Engine Controls - Tests W/codes - Eec-Iv (1.9L): Diagnosis Ford Escort V facelift

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 service codes. CIRCUIT TESTS check circuits, sensors and actuators.

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

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 SERVICE CODE-TO-TEST MENUS to find correct CIRCUIT TEST.

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 light, service codes are displayed as flashes.

Scan tester, if used, will count pulses and display them as a digital code. STAR Series Tester will add a zero (0) to single-digit Separator Code (10) and Dynamic Response Code (10). Dynamic Response Code is displayed in KOER SELF-TEST. see scheme 1

Diagnostic Aids

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

Scheme 63

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 on gasoline vehicles. Turn ignition off. Wait 10 seconds. Ensure test equipment is properly attached. Turn ignition on (engine off). Record all KOEO and Continuous Memory Codes.

If a Code 11 or 111 (pass code) is not retrieved, service KOEO codes. See SERVICE CODE-TO-TEST MENUS. If PCM will not output codes, go to CIRCUIT TEST QA. If service codes are retrieved

1. If CHECK ENGINE or SERVICE ENGINE SOON light is on, service codes in order retrieved. See SERVICE CODE-TO-TEST MENUS.
2. On DIS and EDIS models, see IGNITION SYSTEM in I - EEC-IV SYS/COMP TESTS article in this section if Continuous Memory Code 45, 46, 48, 215, 216, 217, 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) or CIRCUIT TEST AC (EI).
4. If vehicle displays a Code 11 or 111 (pass code) and does not have any of symptoms described in previous steps, go to COMPUTED TIMING CHECK.

DO NOT enter this test sequence until a Code 11 or 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 service codes displayed. Check following items

1. If engine starts and stalls (or stalls during self-test), go to CIRCUIT TEST S.
2. If Code 98 or 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 Switch (PSP), turn steering wheel at least 1/2 turn and release within 1-2 seconds after ID code portion of test.
5. On vehicles with E4OD transmissions, Overdrive Cancel Switch (OCS) must be cycled after ID code portion of test.
6. If Dynamic Response Code appears, perform a brief Wide Open Throttle (WOT). DO NOT perform WOT unless requested.
7. If a Code 11 or 111 (pass code) is retrieved during KOER SELF-TEST, service Continuous Memory Codes retrieved in KOEO SELF-TEST. See SERVICE CODE-TO-TEST MENUS.
8. If KOER codes are present, see SERVICE CODE-TO-TEST MENUS. If system will not output codes, go to CIRCUIT TEST QA.
9. If a Code 11 or 111 (pass code) is retrieved during Continuous Memory Code portion of KOEO SELF-TEST (Code 11-1-11 or Code 111-1-111) and no driveability problem exists, EEC-IV testing is complete. If driveability problems are still present, go to TESTS W/O CODES article in the ENGINE PERFORMANCE Section.
10. If a Code 11 or 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 3 Turn ignition on, and 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 service code may be stored in memory and indicated at diagnostic tester or scan tester. Retrieve code, and perform appropriate test. See SERVICE CODE-TO-TEST MENUS.

KOER Wiggle Test Procedure

Connect test equipment. see scheme 3 Turn ignition off, and wait 10 seconds. 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 service code may be stored in memory and indicated at diagnostic tester or scan tester. Retrieve code, and perform appropriate test. See SERVICE CODE-TO-TEST MENUS.

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 SERVICE 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 completed. Total test time is about 3 minutes.

CYLINDER BALANCE TEST SERVICE CODES

Fuel-contaminated engine oil may affect some codes. If oil contamination is suspected, remove PCV valve from valve cover and repeat QUICK TEST. If problem is corrected, change engine oil.

On CIRCUIT TEST H and CIRCUIT TEST J, vacuum leaks in non-EEC related areas may cause Code 41 or 91 to be displayed. Check vacuum motors, engine seals, EGR system, PCV system, Canister Purge (CANP), HO2S air intake system and between airflow meter and throttle body for unmetered air leaks. Code 42 or 92 may be caused by fuel-contaminated engine oil, ignition misfire, or EGR system or CANP problems.

Note. In following tests, circuit diagrams and illustrations are courtesy of Ford Motor Co.

CIRCUIT TESTS are grouped as follows

1. A-C - No Start & Voltage Tests.
2. DA-DS - Input Sensor Tests.
3. FD-FF - Additional Input Component Tests.
4. G-J - Fuel Control Systems.
5. KC-XB - PCM (Processor) Output Tests.

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.

Ignition System Wiring Diagram (1.9L). Scheme 64

TEST PIN NO. 4 (IDM) WIRE COLOR I.D.

TEST PIN NO. 36 (SAW) WIRE COLOR I.D.

TEST PIN NO. 56 (PIP) WIRE COLOR I.D.

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 TPS Turn ignition off. Disconnect Throttle Position Sensor (TPS). Turn ignition on (engine off). Measure voltage between VREF and SIG RTN at TPS harness connector. (Scheme 65) If voltage is not 4-6 volts, go to CIRCUIT TEST C. If voltage is 4-6 volts, reconnect TPS and go to step 3).

Identifying TPS Harness Connector Terminals. Scheme 65

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 step 4). If spark is not present, check ignition system. See IGNITION SYSTEM in I - SYS/COMP TESTS article in this section.

4) Check IGN GND Continuity Turn ignition off, and wait 10 seconds. 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 and repeat QUICK TEST. If reading is less than 5 ohms, go to step 5).

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 greater than 7 volts, repair PIP circuit short to power and repeat QUICK TEST. If voltage is not greater than 7 volts, go to step 6).

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 step 7). If resistance is 5 ohms or more, repair open PIP circuit 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 and repeat QUICK TEST. If engine still does not start, go to step 8). If all readings are 10,000 ohms or more, go to step 8).

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. Measure resistance between test pin No. 56 and test pins No. 40 and 60 for short to ground. If any resistance is not 15,000-150,000 ohms, replace PCM and repeat QUICK TEST. If all resistances are 15,000-150,000 ohms, go to step 9).

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 step 10). If voltage is not 3-7 volts, replace ICM 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 step 11). If voltage is not3-7 volts, replace PCM 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 I - SYS/COMP TESTS article in this 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 Circuits Terminals. Scheme 66

TEST PIN NO. 1 (KAPWR) WIRE COLOR I.D.

TEST PIN NO. 17 (STO) WIRE COLOR I.D.

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

TEST PIN NO. 46 (SIG RTN) WIRE COLOR I.D.

TEST PIN NO. 48 (STI) WIRE COLOR I.D.

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 step 2).

2) Check Continuity Of PWR GND Circuit Turn ignition off. Wait 10 seconds. 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 resistance is 5 ohms or more, repair open in PWR GND circuit, and repeat QUICK TEST. If both resistances are less than 5 ohms, go to step 3).

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 readings are 5 ohms or more, replace PCM and repeat QUICK TEST. If readings are less than 5 ohms, go to step 4).

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 and repeat QUICK TEST. If reading is less than 5 ohms, go to step 5).

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 step 6).

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 and repeat QUICK TEST. If voltage is 10.5 volts or more, go to step 7).

7) Check PWR GND Circuit Continuity Turn ignition off, and wait 10 seconds. 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 and repeat QUICK TEST. If reading is less than 10 ohms, go to step 8).

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. Repeat QUICK TEST. If reading is less than 5 ohms, go to step 9).

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. Repeat QUICK TEST. If voltage is less than 10.5 volts, replace EEC power relay. Repeat QUICK TEST.

Perform this test when a check for VREF signal has failed in sensor input CIRCUIT TESTS AA-AC 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 Terminals. Scheme 67

TEST PIN NO. 26 (VREF) WIRE COLOR I.D.

TEST PIN NO. 46 (SIG RTN) WIRE COLOR I.D.

1) Check Battery Power Circuit Turn ignition off, and wait 10 seconds. 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 self-test connector. 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 step 2).

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 step 3). 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. 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. If either reading is 5 ohms or more, repair open in VREF or SIG RTN circuit. Remove breakout box, 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 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. Replace PCM if fault still occurs.

5) Check For Shorted TPS Turn ignition off. Connect PCM to breakout box. Disconnect Throttle Position Sensor (TPS) 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 TPS, remove breakout box and repeat QUICK TEST. If voltage is less than 4 volts on models with EVP, PFE or DPFE sensor, go to step 6). 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, and wait 10 seconds. 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 and repeat QUICK TEST. If voltage is less than 4 volts, reconnect EVP/PFE/DPFE sensor and go to step 7).

7) Check For Shorted MAP/BARO Sensor On models not equipped with a MAP/BARO sensor, go to step 8). 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, and repeat QUICK TEST. If voltage is less than 4 volts, reconnect MAP/BARO sensor and to step 8).

8) Check VREF Circuit For Short To Ground Turn ignition off. Disconnect PCM. Disconnect TPS, MAP/BARO sensor and EVP/PFE/DPFE sensor. 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, and repeat QUICK TEST. If original problem still exists, replace PCM and repeat QUICK TEST. If readings are 1000 ohms or more, replace PCM 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 greater than 50°F (10°C) to pass KOEO SELF-TEST and greater 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% 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 Terminals. Scheme 68

TEST PIN NO. 7 (ECT) WIRE COLOR I.D.

TEST PIN NO. 25 (IAT) WIRE COLOR I.D.

TEST PIN NO. 46 (SIG RTN) WIRE COLOR I.D.

1) Code 21/116 Or 24/114: Code 21/116 (ECT) or 24/114 (IAT) indicates corresponding sensor is out of self-test range. Correct range for measurement is .3-3.7 volts. Check for following possible causes

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

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 21, 24, 114 or 116 is present, go to step 2). If none of these codes are present, service other codes as necessary.

2) Check VREF Circuit Voltage At TPS Turn ignition off. Disconnect Throttle Position Sensor (TPS). With ignition on and engine off, measure voltage at TPS wiring harness connector between VREF and SIG RTN. (Scheme 69) If voltage is 4-6 volts, reconnect TPS and go to step 3). If voltage is not 4-6 volts, go to CIRCUIT TEST C.

3) Check Temperature Sensor Resistance (KOEO) Turn ignition off. Disconnect suspect sensor. Measure resistance between SIG RTN terminal at sensor and SIG RTN terminal at sensor wiring harness connector. 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 21/116 at this time. Go to CIRCUIT TEST AA for models equipped with distributor and CIRCUIT TEST AB or CIRCUIT TEST AC for models not equipped with distributor.
2. For other vehicles, go to step 4).

Identifying TPS Harness Connector Terminals. Scheme 69

4) Check Temperature Sensor Resistance (KOER) Warm engine to normal operating temperature. Turn ignition off. Disconnect suspect sensor. Run engine at 2000 RPM for 2 minutes. Measure resistance between SIG RTN terminal at sensor and SIG RTN terminal at sensor wiring harness connector. 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 51/118 Or 54/113: Induce Opposite Code (Code 61/117 Or 64/112) Code 51/118 (ECT) or 54/113 (IAT) indicate corresponding sensor signal is greater 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 QUICK TEST. If Code 61, 64, 112 or 117 is displayed, replace suspect sensor and repeat QUICK TEST. If Code 61, 64, 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 between test pin No. 7 (ECT sensor) or test pin No. 25 (IAT sensor) at breakout box and SIG RTN 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 and repeat QUICK TEST. If either reading 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 11) to step 20). No test procedures have been omitted.

20) Code 61/117 or 64/112: Induce Opposite Code (51/118 or 54/113) Code 61/117 (ECT) or 64/112 (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 51, 54, 113 or 118 is displayed, replace sensor and connect harness. Repeat QUICK TEST. If Codes 51, 54, 113 or 118 is not displayed, go to step 21).

21) Check VREF Circuit Voltage At TPS Turn ignition off. Disconnect wiring harness connector from suspect sensor. Disconnect TPS. Turn ignition on. Measure voltage between VREF and SIG RTN at TPS wiring harness connector. If voltage is not 4-6 volts, go to CIRCUIT TEST C. If voltage is 4-6 volts, connect TPS and go to step 22).

