and MLP sensor disconnected. Measure resistance between test pin No. 30 and test pins No. 37, 57, 40, 46 and 60 at break-out box. Also, measure resistance between test pin No. 30 and chassis ground. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If resistance is more than 10,000 ohms, go to next step.

4) Check MLP Sensor Resistance Turn ignition off. Connect MLP sensor. Leave PCM disconnected. Unlock steering column. Measure resistance between test pins No. 30 and 46 at breakout box while cycling gear selector. See MLP SENSOR RESISTANCE table. If resistance is within specification, replace PCM and repeat QUICK TEST. If resistance is not within specification, replace MLP sensor and repeat QUICK TEST.

MLP SENSOR RESISTANCE

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 4) to step 9). No test procedures have been omitted.

9) Transmission In Third Gear Only While in D/OD Ensure transmission fluid is at correct level and in good condition. Test drive vehicle with shift lever in both D and OD position. If transmission always remains in 3rd gear when vehicle is operated with shift lever in D or OD position, go to step 11). If transmission sometimes shifts okay, go to step 20).

10) Continuous Memory Code 634 Code 634 indicates PCM has received incorrect voltage signals from PNP switch. Test drive vehicle with shift lever in both D and OD position. If transmission always remains in 3rd gear when vehicle is operated with shift lever in D or OD position, go to next step. If transmission sometimes shifts okay, go to step 20).

11) Check IGN START/RUN Circuit At Transmission Turn ignition off. Disconnect 4EAT wiring harness connector at transmission. Turn ignition on. Measure voltage between IGN START/RUN terminal at transmission wiring harness connector and chassis ground. If voltage is 10.5 volts or less, repair open circuit and repeat QUICK TEST. If voltage is more than 10.5 volts, go to next step.

12) Check Transmission Select Switches Leave ignition off and 4EAT wiring harness connector disconnected. Disconnect 3-pin inhibit (PNP) switch connector at transmission. Check test pin and terminal values. (Scheme 63) If values are not correct, go to step 14). If connector terminal values are correct, go to next step.

Inhibit Switch & 4EAT Module Terminal ID (TD5). Scheme 63

13) Check Transmission Switch Input Voltage Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV) or 4EAT tester, leaving PCM disconnected. Reconnect inhibit switch and transmission switch connectors. Turn ignition on. Check test pin and terminal values. (Scheme 63) If values are correct and no other problems can be found, replace PCM and repeat QUICK TEST. If values are not correct, repair circuit(s) and check system operation.

14) MLP Switch Turn ignition off. Check MLP switch circuits and connectors for damage and corrosion. Ensure MLP switch is adjusted correctly. See step 1). If any faults are found, repair or replace as necessary and check system operation. If no faults are found, replace MLP switch. Reconnect all components and check system operation.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 14) to step 20). No test procedures have been omitted.

20) Inspect 4EAT Circuit Turn ignition off. Inspect transmission switches and harness connectors between PCM and transmission for corrosion or damage. Inspect wiring harness for correct routing. If any faults are found, repair or replace as necessary. If no faults are found, go to next step.

21) Check Wiring Harness & Connectors For Intermittent Open Or Short Circuit Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV) or 4EAT tester, leaving PCM disconnected. Turn ignition on. Connect test light between test pin No. 40 and transmission test pin as follows

1. Test pin No. 18 (TRD) with gear selector in D.
2. Test pin No. 23 (TRR) with gear selector in R.
3. Test pin No. 38 (TROD) with gear selector in OD.
4. Test pin No. 45 (TRL) with gear selector in L.

Test light should be on when gear selector is in the same gear as the circuit being tested. Shake and wiggle transmission switch wiring harness between PCM and transmission. Lightly tap on inhibit switch to simulate road shock. If test light dims, flickers or goes off, fault is indicated. Isolate fault and repair as necessary. Remove breakout box, reconnect all components and check system operation. If test light stays on, fault cannot be duplicated at this time.

PNP input (pin No. 30) should be monitored. With PNP switch referenced to GND, the voltage should be about zero volts in Park or Neutral and more than 3.0 volts in all other gear positions.

Drive vehicle to create conditions so that symptom will occur. Information provided by vehicle operator may help when trying to recreate symptom. When symptom occurs, assistant should observe and record changes in voltage signals.

Information about symptom, operating condition value of voltage signal and any other information available should be recorded for analysis. After test is completed, analyze results to locate and repair fault causing symptom. If problem cannot be identified, proceed to TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section for other possible causes of symptom.

4EAT Transmission Select Switch Specifications (TD6). Scheme 64

Perform this test only when directed by QUICK TEST. To prevent replacing good components, be aware the following non-EEC areas may be at fault

1. Engine and/or transmission fluid level.
2. Engine and/or transmission fluid temperature.
3. Ambient temperature.

This test is intended to diagnose

1. TFT sensor.
2. Wiring harness circuits TFT and SIG RTN.
3. Faulty Powertrain Control Module (PCM).

Transmission Fluid Temp. (TFT) Sensor Circuit (TE4 - Probe). Scheme 65

TFT SENSOR (AX4S, AODE & CD4E) SPECIFICATIONS

TFT SENSOR (4EAT) SPECIFICATIONS

1) KOEO Code 636 KOEO Code 636 indicate TFT sensor is out of self-test range. Possible causes for these faults are

1. Transmission fluid level incorrect.
2. Transmission fluid temperature incorrect.
3. Sensor resistance out of specification.
4. Faulty Powertrain Control Module (PCM).

Ensure transmission fluid temperature is more than 50°F (10°C). Repeat QUICK TEST. If Code 636 is present, go to next. If Code 636 is not present, no problem is indicated at this time. Test is complete.

2) Check VREF At Throttle Position (TP) Sensor Turn ignition off. Disconnect TP sensor wiring harness connector. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Turn ignition on. Measure voltage between VREF and SIG RTN terminals at TP sensor wiring harness connector. see scheme 26 If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to CIRCUIT TEST C.

3) Check TFT Sensor Resistance Turn ignition off. Disconnect PCM from breakout box. Allow transmission to cool. Measure and record resistance between test pin No. 46 and TFT test pin at breakout box. Reconnect PCM. Drive vehicle until transmission fluid is normal operating temperature. Disconnect PCM from breakout box. Measure resistance voltage between test pin No. 46 and TFT test pin at breakout box. If cold resistance measurement is higher than warm resistance measurement, and warm resistance is within specification, replace PCM and repeat QUICK TEST. See appropriate TFT SENSOR SPECIFICATIONS table at beginning of this circuit test. If resistance is not as specified, fault is in transmission.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 3) to step 10). No test procedures have been omitted.

10) KOEO Code 637 KOEO Code 637 indicates TFT sensor output exceeds self-test maximum voltage (4.8 volts). Possible causes for these faults are

1. Transmission fluid level incorrect.
2. Open wiring harness circuit.
3. Faulty TFT sensor.
4. Faulty PCM.

Turn ignition off. Disconnect TFT wiring harness connector. Inspect terminals, and repair if damaged. Connect jumper wire between TFT and SIG RTN terminals. Perform KOEO SELF-TEST. If Code 638 is present, fault is in transmission. If Code 638 is not present, remove jumper wire and go to next step.

11) Check TFT & SIG RTN Circuit Continuity Turn ignition off. Leave TFT sensor disconnected. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between TFT circuit at TFT wiring harness connector and TFT test pin at breakout box. Also, measure resistance between SIG RTN circuit at TFT wiring harness connector and test pin No. 46 at breakout box. If any reading 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are less than 5 ohms, go to next step.

12) Check TFT Sensor For Short To VPWR Turn ignition off. Leave PCM and TFT sensor disconnected. Measure resistance between TFT test pin and test pins No. 37 and 57 at breakout box. If all readings are more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 20). No test procedures have been omitted.

20) KOEO Code 638 KOEO Code 638 indicates TFT sensor output is lower than self-test minimum voltage. Possible causes for these faults are

1. Damaged TFT sensor.
2. Shorted wiring harness circuit.
3. Faulty PCM.

Turn ignition off. Disconnect transmission wiring harness connector. Inspect terminals, and repair if damaged. Perform KOEO SELF-TEST. If Code 637 is present, fault is in transmission. If Code 637 is not present, go to step 21).

21) Check VREF At Throttle Position (TP) Sensor Turn ignition off. Disconnect TP sensor wiring harness connector. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Turn ignition on. Measure voltage between VREF and SIG RTN terminals at TP sensor wiring harness connector. see scheme 72 If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to CIRCUIT TEST C.

22) Check TFT Circuit For Short To Ground Turn ignition off. Disconnect PCM from breakout box. Measure resistance between TFT test pin at breakout box and test pins No. 40, 46 and 60. If all readings are more than 10,000 ohms, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 25). No test procedures have been omitted.

25) Check Transmission Wiring Harness Turn ignition off. Check transmission internal and external wiring and connectors for damage and corrosion. Repair or replace if necessary. If wiring is okay, replace TFT sensor and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 25) to step 90). No test procedures have been omitted.

90) Continuous Memory Code 637 Or 638 Continuous Memory Code 637 or 638 indicates a fault has been detected in TFT circuit during previous 80 warm-up cycles. Possible causes for these faults are

1. Incorrect fluid level.
2. Intermittent fault in TFT sensor.
3. Intermittent short or open in wiring harness.

Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Connect DVOM between test pins No. 2 and 46 at breakout box. Turn ignition on. Shake and bend TFT and SIG RTN wires between transmission and PCM. Voltage should remain stable or change gradually. If voltage drops to zero, a short to ground is indicated. If voltage increases up to 5 volts, an open circuit is indicated. If voltage increases to more than 5 volts, a short to power is indicated. If fault is indicated, isolate and repair as necessary. If no faults are found, go to CIRCUIT TEST TD, step 22).

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 90) to step 100). No test procedures have been omitted.

100) Continuous Memory Code 657 Continuous Memory Code 657 indicates excessive transmission temperatures. Possible causes for these faults are

1. Damage in transmission cooling system.
2. Pulling overweight trailer.
3. Incorrect fluid level.
4. Damaged clutch.
5. Fault in TFT sensor.
6. Intermittent short or open in wiring harness.

Turn ignition off. Disconnect transmission wiring harness connector. Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary and reconnect connector. Perform KOEO SELF-TEST. If no code(s) is present, fault is in transmission. If Code 657 is present, fault is in transmission. If any other code(s) is present, service as necessary and repeat QUICK TEST.

Perform this test only when directed by QUICK TEST. This test is intended to diagnose

1. Wiring harness circuit TSS.
2. Faulty Powertrain Control Module (PCM).

Transmission Speed Sensor Circuit (TF2 - 2.0L CD4E). Scheme 66

Transmission Speed Sensor Circuit (TF3 - Except 2.0L CD4E). Scheme 67

TEST PIN NO. 5 (TSS) WIRE COLOR IDENTIFICATION

1) KOER Code 639 KOER Code 639 indicates input from Transmission Speed Sensor (TSS) to PCM is out of calibration. Possible causes for this fault are

1. Faulty TSS sensor.
2. Circuit open or grounded.
3. Faulty Powertrain Control Module (PCM).

Turn ignition off. Disconnect TSS wiring harness connector. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between TSS+ terminal at TSS wiring harness connector and test pin No. 5 at breakout box. Also, measure resistance between SIG RTN terminal at TSS wiring harness connector and test pin No. 46 at breakout box. If any reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If both readings are less than 5 ohms, go to next step.

2) Check Circuit For Short To Power Or Ground Leave ignition off and TSS disconnected. Measure resistance between test pin No. 5 and test pins No. 37 and 57 at breakout box. Measure resistance between test pin No. 5 and test pins No. 40, 46 and 60 at breakout box. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are more than 10,000 ohms, go to next step.

3) Measure TSS Resistance Leave ignition off and TSS disconnected. Measure resistance between TSS sensor terminals. On AODE equipped vehicles, resistance should be 450-750 ohms. On AX4S and CD4E equipped vehicles, resistance should be 80-200 ohms. If resistance is not as specified, replace TSS and repeat QUICK TEST. If resistance is as specified, check internal transmission components. If transmission is okay, replace PCM and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 3) to step 10). No test procedures have been omitted.