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 pins No. 40, 46 and 60. If any reading is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If all readings are 10,000 ohms or more, replace PCM 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 51/118, 54/113, 61/117 Or 64/112: Check Sensor A Continuous Memory Code 51/118 or 54/113 indicates sensor signal is greater than self-test maximum of 4.6 volts. Code is set during normal driving conditions. Continuous Memory Code 61/117 or 64/112 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 step 91).

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 step 92).

92) Inspect PCM & Wiring Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector. Inspect both connector and connector terminals for damage. 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 article in this 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.

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 Temp. (EGRT) Sensor Circuits & Connector Terminals. Scheme 70

TEST PIN NO. 43 (EGRT) WIRE COLOR I.D.

TEST PIN NO. 46 (SIG RTN) WIRE COLOR I.D.

1) Continuous Memory Code 327 Verification Code 327 indicates that at least once within previous 80 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 step 2).

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 step 3). If Code 337 is displayed, replace EGRT sensor.

3) Check EGRT Circuit For Short To Ground Turn ignition off. Wait 10 seconds. Disconnect PCM 60-pin connector. Inspect and repair any damaged wiring. 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 resistance is 10,000 ohms or more, replace PCM and repeat QUICK TEST. If resistance is less than 10,000 ohms, repair short 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) Continuous Memory Code 337 Code 337 indicates that at least once within previous 80 warm-up cycles, EGRT sensor signal was greater 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 step 6).

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 step 7).

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 and repeat QUICK TEST. If Code 327 is not displayed, go to step 8).

8) Check Continuity Of Circuits Turn ignition off, and wait 10 seconds. 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. 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, service open circuit. Repeat QUICK TEST. If both readings are less than 5 ohms, replace PCM.

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 80 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 step 11).

11) Repeat KOEO SELF-TEST. If Continuous Memory Code 326 is not present, go to step 90). If Continuous Memory Code 326 is present, disconnect PCM 60-pin connector. Inspect it for damaged wiring, and repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between EGRT terminal at EGRT wiring harness connector and test pin No. 43 at breakout box. 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, service open circuit. Repeat QUICK TEST. If either resistance is less than 5 ohms, replace EGRT sensor.

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) 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 step 21).

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 step 22). 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 I - EEC-IV SYS/COMP TESTS article in this 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 TPS 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 step 91).

91) Check PCM & Harness Connectors Turn ignition off, and wait 10 seconds. Disconnect PCM 60-pin connector. Inspect connector and terminals for damage, and 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 26/159, retrieved during KOEO SELF-TEST, indicates voltage exceeded .7-volt test range. Code 26/159, retrieved during KOER SELF-TEST, indicates voltage is not within .2-1.5 volts operating range. Possible causes are faulty MAF sensor or PCM.

Mass Airflow (MAF) Sensor Circuits & Connector Terminals. Scheme 71

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

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

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

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

MAF SIGNAL VOLTAGE (1)

Note. Code 26/159 may be caused by use of a garage exhaust ventilation system. Ensure vehicle is vented to outside atmosphere before repeating QUICK TEST.

1) Code 26/159: Check VPWR Circuit Voltage Code 26/159 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 12 or 412 is present, go to CIRCUIT TEST KE, step 1). If Code 13 or 411 is present, go to CIRCUIT TEST KE, step 15). If Code 12, 13, 411 or 412 is not present, go to step 2).

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 step 3).

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 66/157: Check For Intermittent Sensor Failure Continuous Memory Code 66/157 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.

Start engine and allow to idle for 5-10 minutes. Perform KOEO SELF-TEST. If Code 66/157 is present, go to step 13). If Code 66/157 is not present, go to next step.

11) Turn ignition off. Disconnect and inspect 60-pin connector at PCM. Service if 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 66/157 Or 72/129: 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. 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. Measure resistance between MAF terminal of MAF sensor wiring harness connector and test pin No. 50 (Sequential Fuel Injected engines) or test pin No. 14 (except Sequential Fuel Injected engines). If resistance is more than 5 ohms, repair open circuit 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 (Sequential Fuel Injected engines) or between test pin No. 14 and test pins No. 15, 40 and 60 (except Sequential Fuel Injected engines). If resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If resistance is 10,000 ohms or more, go to next step.

16) Turn ignition off. Ensure MAP sensor and PCM wiring harness connector 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 and repeat QUICK TEST. If resistance is less than 10 ohms, go to 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 (Sequential Fuel Injected engines) or test pin No. 15 (except Sequential Fuel Injected engines). If resistance is more than 5 ohms, repair open circuit 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 (Sequential Fuel Injected engines) or between test pin No. 14 and test pins No. 15, 40 and 60 (except Sequential Fuel Injected engines). If resistance is less than 10,000 ohms, replace PCM and repeat QUICK TEST. If resistance is 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 resistance between test pin No. 50 and negative battery terminal (Sequential Fuel Injected engines) or between test pin No. 14 and negative battery terminal (except Sequential Fuel Injected engines). If voltage is .36-1.50 volts, go to next step. If voltage is not .36-1.50 volts, replace MAF sensor and repeat QUICK TEST.

20) With engine running, measure resistance between test pin No. 9 and test pin No. 50 (Sequential Fuel Injected engines) or between test pin No. 14 and test pin No. 15 (except Sequential Fuel Injected engines). If voltage is .36-1.50 volts, replace PCM and repeat QUICK TEST. If voltage is not .36-1.50 volts, replace MAF sensor and repeat QUICK TEST.

21) Code 56/158 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 66 or 157 is present, replace MAF sensor and repeat QUICK TEST. If Code 66 or 157 is not present, go to step 22).

22) Check MAF Circuit For Short To VPWR Turn ignition off. Disconnect PCM 60-pin connector, and inspect it for damaged or corroded terminals. Service if necessary. Measure resistance between MAF and VPWR terminals at MAF sensor wiring harness connector. If resistance is 10,000 ohms or more, replace PCM and repeat QUICK TEST. If resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST.

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

1. Flexible Fuel (FF) sensor.
2. Wiring harness circuits (FFS SIG, VPWR and PWR GND).
3. Powertrain Control Module (PCM).

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

1. Fuel system.
2. Ignition system.

Identifying Flexible Fuel Connector Terminals. Scheme 72

1) Code 193: Check FF Sensor VPWR Circuit Code 193 indicates failure in the FF sensor and/or circuit. Possible causes for this fault are

1. Faulty FF sensor.
2. Open or shorted wiring harness circuits.
3. Fuel separation.
4. Faulty Powertrain Control Module (PCM).

Turn ignition off. Disconnect FF wiring harness connector at sensor. Turn ignition on. Measure voltage between VPWR terminal at FF sensor wiring harness connector and battery ground. If voltage is 10.5 volts or more, go to next step. If voltage is less than 10.5 volts, repair open or short in VPWR circuit and repeat QUICK TEST.

2) Check FF Sensor Ground Circuit Continuity Leave FF sensor disconnected. Turn ignition off. Measure resistance between BATT GND terminal of FF sensor wiring harness connector and negative battery terminal. If resistance is more than 10,000 ohms, repair open circuit and repeat QUICK TEST. If resistance is 10,000 ohms or less, go to next step.

3) Check FFS SIG Circuit Continuity Leave FF sensor disconnected. Turn ignition off. Disconnect PCM 60-pin connector. Inspect for damage, and repair if necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between FFS SIG terminal of FF sensor wiring harness connector and test pin No. 45. If resistance is more than 5 ohms, repair open circuit and repeat QUICK TEST. If resistance is 5 ohms or less, go to next step.

4) Check FFS SIG Circuit Short To Power Leave PCM and FF sensor disconnected. Turn ignition off. Measure resistance between test pin No. 45 and test pins No. 26, 37 and 57. If resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If resistance is 10,000 ohms or more, go to next step.

5) Check FFS SIG Circuit Short To Ground Leave PCM and FF sensor disconnected. Turn ignition off. Measure resistance between test pin No. 45 and test pins No. 40, 46 and 60. If resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If resistance is 10,000 ohms or more, go to next step.

6) Check Output Frequency Stability Leave PCM and FF sensor disconnected. Turn ignition off. Connect Megameter (Rotunda 014-00768) as follows

1. Red lead to test pin No. 45.
2. Black lead to negative battery terminal.
3. Meter selector on FREQUENCY MODE.

Turn ignition on. Check megameter frequency display. If frequency fluctuates erratically 40-60 Hz, go to next step. If frequency does not fluctuate erratically 40-60 Hz, go to step 9).

7) Check For Fuel Separation Turn ignition off. Remove fuel filter and pour contents into a clear container. Examine contents of container. If fuel separation is present, drain and refill fuel tank. Go to step 8). If fuel separation is not present, replace fuel filter and repeat QUICK TEST.

8) Check Frequency For Correct Response Reconnect FF sensor. Leave breakout box and megameter connected. Start engine and allow to idle. Check frequency reading on megameter. If gasoline is being used in vehicle, frequency should be 30-70 Hz. If methanol is being used, frequency should be 115-155 Hz. If FF sensor output frequency matches fuel used, replace PCM and repeat QUICK TEST. If frequency does not match fuel used, replace FF sensor and repeat QUICK TEST.

Identifying Data Link Connector (DLC) Terminals. Scheme 73

9) Fuel Composition Test Rotunda FFV Fuel Test Kit (014-00770), or equivalent, is required for this test. Turn ignition off. Ensure FF sensor is connected. Connect fuel drain hose to fuel pressure relief valve on cold start injector. Turn valve clockwise to open. Place opposite end of hose in clean gas can. Connect jumper wire between Diagnostic Link Connector (DLC) terminal FP and ground. Turn ignition on and leave on until at least 20 ml of fuel is pumped into gas can. Fill beaker with 4 ml of clean water. Pour fuel and water into 25 ml graduated cylinder. Plug cylinder and shake cylinder. Let cylinder stand for 3 minutes. Water and methanol will blend and settle on the bottom of cylinder. Gasoline will rise to the top.

Testing Flexible Fuel Sample. Scheme 74

To determine the percentage of methanol in fuel, perform the following equation

1. Note the point on the cylinder where the gasoline meets the methanol/water mixture.
2. Subtract 4 from number on cylinder where gasoline meets methanol/water mixture.
3. Multiply the number by 5. This number is the percentage of methanol in the fuel.

The accuracy of this equation is plus or minus 10 percent. Dispose of fuel properly and go to next step.

10) Fuel Sample Test Turn ignition off. Leave megameter and breakout box installed as in step 6). Ensure FF sensor is connected. Turn ignition on. Record frequency displayed on meter. Using the chart in Fig. (Scheme 75), determine the frequency range for the methanol percentage value calculated in step 9). If the FF sensor frequency is within the correct range, replace the PCM and repeat QUICK TEST. If the FF sensor frequency is not within the correct range, replace the FF sensor and repeat QUICK TEST.

FF Sensor Frequency Range. Scheme 75

CKT TEST DF - MANIFOLD ABSOLUTE PRESSURE (MAP)/BAROMETRIC

PRESSURE (BARO) SENSOR

Perform this test when directed by QUICK TEST or CIRCUIT TEST S. 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 Circuits, Terminals & Tester Hookup. Scheme 76

TEST PIN NO. 26 (VREF) WIRE COLOR I.D.

TEST PIN NO. 45 (MAP/BARO SIG) WIRE COLOR I.D.

TEST PIN NO. 46 (SIG RTN) WIRE COLOR I.D.

MAP SENSOR SPECIFICATIONS

MAP/BARO SENSOR SPECIFICATIONS

1) Code 22/126: Check Power To MAP/BARO Sensor Code 22/126 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 step 2). 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 Green light on tester is lit, replace MAP/BARO sensor and repeat QUICK TEST. If Green light is not on, 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 step 4). 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 it for damaged wiring, and repair 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 Ckt For Short To VREF, SIG RTN & Ground Turn ignition off, and wait 10 seconds. Disconnect PCM 60-pin connector. Inspect it for damaged wiring, and 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 resistance is less than 10,000 ohms, repair short circuit. Repeat QUICK TEST. If all readings are 10,000 ohms or more, replace MAP/BARO sensor. 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 22/126: Check For EGR-Related Codes Code 22/126 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 mis-routed MAP/BARO sensor vacuum hose.
3. Faulty MAP/BARO sensor.