10) Code 639: Check TSS Resistance Code 639 indicates incorrect input signal from TSS. Possible causes for this fault are

1. Faulty TSS.
2. Circuit open or grounded.
3. Faulty PCM.

Turn ignition off. Disconnect transmission 12-pin connector. Measure resistance between TSS (-) and TSS (+) terminal at sensor wiring harness connector. If resistance is not 200-600 ohms, check wiring for damage and corrosion. If wiring is okay, replace TSS and repeat QUICK TEST. If resistance is 200-600 ohms, go to next step.

Transmission 12-Pin Connector Terminal ID (TF4). Scheme 68

11) Check TSS Circuit For Short To Power Leave ignition off and transmission 12-pin connector disconnected. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Turn ignition on. Measure voltage between TSS (+) terminal at sensor wiring harness connector and chassis ground. Also, measure voltage between TSS (-) terminal at sensor wiring harness connector and chassis ground. If both readings are less than 0.5 volt, go to next step. If any reading is 0.5 volt or more, repair short circuit. Reconnect all components and repeat QUICK TEST.

12) Turn ignition off. Leave transmission connector and PCM disconnected. Measure resistance between TSS (+) terminal at sensor wiring harness connector and chassis ground. Measure resistance between TSS (-) terminal at sensor wiring harness connector and chassis ground. Also, measure resistance between TSS (+) terminal and TSS(-) terminal at 12-pin connector. If any reading is 10,000 ohms or less, repair short circuit and repeat QUICK TEST. If any reading is more than 10,000 ohms, go to next step.

13) Check TSS Circuit Continuity Leave ignition off and transmission 12-pin connector removed. Install EEC-IV Breakout Box (T83L-50-EEC-IV) or 4EAT tester, leaving PCM disconnected. Measure resistance between TSS (+) terminal at 12-pin connector and test pin No. 24 at breakout box. Also, measure resistance between TSS (-) terminal at 12-pin connector and test pin No. 44 at breakout box. If any reading is 5 ohms or more, repair open circuit and repeat QUICK TEST. If both readings are less than 5 ohms, go to next step.

14) Check PCM For Internal Shorts Turn ignition off. Connect PCM to breakout box. Leave transmission wiring harness connector disconnected. Measure resistance between test pin No. 24 and pins No. 37, 40, 44, 57 and 60 at breakout box. If any reading is 500 ohms or less, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If all readings are more than 500 ohms, go to next step.

15) Check TSS Output Turn ignition off. Leave PCM connected to breakout box. Reconnect transmission 12-pin connector. Set DVOM on AC voltage scale. Start engine. Measure voltage between breakout box test pins No. 24 and 44 while varying engine speed. If AC voltage varies more than 0.5 volt, replace PCM. Remove breakout box, reconnect all components, and repeat QUICK TEST. If AC voltage does not vary more than 0.5 volt, replace TSS. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 15) to step 90). No test procedures have been omitted.

90) Continuous Memory Code 639 Code 639 indicates PCM detected incorrect output signal from TSS during previous 40-80 warm-up cycles. Possible causes for this fault are

1. Faulty TSS.
2. Faulty transmission.
3. Circuit open or grounded.
4. Faulty PCM.

Record and clear continuous memory codes. While test driving vehicle, stop, ensure transmission gear selector is in Drive position and accelerate heavily to 35 MPH. After test drive, perform QUICK TEST and record all codes. If Continuous Memory Code 639 does not repeat, problem cannot be duplicated at this time. If Continuous Memory Code 639 is repeated, go to next step.

91) Check TSS Circuit Continuity Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Disconnect TSS wiring harness connector. Measure resistance at TSS terminal at TSS connector and test pin No. 5 at breakout box. Also, measure resistance between SIG RTN terminal at TSS connector and test pin No. 46 at breakout box. If any reading is 5 ohms or more, repair open circuit. Repeat step 90) to verify code elimination. If both readings are less than 5 ohms, go to next step.

92) Check Circuit For Short To Power Or Ground Turn ignition off. Leave TSS disconnected. Measure resistance between test pin No. 5 and test pins No. 37 and 57 at breakout box. Also, measure resistance between test pin No. 5 and test pins No. 40, 46 and 60 at breakout box. If any reading is 500 ohms or less, repair short circuit. Repeat step 90) to verify code elimination. If both readings are more than 500 ohms, go to next step.

93) Measure TSS Sensor Resistance Turn ignition off. Leave sensor disconnected. Measure resistance between sensor terminals. If resistance is 80-200 ohms, replace PCM and repeat step 90) to verify code elimination. If resistance is not 80-200 ohms, replace sensor and repeat step 90) to verify code elimination.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 93) to step 95). No test procedures have been omitted.

95) Continuous Memory Code 639: Check TSS Wiring Continuous Memory Code 639 indicates an error in TSS sensor output during previous 80 warm-up cycles. Possible causes for this fault are

1. Intermittent fault in TSS sensor.
2. Intermittent short or open in wiring harness.
3. Transmission placed in gear when fluid level is low.

Turn ignition off. Visually inspect TSS wires and connectors for damage. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Connect DVOM between test pins No. 24 and 44 at breakout box. Start engine. Shake and bend TSS wires between transmission and PCM. Lightly tap circuit connectors. Voltage should remain stable or change gradually. If voltage drops or surges abruptly, fault in circuit is indicated. If fault is indicated, isolate and repair as necessary. If no faults are found, go to next step.

96) Check PCM & Harness Connectors Turn ignition off. Disconnect all connectors related to TSS circuit. Inspect circuits and connectors for damage. Repair as necessary and repeat QUICK TEST. If fault cannot be found, problem is intermittent and cannot be duplicated at this time.

Drive vehicle to create conditions so that symptom will occur. Information provided by vehicle operator may help when trying to recreate symptom. When symptom occurs, assistant should observe and record changes in voltage signals.

Information about symptom, operating condition value of voltage signal and any other information available should be recorded for analysis. After test is completed, analyze results to locate and repair fault causing symptom. If problem cannot be identified, proceed to TESTS W/O CODES - EEC-IV (2.0L) article in the ENGINE PERFORMANCE section for other possible causes of symptom.

Perform this test only when directed by QUICK TEST. To prevent replacing good components, be aware the following non-EEC areas may be at fault

1. Transmission fluid level.
2. Engine/transmission fluid temperature.
3. Ambient temperature.
4. Faulty wiring harness connectors.

This test is intended to diagnose

1. Wiring harness circuits CCS, SS1, SS2, SS3, EPC, TCC, TFT, and MLP.
2. Powertrain Control Module (PCM)

CD4E Electronic Transmission Circuit (TG3 - Probe). Scheme 69

Note. Procedure begins with step 90). No test procedures have been omitted.

90) Perform Drive Cycle Test Ensure all components are connected. Ensure transmission fluid is correct level. Warm engine to normal operating temperature. Perform KOEO and CONTINUOUS MEMORY CODE SELF-TEST. Clear all codes. Perform appropriate DRIVE CYCLE TEST.

Drive Cycle Test (AX4S)

With transmission gear selector in Overdrive position, moderately accelerate vehicle to 50 MPH for at least 15 seconds. Transmission should be in 4th gear. While holding speed steady, lightly apply and release brake for about 5 seconds. Stop and park vehicle for a minimum of 20 seconds with transmission gear selector in Drive position. Repeat procedure 5 times. After completing drive cycle test, perform KOEO and CONTINUOUS MEMORY CODE SELF-TEST. If Code 111 is present, fault cannot be duplicated at this time. If Code 624, 634 or 651 is present, go to step 91). If Code 452 is present, go to CIRCUIT TEST DP. If Code 659, 667, 668 or 675 is present, go to step 93). If any other code(s) is present, go to step 92).

Drive Cycle Test (AODE & CD4E)

With transmission gear selector in Drive position, press Transmission Control Switch (TCS). Transmission Control Indicator Light (TCIL) should come on. Moderately accelerate vehicle to 40 MPH for at least 15 seconds (30 seconds above 4000 ft. elevation). Transmission should be in 3rd gear. While holding speed steady, press TCS. TCIL should go off. Accelerate from 40 MPH to 50 MPH. Transmission should shift from 3rd gear to 4th gear. Hold speed steady for 15 seconds. While holding speed steady, lightly apply and release brakes to turn brakelights on. Maintain 50 MPH for about 5 seconds. Stop and park vehicle for a minimum of 20 seconds with transmission gear selector in Drive position. Repeat procedure 5 times. After completing drive cycle test, perform KOEO and CONTINUOUS MEMORY CODE SELF-TEST. If Code 111 is present, fault cannot be duplicated at this time. If Code 624, 634 or 651 is present, go to next step. If Code 452 is present, go to CIRCUIT TEST DP. If Code 659, 667, 668 or 675 is present, go to step 93). If any other code(s) is present, go to step 92).

91) Code 624, 634 Or 651 Code 624 and 651 indicate Electronic Pressure Control (EPC) failure. Code 634 indicates that Manual Lever Position (MLP) sensor is out of calibration. Possible causes for these faults are

1. Faulty EPC solenoid.
2. Faulty MLP sensor.
3. Circuit open or grounded.
4. Damaged PCM connector pins.

Turn ignition off. Disconnect 60-pin PCM connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. To test EPC solenoid, connect DVOM to EPC test pin and EPC VPWR test pin at breakout box. To test MLP sensor, connect DVOM to MLP test pin and test pin No. 46 at breakout box. For EPC solenoid and MLP sensor, turn ignition on. Voltage for EPC should be less than 10 volts. Voltage for MLP should be less than 5 volts. Shake and bend EPC/MLP wiring harness. Lightly tap on components to simulate road shock. Voltage should remain stable. If voltage changes or exceeds specification, fault in circuit is indicated. If fault is indicated, isolate and repair as necessary. Clear continuous memory codes, and repeat QUICK TEST. If no faults are found, problem cannot be located at this time.

92) Check Circuit Harness & Connectors Enter CONTINUOUS MONITOR MODE. Shake and bend EEC wiring harness while observing analog VOM or scan tool. Lightly tap on components to simulate road shock. If VOM indicator has erratic movement or scan tool beep, fault is indicated. If fault is indicated, isolate and repair as necessary. Clear continuous memory codes, and repeat QUICK TEST. If no faults are found, problem cannot be located at this time.

CIRCUIT TEST KOEO CONTINUOUS MEMORY CODES

93) Check For Code 659 Code 659 indicates high vehicle speed detected while vehicle was in Park. Possible causes for this fault are

1. Faulty Manual Lever Position (MLP) sensor.
2. Faulty Powertrain Control Module (PCM).

If Code 659 was present after performing drive cycle test in step 90), go to step 103). If Code 659 was not present after performing drive cycle test in step 90), go to next step.

94) Check For Code 675 Code 675 indicates MLP circuit voltage was out of range. Possible causes for this fault are

1. Faulty MLP sensor.
2. Open or short circuit.
3. Short to power or ground in SIG RTN circuit.
4. Faulty Powertrain Control Module (PCM).

If Code 675 was present after performing drive cycle test in step 90), go to next step. If Code 675 was not present after performing drive cycle test in step 90), go to step 98).

95) Check For Codes 675 & 667 Code 667 indicates MLP circuit voltage was less than self-test minimum voltage allowed. Possible causes for this fault are

1. Faulty MLP sensor.
2. Open or short in MLP circuit.
3. Short to power in MLP circuit.
4. Faulty Powertrain Control Module (PCM).

If Codes 675 and 667 were present after performing drive cycle test in step 90), go to step 99). If Codes 675 and 667 were not present after performing drive cycle test in step 90), go to next step.

96) Check For Codes 675 & 668 Code 668 indicates MLP circuit voltage was more than self-test maximum voltage allowed. Possible causes for this fault are

1. Faulty MLP sensor.
2. Open MLP circuit.
3. Short to power in SIG RTN circuit.
4. Faulty Powertrain Control Module (PCM).

If Codes 675 and 668 were present after performing drive cycle test in step 90), go to step 101). If Code 675 and 668 were not present after performing drive cycle test in step 90), go to next step.

97) Check MLP Alignment Turn ignition off. Apply parking brake. Place transmission gear selector in Neutral position. Place MLP Sensor Gauge (T91P-7010-AHT) in sensor slot. If gauge does not fit, loosen MLP mounting bolts and adjust sensor as necessary. Clear codes and repeat QUICK TEST. If gauge fits, remove gauge and go to next step.

98) Check For Code 667 Code 667 indicates MLP circuit voltage less than self-test minimum voltage allowed. Possible causes for this fault are

1. Faulty MLP sensor.
2. Open or short to ground in MLP circuit.
3. Faulty Powertrain Control Module (PCM).

If Code 667 was present after performing drive cycle test in step 90), go to next step. If Code 667 was not present after performing drive cycle test in step 90), go to step 101).