If Code 31, 32, 33, 34, 35, 326, 327, 328, 332, 334, 336 or 337 is present, perform applicable CIRCUIT TEST. See SERVICE CODE-TO-TEST MENUS. If codes are not present, go to step 8).

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 is not held, replace sensor and repeat QUICK TEST. If MAP sensor holds vacuum, release vacuum and go to step 9).

9) Attempt To Eliminate Code 22/126 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 22/126, disregarding any other codes at this time. If Code 22/126 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 72/129: Repeat Dynamic Response Test Code 72/129 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 mis-routed 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 72/129 is still present, go to step 11). If code is not present, service any other codes as necessary.

11) Continuous Memory Code 81/128 Continuous Memory Code 81/128 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 step 12).

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 step 13). 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 22/126 Code 22/126 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 step 91).

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 step 92).

92) Check PCM & Wiring Harness Connectors Turn ignition off, and wait 10 seconds. 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 article in this 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.

TEST PIN NO. 23 (KS) WIRE COLOR I.D.

TEST PIN NO. 46 (SIG RTN) WIRE COLOR I.D.

1) Code 25/225: Generate Knock Signal Manually Code 25/225 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 step 2). If DC voltage is less than 2.4 volts, go to step 4). If DC voltage is more than 2.4-2.6 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 wiring harness connector. Measure resistance between SIG RTN terminal at KS wiring harness connector and test pin No. 46 at breakout box. 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 and repeat QUICK TEST. If both readings are less than 5 ohms, go to step 4).

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 and repeat QUICK TEST. If Code 25/225 is still present, replace PCM. If any reading is less than 10,000 ohms, repair short circuit 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 and repeat QUICK TEST. If reading is less than 0.5 volt, replace PCM 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. see scheme 22

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. Choke cam adjustment (if equipped).
4. TP sensor not seated.

TEST PIN NO. 26 (VREF) WIRE COLOR I.D.

TEST PIN NO. 46 (SIG RTN) WIRE COLOR I.D.

TEST PIN NO. 47 (TP) WIRE COLOR I.D.

TP Sensor Specification Chart. Scheme 77

1) KOER Code 23/121: Check For Other Codes KOER Code 23/121 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 31/327. If either of these codes are present with Code 23/121, service Code 31/327 and repeat QUICK TEST. If these codes are not present, go to step 2).

2) Code 23/121: 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, etc. Repair as necessary, and repeat QUICK TEST. If no mechanical problem is found, go to step 3).

3) Code 53/123: Attempt To Generate Code 63/122 Code 53/123 indicates TP sensor signal is greater 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. Ignore all other codes at this time. If Code 63/122 is not displayed, go to step 5). If Code 63/122 is displayed, go to step 4).

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 it for damage and 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. If either resistance is less than 10,000 ohms, repair short circuit in wiring harness and repeat QUICK TEST. If both resistances are 10,000 ohms or more, replace PCM 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 63/122: Attempt To Generate Code 53/123 Or 23/121 Code 63/122 indicates TP signal is less than minimum self-test value. (Scheme 77) 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, and wait 10 seconds. 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 53/123 and 23/121 are not present, remove jumper wire and go to step 11). If either Code 53/123 or 23/121 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, reconnect all components and go to CIRCUIT TEST C. If voltage is 4-6 volts, go to step 12).

12) Check TP Sensor Circuit Continuity Turn ignition off. Leave TP sensor disconnected. Disconnect PCM 60-pin connector. Inspect connector and repair if 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 and repeat QUICK TEST. If resistance is less than 5 ohms, go to step 13).

13) Check TP Circuit For Shorts To Ground Turn ignition off. Leave TP sensor disconnected. Ensure both 4EAT module wiring harness connectors are disconnected (if applicable). Disconnect PCM 60-pin connector. Inspect wiring, and 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. If any reading is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If all readings are 10,000 ohms or more, replace PCM 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 73/167: Repeat Dynamic Response Test KOER Code 73/167 indicates TP sensor did not exceed 25% 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 WOT is completed during dynamic response portion of test. If Code 73/167 is still present, go to step 21). If code is not present, system is unable to duplicate Code 73/167 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 wiring, and 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 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. 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 53/123 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 self-test connector. 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 step 91).

91) Measure TP Circuit Voltage While Exercising TP Sensor Turn ignition off, and wait 10 seconds. Disconnect PCM 60-pin connector. Inspect for damage and repair if 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 53/123. 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 step 93).

93) Check PCM & Harness Connectors Turn ignition off, and wait 10 seconds. Disconnect PCM 60-pin connector from breakout box. Inspect connectors and terminals for damage, and 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 53/123 testing is complete.

94) Continuous Memory Code 63/122 Enter wiggle test. See CONTINUOUS MONITOR MODE (WIGGLE TEST) under QUICK TEST. Connect DVOM or diagnostic tester to STO terminal of self-test connector. 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 step 96).

96) Check PCM & Harness Connectors Turn ignition off. Inspect PCM 60-pin connector and terminals for damage. Repair connector terminals if 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 63/122 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 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 Solenoid Connector Terminals. Scheme 78

TEST PIN NO. 26 (VREF) WIRE COLOR I.D.

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

TEST PIN NO. 33 (EVR) WIRE COLOR I.D.

TEST PINS NO. 37 & 57 WIRE COLOR I.D.

TEST PIN NO. 46 (SIG RTN) WIRE COLOR I.D.

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 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. Repeat QUICK TEST. If Code 337 is not present, remove jumper wire and go to step 2).

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 step 3). 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 terminals, and repair if damaged. 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. Repeat QUICK TEST. If reading is 5 ohms or less, go to step 4).

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 resistance is less than 10,000 ohms, repair short circuit. Repeat QUICK TEST. If all resistance readings are 10,000 ohms or more, replace PCM. Repeat QUICK TEST.

5) Code 337: Generate Code 327 Code 337 indicates PFE/DPFE sensor signal is greater 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 step 6).

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 reading is 4-6 volts, replace PFE/DPFE sensor. Repeat QUICK TEST. If reading 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 terminals, and repair if damaged. 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 resistance reading is less than 10,000 ohms, repair short circuit. Repeat QUICK TEST. If all resistance readings are 10,000 ohms or more, replace PCM. 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 step 9).

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 step 10).

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 reading 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 terminals. If resistance is 25-70 ohms, go to step 12). 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 step 13).

13) Check EVR Circuit Continuity Turn ignition off. Leave EVR solenoid connector disconnected. Disconnect PCM 60-pin connector. Inspect terminals and repair if damaged. 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 and repeat QUICK TEST. If reading is less than 5 ohms, go to step 14).

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 resistance reading is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If code is repeated, replace PCM. If all readings are 10,000 ohms or more, replace PCM 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 32/326 is present, go to step 21).

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 step 22). 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. 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 terminals and repair if damaged. 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 2.9 volts (PFE) or 0.2 volt (DPFE), replace sensor and repeat QUICK TEST. If voltage is more than specified, replace PCM and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 23) to step 25). No test procedures have been omitted.

25) Codes 336 & 337: Check PFE Input Pressure Code 336 indicates PFE voltage is too high. On PFE, excessive exhaust backpressure is a possibility. Code 337 indicates PFE circuit voltage is excessively higher than self-test maximum. Possible causes for these codes are

1. Exhaust system restricted.
2. PFE sensor faulty.
3. Faulty PCM.

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. 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 terminals and repair if damaged. 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 10,000 ohms, go to next step. If any resistance is 10,000 ohms or more, repair open circuit 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 each resistance is greater than 10,000 ohms, replace PFE sensor and repeat QUICK TEST. If any resistance is 10,000 ohms or less, repair short circuit. 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 greater 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 step 31).

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 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. Replace PFE/DPFE sensor and 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 terminals, and repair if damaged. 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 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 all resistance checks are less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If all resistance checks are 10,000 ohms or more, replace PCM 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. Exhaust system restricted.
2. EGR sensor faulty.
3. EVR sensor faulty.
4. PFE 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.

51) Check DPFE Sensor Output With Engine Idling Turn ignition off. Disconnect PCM 60-pin connector. Inspect terminals and repair if damaged. 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 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 step 91). 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 and repeat QUICK TEST. If no faults are present, 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 step 93). 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, isolate fault and repair as necessary. Repeat QUICK TEST. If no fault is indicated, go to step 95).

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) Check PCM Wiring Harness Connector Turn ignition off, and wait 10 seconds. Disconnect PCM 60-pin connector. Inspect connector and terminals for damage. 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 step 96).
2. Code 336 on models equipped with PFE; go to step 100).
3. Code 336 or 337 on models equipped with DPFE; go to step 96).
4. If no codes are present, 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, 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 and EGR supply hose for liquids or restrictions. Repair as necessary. 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 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 correct, 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 105 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 as necessary. 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. 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. 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 terminals and repair if damaged. 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. 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. 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

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).

Identifying EVP Sensor & EVR Solenoid Connector Terminals. Scheme 79

TEST PIN NO. 26 (VREF) WIRE COLOR I.D.

TEST PIN NO. 27 (EVP) WIRE COLOR I.D.

TEST PIN NO. 33 (EVR) WIRE COLOR I.D.

TEST PIN NO. 46 (SIG RTN) WIRE COLOR I.D.

Note. EVR sensor is preloaded when attached to EGR valve. Valve failure causing EVR sensor to lose preload may set Code 31/327.

1) Code 31/327: Generate Code 35/337 Code 31/327 indicates EVP sensor signal is less than self-test minimum of 0.2 volt. Possible causes for this fault are

1. Faulty EVP sensor.
2. Faulty EGR valve.
3. Open or grounded harness.
4. Faulty PCM.

Turn ignition off. Disconnect EVP wiring harness connector at sensor. 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 35/337. Ignore all other codes at this time. If Code 35/337 is present, replace EVP sensor and repeat QUICK TEST. If Code 35/337 is not present, remove jumper wire and go to step 2). If no codes are present, 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 step 3). If voltage is not 4-6 volts, go to CIRCUIT TEST C.

3) Check EVP Circuit Resistance Turn ignition off, and wait 10 seconds. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. 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 and repeat QUICK TEST. If reading is less than 5 ohms, go to step 4).

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 resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If all readings are 10,000 ohms or more, replace PCM and repeat QUICK TEST.

5) Code 35/337: Generate Code 31/327 Code 35/337 indicates EVP sensor signal is greater 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 31/327. Ignore all other codes at this time. If Code 31/327 is present, go to step 6). If Code 31/327 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 reading is 4-6 volts, replace EVP sensor. Repeat QUICK TEST. If reading 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 terminals, and repair if damaged. 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 either reading is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If both readings are 10,000 ohms or more, replace PCM 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 84/558: Check EVR Solenoid Resistance Code 84/558 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 across EVR solenoid terminals. If reading is not 20-70 ohms, replace EVR solenoid assembly and repeat QUICK TEST. If reading is 20-70 ohms, go to step 11).

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 step 12).

12) Check EVR Circuit Continuity Turn ignition off. Disconnect EVR solenoid. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. 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 reading is less than 5 ohms, go to step 13). If reading is 5 ohms or more, repair open circuit and repeat QUICK TEST.

13) Check EVR Circuit For Shorts To Power Or Ground Measure resistance between test pin No. 33 and pins No. 37, 40, 46, 57 and 60 at breakout box with ignition off. If any reading is less than 10,000 ohms, repair short circuit 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, 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 34/334: Check For Code 84/558 Code 34/334 indicates EGR valve and/or EVP is not fully seated in closed position. EVP voltage signal, in closed position, is greater 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. 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 84/558 is present, return to step 10). If Code 84/558 is not present, go to step 21).

21) Perform SELF-TEST Without EGR Remove and plug vacuum line to EGR valve. Perform KOEO SELF-TEST and KOER SELF-TEST. If Code 34/334 is still present, go to step 22). If Code 34/334 is not present, check EVR solenoid for obstructions. If no obstructions are present, replace EVR solenoid.

22) Check EGR Valve & EVP Sensor Operation Turn ignition off. Disconnect EVP sensor. Inspect harness and connector, and service if necessary. Remove and plug vacuum hose to EGR valve. Install vacuum gauge at EGR valve vacuum hose. 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 34/334 is present, go to step 23). If Code 34/334 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 terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Turn ignition on. Measure voltage between test pin No. 27 and test pin No. 46 at breakout box. If voltage is less than 0.67 volt, replace PCM and repeat QUICK TEST. If voltage is greater than 0.67 volt, go to step 24).

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 as necessary. Install EGR valve and EVP sensor. Perform KOEO SELF-TEST and KOER SELF-TEST. If Code 34/334 is still present, replace EGR valve. If Code 34/334 is not present, testing is complete.

25) Service Code 32/328 Service Code 32/328 indicates EVP sensor is lower than normal (0.24 volt) in closed position. 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 32/328 is not present, original fault was caused by poor continuity at EVP sensor connector or binding/sticking of EGR valve stem. If Code 32/328 is present, go to step 26).

26) Check EVP Signal Voltage Turn ignition off. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. 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 pin No. 27 and test pin No. 46 at breakout box while performing following: apply 6 in. Hg to EGR valve and slowly bleed vacuum completely off. If voltage does not drop to less than 0.24 volt, replace PCM and repeat QUICK TEST. If voltage drops to less than 0.24 volt, go to step 27).

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 32/328 is present, check EGR valve for mechanical malfunction. If Code 32/328 is not present, replace original EVP sensor. Repeat QUICK TEST.

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 33/332: Check Vacuum At EGR KOER Code 33/332 indicates EVP sensor input did not change after PCM signaled operation of EGR. Because Code 84/558 was not retrieved in KOEO SELF-TEST, EVR solenoid electrical function is okay. Lack of Code 32/328 or 34/334 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.
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, go to step 41).

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 step 42). 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 if 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. After repairs are made, 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 33/332 is still present, go to step 44). If Code 33/332 is not present, original code was set either by poor continuity at EVP sensor connector or sticking EGR valve. Test is complete.

44) Verify EGR Valve Vacuum Control Turn ignition off. Install tachometer. Remove Idle Air Control (IAC) wiring harness connector. Remove and plug vacuum hose from 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, 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 31/327, 32/328 Or 35/337 Continuous Memory Code 31/327 or 32/328 indicates EGR valve closed further than normal or EVP circuit failed with intermittent low voltage sometime during engine operation. Code 35/337 indicates EVP signal to PCM was above maximum self-test limit sometime during engine operation. Possible causes for these faults are

1. Obstructed vacuum valve.
2. Faulty EVP sensor.
3. Faulty EVP sensor.
4. EGR valve.

Turn ignition off, and wait 10 seconds. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. 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 step 91). If voltage is erratic or not within .24-.67 volt range, remove and inspect EVP sensor wiring harness connector. Repair or replace if 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 step 92).

92) Measure EVP Signal Voltage While Exercising EVP Sensor Remove and plug vacuum hose to EGR valve. Install vacuum gauge at EGR valve vacuum hose. Turn ignition on. Measure voltage between test pin No. 27 and test pin No. 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 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 33/332 Code 33/332 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 step 111). If EGR valve does not open and hold vacuum, service or replace EGR valve as necessary and repeat QUICK TEST.

111) EVR Solenoid & Wiring Harness Check Turn ignition off. Disconnect vacuum hose from EGR valve. Connect EGR valve hose to vacuum gauge. Disconnect PCM 60-pin connector and inspect it for damaged terminals. Repair or replace 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. 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 111) to step 115). No test procedures have been omitted.

115) Continuous Memory Code 34/334: Code 34/334 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 below 1.0 in. Hg and/or has sudden vacuum increase, service or replace EVR solenoid. If vacuum gauge reading remains below 1.0 in. Hg with no sudden increase, go to step 116).

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. If vacuum gauge does not show an increase in vacuum, go to step 117).

117) Check EVR Signal At PCM Turn ignition off, and wait 10 seconds. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. 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 voltage is still more than 0.67 volt, replace EVP sensor. 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. Scheme 80

TEST PIN NO. 3 (VSS +) WIRE COLOR I.D.

TEST PIN NO. 6 (VSS -) WIRE COLOR I.D.

CID signal provides PCM information for fuel injector synchronization. The CID signal originates from the 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 (1.9L). Scheme 81

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 CKP sensor.
4. Faulty ICM.
5. Faulty PCM.

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

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 step 3).

3) Check Continuity Of CID Circuits Disconnect the CMP sensor. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. 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. If any resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST. If each resistance is less than 5 ohms, go to next step.

4) Check CID Circuit For Short To Power Turn ignition off. Ensure PCM and CKP/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 step 5). If voltage is 1.0 volt or more, repair circuit short to power.

5) Check CID Circuit For Short To Ground Turn ignition off. Ensure PCM and CKP/CMP sensor are disconnected. Measure resistance between CID or CID (+) test pin and pins No. 16, 40 and 46 at breakout box. If resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If resistance is more than 10,000 ohms, go to IGNITION SYSTEMS in I - SYSTEM/COMPONENT TESTS - EEC-IV article in this section.

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 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 CKP/CMP is disconnected. Connect PCM to breakout box. Measure resistance between test pin No. 24 and pins No. 37, 40, 46, 57 and 60 at breakout box. If each resistance is more than 500 ohms, go to step 8). If any resistance is 500 ohms or less, replace PCM and repeat QUICK TEST.

8) Check CKP/CMP Sensor Output Turn ignition off. Reconnect CKP/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. If voltage varies more than 0.1 volt, replace PCM and repeat QUICK TEST. If voltage does not vary more than 0.1 volt, replace CKP/CMP sensor 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 I - EEC-IV SYS/COMP TESTS article in this section.

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. See SYMPTOMS in TESTS W/O CODES article in this 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. Scheme 82

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

TEST PIN NO. IDENTIFICATION

1) Code 74/536: Verify Brake Pedal Was Depressed Code 74/536 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 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 step 2).

2) Check Operation Of Brakelights With ignition on, check operation of brakelights. If brakelights operate normally, go to step 3). 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. Wait 10 seconds. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. 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 Brake 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 greater 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 step 6). 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 step 7). If brakelights are not on, 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 not on, repair short circuit in shift lock actuator circuit, cruise control system circuit or ABS circuit. Repeat QUICK TEST.

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. Scheme 83

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 terminals, and repair if damaged. 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 test pin No. 14 at breakout box and chassis ground. If voltage is not 10-17 volts, go to step 13). If voltage is 10-17 volts, go to step 11).

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 test pin No. 14 at breakout box and chassis ground. 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 step 12).

12) Check Blower Circuit For Short To Power Turn ignition off. Disconnect blower motor relay. Measure resistance between test pin No. 14 and pins No. 37 and 57 at breakout box. If resistance is more than 10,000 ohms, check for damaged blower motor or relay. If resistance is 10,000 ohms or less, repair short circuit. Repeat QUICK TEST.

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. 14 at breakout box. If resistance is 5 ohms or more, repair open circuit. Repeat QUICK TEST. If resistance is less than 5 ohms, go to step 14).

14) Check Blower Circuit For Short To Power Turn ignition off. Disconnect blower motor relay. Measure resistance between test pin No. 14 and test pins No. 40, 46 and 60 at breakout box. If resistance is more than 10,000 ohms, check for damaged blower motor switch or relay. If resistance is 10,000 ohms or less, repair short circuit. 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) Check DRL Circuit Voltage (Headlights On) Turn ignition and all accessories off. Remove PCM 60-pin connector. Inspect terminals, and repair if damaged. 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 test pin No. 42 at breakout box and chassis ground. If voltage is not 10-17 volts, go to step 23). If voltage is 10-17 volts, go to step 21).

21) Check DRL Circuit Voltage (Headlights Off) Turn headlights off. Release parking brake. Turn ignition on. Measure voltage between test pin No. 42 at breakout box and chassis ground. 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 step 22).

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. 42 and pins No. 37 and 57 at breakout box. If resistance is more than 10,000 ohms, check daytime running lights module for malfunction. If resistance is 10,000 ohms or less, repair short circuit 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. 42 at breakout box. If resistance is 5 ohms or more, repair open circuit and confirm idle speed fault has been corrected. If resistance is less than 5 ohms, go to step 24).

24) Check DRL Circuit For Short To Power Turn ignition off. Measure resistance between test pin No. 42 and test pins No. 40, 46 and 60 at breakout box. If resistance is more than 10,000 ohms, check daytime running lights module for malfunction. If resistance is 10,000 ohms or less, repair short circuit 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 and all accessories off. Remove PCM 60-pin connector, and inspect it for damaged terminals. Repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn all accessories off. Turn ignition on. Measure voltage between test pin No. 45 at breakout box and chassis ground. If voltage is 1.5 volts or more, go to step 34). If voltage is less than 1.5 volts, go to step 31).

31) Check Headlight Circuit Voltage (Headlights On) Turn all accessories off. Turn ignition on. Turn headlights on. Measure voltage between test pin No. 45 at breakout box and chassis ground. If voltage is 10-17 volts, replace PCM and confirm idle speed fault has been corrected. If voltage is not 10-17 volts, go to step 32).

32) Check HDL Circuit Continuity Turn ignition off. Disconnect headlight relay. Measure resistance between HDL terminal at power distribution box and test pin No. 45 at breakout box. If resistance is 5 ohms or more, repair open circuit and confirm idle speed fault has been corrected. If resistance is less than 5 ohms, go to step 33).

33) Check HDL Circuit For Short To Ground Turn ignition off. Disconnect headlight relay. Measure resistance between test pin No. 45 and test pins No. 40, 46 and 60 at breakout box. If each resistance is more than 10,000 ohms, check headlight switch for malfunction. If any circuit resistance is 10,000 ohms or less, repair short circuit 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. 45 and pins No. 37 and 57 at breakout box. If resistance is more than 10,000 ohms, check headlight switch for malfunction. If resistance is 10,000 ohms or less, repair short circuit 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 terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Measure voltage between test pin No. 15 at breakout box and chassis ground. If voltage is 10-17 volts, go to step 41). 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 test pin No. 15 at breakout box and chassis ground. If voltage is less than 3 volts, replace PCM and confirm idle speed fault has been corrected. If voltage is 3 volts or more, go to step 42).

42) Check DEF Circuit For Short To Power Turn ignition off. Disconnect rear window defroster relay. Measure resistance between test pin No. 15 and test pins No. 37 and 57 at breakout box. If resistance is more than 10,000 ohms, check DEF switch or relay for malfunction. If resistance is 10,000 ohms or less, repair short circuit 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. 15 at breakout box. If resistance is less than 5 ohms, go to step 44). If resistance is 5 ohms or more, repair open circuit 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. 15 and test pins No. 40, 46 and 60 at breakout box. If each circuit resistance is more than 10,000 ohms, check DEF switch and relay circuit for malfunction. If any circuit resistance is 10,000 ohms or less, repair short circuit and confirm idle speed fault has been corrected.

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.

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) Continuous Memory Code 121, 124 Or 125: TPS Integrity 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 off. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Connect DVOM to test pins No. 46 and 47. 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 TPS is properly installed. If TPS is properly installed, replace TPS and repeat QUICK TEST. If voltage is okay, go to step 7) for Code 121 or step 2) for all other codes.

2) Check Idle Ensure idle is correct. If idle is correct, go to next step. If idle is incorrect, see IDLE SPEED in ADJUSTMENTS article in this section.

3) 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 and repeat QUICK TEST. If no problems are found, go to step 4).

4) Check MAP/BARO Sensor Output Refer to CIRCUIT TEST DF for MAP/BARO sensor output check. 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 step 5). See MAP SENSOR VOLTAGE OUTPUT table for specification. If output voltage is not within range, replace MAP/BARO sensor 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.

MAP SENSOR VOLTAGE OUTPUT

5) Check IAT Sensor Ensure ambient temperature is more than 50°F (10°C) before performing this test. 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.