99) Check MLP Circuit Resistance Turn ignition off. Disconnect 60-pin PCM connector. Disconnect MLP sensor. Inspect connectors for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 30 at breakout box and MLP terminal at MLP sensor connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

100) Check For Shot To Ground In MLP Circuit Turn ignition off. Ensure breakout box is installed and MLP sensor and PCM are disconnected. Measure resistance between test pin No. 30 and chassis ground. If resistance is more than 10,000 ohms, go to step 103). If resistance is 10,000 or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

101) Code 668 Code 668 indicates MLP circuit voltage was more than self-test maximum voltage allowed. Possible causes for this fault are

1. Faulty MLP sensor.
2. Open MLP circuit.
3. Faulty MLP sensor circuit.
4. Faulty Powertrain Control Module (PCM).

Turn ignition off. Disconnect 60-pin PCM connector. Disconnect MLP sensor. Inspect connectors for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pins No. 46 at breakout box and SIG RTN terminal at MLP sensor connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

102) Check For Short To Power Ensure PCM and MLP sensor are disconnected. Measure resistance between test pin No. 30 and test pins No. 37, 40, 46, 57 and 60 at breakout box. If all readings are more than 10,000 ohms, go to next step. If any reading is 10,000 ohms or less, repair short circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

103) Check MLP Sensor Resistance Turn ignition off. Connect MLP sensor. Leave PCM disconnected. Unlock steering column. Measure resistance between test pins No. 30 and 46 at breakout box while cycling gear selector. See MLP SENSOR RESISTANCE table. If resistance is within specification, replace PCM and repeat QUICK TEST. If resistance is not within specification, replace MLP sensor and repeat QUICK TEST.

MLP SENSOR RESISTANCE

CCRM interfaces with the EEC-IV system to provide control for cooling fan and A/C clutch. CCRM also contains EEC-IV power relay, which provides battery power (VPWR) to the Powertrain Control Module (PCM) and EEC-IV system.

Perform this test only when instructed by QUICK TEST or if directed by CIRCUIT TEST C, CIRCUIT TEST DC, CIRCUIT TEST PA or CIRCUIT TEST PB. This test is only intended to diagnose the following

1. CCRM (battery voltage and all relays).
2. Harness circuits (B+, FP, FC KPWR, PWR GND, LFC, HFC, A/C, ACCS and WAC).
3. PCM.

To prevent replacing good components, be aware the following non-EEC related components or systems may be at fault

1. A/C system.
2. Fuel system.
3. Starting and charging system.

PCM & CCRM Connector (X1). Scheme 70

1) Check Battery Supply Voltage Turn ignition on. Set DVOM on 20-volt scale. Measure voltage across battery terminals. If reading is less than 10.5 volts, recharge or replace battery. If reading is 10.5 volts or more, go to step 2).

2) Check Battery Ground Leave ignition on. Measure voltage between negative battery terminal and SIG RTN circuit in Data Link Connector (DLC). If reading is less than .5 volt, go to step 6). If reading is .5 volt or more, go to step 3).

3) Isolate Ground Fault Turn ignition off. Disconnect PCM 60-pin connector. Inspect wiring, and repair if damaged. Install breakout box. Connect PCM wiring harness to breakout box. Turn ignition on. Measure voltage between negative battery terminal and test pins No. 40 and 60. If either voltage reading is .5 volt or more, repair open ground circuit. Remove breakout box, and repeat QUICK TEST. If both readings are less than .5 volt, go to step 4).

4) PCM Ground Fault Isolation Ensure ignition is off. Leave breakout box installed with PCM connected. Measure resistance between test pin No. 46 and test pins No. 40 and 60. If each resistance is 5 ohms or more, replace PCM. Remove breakout box, and repeat QUICK TEST. If both readings are less than 5 ohms, go to step 5).

5) Check Continuity Of SIG RTN Circuit Turn ignition off. Disconnect PCM from breakout box. Measure resistance between test pin No. 46 and SIG RTN circuit at Data Link Connector (DLC). If reading is less than 5 ohms, system is okay. Remove breakout box, and reconnect PCM. Repeat QUICK TEST. If reading is 5 ohms or more, repair open SIG RTN circuit. Remove breakout box, and repeat QUICK TEST.

6) Measure Voltage & Ground To CCRM Leave ignition off. Disconnect CCRM. Measure voltage between pins No. 8 and 15 at CCRM wiring harness connector.

7) Check Key Power To CCRM Leave CCRM disconnected. Turn ignition on. Measure voltage between pins No. 13 and 15 at CCRM wiring harness connector. If reading is less than 10.5 volts, repair open between pin No. 13 and ignition switch. Reconnect CCRM, and repeat QUICK TEST. If reading is 10.5 volts or more, go to step 8).

8) Check Continuity Of VPWR Circuit Turn ignition off. Disconnect PCM 60-pin connector. Inspect wiring, and repair if damaged. Install breakout box, leaving PCM disconnected. Measure resistance between test pins No. 37 and 57 at breakout box and pin No. 24 at CCRM wiring harness connector.

9) Check Continuity Of Power Ground To CCRM Leave ignition off and CCRM disconnected. Measure resistance between CCRM harness connector pin No. 15 and negative battery terminal. If resistance is 5 ohms or more, repair open in ground circuit to CCRM harness connector pin No. 15. Repeat QUICK TEST. If reading is less than 5 ohms, repair open in battery positive to pin No. 8 of CCRM harness connector. Repeat QUICK TEST.

10) DTC Code 562: Check For Power to Pusher Fan Control (PFC) Possible causes for DTC 562 are damaged circuit, PFC relay, or PCM. Turn ignition off. Disconnect PFC relay. Turn ignition on. Measure voltage between VPWR terminal of PFC relay wiring harness connector and negative battery terminal. If voltage is less than 10.5 volts, repair open in VPWR circuit to PFC relay. Repeat QUICK TEST. If voltage is 10.5 volts or more, go to next step.

PFC Wiring Harness Connector Terminal ID (X10). Scheme 71

11) Check PFC Relay Turn ignition off. Leave PFC relay disconnected. Measure resistance between PFC relay terminals No. 85 and 86. Measure resistance between PFC relay terminal No. 85 and terminals No. 30 and 87. If resistance is 10,000 ohms or more, go to next step. If resistance is less than 10,000 ohms, replace PFC relay and repeat QUICK TEST.

PFC Relay Terminal ID (X11). Scheme 72

12) Check PFC Circuit Leave ignition off and PFC relay disconnected. Turn ignition off. Disconnect PFC relay. Disconnect PCM 60-pin connector. Inspect wiring, and repair if damaged. Install breakout box, leaving breakout box disconnected. Turn ignition on. Measure voltage between test pins No. 34 and 40. If voltage is one volt or more, repair short circuit. Remove breakout box, and repeat QUICK TEST. If voltage is less than one volt, go to next step.

13) Turn ignition off. Leave PFC relay and PCM disconnected. Measure resistance between test pins No. 34 and 40. If resistance is 10,000 ohms or more, go to next step. If resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST.

14) Leave ignition off. Measure resistance between PFC terminal of PFC relay wiring harness connector and test pin No. 34. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST. If resistance is less than 5 ohms, replace PCM.

15) Code 563: Check HFC Relay Resistance Code 563 indicates failed HFC circuit. Possible causes are damaged circuit, CCRM or PCM. Turn ignition off. Disconnect CCRM. Measure resistance of CCRM between terminals No. 17 and 24. If reading is not 50-100 ohms, replace CCRM and repeat QUICK TEST. If reading is 50-100 ohms, go to next step.

16) Check VPWR To CCRM Leave CCRM disconnected. Turn ignition on. Measure voltage between CCRM wiring harness connector terminal No. 13 and negative battery terminal. If reading is less than 10.5 volts, repair open in VPWR circuit between EEC-IV power relay and CCRM. Repeat QUICK TEST. If reading is more than 10.5 volts, go to next step.

17) Check HFC Circuit Continuity Turn ignition off. Disconnect PCM 60-pin connector. Inspect wiring, and repair if damaged. Install breakout box, leaving PCM disconnected. Disconnect CCRM connector. Measure resistance between breakout box HFC test pin and CCRM wiring harness connector terminal No. 17. See HFC TEST PIN IDENTIFICATION table. If reading is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open in HFC circuit and repeat QUICK TEST.

HFC TEST PIN IDENTIFICATION

18) Check HFC Circuit For Short To Power Leave CCRM and PCM disconnected. Turn ignition on. Measure voltage between HFC test pin at breakout box and negative battery terminal. If reading is more than one volt, repair short to power and repeat QUICK TEST. If Code 563 is still present, replace PCM. If reading is less than one volt, go to next step.

19) Check HFC Circuit For Short To Ground With PCM and CCRM disconnected, measure resistance between HFC test pin and test pin No. 40 at breakout box. If reading is more than 10,000 ohms, replace PCM and repeat QUICK TEST. If resistance is 10,000 ohms or less, repair short to ground in HFC circuit and repeat QUICK TEST.

20) Code 564 If cooling fan is always on when ignition is on, go to step 24). If cooling fan is not always on when ignition is on, go to step 22).

21) Check VPWR To CCRM Turn ignition off. Disconnect CCRM. Turn ignition on. Measure voltage between CCRM wiring harness connector terminal No. 13 and negative battery terminal. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in VPWR circuit between EEC-IV power relay and CCRM.

22) Check FC/LFC Signal For Short To Ground Turn ignition off. Disconnect PCM 60-pin connector. Inspect wiring, and repair if damaged. Install breakout box, leaving PCM disconnected. Disconnect CCRM connector and perform appropriate test

Measure resistance between test pin No. 13 and test pin No. 40 or 60 at breakout box. If resistance is more than 10,000 ohms, go to step 23). If reading is 10,000 ohms or less, repair short to ground in FC/LFC circuit, and repeat QUICK TEST.

23) Check Fan Running Mode With ignition off and breakout box installed, disconnect PCM and connect CCRM connector. Turn ignition on. If fan runs, replace PCM. Remove breakout box, and reconnect all components. Repeat QUICK TEST. If fan does not run, replace CCRM. Remove breakout box. Reconnect all components, and repeat QUICK TEST.

24) Check FC/LFC Circuit Continuity Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install breakout box, leaving PCM disconnected. Disconnect CCRM connector. Set DVOM on 200-ohm scale, and perform appropriate test

Measure resistance between test pin No. 13 at breakout box and terminal No. 14 at CCRM harness connector. If reading is 5 ohms or less, go to step 24). If reading is more than 5 ohms, repair open in FC/LFC circuit and repeat QUICK TEST.

25) Check FC/LFC Circuit For Short To Power Turn ignition off. Install breakout box, leaving PCM disconnected. Disconnect CCRM connector. Set DVOM on 20-volt scale, turn ignition on and perform appropriate test

Measure resistance between breakout box test pin No. 13 and negative battery terminal. If reading is less than one volt, go to step 26). If reading is one volt or more, repair short to power in FC/LFC circuit. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

26) FC/LFC Circuit Fault Isolation Check Leave ignition off. Connect CCRM to wiring harness connector. Turn ignition on. Using jumper wire, perform appropriate test

Connect test pin No. 13 to test pin No. 40 or 60 at breakout box. If fan continues to run and Code 564 is present, go to step 150). If fan continues to run and Code 564 is not present, replace CCRM. Remove breakout box, and reconnect all components. Repeat QUICK TEST. If fan does not run, replace PCM. Remove breakout box. Reconnect all components, and repeat QUICK TEST.

27) Go to next step.

28) Cooling Fan Always On Turn all accessories off. Turn ignition on. If the pusher fan (located in front of radiator) is on, go to next step. If fan is not on, go to step 30).

29) Check Pusher Fan Control Relay Turn ignition off. Disconnect Pusher Fan Control (PFC) relay. Turn ignition on. If the pusher fan is still on, repair circuit short to power. If fan is not on, replace PFC relay.

30) Fan Always On; Check CCRM-To-Fan Circuit Turn ignition on. Turn all accessories off. Verify fan is always on. Turn ignition off. Disconnect CCRM. Turn ignition on. If fan is no longer on, replace CCRM and recheck system operation. If fan is still on, go to step 31).