6) 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 all checks are okay, go to step 9).

7) Check MAF Sensor Circuit Voltage Turn ignition off. Disconnect PCM 60-pin connector. Inspect and repair any damaged terminals. 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 pins No. 40 and 60 and MAF test pin at breakout box. See MAF TEST PIN NO. IDENTIFICATION table. If voltage is not within specification, replace MAF sensor and repeat QUICK TEST. See MAF SENSOR DATA table. If voltage is within acceptable range, system is operating normally at this time. See SYMPTOMS in TESTS W/O CODES article in this section.

MAF TEST PIN NO. IDENTIFICATION

MAF SENSOR DATA

8) 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. Make necessary repairs, and repeat QUICK TEST. If all checks are okay, go to step 9).

9) 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 step 10). For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. If fuel pressure is not within specifications, repair as necessary. See FUEL SYSTEM in I - EEC-IV SYS/COMP TESTS article in this section.

10) Verify Fuel Pressure Retention Ability Turn ignition on. If fuel pressure remains at specification for 60 seconds, go to next step (SFI). If fuel pressure does not remain at specification, repair fuel delivery system as necessary. See FUEL SYSTEM in I - EEC-IV SYS/COMP TESTS article in this section.

11) 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 6). 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 41/172, 91/136, 42/173 and 92/137. 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 (1.9L). Scheme 84

CIRCUIT TEST H ACRONYMS

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 KOER codes. If vehicle is a no-start, KOER Code 41/172, 42/173, 91/136 or 92/137 or Continuous Memory Code 171, 172, 173, 174, 175, 176, 177, 178, 41/144 or 91/139 is set, install PCV valve and go to step 2). 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 step 3). If pressure is not within specification, go to FUEL SYSTEM in I - EEC-IV SYS/COMP TESTS article in this 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 step 4) (no-starts), step 6).

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 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 article in this section. If fuel pressure drop is less than 5 psi, remove fuel pressure gauge. Connect inertia switch. Go to step 8). for SFI.

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 fault codes are present, go to step 8). Code 77/538 indicates throttle was touched when test was ran 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 SERVICE CODE-TO-TEST MENUS for instruction. For symptoms or Code 41/172, 91/136 or 176, go to step 13). For Code 42/173, 92/137 or 177, go to step 24). For all other codes, go to step 14).

CYLINDER BALANCE TEST SERVICE CODES

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 6) to step 8). No test procedures have been omitted.

8) Check Injector & Harness Resistance (SFI) Turn ignition off and wait 10 seconds. Disconnect PCM 60-pin connector. Inspect pins for damage. 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. 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.

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. 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 step 10). 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 Harness Ckt For Short To Power Or Ground Turn ignition off, and wait for 10 seconds. With breakout box installed and PCM disconnected, disconnect fuel injector wiring harness connector. Measure resistance between injector test pin(s) and test pins No. 37, 40, 46, 57 and 60. 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. 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.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 10) to step 12). No test procedures have been omitted.

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. 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 step 14). A HO2S which is always lean could be caused by thermactor air being diverted upstream from HO2S. With dual HO2S, Code 41/172 applies to right or rear HO2S and Code 91/136 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 41/172, 91/136 or 176 is present, reconnect thermactor air hoses and go to next step. 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 step 15) (MAP sensor-equipped models) or step 16) (MAF sensor-equipped models). If no code is present, go to step 21).

15) Check HO2S (Engines With MAP Sensors) Vacuum or air leaks in non-EEC-IV areas could cause Code 41, 91, 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 41, 91, 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 step 17). 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 step 18) 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 step 19).

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 41/144, 91/139, 171, 174, 175 and 178, go to step Step 90) .
2. For all other codes, go to step 20) 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 41/172, 91/136 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 41/172, 91/136 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. TESTS W/O CODES article in this 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 if 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 resistance is 2-5 ohms. If resistance is within specification, go to step 22). 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. TESTS W/O CODES article in this section. If voltage is less than 10.5 volts, go to step 23).

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 42/173, 92/137 Or 177: Check HO2S SIGNAL For Short To Power On dual HO2S systems, Code 42/173 applies to right or rear sensor. Codes 92/137 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 step 25).

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, and wait 10 seconds. 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 step 27) for Codes 42/173, 92/137 and 177 or step 28) (MAP sensor) or 30) (MAF sensor) for codes 171, 174, 175 and 178. 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 41/172, 91/136 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 41/172, 91/136 or 176 is present, remove jumper wire and go to step 28) for engines with MAP sensor or step 30) for engines with MAF sensor. If Codes 41/172, 91/136 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 22/126. 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 step 29).

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 1 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 step 91). 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 if necessary. Disconnect PCM 60-pin connector, and inspect it for damaged or pushed-out pins, corrosion and other damage. 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. See INTERMITTENTS in TESTS W/O CODES article in this 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 183

Indicates single right or rear HO2S detected a problem and adaptive fuel rich limit has been reached at idle.

1. Code 192

Indicates left or front HO2S detected a problem and adaptive fuel rich limit has been reached at idle.

1. Code 181

Indicates single right or rear HO2S detected a problem and adaptive fuel rich limit has been reached.

1. Code 189

Indicates left or front HO2S detected a problem and adaptive fuel rich limit has been reached.

1. 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.

1. Code 182

Indicates right or rear HO2S detected a problem and adaptive fuel lean limit has been reached at idle.

1. Code 188

Indicates left or front HO2S detected a problem and adaptive fuel lean limit has been reached.

1. Code 191

Indicates left or front HO2S detected a problem and adaptive fuel lean limit has been reached.

Possible causes for these codes are

1. Incorrect fuel pressure.
2. Faulty fuel injector or circuit.
3. Leaking or restricted air intake.
4. Faulty MAP sensor.
5. 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 I - SYS/COMP TESTS article in this 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 step 4) (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. See FUEL SYSTEM in I - SYS/COMP TESTS article in this section.

4) Check MAP/BARO Frequency Turn ignition off. Connect MAP/BARO tester to MAP/BARO sensor. (Scheme 85)in CIRCUIT TEST DF. Turn ignition on. If MAP/BARO voltage is within specification, go to step 5) (MAP/BARO equipped vehicles) or step 6) (all other vehicles). 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.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 4) to step 6). No test procedures have been omitted.

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

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 6) to step 8). No test procedures have been omitted.

8) Check Injector & Circuit Resistance (SFI) Turn ignition off and wait 10 seconds. Disconnect PCM 60-pin connector. Inspect pins for damage. 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. 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, go to step 9).

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. 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 step 10). 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. 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. 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. 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 step 12). 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. 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.

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 (Escort & Tracer). Scheme 85

1) Code 87/556: Check VPWR To Fuel Pump Relay Code 87/556 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 step 2). 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. On all other relays, measure resistance between VPWR pin and FUEL PUMP circuit pin at fuel pump relay. Both resistances 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 pin and both POWER-TO-PUMP and B+ pins at fuel pump relay. All resistances should be greater than 10,000 ohms. If resistances are as specified, go to step 3). If resistances are not as specified, replace fuel pump relay and repeat QUICK TEST.

Identifying Fuel Pump Relay Connector Terminals. Scheme 86

3) Check For Short To Power Turn ignition off. Disconnect fuel pump relay. 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 test pin No. 22 and negative battery terminal. If voltage is less than 1.0 volt, go to step 4). If voltage is 1.0 volt or more, repair short circuit. Reconnect PCM, and attempt to start vehicle. If vehicle fails to start, replace PCM. 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. If resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If resistance is 10,000 ohms or more, go to step 5).

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 wiring harness connector and test pin No. 22 at breakout box. If resistance is less than 5 ohms, replace PCM and repeat QUICK TEST. 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 5) to step 10). No test procedures have been omitted.

10) Code 95/542 A KOEO Code 95/542 indicates one of the following conditions

Due to internal circuitry of PCM, a left/front HO2S signal short to power could produce a Code 95/542 or 96/543.

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 10,000 ohms or more, go to step 26). If resistance is less than 10,000 ohms, replace HO2S sensor. Clear KAM, and repeat QUICK TEST.

HO2S Sensor Connector. Scheme 87

HO2S Sensor Wiring Harness Connector. Scheme 88

26) Check HO2S Circuit For Short To Power Turn ignition off. Leave left or front HO2S sensor disconnected. Disconnect PCM. Inspect and repair any damaged terminals. 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 and repeat QUICK TEST. If voltage is 2 volts or more, repair short circuit. 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 95/542 Code 95/542 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 harness connectors for corrosion and damage. Isolate and repair any faults. Clear continuous memory, and repeat QUICK TEST. If no faults are found, go to step 91).

91) Check FPM Circuit Turn ignition off. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Connect test light between test pin No. 8 (No. 19 on Escort, and Tracer) 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 and repeat QUICK TEST. If no fault is found, go to step 92).

92) Check For Shorts To Power Connect a test light between breakout box test pin No. 8 (No. 19 on Escort, and Tracer) 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 96/543: Check For Continuous Memory Code 87/556 If Code 87/556 is present, go to step 95). If Code 87/556 is not displayed, go to step 94).

94) Check EEC-IV Harness A Continuous Memory Code 96/543, without an accompanying Continuous Memory Code 87/556, 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 and repeat QUICK TEST. If no fault is found, a Continuous Memory Code 95/543 may have been set without a Continuous Memory Code 87/556, even though a fault has occurred in fuel pump primary circuit. Go to step 95) for fuel pump primary circuit check.

95) Continuous Memory Code 87/556: Check EEC-IV Harness A Continuous Memory Code 87 or 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. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. If fault is found, isolate and repair as necessary. Repeat QUICK TEST. If no faults are found but Code 96/543 is found, go to step 96) (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 95/542 or 96/543.

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. Clear Keep-Alive Memory (KAM), 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. Step 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 87/556 (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 87/556 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, go to TESTS W/O CODES article in this 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 EVT. 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) Solenoid Circuits Terminals. Scheme 89

1) 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 ground 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. 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 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 step 2).

2) Check EVR Solenoid Electrical Turn ignition off. Remove EVR solenoid wiring harness connector. Connect DVOM positive lead to VPWR terminal and negative test lead to EVR terminal at EVR solenoid 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 step 3). 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 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 step 4). If vacuum gauge does not show vacuum cycling at output port, replace EVR solenoid and 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 step 5).

5) Check EVR Solenoid VPWR Turn ignition off. Disconnect EVR solenoid wiring harness connector. Turn ignition on. Measure voltage between VPWR terminal at wiring harness connector and negative battery terminal. If voltage is 10.5 volts or more, go to step 6). If voltage is less than 10.5 volts, repair open VPWR circuit and repeat QUICK TEST.

6) Check EVR Solenoid Circuit Continuity Turn ignition off. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. 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 step 7). If resistance is 5 ohms or more, repair open circuit 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. Measure resistance between test pin No. 31 and test pins No. 40, 46 and 60 at breakout box. If each resistance is 10,000 ohms or more, replace PCM and repeat QUICK TEST. If reading is less than 10,000 ohms, repair short circuit 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. Scheme 90

Identifying CANP Valve Circuit & Connector Terminals. Scheme 91

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 ground 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. 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 increase can be obtained, remain in OUTPUT STATE CHECK and go to step 2).

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 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 step 3). 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 connectors 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 step 4).

4) Check CANP Valve For Vacuum Leaks Leave CANP valve connectors 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, got to next step.

5) Check CANP Valve Electrical/Mechanical Reconnect Leave 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 CANP valve wiring harness connector terminal VPWR and battery ground. If 10.5 volts or more is present, go to next step. If less than 10.5 volts is present, repair open circuit and repeat QUICK TEST.

8) Check CANP Circuit Continuity Turn ignition off. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. 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 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 step 9).

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 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 and repeat QUICK TEST. If all readings are 10,000 ohms or more, replace PCM 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. Scheme 92

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

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

1) Check System Function 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. 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 step 2). 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 step 3).

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 step 4).

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 step 5). 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 85/565 Or 569: Check CANP Solenoid Resistance Code85/565 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 40-90 ohms, go to step 7). If resistance is not 40-90 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 harness connector and negative battery terminal. If reading is 10.5 volts or more, go to step 8). If reading is less than 10.5 volts, 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 terminals, and repair if damaged. 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 reading is less than 5 ohms, go to step 9). If reading is 5 ohms or more, repair open circuit and repeat QUICK TEST.

9) Check CANP Circuit For Short To Ground Turn ignition off. 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 10,000 ohms or more, go to step 10). If any reading is less than 10,000 ohms, repair short to ground 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 and test pins No. 37 and 57. If all readings are 10,000 ohms or more, replace PCM and repeat QUICK TEST. If any reading is less than 10,000 ohms, repair short to power 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.

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. Scheme 93

TEST PIN NO. 21 (IAC) WIRE COLOR I.D.

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

1) Code 12/412 Or 16 Code 12/412 indicates engine RPM could not be controlled within upper RPM limit during KOER SELF-TEST. Code 16 indicates engine RPM was too low to perform HO2S test 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 step 2). If RPM does not drop or engine does not stall, go to step 3).

2) Check For EGR Codes If EGR service Code 31/327, 32/326/328, 33/332, 34/232/334/336 or 213 is displayed, reconnect IAC solenoid. Go to appropriate KOER SELF-TEST. See SERVICE CODE-TO-TEST MENUS. If these codes are not displayed, go to step 3).

3) Check For Other Diagnostic Test Codes If Code 22/126, 41/172, 42/173, 91/136 or 92/137 is displayed, reconnect IAC solenoid. Go to appropriate KOER SELF-TEST. See SERVICE CODE-TO-TEST MENUS. If these codes are not displayed, go to step 4).

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 94) 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 step 5).

IAC Solenoid Connector. Scheme 94

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 reading is more than 10,000 ohms, go to step 6). If reading 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 harness connector and battery ground terminal. If voltage is 10.5 volts or more, go to step 7). If voltage is less than 10.5 volts, 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 terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 21 and IAC terminal at IAC wiring harness connector. If reading is 5 ohms or less, go to step 8). If reading is more than 5 ohms, 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 less than 10,000 ohms, repair short to ground and repeat QUICK TEST. If all readings are 10,000 ohms or more, go to step 9).

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 more than 1.0 volt, repair short circuit and repeat QUICK TEST. If code or symptom is still present, replace PCM. If voltage is 1.0 volt or less, go to step 10).

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 DVOM voltage reading is 3.0-11.5 volts, go to step 11). If DVOM voltage reading 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 ADJUSTMENTS article in this section. If base idle speed is within 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 base idle speed is not correct, reset idle speed to specification. Repeat QUICK TEST. If unable to set idle to specification, go to step 12).

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. Repair or replace 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 13/411 Code 13/411 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.

If everything checks okay, go to step 17). 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 reading is more than 10,000 ohms, go to step 18). If reading 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 terminals, and repair if damaged. 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 less than 10,000 ohms, repair short to ground. Reconnect components, and repeat QUICK TEST. If all readings are 10,000 ohms or more, go to step 19).

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 and decreasing engine RPM. If voltage is 3.0-11.5 volts, remove IAC solenoid and inspect for contamination. Repair or replace 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.

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 closed for 1.9L.

Perform this test only when directed here by QUICK TEST or a drive-ability 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 (1.9L). Scheme 95

LFC/HFC Circuit Connector Terminals (Typical). Scheme 96

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 wiring harness connector and chassis ground. If voltage is 10.5 volts or more, go to step 2). If voltage is less than 10.5 volts, check fuse and circuit to LFC/HFC. If fuse 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. 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 step 3). 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 specification, 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 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 and repeat QUICK TEST. If voltage does not cycle, remove jumper and go to step 4).

4) Check Continuity Of LFC/HFC Circuit Turn ignition off. Disconnect LFC or HFC relay. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. 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 wiring harness connector.

1. Code 564

Measure resistance between breakout box LFC test pin and LFC terminal at LFC relay 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.

5) 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 step 6). If voltage is 1.0 volt or more, repair short circuit and repeat QUICK TEST. If code is still present, replace PCM.

6) 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 and repeat QUICK TEST. If resistance is 10,000 ohms or less, repair short circuit and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 6) 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 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 step 11).

LFC Relay Wiring Harness Connector (1.9L). Scheme 97

11) Check For Voltage To HFC Relay Turn ignition off. Disconnect LFC and HFC relays. Turn ignition on. Measure voltage between IGNITION RELAY terminal at HFC relay wiring harness connector and negative battery terminal. If voltage is more than 10.5 volts, go to step 12). If voltage is 10.5 volts or less, check fuse and ignition relay (1.9L). If fuse and/or relay are okay, repair open circuit and repeat QUICK TEST.

HFC Relay Wiring Harness Connector (1.9L). Scheme 98

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. (Scheme 99) 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.

Identifying LFC & HFC Relay Terminals (1.9L). Scheme 99

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. (Scheme 100) Turn ignition on. If fan operates, remove jumper and go to step 16). If fan does not operate, remove jumper wire and go to step 14).

LFC Relay Wiring Harness Connector (1.9L). Scheme 100

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 5 ohms or less, go to step 15). If resistance is more than 5 ohms, repair open circuit and check system operation.

LFC & Cooling Fan Wiring Harness Connector (1.9L). Scheme 101

15) Check Cooling Fan Ground Circuit Turn ignition off. Leave LFC relay and cooling fan disconnected. Measure resistance between GND terminal at cooling fan wiring harness connector and negative battery terminal. If resistance is less than 5 ohms, replace cooling fan. If resistance is 5 ohms or more, repair open circuit and check system operation.

16) Check Circuits From HFC Relay To Fan Turn ignition off. Disconnect 60-pin PCM connector. Inspect terminals. Repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. On 1.9L, install a jumper wire between test pins No. 31 and 40 at breakout box. Turn ignition on. If fan runs at high speed, replace LFC relay. Repeat QUICK TEST. If fan does not run at high speed, remove jumper wire and go to step 17).

17) Check HFC Power-To-Fan Voltage At Fan Turn ignition off.Leave LFC relay and cooling fan disconnected. On 1.9L, install a jumper wire between test pins No. 31 and 40 at breakout box. Turn ignition on. Measure voltage between HFC POWER-TO-FAN circuit at cooling fan wiring harness connector and negative battery terminal. If voltage is more than 10.5 volts, replace cooling fan. Repeat QUICK TEST. If voltage is 10.5 volts or less, remove jumper wire and go to step 18).

Cooling Fan Wiring Harness Connector (1.9L). Scheme 102

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 wiring harness connector and HFC POWER-TO-FAN terminal at cooling fan wiring harness connector. If resistance is 5 ohms or less, replace HFC relay. Repeat QUICK TEST. If resistance is more than 5 ohms, repair open circuit and check system operation.

HFC Relay Wiring Harness Connector (1.9L). Scheme 103

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 Ensure A/C is off. If cooling fan is always on with ignition off but operates normally with ignition on, ensure that ignition relay contacts are open. Replace relay if necessary. If relay is okay, check circuit between ignition relay and fan for a short to power. If system does not operate as described, 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 step 27). 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 step 28). If fan does not continue to run, replace HFC relay and check system operation.

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 wiring harness connector and negative battery terminal. If voltage is 1.0 volt or more, repair short to power in LFC POWER-TO-FAN circuit. If voltage is less than 1.0 volt, repair short to power in HFC POWER-TO-FAN circuit. Repeat QUICK TEST.

Cooling Fan Wiring Harness Connector (1.9L). Scheme 104

Perform this test only when directed here by a drive-ability symptom. This test is only intended to diagnose

1. Wiring harness circuits (SIL).
2. Top gear switch.
3. SIL dimmer relay.
4. SIL bulb and SIL circuit fuse.
5. Powertrain Control Module (PCM).

Shift Indicator Light (SIL) Circuits (1.9L). Scheme 105

1) Check SIL Operation Inspect SIL while driving vehicle. SIL should turn on when optimum-shift RPM for each gear is reached. Light should be off in top gear. If SIL light is always on, check for short to ground in SIL circuit. If light is always off, check for open in SIL circuit. If light is always on, go to step 11) (1.9L). If light is not always on, go to step 2).

2) Check SIL Circuit Fuse Turn ignition off. Remove and inspect SIL fuse. If fuse is okay, go to step 3). Replace fuse if blown. If fuse blows again, repair short to ground between fuse and SIL bulb. Check SIL operation.

3) Check SIL Bulb Turn ignition off. Remove and inspect SIL bulb. If bulb is burned out, replace bulb and check SIL operation. If bulb is okay, go to step 15) (1.9L).

4) Check Continuity Of SIL Dimmer Relay Turn ignition off. Disconnect SIL dimmer relay. Set DVOM on 200-ohm scale. Measure resistance between pins No. 3 and 5 on SIL dimmer relay. If resistance is less than 5 ohms, go to step 5). If resistance is 5 ohms or more, replace SIL dimmer relay.

5) Check SIL Dimmer Relay Function Turn ignition off. Apply 12 volts across pins No. 1 and 2 of SIL dimmer relay. Measure resistance between pins No. 3 and 5 on SIL dimmer relay. If resistance is not 40-55 ohms, replace SIL dimmer relay. If resistance is 40-55 ohms, go to step 6).

6) Check Voltage At SIL Dimmer Relay Leave SIL dimmer relay disconnected. Turn ignition on. Measure voltage between terminal No. 5 of SIL dimmer relay wiring harness connector and negative battery terminal. If voltage is more than 5 volts, reconnect relay and go to step 7). If voltage is 5 volts or less, repair open circuit between SIL fuse and SIL dimmer relay.

7) Check Continuity Of SIL Circuit Turn ignition off. Disconnect SIL dimmer relay. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 53 and terminal No. 3 of SIL dimmer relay wiring harness connector. If resistance is 5 ohms or less, replace PCM and repeat QUICK TEST. If resistance is more than 5 ohms, repair open circuit between SIL dimmer relay and PCM. Reconnect all components, and check operation of SIL.

8) Check SIL Circuit For Short To Ground Turn ignition off. Disconnect SIL dimmer relay. Turn ignition on. If SIL is on, repair short circuit between SIL dimmer relay and SIL bulb. If SIL is not on, go to next step.

9) Check SIL Circuit For Short To Ground Turn ignition off. Leave SIL relay disconnected. Measure resistance between SIL relay wiring harness connector terminals No. 1 and 3. If resistance is less than 5 ohms, replace SIL dimmer relay and check system operation. If resistance is 5 ohms or more, go to next step.

10) Check SIL Circuit For Short To Ground Turn ignition off. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. Turn ignition on. If SIL remains on, repair short to ground between SIL dimmer relay and PCM. If SIL does not come on, replace PCM and check system operation.

11) Check SIL Circuit For Short To Ground Turn ignition off. Put transmission in high gear. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pins No. 53 and 60 at breakout box. If resistance is 10,000 ohms or less, repair short between top gear switch and PCM. Repeat QUICK TEST. If resistance is more than 10,000 ohms, replace PCM and repeat QUICK TEST.

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 For Voltage To SIL Socket Turn ignition off. Remove SIL bulb. Place transmission in any gear except top gear. Turn ignition on. Measure voltage between power contact at SIL socket and chassis ground. If voltage is more than 10.5 volts, go to step 17). If voltage is 10.5 volts or less, connect SIL bulb. Go to step 16).

16) Check Operation Of Top Gear Switch Top gear switch is normally closed and should only be open when vehicle is shifted into top gear. Turn ignition off. Disconnect top gear switch. Place transmission in any gear except top gear. Measure resistance of top gear switch. If resistance is less than 5 ohms, repair open in IGNITION RUN circuit to SIL bulb socket. Repeat QUICK TEST. If resistance is 5 ohms or more, replace top gear switch. Repeat QUICK TEST.

17) Check Continuity Of SIL Circuit Turn ignition off. Remove SIL bulb. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 53 and SIL power contact at SIL bulb socket. If resistance is less than 5 ohms, replace PCM. Repeat QUICK TEST. 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 17) to step 19). No test procedures have been omitted.