31) Check Low Speed Power-To-Fan Circuit For Short To Power Turn ignition off. Disconnect CCRM and fan connectors. Set DVOM to 20-volt scale. Measure voltage between terminal No. 1 at CCRM connector and negative battery terminal. If reading is less than one volt, repair short in high speed power-to-fan circuit. Reconnect all components. Recheck system operation. If reading is one volt or more, repair short in low speed power-to-fan circuit. Reconnect all components. Recheck system operation.

32) Check Dual Function A/C Pressure Switch (ACPSW) Turn ignition off. Connect CCRM to wiring harness connector. Disconnect dual function ACPSW wiring harness connector. Start engine. If cooling fan is on, go to next step.

33) Check PCM Turn ignition off. Disconnect CCRM and PCM wiring harness connectors. Turn ignition on. If cooling fan comes on, replace CCRM. If cooling fan does not come on, go to next step.

34) Check ACPSW For Short To Ground Turn ignition off. Leave ACPSW and PCM wiring harness connectors disconnected. Measure resistance between ACPSW terminal of ACPSW wiring harness connector and negative battery terminal. If resistance is 10,000 ohms or more, replace PCM. If resistance is less than 10,000 ohms, repair ACPSW short to ground.

ACPSW Wiring Harness Connector Terminal ID (X12). Scheme 73

35) No Fan Operation Turn ignition off. Disconnect CCRM. Connect negative probe of DVOM to negative battery terminal. Perform appropriate test

Measure voltage between negative battery terminal and CCRM wiring harness connector terminals No. 3 and 4. If all readings are 10.5 volts or more, go to step 36). If any reading is less than 10.5 volts, repair open in battery power circuit. Reconnect CCRM, and recheck system operation.

36) Check Fan Motor Operation Turn ignition off, and disconnect CCRM connector. Perform appropriate test

Install a jumper wire between CCRM harness connector terminals No. 3 and 6. If cooling fan does not run, go to step 38). If cooling fan runs, go to step 37).

37) Check Fan Motor Operation Turn ignition off. Disconnect CCRM. Install a jumper between terminals No. 3 and 6 at CCRM wiring harness connector. If fan does not run, go to step 40). If fan runs, go to step 41).

38) Check Battery Voltage At Fan With CCRM By-Passed Turn ignition off. Disconnect cooling fan and CCRM connectors. Perform appropriate test

Install a jumper wire between CCRM harness connector terminals No. 3 and 6. Measure voltage at cooling fan harness connector. If reading is less than 8 volts, go to step 39). If reading is 8 volts or more, replace cooling fan motor. Reconnect CCRM, and re-evaluate symptom.

39) Check Cooling Fan Ground Circuit Turn ignition off. Disconnect cooling fan and CCRM connectors. Perform appropriate test

Install a jumper wire between CCRM harness connector terminals No. 3 and 6. Measure voltage between cooling fan harness connector and negative battery terminal. If reading is 8 volts or more, repair open in ground circuit to fan. After repairs, reconnect CCRM and recheck system operation. If reading is less than 8 volts, repair open in power-to-fan circuit from CCRM wiring harness connector to cooling fan wiring harness connector.

40) Check Voltage At Fan With CCRM By-Passed Turn ignition off. Disconnect cooling fan and CCRM connectors. Install a jumper wire between terminals No. 2 and 3 at CCRM wiring harness connector. Measure voltage at cooling fan wiring harness connector between power and ground terminals. If reading is more than 8 volts, replace fan motor. If reading is 8 volts or less, repair open circuit in power-to-fan circuit from terminals No. 1 and 2 of CCRM wiring harness connector to cooling fan wiring harness connector.

41) Check Fan Running Mode (Low Speed) Turn ignition off. Disconnect PCM. Reconnect CCRM. Turn ignition on. If fan runs, go to step 43). If fan does not run, replace CCRM.

42) Check High Fan Control (HFC) Signal To Ground Turn ignition off. Disconnect PCM 60-pin connector. Inspect pins and wiring, and repair if damaged. Install breakout box, leaving PCM disconnected. Ensure CCRM is connected. Turn ignition on. Perform appropriate test

Install a jumper wire between test pins No. 31 and 40 at breakout box. If fan speed changes from low to high, go to step 44). If fan speed does not change from low to high, replace CCRM.

43) Check Continuity Of High Speed Power-To-Fan Circuit Turn ignition off. Disconnect CCRM and 2-speed cooling fan. Measure resistance between terminal No. 1 and No. 12 of CCRM wiring harness connector. If resistance is less than 5 ohms, replace CCRM. If resistance is 5 ohms or more, repair open circuit and replace CCRM.

44) Check ECT Sensor Turn ignition off. Check engine coolant level. With breakout box installed, connect PCM to breakout box. While measuring voltage between test pins No. 7 and No. 46 at break-out box, warm engine to normal operating temperature. Allow engine to continue at idle. If fan comes on during testing, fault is intermittent and cannot be duplicated at this time. Testing is complete. If fan does not come on during testing, and voltage drops below .45 volt, turn ignition off and replace PCM. If fan does not come on during testing and voltage does not drop below .45 volt, disconnect Engine Coolant Temperature (ECT) sensor connector. Check wires and sensor for high resistance. Verify system is operating properly. If system operation is okay, replace ECT sensor and remove breakout box. Reconnect all connectors and recheck system operation.

45) Cooling Fan Does Not Operate If pusher fan operates, go to step 35). If pusher fan does not operate, turn ignition off. Disconnect Pusher Fan Control (PFC) relay. Measure voltage between PFC relay wiring harness connector B+ terminal and negative battery terminal. If 10.5 volts or more are present, go to step 47). If less than 10.7 volts are present, repair open in B+ circuit.

PFC Relay Wiring Harness Connector Terminal ID (X13). Scheme 74

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 45) to step 47). No test procedures have been omitted.

47) Check Pusher Fan Ground Circuit Turn ignition off. Disconnect PFC relay. Disconnect pusher fan. Measure resistance between ground terminal of pusher fan wiring harness connector and negative battery cable. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in ground circuit.

48) Check Power-To-Pusher Fan Circuit Continuity Turn ignition off. Disconnect PFC relay. Disconnect pusher fan. Measure resistance between Pusher-To-Power Fan terminal of PFC relay and Pusher-To-Power Fan terminal of pusher fan wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Power-To-Pusher Fan circuit.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 48) to step 50). No test procedures have been omitted.

50) Low Or No Voltage At A/C Clutch Turn ignition off. Disconnect A/C clutch connector and CCRM. Measure resistance between CCRM terminal No. 23 and power side of A/C clutch wiring harness connector. Measure resistance between CCRM terminal No. 26 and ground side of A/C clutch wiring harness connector. If each resistance is less than 5 ohms, go to next step. If either resistance is 5 ohms or more, repair open circuit.

51) Check A/C Switch Voltage To CCRM Disconnect CCRM. Turn ignition on. Set A/C demand switch to ON position. Measure voltage between terminal No. 21 of CCRM wiring harness connector and negative battery terminal. If voltage is 10.5 volts or more, go to step 57). If voltage is less than 10.5 volts, go to step 54) for vehicles using R-12 refrigerant or step 52) for all others.

52) Check Voltage To A/C Pressure Switch (ACPSW) Turn ignition off. Disconnect ACPSW. Turn ignition on. Set A/C demand switch to ON position. Measure voltage between A/C DEMAND SW CYCLIC PRESSURE SW and negative battery terminal. (Scheme 75) If voltage is 10.5 volts or more, go to step 53). If voltage is less than 10.5 volts, go to step 54).

ACPSW Wiring Harness Connector Terminal ID (X15). Scheme 75

53) Check Continuity Between ACPSW & CCRM Turn ignition off. Disconnect ACPSW and CCRM connector. Measure resistance between A/C Demand-to-CCRM terminal at ACPSW wiring harness connector and Terminal No. 21 of CCRM wiring harness connector. If resistance is less than 5 ohms, fault is intermittent and cannot be located at this time. If resistance is 5 ohms or more, repair open circuit.

54) Check Voltage To Cyclic Pressure Switch Turn ignition off. Disconnect cyclic pressure switch. Turn ignition on. Set A/C demand switch to ON position. Set DVOM to 20-volt scale. Measure voltage between/C demand switch side of cyclic pressure switch wiring harness connector and negative battery terminal. If reading is 10.5 volts or more, go to step 55). If reading is less than 10.5 volts, EEC-IV system is okay. Remove breakout box, reconnect all components and diagnose A/C system.

55) Check Continuity Between Cyclic Pressure Switch & ACPSW/CCRM. Turn ignition off. Leave ACPSW (if equipped) and CCRM disconnected. Measure resistance between A/C DEMAND TO CCRM terminal of the cyclic pressure switch wiring harness connector and terminal No. 21 of the CCRM wiring harness connector. If resistance is less than 5 ohms, EEC-IV system is okay. Remove breakout box, reconnect all components and diagnose A/C system. If resistance is 5 ohms or more, repair open circuit and re-evaluate symptom

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 55) to step 57). No test procedures have been omitted.

57) Check A/C Demand Switch Voltage To PCM Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins and repair as necessary. Install breakout box, leaving PCM disconnected. Disconnect CCRM connector. Turn ignition on. Set A/C demand switch to ON position. Measure voltage between test pin No. 10 at breakout box and chassis ground. If reading is more than 10.5 volts, go to step 58). If reading is 10.5 volts or less, repair open circuit between ACCS and PCM. Reconnect all connectors and recheck system operation.

58) Check WAC Circuit For Short To Ground Turn ignition off. Measure resistance between breakout box test pin No. 54 and chassis ground. If resistance is less than 10,000 ohms, repair short to ground in Wide Open Throttle A/C Cut-Off (WAC) circuit. If all readings are 10,000 ohms or more, go to step 62).

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 58) to step 60). No test procedures have been omitted.

60) Check WAC Circuit Continuity Ensure ignition is off and CCRM is disconnected. Install breakout box leaving PCM disconnected. Measure resistance between breakout box test pin No. 54 and CCRM wiring harness connector terminal No. 22. If reading is 5 ohms or less, go to step 61). If reading is more than 5 ohms, repair open in WAC circuit. Recheck system operation.

61) Check WAC Circuit For Short To Power Turn ignition off. Leave breakout box installed and PCM disconnected. Turn ignition on. Measure voltage between breakout box test pin No. 54 and negative battery terminal. If reading is less than one volt, go to step 62). If reading is more than one volt, repair short to power in WAC circuit and recheck system operation.

62) Isolate Fault To PCM Or CCRM Turn ignition off. Leave breakout box installed and PCM disconnected. Connect CCRM and A/C clutch connectors. Turn ignition on. Set A/C demand switch to ON position. Connect jumper wire between breakout box test pins No. 40 and 54. Disconnect and reconnect jumper wire several times while observing A/C clutch. If A/C clutch engages and disengages, and no A/C symptom is present, go to step 63). If A/C clutch engages and disengages, and no WAC symptom is present, replace PCM and recheck system operation. If A/C clutch does not engage and disengage, replace CCRM. Remove breakout box, reconnect all components and recheck system operation.

63) Check ECT & TP Inputs Turn ignition off. Leave breakout box installed. Connect PCM to breakout box. Start engine. Set A/C demand switch to ON position. To check ECT input, connect jumper wire between breakout box test pins No. 7 and 40. See ECT SENSOR SPECIFICATIONS table. To check TP input, connect jumper wire between breakout box test pins No. 40 and 47. See TP SENSOR SPECIFICATIONS table. If specifications are not correct, replace PCM and repeat QUICK TEST. If specifications are correct, fault is intermittent and cannot be isolated.

ECT SENSOR SPECIFICATIONS

TP SENSOR SPECIFICATIONS

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 63) to step 65). No test procedures have been omitted.

65) Check ACPSW Input Turn ignition off. Turn A/C control switch off. Disconnect ACPSW wiring harness connector. Connect jumper wire between ACPSW and GND terminal of ACPSW wiring harness connector. (Scheme 75) If high speed fan does not come on, go to next step. If high speed fan does come on, circuit is okay; diagnose A/C system. 66) Check Ground Circuit To ACPSW

Leave engine running and ACPSW disconnected. Connect jumper wire between ACPSW terminal of ACPSW wiring harness connector and negative battery terminal. If high speed fan does not come on, go to next step. If high speed fan does come on, repair open ground circuit to ACPSW.