19) Check SIL Circuit Fuse Turn ignition off. Remove and inspect SIL fuse. If fuse is okay, reconnect and go to step 20). If fuse is blown, repair short to ground between fuse and SIL bulb. Replace fuse, and check SIL operation.

20) Check SIL Bulb Turn ignition off. Remove and inspect SIL bulb. If bulb is okay, go to step 21). If bulb is burned out, replace bulb and check SIL operation.

21) Check For Voltage To SIL Socket Turn ignition off. Remove SIL bulb. Turn ignition on. Measure voltage between power contact at SIL socket and chassis ground. If voltage is more than 10.5 volts, go to step 22). If voltage is 10.5 volts or less, repair open in IGNITION START/RUN circuit to SIL bulb socket.

22) Check Continuity Of SIL Circuit 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. Measure resistance between test pin No. 53 at breakout box and SIL power contact at SIL bulb socket. If resistance is less than 5 ohms, replace PCM. Repeat QUICK TEST. If resistance is 5 ohms or more, repair open circuit and check SIL operation. Repeat QUICK TEST.

23) Check SIL Circuit For Short To Ground With PCM disconnected, turn ignition on. If SIL is on with PCM disconnected, repair short to ground between SIL bulb and PCM. If SIL is not on with PCM disconnected, replace PCM. Repeat QUICK TEST.

CIRCUIT TEST KM - WIDE OPEN THROTTLE A/C CUT-OUT (WAC) & A/C

DEMAND SWITCH

Perform this test when diagnosing a symptom. 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. A/C fan controller.
4. Faulty PCM.

WOT A/C Cut-Out Circuit (Escort & Tracer). Scheme 106

TEST PIN NO. 10 (ACCS) WIRE COLOR I.D.

TEST PIN NO. 54 (WAC) WIRE COLOR I.D.

1) No A/C: Check For Voltage At A/C Clutch Check all A/C-related fuses in fuse panel before proceeding with this test. Turn ignition off. Disconnect A/C clutch wiring harness connector. Turn A/C switch to A/C position. Turn blower switch on (1.9L). Start engine, and wait 10 seconds. Measure voltage between power side of A/C clutch wiring harness connector and negative battery terminal. If voltage is 10.5 volts or more, EEC system is okay. Check A/C system. If voltage is less than 10.5 volts, go to next step.

2) Check Continuity Of POWER-TO-CLUTCH Circuit Turn ignition off. Disconnect A/C clutch and WAC relay wiring harness connectors. Measure resistance between power side of A/C clutch wiring harness connector and POWER-TO-CLUTCH terminal at WAC relay wiring harness connector. If resistance is 5 ohms or less, reconnect A/C clutch and go to step 3). If resistance is more than 5 ohms, repair open circuit and retest system.

3) Check For Power On A/C Demand Circuit Turn ignition on. Turn A/C switch on. Leave WAC relay disconnected. Perform following procedure as applicable

1. 1.9L - Turn blower motor switch to any speed. Measure voltage between A/C relay input terminal at WAC relay wiring harness connector and chassis ground.
2. Except 1.9L - Measure voltage between A/C DEMAND SWITCH terminal at WAC relay wiring harness connector and chassis ground.

If voltage is 10.5 volts or more, go to step 5). If voltage is less than 10.5 volts for 1.9L models, go to step 4). For all other vehicles, verify operation of A/C clutch cycling pressure switch and A/C demand switch. If components are okay, repair open circuit and recheck system.

4) Check Continuity Between WAC Relay & A/C Relay Turn ignition off. Remove WAC and A/C relay wiring harness connectors. Measure resistance between A/C RELAY terminal at WAC relay connector and A/C RELAY terminal at A/C relay connector. If resistance is less than 5 ohms, check A/C relay for low output voltage. If resistance is 5 ohms or more, repair open circuit. Connect relays, and check system operation.

5) Check WAC Circuit For Short To Ground Turn ignition off. Leave WAC relay disconnected. Disconnect 60-pin PCM connector. Inspect wiring, and repair if damaged. Measure resistance between WAC terminal at WAC relay wiring harness connector and chassis ground. If resistance is less than 10,000 ohms, repair short and check system operation. If resistance is 10,000 ohms or more, go to step 6).

6) Check For Voltage At ACCS Input To PCM Turn ignition off. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Set A/C switch to A/C position. On 1.9L models, turn blower switch on. Turn ignition on. Measure voltage between test pins No. 10 and 40 at breakout box. If voltage is less than 10.5 volts, repair open circuit and check system operation. If voltage is 10.5 volts or more, go to step 7).

7) Check WAC Relay Turn ignition off. Connect WAC relay, leaving A/C clutch disconnected. Leave A/C and blower switch positioned as listed in step 6). Turn ignition on. Measure voltage between POWER-TO-CLUTCH terminal of A/C clutch wiring harness connector and negative battery terminal. If voltage is 10.5 volts or more, replace PCM. If voltage is less than 10.5 volts, replace WAC relay.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 7) to step 15). No test procedures have been omitted.

15) No A/C Output At WOT: 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. 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 10.5 volts or more, remain in OUTPUT STATE CHECK and go to step 16). If voltage does not increase to 10.5 volts, depress throttle to WOT and release. If STO voltage does not go high, go to CIRCUIT TEST QC, step 2).

16) Check For VPWR To Relay With vehicle in OUTPUT STATE CHECK, disconnect wiring harness from WAC relay. Measure voltage between VPWR terminal (IGN RUN terminal for 1.9L) at WAC relay wiring harness connector and chassis ground. If voltage is less than 10.5 volts, repair open in VPWR circuit between EEC power relay and WAC relay (IGN RUN circuit between WAC relay and joint box on 1.9L), and retest system. If voltage is 10.5 volts or more, go to step 17).

17) Check WAC System For Cycling Leave vehicle in OUTPUT STATE CHECK. Disconnect WAC relay wiring harness connector. Connect DVOM positive test lead to VPWR terminal (IGN RUN terminal for 1.9L). Connect negative test lead to WAC terminal at WAC relay wiring harness connector. Check DVOM while depressing and releasing throttle several times to cycle output on and off. If voltage cycles about one volt high to low, replace WAC relay. If voltage does not cycle, remove test leads. Reconnect speed control servo, and go to step 18).

18) Check Continuity Of WAC Circuit 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. Measure resistance between test pin No. 54 and WAC terminal at WAC relay wiring harness connector. If reading is 5 ohms or more, repair open circuit. Reconnect all components, and retest system. If reading is less than 5 ohms, go to step 19).

19) Check WAC Circuit For Short To Power Turn ignition off. Leave PCM and WAC relay disconnected. Turn ignition on. Measure voltage between test pin No. 54 and chassis ground. If voltage is 1.0 volt or less, replace PCM and retest system. If voltage is more than 1.0 volt, repair short circuit. If symptom is still present, replace PCM.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 19) to step 30). No test procedures have been omitted.

A low idle with A/C on may be caused by PCM not receiving or recognizing A/C input from pin No. 10.

30) Check A/C Input Circuit Turn A/C switch to A/C position. Turn blower motor switch to lowest speed. Perform KOEO SELF-TEST. If Code 67 or 79/539 is present, PCM is receiving and recognizing A/C input from pin No. 10. Check for other possible causes of low idle. If Codes 67 and 79/539 are not present, go to step 31).

31) Check A/C Input Circuit Turn ignition off. Install breakout box, leaving PCM disconnected. Turn A/C on. Turn ignition on. Measure voltage between test pins No. 10 and 40. If voltage is 10.5 volts or more, replace PCM and repeat QUICK TEST. If voltage is less than 10.5 volts, repair open A/C circuit and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 31) to step 40). No test procedures have been omitted.

Before entering this test, ensure A/C selector is in OFF position and shift selector is in PARK (A/T). If A/C was on, repeat QUICK TEST. If Code 67 or 79/539 is present, continue with this test.

40) Code 67 Or 79/539: Check A/C Input Code 79/539 indicates ACCS input to PCM was high during SELF-TEST. Code 67 indicates Neutral Drive Switch (NDS) or ACCS circuit voltage was high during SELF-TEST. 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. Turn ignition on. Measure voltage between test pin No. 10 at breakout box and chassis ground. If voltage is 1.0 volt or more, repair short to power in A/C circuit and repeat QUICK TEST. If voltage is less than 1.0 volt, replace PCM and repeat QUICK TEST.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 40) to step 50). No test procedures have been omitted.

50) No A/C: 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 less than 10.5 volts, repair open circuit and check system operation. If voltage is 10.5 volts or more, 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 the POWER-TO-CLUTCH terminal of the A/C clutch connector and A/C relay connector. If resistance is more than 5 ohms, repair open circuit and check system operation. If resistance is 5 ohms or less, 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 10.5 volts or more, EEC system is okay. Check for problem in A/C system. If voltage is less than 10.5 volts, 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 low pressure switch. Measure resistance at low pressure switch wiring harness connector terminal to A/C demand switch (White wire) and chassis ground. If resistance is more than 5 ohms, check for defective A/C demand switch. If resistance is 5 ohms or less, 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 more than 5 ohms, EEC system is okay. Check for problem in A/C system. If resistance is 5 ohms or less, go to next step.

57) Check PCM-To-Low Pressure Switch Circuit Continuity Turn ignition off. Leave A/C 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. Measure resistance between test pin No. 23 and ACD terminal of low pressure switch wiring harness connector. If resistance is more than 5 ohms, repair open circuit and check system operation. If resistance is 5 ohms or less, replace PCM 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 less than 10.5 volts, repair open circuit and repeat QUICK TEST. If voltage is 10.5 volts or more, go to next step.

Identifying A/C Relay Wiring Harness Connector Terminals. Scheme 107

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. 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. If resistance is as specified, go to next step.

Identifying A/C Relay Terminals. Scheme 108

62) Check ACON Circuit For Short To Power Turn ignition off. Leave A/C 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 test pin No. 54 and chassis ground. If voltage is more than 1.0 volt, repair short circuit to power. If voltage is 1.0 volt or less, 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 less than 10,000 ohms, repair short circuit to ground. If resistance is 10,000 ohms or more, 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 less than 5 ohms, replace PCM and repeat QUICK TEST. 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 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 at low pressure switch wiring harness connector terminal to A/C demand switch (White wire) and chassis ground. If resistance is less than 10,000 ohms, check for defective A/C demand switch. If resistance is 10,000 ohms or more, 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 less than 10,000 ohms, replace switch and check system operation. If each resistance is 10,000 ohms or more, 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 terminals, and repair if damaged. Measure resistance between PCM pin No. 23 and chassis ground. If resistance is less than 10,000 ohms, repair short circuit to ground and check system operation. If resistance is 10,000 ohms or more, replace PCM 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 wiring harness connector and negative battery terminal. If voltage is more than 1.0 volt, repair short to power and check system operation. If voltage is 1.0 volt or less, go to next step.

81) Check A/C Relay Turn ignition off. Leave A/C relay disconnected. Measure resistance between POWER-TO-CLUTCH and the following A/C relay terminals; B(+) and IGN RUN. If resistance is more than 10,000 ohms, EEC system is okay. Check for fault in A/C system. If resistance is 10,000 ohms or less, replace A/C relay 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 Circuit. Scheme 109

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. 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 step 2). If voltage does not increase, depress throttle to WOT and release. If voltage increases, remain in OUTPUT STATE CHECK and go to step 2). If voltage does not increase, leave test equipment connected and go to CIRCUIT TEST QC.

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 5). If FPRC solenoid output voltage varies more than 1.0 volt, go to step 3).

3) Check FPRC Vacuum Signal Disconnect and inspect FPRC vacuum hose. Repair or replace if necessary. Start engine, and warm it to normal operating temperature. Turn ignition off. Connect vacuum gauge between FPRC solenoid and fuel pressure regulator. Start engine. If vacuum is present after about 2 minutes of engine idle, check fuel system for malfunction. See FUEL SYSTEM in I - SYS/COMP TESTS article in this section. If vacuum is not present, remove vacuum gauge and go to step 4).