67) Check ACPSW Circuit Continuity To PCM Turn ignition off. Leave ACPSW disconnected. Disconnect PCM 60-pin connector. Inspect connector for damaged pins and repair as necessary. Install breakout box, leaving PCM disconnected. Measure resistance between ACPSW terminal of ACPSW wiring harness connector and test pin No. 22 at breakout box. If resistance is less than 5 ohms, replace PCM and re-evaluate symptom. If resistance is 5 ohms or more, repair open circuit and re-evaluate symptom.

68) Check ACPSW Circuit Continuity To PCM Leave ignition off and ACPSW disconnected. Disconnect CCRM. Measure resistance between ACPSW terminal of ACPSW wiring harness connector and test pin No. 17 of the CCRM wiring harness connector. If resistance is less than 5 ohms, go to step 160). If resistance is 5 ohms or more, repair open circuit and re-evaluate symptom.

69) Check High Speed Fan Operation Turn ignition off. Leave ACPSW and CCRM disconnected. Connect jumper wire between CCRM terminals No. 3 and 6. If fan comes on, replace CCRM. If fan does not come on, check for continuity between CCRM and cooling fan and repair as necessary. If circuit is okay, replace cooling fan.

70) Code 556 Or 557 Code 556 indicates fuel pump primary circuit failure. Code 557 indicates low speed fuel pump primary circuit failure. Following are possible causes for this fault.

1. Faulty CCRM.
2. Faulty PCM.
3. Faulty Circuit.

Turn ignition off. Disconnect CCRM wiring harness connector. Perform appropriate procedure.

Measure resistance between terminal No. 18 and No. 24 at CCRM wiring harness connector. If resistance is not 65-120 ohms, replace CCRM and repeat QUICK TEST. If resistance is 65-120 ohms, go to step 73).

71) Check Voltage To Fuel Pump Relay Turn ignition off. Disconnect CCRM. Turn ignition on. Measure voltage between CCRM wiring harness connector pin No. 10 and negative battery terminal. If voltage is more than 10.5 volts, go to step 73). If voltage is 10.5 volts or less, ensure Inertia Fuel Shutoff (IFS) switch has not tripped. If okay, repair IGNITION START/RUN circuit between ignition switch and CCRM.

72) Check Power To CCRM Leave CCRM disconnected. Turn ignition on. Measure voltage between CCRM wiring harness connector pin No. 13 and negative battery terminal. If voltage is more than 10.5 volts, go to step 73). If voltage is 10.5 volts or less, repair open circuit between EEC-IV power relay and CCRM.

73) Check Continuity Of Fuel Pump Circuit Turn ignition off. Leave CCRM disconnected. Disconnect PCM 60-pin connector. Inspect wiring, and repair if damaged. Install breakout box, leaving PCM disconnected. Measure resistance between terminal No. 18 at CCRM wiring harness connector and test pin No. 22 at breakout box.

74) Check Fuel Pump Circuit For Short To Power Leave PCM and CCRM disconnected. Turn ignition on. Measure voltage between test pin No. 22 at breakout box and negative battery terminal. If voltage is less than 1.0 volt, go to step 75). If voltage is 1.0 volt or more, repair short to power and repeat QUICK TEST.

75) Check Fuel Pump Circuit For Short To Ground Leave PCM and CCRM disconnected. Measure resistance between test pin No. 22 at breakout box and negative battery terminal. If resistance is 10,000 ohms or more, replace PCM and repeat QUICK TEST. If resistance is less than 10,000 ohms, repair fuel pump circuit short to ground and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 75) to step 80). No test procedures have been omitted.

80) Code 542 Code 542 indicates one of the following conditions.

Test lights and DVOM are useful during diagnosis. For example: with Continuous Memory Code 556 (fuel pump primary circuit failure) and a surge or stall symptom, connect a test light to fuel pump relay between VPWR and ground. Connect DVOM between FP circuit at fuel pump relay and breakout box test pin No. 1. Under normal driving conditions, test light will be on and DVOM will read battery voltage.

If vehicle stalls, PCM will open FP circuit and DVOM voltage will be low. If fault is in fuel pump circuit, test light and DVOM status will change as fault occurs. If test light at VPWR circuit goes out, fault is in VPWR circuit to fuel pump relay. If test light and DVOM status do not change and Continuous Memory Code 556 is set again, replace fuel pump relay. If only FP voltage goes low, fault is in FP circuit or PCM. To diagnose FP circuit and PCM, connect DVOM between breakout box test pin No. 1 and 22. If voltage goes low as symptom occurs, replace PCM. If voltage stays high as symptom occurs, fault is in FP circuit. For fuel pump secondary circuit Codes 95/542 and 96/543, circuits B+, POWER-TO-PUMP and FPM can be diagnosed using same procedure.

Drive vehicle and attempt to induce symptom. Information provided by vehicle operator may help when trying to recreate symptom. When symptom occurs, assistant should observe and record changes in voltage signals. Information about symptom and operating condition value of voltage signal and any other information available should be recorded for analysis. If unable to duplicate symptom during road test, verify EEC-IV values are within acceptable range. After test is completed, analyze results to locate and repair fault causing symptom. If problem cannot be identified, see the article TESTS W/O CODES - EEC-IV (2.0L) in the ENGINE PERFORMANCE section for other possible causes of symptom.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 120) to step 130). No test procedures have been omitted.

130) Diagnostic Trouble Code 381 Continuous Memory Code indicates excessive A/C compressor clutch cycling (more than once every 8.5 seconds). Possible causes are mechanical problems such as low refrigerant, damaged cyclic pressure switch, etc. If fault is indicated, locate and repair as necessary. If no fault is indicated, go to next step.

131) Check For Intermittent Open Between Electronic Automatic Temperature Control (EATC) Module & PCM Terminal No. 10 Turn ignition off. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Connect a non-powered test light between test pins No. 10 and 40. Turn ignition on. Test light should come on. Check for indication of fault (test light goes off) while performing one of following

1. Shake and bend circuits between EATC module and PCM. (Scheme 76)
2. Lightly tap cyclic pressure switch to simulate road shock.
3. Turn ignition off. Disconnect and inspect cyclic pressure switch and EATC connector for damage.

If fault is indicated, isolate and repair as necessary. Repeat QUICK TEST. If fault is not indicated, problem is intermittent and cannot be duplicated or identified at this time.

CCRM Test Circuit (X19). Scheme 76

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 131) to step 140). No test procedures have been omitted.

140) Check Continuity Of High Speed Power To Fan Circuits Turn ignition off. Disconnect cooling fan and CCRM wiring harness connectors. Measure resistance between CCRM wiring harness connector terminals No. 1 and 12. If resistance is less than 5 ohms, repair open in high speed to power fan circuit and re-evaluate symptom. If resistance is 5 ohms or more, repair open in high speed to power fan circuit and go to next step.

141) Verify operation Of HFC Relays Turn ignition off. Leave CCRM disconnected. Connect jumper wire between CCRM terminal No. 13 and positive battery terminal. Connect another jumper wire between CCRM terminal No. 17 and negative battery terminal. Measure resistance between CCRM terminal No. 4 and terminals No. 1 and 2. If resistance is less than 5 ohms, both HFC relays are okay. Reconnect all components and re-evaluate symptom. If resistance is 5 ohms or more, replace CCRM.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 141) to step 150). No test procedures have been omitted.

150) Check HFC Circuit For Short To Ground Ensure ignition is off. With, measure resistance between test pin No. 40 and HFC test pin at breakout box. (Scheme 70) If resistance is less than 10,000 ohms, repair short to ground in HFC circuit. If resistance is more than 10,000 ohms, replace CCRM.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 150) to step 155). No test procedures have been omitted.

155) Check A/C Pressure Switch (ACPSW) Ensure ignition is off and breakout box is installed with PCM disconnected. Ensure ACPSW and CCRM wiring harness connectors are disconnected. Measure resistance between test pins No. 31 and 40. If resistance is now greater than 10,000 ohms, check ACPSW for correct operation and repair as necessary. If resistance is less than 10,000 ohms, repair short to ground in HFC circuit.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 155) to step 160). No test procedures have been omitted.

160) Check ACPSW Relay Primary Circuit For Open In CCRM Turn ignition off. Ensure ACPSW and CCRM wiring harness connectors are disconnected. Measure resistance between CCRM pins No. 17 and 24. If resistance is 50-100 ohms, no fault is present at this time. Connect components and re-evaluate symptom. If resistance is not 50-100 ohms, replace CCRM.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 160) to step 165). No test procedures have been omitted.

165) Diagnostic Trouble Code (DTC) 557 DTC 557 indicates a low speed fuel pump primary circuit failure. Possible causes are as follows

1. Open or shorted circuit.
2. Damaged LFP relay.
3. Damaged PCM.

Turn ignition is off. Disconnect LFP relay. Turn ignition on. Measure voltage between VPWR terminal of LFP relay wiring harness connector and negative battery terminal. (Scheme 77) If 10.5 volts or more are present, go to next step. If less than 10.5 volts are present, repair open in VPWR circuit between CCRM and LFP relay.

LFP Wiring Harness Connector Terminal (X20). Scheme 77

166) Check LFP Relay Turn ignition off. Leave LFP relay disconnected. Measure resistance between fuel pump relay terminals LFP and VPWR. (Scheme 78) Resistance should be 40-85 ohms. Measure resistance between fuel pump relay terminal LFP and terminals PUMP-TO-POWER and B+. Both measurements should be 10,000 ohms or more. If all resistances are correct, go to next step. If all resistances are not correct, replace LFP relay.

Fuel Pump Relay Terminal (X21). Scheme 78

167) Check LFP Relay For Shot To Power Leave ignition off and LFP relay disconnected. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Measure voltage between breakout box test pin No. 32 and negative battery terminal. If less than one volt is present, go to next step. If one volt or more is present, repair short to power and repeat QUICK TEST.

168) Check Circuit For Short To Ground Turn ignition off. Leave LFP relay disconnected. Measure resistance between breakout box test pins No. 40 and 60. If resistance is 10,000 ohms or more go to next step. If resistance is less than 10,000 ohms, repair short to ground and repeat QUICK TEST.

169) Check LFP Circuit Continuity Turn ignition off. Leave LFP relay disconnected. Measure resistance between breakout box test pin No. 32 and LFP terminal at LFP relay wiring harness connector. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST. If resistance is less than 5 ohms, replace PCM.

Perform this test only when instructed by QUICK TEST or directed by other test procedures. VCRM is located in left front of vehicle behind front grille. This test is only intended to diagnose following.

1. Variable Control Relay Module (VCRM).
2. Powertrain Control Module (PCM).
3. Harness Circuits Associated With VCRM.

Refer to illustration for VCRM connector terminal identification. (Scheme 79) For VCRM terminals and wiring identification, see WIRING DIAGRAMS. To prevent replacing good components, be aware that the following unrelated components or systems may be at fault.

1. Ignition switch, battery cables and ground straps.
2. Alternator and voltage regulator.

VCRM Connector Terminal ID (XB1). Scheme 79

1) Check Battery Supply Power With Key On Engine Off (KOEO), set DVOM on 20-volt scale. Measure voltage across battery terminals. If reading is less than 10.5 volts, service or replace discharged battery. If reading is 10.5 volts or more, go to next step.

2) PCM Ground Fault Isolation Ensure ignition is off. Install breakout box, and connect PCM. Set DVOM on 20-volt scale. Measure voltage between positive battery terminal and SIG RTN terminal (Gray/Red wire) at Data Link Connector (DLC). If voltage is less than 10.5 volts, go to next step. If voltage is 10.5 volts or more, go to step 10).

3) Check Continuity Of SIG RTN Circuit Turn ignition off. With break-out box installed, disconnect PCM. Measure resistance between test pin No. 46 at breakout box and SIG RTN terminal (Gray/Red wire) at DLC. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open SIG RTN circuit. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

4) Check PCM Ground Circuit Turn ignition off. With breakout box installed and PCM disconnected, measure resistance between negative battery terminal and test pins No. 40 and 60 at breakout box. If both readings are less than 5 ohms, go to next step. If any reading is 5 ohms or more, repair open in ground circuit. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

5) Check Internal PCM Ground Circuits Turn ignition off. With breakout box installed, reconnect PCM connector. Measure resistance between test pins No. 46 and 40 and between test pins No. 46 and 60 at breakout box. If resistance is less than 5 ohms, system tests okay. Remove breakout box. Reconnect PCM, and repeat QUICK TEST. If resistance is 5 ohms or more, replace PCM. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 5) to step 10). No test procedures have been omitted.

10) Check Continuity Of VPWR Circuit Turn ignition off. With breakout box installed, disconnect PCM connector. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between terminal No. 7 (Red wire) at VCRM connector and test pins No. 37 and 57 at breakout box. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in VPWR circuit between PCM and VCRM. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

11) Check For B (+) & IGN START/RUN Power To VCRM Turn ignition off. With breakout box installed and PCM and VCRM disconnected, measure voltage between terminal No. 6 (Yellow wire) at VCRM connector and negative battery terminal. Record voltage reading. Turn ignition on. Measure voltage between terminal No. 17 (Red/Light Green wire) at VCRM connector and negative battery terminal. If both readings are 10.5 volts or more, go to next step. If any reading is less than 10.5 volts, turn ignition off. Repair open in B (+) or IGN START/RUN circuit. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

12) Check VCRM Ground (Terminal No. 16) Turn ignition off. With breakout box installed and PCM and VCRM disconnected, measure resistance between terminal No. 16 (Black wire) at VCRM connector and negative battery terminal. If resistance is less than 5 ohms, replace VCRM. Remove breakout box, and reconnect all components. Repeat QUICK TEST. If resistance is 5 ohms or more, repair open ground circuit. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 15). No test procedures have been omitted.

15) Continuous Memory Code 584 Continuous Memory Code 584 indicates VCRM PWR GND circuit is open. This could be due to a hard fault or an intermittent condition. Following are possible causes for this fault.

1. Open VCRM PWR GND circuit.
2. Damaged VCRM.

Clear continuous memory. See CLEARING CODES under SELF-DIAGNOSTIC SYSTEM. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 584 is present (hard code), go to next step. If Code 584 is not present (intermittent), go to step 18).

16) Check Continuity Of VCRM PWR GND Circuit Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between terminal No. 1 (Black wire) at VCRM connector and negative battery terminal. If resistance is less than 5 ohms, replace VCRM. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If resistance is 5 ohms or more, repair open in ground circuit (Black wire). Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 16) to step 18). No test procedures have been omitted.

18) Check VCRM PWR GND Circuit Turn ignition off. Visually inspect VCRM PWR GND circuit (Black wire) between terminal No. 1 at VCRM connector and ground. VCRM circuit is grounded at a weld nut on right side of radiator support. Repair wiring as necessary. Start engine. Turn A/C on. Shake, wiggle and bend VCRM PWR GND circuit between VCRM and circuit's ground point. Also, lightly tap on VCRM to simulate road shock. An open circuit will be indicated by fan speed increasing to 100 percent (open circuit must be present for 5 seconds). If an open circuit is detected, isolate fault and repair as necessary. Clear continuous memory (Code 584 should have been set). Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If an open circuit is not detected, turn A/C and ignition off. Go to next step.

19) Check VCRM PWR GND Circuit (Cont.) Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Connect a test light between terminals No. 1 (Black wire) and No. 5 (Yellow wire) of VCRM connector. Observe test light, and shake, wiggle and bend VCRM PWR GND circuit between VCRM and circuit's ground point at right side of radiator support. Test light will go out if a fault is detected, indicating open circuit. If an open circuit is detected, isolate fault and repair as necessary. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If open circuit is not detected, fault is intermittent and cannot be duplicated at this time. Testing is complete. Reconnect all components.

20) Continuous Memory Code 581 Continuous Memory Code 581 indicates that when cooling fan was activated, power to cooling fan circuit exceeded normal current draw. This could be due to a hard fault or an intermittent condition. Following are possible causes for this fault.

1. Short to ground in power to cooling fan circuit.
2. Faulty cooling fan motor.
3. Faulty VCRM

Clear continuous memory. See CLEARING CODES under SELF-DIAGNOSTIC SYSTEM. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 581 is present (hard code), go to next step. If Code 581 is not present (intermittent), go to step 24).

21) Check Cooling Fan Motor Clear continuous memory. Disconnect cooling fan motor connector. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Perform Key On Engine Off (KOEO) self-test. If Code 581 is present, go to next step. If Code 581 is not present, replace cooling fan motor. Reconnect all connectors. Repeat QUICK TEST.

22) Check For Short To Ground In Cooling Fan Circuit Turn ignition off. Ensure cooling fan motor connector is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between Light Blue wire at cooling fan connector and negative battery terminal. If resistance is more than 10,000 ohms, replace VCRM. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If resistance is 10,000 ohms or less, repair short to ground in Light Blue wire. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 22) to step 24). No test procedures have been omitted.

24) Check For Intermittent Short To Gnd. In Cooling Fan Ckt. Turn ignition off. Visually inspect power-to-cooling fan circuit between terminal No. 2 (Light Blue wire) of VCRM connector and cooling fan motor connector. Repair wiring as necessary. Start engine. Turn A/C on. Shake, wiggle and bend power to cooling fan circuit between VCRM and cooling fan motor connector. A short to ground will be indicated by cooling fan turning off. Turn A/C and ignition off. If a short to ground is detected, isolate fault and repair as necessary. Clear continuous memory (Code 581 should have been set). Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If a short to ground is not detected, go to next step.

25) Check VCRM Connector & Cooling Fan Circuit Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Connect a test light between terminals No. 2 (Light Blue wire) and No. 4 (Yellow wire) at VCRM connector. Test light should glow, but not at full brightness. Observe test light, and shake, wiggle and bend power-to-cooling fan circuit (Light Blue wire) near cooling fan. A short to ground is present if test light gets brighter. If a short to ground is detected, isolate fault and repair as necessary. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If a short to ground is not detected, disconnect and inspect cooling fan connector. Clean or repair connector as necessary. With test light still connected between terminals No. 2 and 4 of VCRM connector, observe test light and repeat power-to-cooling fan circuit wiggle test. If a short to ground is detected (test light gets brighter), isolate fault and repair as necessary. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If a short to ground is not detected, fault is intermittent and cannot be duplicated at this time. Testing is complete. Reconnect all components.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 25) to step 30). No test procedures have been omitted.

30) Code 582 KOEO Code 582 indicates an open or short to power in cooling fan circuit. Following are possible causes for this fault.

1. Open or short to power in cooling fan circuit.
2. Open cooling fan motor ground circuit.
3. Open circuit in cooling fan.
4. Faulty VCRM.

If KOEO Code 587 is also present, repair fault causing KOEO Code 587 to set prior to continuing this test. See step 170). Ensure cooling fan was not turning during KOEO self-test. If fan was turning, feedback voltage could be sent to VCRM through power-to-cooling fan circuit, resulting in an invalid KOEO Code 582. Ensure engine is cooled down (cooling fan off). Ensure defroster and A/C are off. Turn ignition off. Check cooling fan. If cooling fan is on, go to step 35). If cooling fan is off, go to next step.

31) Check Power To Cooling Fan Turn ignition off. Disconnect cooling fan connector. Start engine. Turn A/C on. Measure voltage between ground and power-to-cooling fan circuit (Light Blue wire) at cooling fan connector. If voltage is 6 volts or more, turn ignition off. Replace cooling fan. Repeat QUICK TEST. If voltage is less than 6 volts, go to next step.

32) Check Continuity Of Cooling Fan Circuit Turn ignition off. Ensure cooling fan is disconnected. Measure resistance between ground circuit (Black wire) at cooling fan motor connector and negative battery terminal. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black wire between cooling fan motor connector and ground. Reconnect cooling fan connector. Repeat QUICK TEST.

33) Check Continuity Of Cooling Fan Circuit (Cont.) Turn ignition off. Ensure cooling fan is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between Light Blue wire at cooling fan motor connector and terminals No. 2 and 3 of VCRM connector. If resistance is less than 5 ohms, replace VCRM. Reconnect all components. Repeat QUICK TEST. If resistance is 5 ohms or more, repair open in power-to-cooling fan circuit (Light Blue wire). Reconnect all components. Repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 33) to step 35). No test procedures have been omitted.

35) Check Power To Cooling Fan Circuit For Short To Power Turn ignition off. Disconnect cooling fan motor connector. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Turn ignition on. Measure voltage between Light Blue wire at cooling fan connector and negative battery terminal. If voltage is less than one volt, replace VCRM. Reconnect all components. Repeat QUICK TEST. If voltage is more than one volt, repair short to power in Light Blue wire. Reconnect all components. Repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 35) to step 40). No test procedures have been omitted.

40) Continuous Memory Code 578 Continuous Memory Code 578 indicates A/C Pressure (ACP) sensor VREF circuit is shorted to ground. This could be due to a hard fault or an intermittent condition. Following are possible causes for this fault.

1. ACP sensor VREF circuit is shorted to ground.
2. Faulty ACP sensor.
3. Faulty VCRM.

Clear continuous memory. Start engine. Wait 15 seconds. Turn ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 578 is present (hard code), go to next step. If Code 578 is not present (intermittent), go to step 44).

41) Check ACP Sensor Clear continuous memory. Turn ignition off. Disconnect ACP sensor connector. Start engine and wait 15 seconds. Turn ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 578 is present, go to next step. If Code 578 is not present, replace ACP sensor. Clear continuous memory. Start engine and wait 15 seconds. Turn ignition off. Repeat QUICK TEST.

42) Check ACP VREF Circuit For Short To Ground Ensure ACP sensor is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between ACP VREF circuit (Orange/Light Blue wire) at ACP sensor connector and negative battery terminal. If resistance is more than 10,000 ohms, replace VCRM. Reconnect all components. Clear continuous memory. Start engine and wait 15 seconds. Turn ignition off. Repeat QUICK TEST. If resistance is 10,000 ohms or less, repair short to ground in ACP VREF circuit (Orange/Light Blue wire).

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 42) to step 44). No test procedures have been omitted.

44) Check For Intermittent Short To Ground In ACP VREF Circuit Turn ignition off. Visually inspect ACP VREF circuit between terminal No. 20 (Orange/Light Blue wire) at VCRM connector and ACP sensor connector. Repair wiring as necessary. Disconnect and inspect ACP sensor connector. Clean or repair connector as necessary. Disconnect and inspect VCRM connector. Clean and repair connector as necessary. Connect test light between terminals No. 6 (Yellow wire) and No. 20 (Orange/Light Blue wire) at VCRM connector. Observe test light, and shake, wiggle and bend ACP VREF circuit between ACP sensor connector and VCRM connector. If a fault is detected, test light will turn on, indicating a short to ground. If a short to ground is detected, isolate fault and repair wiring as necessary. Reconnect all components. Start engine and wait 15 seconds. Turn ignition off. Repeat QUICK TEST. If a short to ground is not detected, fault is intermittent and cannot be duplicated. Testing is complete. Reconnect all components.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 44) to step 50). No test procedures have been omitted.

50) Continuous Memory Code 579: Check ACP, VREF and ACP SIG RTN Circuits Continuous Memory Code 579 indicates A/C Pressure (ACP) sensor did not detect a sufficient change in A/C system pressure when A/C system was turned on. This could be due to a problem in ACP sensor circuit or A/C system, and can be a hard fault or an intermittent condition. Following are possible causes for this fault.

1. Open or shorted ACP sensor circuit.
2. Faulty ACP sensor.
3. Faulty VCRM.
4. Power to A/C clutch circuit open. Continuous Memory Code 586 may also be present.

If Continuous Memory Code 586 is present, repair fault causing code prior to continuing this test. See step 80). If Code 586 is not present, turn ignition off. Disconnect ACP sensor. Turn ignition on. Measure voltage between ACP VREF terminal (Orange/Light Blue wire) and ACP SIG RTN terminal (Light Blue/Red wire) at ACP sensor connector. (Scheme 80) If voltage is more than 6 volts, go to step 62). If voltage is less than 4 volts, go to step 63). If voltage is 4-6 volts, go to next step.

ACP Sensor Connector Terminal (XB2). Scheme 80

51) Check If A/C Clutch Engages Turn ignition off. Reconnect ACP sensor. Start engine Turn A/C on and wait 30 seconds. If A/C clutch engages, go to next step. If A/C clutch does not engage go to step 57).

52) Clear And Attempt To Reset Code 579 Clear continuous memory. Start engine. Turn A/C on and wait until clutch engages. Turn A/C off and wait 5 seconds. Repeat turning A/C on and off 4 more times with each engagement lasting about 20 seconds. Turn A/C and engine off. Repeat Key On Engine Off (KOEO) self-test. If Code 579 is present, go to next step. If Code 579 is not present, ACP is now functioning. Either ACP is intermittent or marginal mechanical condition exists in A/C system, go to step 66).

53) Check A/C System Pressure & Pressure Change Turn ignition off. Ensure ACP sensor is disconnected. Install A/C system manifold gauge set. With A/C off, start engine. Observe A/C high pressure gauge reading, and turn A/C on. After 10 seconds, note pressure reading. High pressure should increase. If A/C high pressure gauge reading changes by more than 20 psi within 10 seconds of A/C clutch engagement, turn A/C and ignition off and go to next step. If A/C high pressure gauge reading does not change by more than 20 psi within 10 seconds of turning A/C on, check A/C system for mechanical fault. Service A/C system as necessary. Clear continuous memory. Attempt to reset Code 579 (see Code 52). Repeat QUICK TEST.

54) Check ACP Sensor Output Turn ignition off. Ensure ACP sensor is disconnected. Install A/C system manifold gauge set. Connect jumper wires and DVOM between ACP sensor connector halves as shown. (Scheme 81) Start engine and observe voltage reading on DVOM. Turn A/C on and observe voltage reading for 10 seconds after clutch engages.

Note. Listen to A/C clutch to ensure clutch does not disengage during 10 seconds of testing. If clutch disengages, retest.

If ACP sensor voltage changes by more than .2 volt within 10 seconds of clutch engagement, sensor is operational. Remove jumper wires and go to next step. If ACP sensor voltage does not change by more than .2 volt within 10 seconds of turning A/C on, replace ACP sensor. Remove A/C system manifold gauge set. Remove jumper wires, and reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

Testing ACP Sensor (XB3). Scheme 81

55) Check ACP Circuit For Short To Ground Turn ignition off. Ensure ACP sensor is disconnected. Disconnect VCRM connector. Measure resistance between ACP circuit terminal (Dark Green/White wire) on harness half of ACP sensor connector and negative battery terminal. Record resistance reading.

Measure resistance between ACP circuit terminal (Dark Green/White) and ACP SIG RTN circuit (Light Blue/Red wire) both on harness half of ACP sensor connector. If both resistance measurements are greater than 10,000 ohms, replace VCRM. Reconnect all components, clear continuous memory attempt to reset Code 579 and repeat quick test. If both measurements are not greater than 10,000 ohms, ACP or ACP SIG RTN circuit is shorted to ground. Repair shorted circuit, reconnect all components and clear continuous memory. Attempt to reset Code 579 and repeat quick test.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 55) to step 57). No test procedures have been omitted.

57) Check Voltage To A/C Clutch Turn ignition off. Disconnect A/C cyclic pressure switch. Jumper the 2 terminals of A/C cyclic pressure switch connector together. Disconnect A/C clutch connector. Connect a test light between the 2 terminals of clutch connector. Start engine. Turn A/C on and wait 10 seconds. If test light does not glow, go to next step. If test light glows, circuit is okay. Check A/C system for mechanical problems. Reconnect all components, clear continuous memory. Attempt to reset Code 579 and repeat quick test.

58) Check Continuity Of ACP Circuit Turn ignition off. Ensure ACP sensor is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between ACP signal terminal at ACP connector and terminal No. 19 (Dark Green/White wire) at VCRM connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in ACP circuit (Dark Green/White wire). Remove A/C system manifold gauge set. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

59) Check For Short To Power In ACP Circuit Turn ignition off. Ensure ACP sensor and VCRM are disconnected. Turn ignition on. Measure voltage between ACP signal terminal (Dark Green/White wire) at ACP sensor connector and negative battery terminal. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to power in ACP circuit. Remove A/C system manifold gauge set. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

60) Check If Test Light Will Glow With ACP Circuit Grounded Turn ignition off. Ensure ACP sensor is disconnected. Reconnect VCRM. Disconnect A/C cyclic pressure switch and jumper across the 2 terminals. Disconnect A/C clutch connector. Connect a test light between the 2 terminals on harness side of A/C clutch connector. Connect a jumper wire between ACP circuit (Dark Green White wire) and negative battery terminal. Start engine. Turn A/C on and wait 10 seconds. If test light glows, replace ACP sensor. Turn A/C off. Reconnect all components. Clear continuous memory. Start engine and turn A/C on for 20 seconds then turn ignition off. Repeat quick test. If test light does not glow, replace VCRM. Reconnect all components. Clear continuous memory. Start engine and turn A/C on for 20 seconds then turn ignition off. Repeat quick test.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 60) to step 62). No test procedures have been omitted.

62) Check For Short To Power In ACP VREF Circuit Turn ignition off. Ensure ACP sensor is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Turn ignition on. Measure voltage between ACP VREF terminal (Orange/Light Blue wire) at ACP sensor connector and negative battery terminal. If voltage is less than one volt, replace VCRM. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If voltage is more than one volt, repair short to power in ACP VREF circuit (Orange/Light Blue wire). Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

63) Check Continuity Of ACP SIG RTN & VREF Circuits Turn ignition off. Ensure ACP sensor is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between ACP SIG RTN terminal (Light Blue/Red wire) at ACP sensor connector and terminal No. 12 (Light Blue/Red wire) at VCRM connector. Record resistance reading. Measure resistance between ACP VREF terminal (Orange/Light Blue wire) at ACP sensor connector and terminal No. 20 (Orange/Light Blue wire) at VCRM connector. Record resistance reading. If both readings are less than 5 ohms, go to next step. If any reading is 5 ohms or more, repair open in ACP VREF circuit (Orange/Light Blue wire) or ACP SIG RTN circuit (Light Blue/Red wire). Reconnect all components. Clear continuous memory. Start engine. Attempt to reset Code 579. Repeat QUICK TEST.

64) Check ACP SIG RTN Circuit For Short To VREF Turn ignition off. Ensure ACP sensor and VCRM connectors are disconnected. Measure resistance between ACP SIG RTN terminal (Light Blue/Red wire) and ACP VREF terminal (Orange/Light Blue wire) at ACP connector. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, ACP SIG RTN circuit is shorted to ACP VREF circuit. Repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

65) Check For Short To Power In ACP SIG RTN Circuit Turn ignition off. Ensure ACP sensor and VCRM connectors are disconnected. Turn ignition on. Measure voltage between ACP SIG RTN terminal (Light Blue/Red wire) at ACP sensor connector and negative battery terminal. If voltage is less than one volt, replace VCRM. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If voltage is one volt or more, repair short to power in ACP SIG RTN circuit (Light Blue/Red wire). Reconnect all components. Clear continuous memory. Attempt to reset Code 579. Repeat QUICK TEST.

66) Check A/C Cooling Performance Check A/C system performance. If A/C system cools properly, go to step 67). If A/C system does not cool properly, Check mechanical condition of A/C system. If mechanical condition is okay, go to next step.

67) Check For Intermittent Open In ACP VREF & ACP SIG RTN Circuits Turn A/C and ignition off. Disconnect and inspect ACP sensor connector. Clean or repair connector as necessary. Turn ignition on. Connect test light between ACP VREF terminal (Orange/Light Blue wire) and ACP SIG RTN terminal (Light Blue/Red wire) at ACP sensor connector. Test light should turn on. If test light does not glow sufficiently, a DVOM may be used instead of test light to monitor 5-volt reference signal. Observe test light/DVOM, and shake, wiggle and bend ACP VREF and ACP SIG RTN circuits between ACP sensor connector and VCRM connector. If a fault is detected, test light will turn off or DVOM voltage will drop, indicating open circuit. If open circuit is detected, isolate fault and repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 20 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If open circuit is not detected, go to next step.

68) Check ACP Signal Circuit For Intermittent Short Turn ignition off. Ensure ACP sensor is disconnected. Connect test light or DVOM between ACP VREF terminal (Orange/Light Blue wire) and ACP signal terminal (Dark Green/White wire) at ACP sensor connector. Test light should be off or DVOM reading should be zero volts. Observe test light/DVOM, and shake, wiggle and bend ACP signal circuit (Dark Green/White wire) between ACP sensor connector and VCRM connector. Lightly tap on VCRM to simulate road shock. If a fault is detected, test light will turn on or DVOM reading will show 5 volts, indicating a short to ground. If a short to ground is detected, isolate fault and repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 20 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

If a short to ground is not detected, remove test light/DVOM. Reconnect test light/DVOM between ACP SIG RTN terminal (Light Blue/Red wire) and ACP signal terminal (Dark Green/White wire) at ACP sensor connector. Observe test light/DVOM, and repeat wiggle test of ACP signal circuit. If a fault is detected, test light will turn on or DVOM reading will show 5 volts, indicating a short to power. If a short to power is detected, isolate fault and repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 20 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If short to power is not detected, go to next step.

69) Check ACP Signal Circuit For Intermittent Open Turn ignition off. Ensure ACP sensor is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Using a DVOM, measure resistance of Dark Green/White wire between terminal No. 19 at VCRM connector and ACP signal terminal at ACP sensor connector. If resistance is 5 ohms or more, isolate fault and repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 20 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If resistance is less than 5 ohms, observe DVOM, and shake, wiggle and bend ACP signal circuit (Dark Green/White wire) between ACP sensor connector and VCRM connector. If a fault is detected, DVOM reading will show 5 ohms or more, indicating an open circuit. If an open circuit is detected, isolate fault and repair wiring as necessary. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 20 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If an open circuit is not detected, fault is intermittent and cannot be duplicated at this time. Reconnect all components.

70) Continuous Memory Code 585 Continuous Memory Code 585 indicates that power to A/C clutch exceeded normal current draw when A/C was turned on. This could be due to a hard fault or an intermittent condition. Following are possible causes for this fault.

1. Short to ground in power to A/C clutch circuit.
2. Faulty A/C clutch.
3. Faulty VCRM.

Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 585 is present, go to next step. If Code 585 is not present, go to step 74).

71) Check A/C Clutch Clear continuous memory. Disconnect A/C clutch connector. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat Key On Engine Off (KOEO) self-test. Ignore Code 586 if set. If Code 585 is present, go to next step. If Code 585 is not present, check for short to ground in A/C clutch wiring circuit. Repair wiring as necessary. If wiring is okay, replace A/C clutch. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

72) Check For Short To Ground In A/C Clutch Circuit Turn ignition off. Ensure A/C clutch is disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between Purple wire at A/C clutch connector and negative battery terminal. If resistance is more than 10,000 ohms, replace VCRM. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If resistance is 10,000 ohms or less, repair short to ground in Purple wire. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 72) to step 74). No test procedures have been omitted.

74) Check For Intermittent Short To Ground In Power-To-A/C Clutch Circuit Turn ignition off. Visually inspect Purple wire between A/C clutch and VCRM. Repair wiring as necessary. Start engine and turn A/C on. Shake, wiggle and bend Purple wire between A/C clutch connector and VCRM. A short to ground will be indicated by A/C clutch disengaging for other than normal A/C cycling pressure switch operation. If a short to ground is not detected, go to next step. If a short to ground is detected, isolate fault and repair as necessary. Clear continuous memory (Code 585 should have been set). Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

75) Check A/C Clutch Circuit For Intermittent Short To Ground Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Disconnect and inspect A/C clutch connector. Clean or repair connector as necessary. Connect a test light between terminals No. 4 (Yellow wire) and No. 14 (Purple wire) at VCRM connector. Observe test light, and shake, wiggle and bend Purple wire between A/C clutch connector and VCRM connector. If a fault is detected, test light will turn on, indicating a short to ground. If a short to ground is detected, isolate fault and repair wiring as necessary. Reconnect all components. Start engine and wait 15 seconds. Turn ignition off. Repeat QUICK TEST. If a short to ground is not detected, fault is intermittent and cannot be duplicated at this time. Testing is complete. Reconnect all components.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 75) to step 80). No test procedures have been omitted.

80) Continuous Memory Code 586 Continuous Memory Code 586 indicates open or short to power in A/C clutch circuit. This could be due to a hard fault or an intermittent condition. Following are possible causes for this fault.

1. Open or short to power in A/C clutch wiring harness.
2. Open A/C clutch ground (VCRM terminal No. 13).
3. Open VCRM A/C ground (VCRM terminal No. 15 to weld nut on left side of radiator support).
4. A/C clutch open circuit.
5. Damaged VCRM.

Clear continuous memory. Turn A/C and defroster off. Start engine and wait 15 seconds. Turn ignition off. Perform Key On Engine Off (KOEO) SELF-TEST. If Code 586 is present, go to step 81). If Code 586 is not present, fault is intermittent. Go to step 85).

81) Check Short To Power In A/C Clutch Circuit Turn ignition off. Disconnect A/C clutch connector. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Turn ignition on. Start engine and wait 15 seconds. Turn ignition off. Measure voltage at Purple wire between A/C clutch connector and negative battery terminal. If voltage is less than one volt, go to step 82). If voltage is one volt or more, repair short to power in Purple wire. Reconnect all components. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

82) Check Continuity Of A/C Clutch & VCRM A/C Ground Circuits Turn ignition off. Ensure A/C clutch and VCRM are disconnected. Measure resistance of Purple wire between terminal No. 14 of VCRM connector and A/C clutch connector. Record resistance reading. Measure resistance between terminal No. 13 (Gray/White wire) and A/C clutch ground circuit (Black wire) at A/C clutch connector. Record resistance reading. If both resistance readings are less than 5 ohms, go to step 83). If resistance reading is 5 ohms or more in one or both circuits, repair open in circuit(s). Reconnect all components. Clear continuous memory. With A/C and defroster off, start engine. Wait 15 seconds. Turn ignition off. Repeat QUICK TEST.

83) Check A/C Clutch Continuity Turn ignition off. Ensure A/C clutch and VCRM are disconnected. Measure resistance between A/C clutch terminals. If resistance is less than 10 ohms, replace VCRM. Reconnect all components. Clear continuous memory. With A/C and defroster off, start engine. Wait 15 seconds. Turn ignition off. Repeat QUICK TEST. If resistance is 10 ohms or more, replace A/C clutch. Reconnect all components. Clear continuous memory. With A/C and defroster off, start engine. Wait 15 seconds. Turn ignition off. Repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 83) to step 85). No test procedures have been omitted.

85) Check For Intermittent Open In A/C Clutch & VCRM A/C Ground Circuits Turn ignition off. Visually inspect power-to-A/C clutch circuit (terminal No. 14) and A/C clutch ground circuit (terminal No. 13) between VCRM and A/C clutch. Also check VCRM ground circuit (terminal No. 15) between VCRM connector and ground point at left side of radiator support. Repair wiring as necessary. Start engine. Turn A/C on. Shake, wiggle and bend power-to-A/C clutch circuit (Purple wire), A/C clutch ground circuit (Gray/White wire) and VCRM A/C ground (Black wire) circuit. An open will be indicated by A/C clutch disengaging for other than normal cyclic pressure switch operation. If an open circuit is detected, isolate fault and repair as necessary. Turn A/C and ignition off. Repeat QUICK TEST. If an open is not detected, go to next step.

86) Check For Intermittent Short To Power In A/C Clutch Circuit Ensure A/C is off. Turn ignition on. Shake, wiggle and bend power-to-A/C clutch circuit (Purple wire) between VCRM and A/C clutch. A short to power will be indicated by A/C clutch engaging. If a short to power is detected, isolate fault and repair as necessary. Repeat QUICK TEST. If a short to power is not detected, go to step 87).

87) Check For Intermittent Open In A/C Clutch & VCRM A/C Ground Circuits Turn ignition off. Disconnect and inspect A/C clutch connector. Clean or repair connector as necessary. Connect test light between power-to-A/C clutch terminal (Purple wire) and A/C clutch ground terminal (Gray/White wire) at wiring harness side of A/C clutch connector. Start engine. Turn A/C on. Observe test light, and shake, wiggle and bend power-to-A/C clutch circuit (Purple wire), A/C clutch ground circuit (Gray/White wire) and VCRM A/C ground (Black wire) circuit. Test light will turn off when a fault is detected, indicating an open circuit. If an open circuit is detected, isolate fault and repair as necessary. Reconnect all components. Turn A/C and ignition off. Repeat QUICK TEST. If an open circuit is not detected, disconnect and inspect VCRM connector. Clean or repair connector as necessary. If connector is okay, fault is intermittent and cannot be duplicated at this time. Testing is complete. Reconnect all components.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 87) to step 90). No test procedures have been omitted.

Note. Before proceeding with "No A/C" diagnostic procedures, check related fuses in fuse panel.

90) No A/C (With Code 111); Check Power At A/C Clutch Turn ignition off. Disconnect A/C clutch connector. Connect test light between power-to-A/C clutch circuit (Purple wire) and A/C clutch ground circuit (Gray/White wire) at wiring harness side of A/C clutch connector. Turn A/C on. Start engine and wait 10 seconds. Observe test light. If test light glows, EEC-VI system is okay. Reconnect A/C clutch connector. Check A/C system for mechanical problems (eg. compressor or clutch coil). If test light is off, go to next step.

91) Check If PCM Is Receiving & Recognizing A/C Cyclic Pressure (ACCS) Input Turn ignition off. Remove test light, and reconnect A/C clutch connector. Perform Key On Engine Off (KOEO) SELF-TEST. If KOEO Code 539 is present, PCM is receiving and recognizing ACCS input. Go to next step. If KOEO Code 539 is not present, PCM is not receiving or recognizing ACCS input. Go to step 96).

92) Check A/C Demand Signal Power At VCRM Turn ignition off. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Turn A/C and ignition on. Measure voltage between terminal No. 9 (Black/Yellow wire) at VCRM connector and negative battery terminal. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in A/C demand signal circuit (Black/Yellow wire) between VCRM splice and PCM. Reconnect all components. Recheck system operation.

93) Check For Short To Ground In Wide Open Throttle A/C Cut Off (WAC) Circuit Turn ignition off. Ensure VCRM is disconnected. Disconnect PCM connector. Clean or repair connector as necessary. Measure resistance between terminal No. 11 (Pink/Yellow wire) at VCRM connector and negative battery terminal. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short to ground in WAC circuit. Reconnect all components. Recheck system operation.

94) Verify WAC Circuit Is Not Shorted To Ground In PCM Turn ignition off. Disconnect PCM connector. Reconnect VCRM connector. Disconnect A/C clutch connector. Connect test light between power-to-A/C clutch circuit (Purple wire) and A/C clutch ground circuit (Gray/White wire) at wiring harness side of A/C clutch connector. Turn A/C and ignition on. If test light is on, replace PCM. Reconnect all components. Recheck system operation. If test light is off, replace VCRM. Reconnect all components. Recheck system operation.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 94) to step 96). No test procedures have been omitted.

96) Check For A/C Demand Signal Power At A/C Cyclic Pressure Switch Turn ignition off. Disconnect A/C cyclic pressure switch. Turn A/C and ignition on. Measure voltage between A/C cyclic pressure switch connector (circuit to A/C-heater control panel) and negative battery terminal. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, ensure voltage is available to A/C-heater control panel, and A/C-heater control panel is functioning properly. If voltage to A/C-heater control panel is okay, repair open circuit between A/C-heater control panel and A/C cyclic pressure switch. Reconnect all components. Recheck system operation.

97) Check A/C Cyclic Pressure Switch Continuity Turn ignition off. Disconnect A/C cyclic pressure switch. Check continuity between A/C cyclic switch terminals. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, check A/C system pressure and A/C cyclic pressure switch operation.

98) Check Continuity Between A/C Cyclic Pressure Switch & PCM Turn ignition off. Ensure A/C cyclic pressure switch is disconnected. Install breakout box. Leave PCM disconnected. Measure resistance between test pin No. 10 at breakout box and circuit to PCM/VCRM at A/C cyclic pressure switch. If resistance is less than 5 ohms, replace PCM. Remove breakout box, and reconnect all components. Recheck system operation. If resistance is 5 ohms or more, repair open in circuit between A/C cyclic pressure switch and PCM. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 98) to step 100). No test procedures have been omitted.

100) Lack Of Power With A/C On Verify Wide Open Throttle A/C Cut-Off (WAC) Is Able To Turn Off A/C Clutch. Start engine. Turn A/C on. Perform a brief Wide Open Throttle (WOT) and return to idle.A/C clutch should disengage during WOT, then a few seconds after returning to idle, A/C clutch should re-engage (click noise should be heard when clutch re-engages). Repeat test if necessary to verify results. If clicking noise cannot be heard, disconnect A/C clutch. Connect test light between power-to-A/C clutch circuit and ground circuit at wiring harness side of A/C clutch connector. Perform brief WOT. Test light should turn off during WOT, then turn on a few seconds after engine speed returns to idle. If A/C clutch or test light functions as specified, WAC circuit is okay. Test is complete. If A/C clutch or test light does not function as specified, go to next step.

101) Check WAC Circuit Wiring Harness Continuity Turn ignition off. Disconnect and inspect PCM connector. Clean or repair connector as necessary. Install breakout box. Leave PCM disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between test pin No. 54 at breakout box and terminal No. 11 (Pink/Yellow wire) at VCRM connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in WAC circuit. Remove breakout box, and reconnect all components. Recheck system operation.

102) Check WAC Circuit For Short To Power Turn ignition off. Ensure breakout box is still connected. Ensure VCRM and PCM are disconnected. Turn ignition on. Measure voltage between test pins No. 40 and 54 at breakout box. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to power in WAC circuit. Remove breakout box, and reconnect all components. Recheck system operation.

103) Check VCRM WAC Circuitry Turn ignition off. Ensure breakout box is still connected and PCM is disconnected. Reconnect VCRM connector. Turn ignition and A/C on. Connect a jumper wire to test pin No. 54 at breakout box. Listen to A/C clutch while briefly touching other end of jumper wire to test pin No. 40 at breakout box. Repeat procedure as necessary. If A/C clutch disengages and re-engages as jumper wire is connected and disconnected, replace PCM. Remove breakout box, and reconnect all components. Recheck system operation. If A/C clutch does not disengage and re-engage as jumper wire is connected and disconnected, replace VCRM. Remove breakout box, and reconnect all components. Recheck system operation.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 103) to step 110). No test procedures have been omitted.

110) Code 556 KOEO Code 556 indicates a fuel pump primary circuit failure. Possible causes for this fault are an open or short to fuel pump circuit, damaged VCRM or damaged PCM. Check if engine will start. If engine starts, go to step 115). If engine does not start, go to next step.

111) Check Fuel Pump Circuit Continuity Turn ignition off. Disconnect and inspect PCM and VCRM connectors. Clean or repair connectors as necessary. Install breakout box. Leave PCM and VCRM disconnected. Measure resistance between test pin No. 22 at breakout box and terminal No. 18 (Light Blue/Orange wire) at VCRM connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in fuel pump circuit. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

112) Check For Short To Power In Fuel Pump Circuit Turn ignition off. Ensure breakout box is still connected and PCM is disconnected. Disconnect VCRM connector. Turn ignition on. Measure voltage between test pins No. 22 and 40 at breakout box. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to power in fuel pump circuit. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

113) Check VCRM Fuel Pump Circuit Turn ignition off. Ensure break-out box is still connected and PCM is disconnected. Reconnect VCRM connector. Connect jumper wire between test pins No. 22 and 40 at breakout box. Listen to fuel pump, and turn ignition on. If fuel pump runs, turn ignition off. Remove jumper wire. Replace PCM. Remove breakout box, and reconnect all components. Repeat QUICK TEST. If fuel pump does not run, turn ignition off. Remove jumper wire. Replace VCRM. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 113) to step 115). No test procedures have been omitted.

115) Check For Short To Ground In PCM Turn ignition off. Disconnect and inspect PCM connector. Clean or repair connector as necessary. Turn ignition on. Listen to fuel pump. If fuel pump runs, turn ignition off and go to next step. If fuel pump does not run, turn ignition off. Replace PCM. Reconnect all components. Repeat QUICK TEST.

116) Check For Short To Ground In Fuel Pump Circuit Turn ignition off. Install breakout box. Leave PCM disconnected. Disconnect and inspect VCRM connector. Clean or repair connector as necessary. Measure resistance between test pins No. 22 and 40 at breakout box. If resistance is more than 10,000 ohms, replace VCRM. Remove breakout box, and reconnect all components. Repeat QUICK TEST. If resistance is 10,000 ohms or less, repair short to ground in fuel pump circuit. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 116) to step 120). No test procedures have been omitted.

120) Code 542 KOEO Code 542 indicates that one of the following has occurred.

No-Start

1. Inertia Fuel Shutoff (IFS) switch not reset or open.
2. Open in power-to-fuel pump circuit between fuel pump monitor (FPM) terminal at PCM (terminal No. 8) and fuel pump.
3. Poor fuel pump ground.
4. Open circuit in fuel pump.