4) Ensure engine is warmed to normal operating temperature. Turn ignition off. Connect vacuum gauge between FPRC solenoid and manifold vacuum source. Start engine. If vacuum is present, replace FPRC solenoid and repeat QUICK TEST. If vacuum is not present, replace vacuum hose and repeat QUICK TEST.

5) 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 less than 10.5 volts, repair open circuit and repeat QUICK TEST. If voltage is 10.5 volts or more, go to step 6).

6) Check Continuity Of FPRC Circuit 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. Disconnect FPRC solenoid wiring harness connector. Measure resistance between test pin No. 13 and FPRC terminal at solenoid wiring harness connector. If resistance is more than 5 ohms, repair open circuit. Repeat QUICK TEST. If resistance is 5 ohms or less, go to step 7).

7) Check FPRC Circuit For Short Leave ignition off and FPRC solenoid disconnected. Measure resistance between test pin No. 13 and test pins No. 37 and 57. Measure resistance between test pin No. 13 and test No. 40, 46 and 60. If any resistance is 10,000 ohms or less, repair short circuit and repeat QUICK TEST. If each resistance is more than 10,000 ohms, replace PCM 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. Scheme 110

TEST PINS NO. 18, 29 OR 44 (OCT ADJ) WIRE COLOR I.D.

TEST PIN NO. 46 (SIG RTN) WIRE COLOR I.D.

1) Code 57/341 Code 57/431 indicates Octane Adjust 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 step 2). 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, go to TESTS W/O CODES article in this section. If vehicle does not have modification decal, go to step 3).

3) Check For Code 57/341 Replace OCT ADJ shorting bar. Perform KOEO SELF-TEST. If Code 57/341 is present, go to step 4). If code is not present, testing is complete. If driveability faults are present, go to TESTS W/O CODES article in this 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 terminals, and repair if damaged. 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 more than 5 ohms, repair open OCT ADJ circuit, shorting bar or SIG RTN circuit. Repeat QUICK TEST. If resistance is 5 ohms or less, replace PCM and repeat QUICK TEST.

5) Check For Code 11/111 Start engine. Warm it to normal operating temperature. Turn ignition off. Perform KOEO SELF-TEST. If Code 11 or 111 is present, go to step 6). If Code 57/341 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 Octane Adjust in-line connector. If shorting bar is installed, go to step 8). If shorting bar is not installed, go to step 7).

7) 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, go to TESTS W/O CODES article in this section. If vehicle does not have modification decal, go to step 10).

8) Check For Technical Service Bulletin (TSB) If a TSB authorizing removal of OCT ADJ shorting bar exists, go to step 9). If a TSB authorizing removal of OCT ADJ shorting bar does not exist, testing is complete. If driveability faults are present, go to TESTS W/O CODES article in this 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 step 10). 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 terminals, and repair if damaged. 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 and repeat QUICK TEST. If each resistance is more than 10,000 ohms, go to step 11).

11) Check PCM Turn ignition off. Disconnect OCT ADJ shorting bar. Turn ignition on. Measure voltage between breakout box OCT ADJ test pin terminal and test pins No. 40 and 60. If voltage is 4 volts or less, replace PCM. Repeat QUICK TEST. If engine still detonates, go to TESTS W/O CODES article in this section. If voltage is 4 volts or more, remove breakout box and go to TESTS W/O CODES article in this 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. Scheme 111

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 step 2).

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 step 3). 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 terminals, and repair if damaged. 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 5 ohms or less, go to step 4). If resistance is more than 5 ohms, repair open circuit 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 resistance is 100,000 ohms or more, go to step 5). If resistance is less than 100,000 ohms, repair short circuit 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 atbreakout box. If resistance is 100,000 ohms or more, replace PCM and repeat QUICK TEST. If resistance 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 step 7). If valve(s) do not hold vacuum, replace 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 step 8). 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 step 9).

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). 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 to 10.5 volts or more, remain in OUTPUT STATE CHECK and go to step 10). If voltage does not increase to 10.5 volts, depress throttle to WOT and release. If STO 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 to connector IMRC terminal. Observe DVOM while cycling throttle open and closed. If DVOM does not cycle 0.5 volt, return to step 1). If DVOM does cycle 0.5 volt, 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. Use vacuum pump to 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.

1) Code 77/538 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 77/538 is present, replace PCM. If Code 77/538 is not present, vehicle has passed dynamic response test. Service other codes if necessary.

CIRCUIT TEST ML - SELF-TEST OUTPUT (STO) OR MALFUNCTION

INDICATOR LIGHT (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 I.D.

TEST PIN NO. 18, 28 OR 44 (DATA +) WIRE COLOR I.D.

TEST PIN NO. 8, 9 OR 19 (DATA -) WIRE COLOR I.D.

1) Malfunction Indicator Light (MIL) Always On If vehicle will not start, go to appropriate circuit test

1. 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 terminals, and repair if damaged. 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 more than 5 ohms, replace PCM and repeat QUICK TEST. If reading is 5 ohms or less, repair short between test pin No. 17 and Diagnostic Link Connector (DLC) terminal No. 17 or MIL. 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 step 5).

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 step 7).

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 step 8). 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 terminals, and repair if damaged. 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. If resistance is 5 ohms or more, repair open 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 terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between STI connector and engine ground. If resistance is 10,000 ohms or less, repair short circuit. Reconnect PCM, and turn ignition on to verify correct MIL operation. If resistance is more than 10,000 ohms, 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 11-10-11 (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 DLC Message Displayed Codes 529 and 533 indicate circuit fault has occurred on Data Link Connector (DLC). These codes can occur alone or with another code. Fault will occur under following conditions

1. Code 529 indicates PCM or DLC circuit failure.
2. Code 533 indicates DLC 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 11-10-11 or 111-10-111), fault is in instrument cluster. If pass code is not displayed, service codes as necessary.

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, see I - SYS/COMP TESTS article in this 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.

TEST PIN NO. 4 (IDM) WIRE COLOR I.D.

TEST PIN NO. 36 (SPOUT) WIRE COLOR I.D.

1) Continuous Memory Code 14/211 Code 14/211 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. Secondary ignition short to ground.
3. On-board transmitter equipment (2-way radio).

Repair if necessary. Clear code, and repeat QUICK TEST. If problem is not found, go to step 2). If vehicle does not start, go to CIRCUIT TEST AB.

2) Continuous Memory Code 18/212: Check IDM Circuit Continuity Continuous Memory Code 18/212 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, go to CIRCUIT TEST AB. If vehicle starts, go to step 4).

3) Check IDM Circuit Continuity (Non-CCD) 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. Disconnect ICM. Measure resistance between test pin No. 4 at breakout box and IDM terminal at ICM wiring harness connector. If resistance is 5 ohms or less, go to step 5). If resistance is more than 5 ohms, repair open circuit, and repeat QUICK TEST.

4) Check IDM Circuit Continuity (CCD) 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. Disconnect ignition coil and ICM. Measure resistance between test pin No. 4 at breakout box and IDM terminal at ICM wiring harness connector. If resistance is not 20,000-24,000 ohms, repair open circuit and repeat QUICK TEST. If resistance is 20,000-24,000 ohms, go to step 5).

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 voltage is more than 10.5 volts, repair short circuit. Clear codes, and repeat QUICK TEST. If voltage is 10.5 volts or less, go to step 6).

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 break-out box. For shorts to VREF, measure resistance between test pinNo. 4 and test pins No. 20, 40, 46 and 60 at breakout box. If each resistance is 10,000 ohms or less, repair short circuit and repeat QUICK TEST. If each resistance is more than 10,000 ohms, go to step 7).

7) Check IDM Circuit For Short To Ground Turn ignition off. Leave ignition coil, 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 step 8). If any resistance is 10,000 ohms or less, repair short to ground in IDM, SIG RTN, or PWR GND circuit. Clear codes, and repeat QUICK TEST.

8) Check ICM Turn ignition off. Connect PCM to breakout box. Reconnect ICM and ignition coil to wiring harness connectors. 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 to simulate road shock. Wiggle all ICM and CMP sensor wiring and harness connectors. If fault (voltage surge) is indicated, disconnect and inspect wiring harness connectors and terminals for damage. If fault (voltage surge) is indicated, go to step 9). If connectors and terminals are okay, check ignition system. See I - SYS/COMP TESTS article in this section.

9) Check PCM & Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. If connector is damaged, repair as necessary. Clear codes, and repeat QUICK TEST. If connector is okay, go to step 10).

10) Check PCM For Short To Power Turn ignition off. Connect PCM to breakout box. Disconnect the following sensors as applicable.

1. On vehicles with remote mount ICM and CMP, disconnect ICM and CMP wiring harness connector.
2. On all other models, disconnect ICM wiring harness connector.

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 either voltage reading is more than 10.5 volts, replace PCM and repeat QUICK TEST. If both voltage readings are 10.5 volts or less, go to step 11).

11) 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 resistance is more than 10,000 ohms, check ignition system. See I - SYS/COMP TESTS article in this section. If resistance is 10,000 ohms or less, replace PCM 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, see I - SYS/COMP TESTS article in this 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).

IDM Circuit Schematic (3.0L Flexible Fuel). Scheme 112

IDM Circuit Schematic (4.6L). Scheme 113

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 and repeat QUICK TEST. If problem is not found, go to step 4).

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, go to IGNITION SYSTEMS in I - SYS/COMP TESTS article in this 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, go to IGNITION SYSTEMS in I - SYS/COMP TESTS article in this section. If Code 215, 216 or 217 is not present, go to step 4).

4) Code 212: Check IDM Circuit Continuity Turn ignition off. Disconnect ICM. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. 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 and repeat QUICK TEST. If resistance is less than 5 ohms, go to step 5).

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 either voltage reading is more than 10.5 volts, repair short circuit and repeat QUICK TEST. If voltage is 10.5 volts or less, go to step 6).

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 either resistance is 10,000 ohms or less, repair short circuit and repeat QUICK TEST. If each resistance is more than 10,000 ohms, go to step 7).

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 less than 10,000 ohms, repair short to ground in IDM circuit and repeat QUICK TEST. If all resistances are 10,000 ohms or more, go to step 8).

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. See I - SYS/COMP TESTS article in this 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 step 10).

10) Check PCM & Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. If connector is damaged, repair as necessary. Clear codes, and repeat QUICK TEST. If connector is okay, go to step 11).

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 No. 40 and 60. If either voltage is more than 10.5 volts, replace PCM and repeat QUICK TEST. If each voltage 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 No. 16, 20, 40, 46 and 60. If each resistance is more than 10,000 ohms, EEC system is okay. Check ignition system. See I - SYS/COMP TESTS article in this section. If any resistance is 10,000 ohms or less, replace PCM 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 Circuit. Scheme 114

TEST PIN NO. 36 (SPOUT) WIRE COLOR I.D.

1) Check For Power To PCM 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. 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 voltage reading is less than 10.5 volts, go to CIRCUIT TEST B. If both voltage readings are 10.5 volts or more, go to step 2).

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 more than 5 ohms, repair open circuit. Reconnect all components, and check ignition timing. If resistance is 5 ohms or less, go to step 3).

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 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 test for shorts to PIP, measure resistance between test pins No. 36 and 56 at breakout box. If either resistance is 10,000 ohms or less, repair short circuit and repeat QUICK TEST. If each resistance is more than 10,000 ohms, EEC system is okay. Check ignition system. See IGNITION SYSTEMS in I - SYS/COMP TESTS article in this section.

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.

Identifying ICM Connector Terminals (1.9L). Scheme 115

1) Check For Power To PCM 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. Turn ignition on. Measure voltage between test pins No. 37 and 40 at breakout box. Measure voltage between test pins No. 57 and 60 at breakout box. If both readings are 10.5 volts or more, go to step 2). If either reading is less than 10.5 volts, 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 5 ohms or less, go to step 3). If resistance is more than 5 ohms, 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 and repeat QUICK TEST. If voltage is 10.5 volts or less, go to step 4).

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 each resistance is more than 10,000 ohms, check ignition system. See IGNITION SYSTEM in I - SYS/COMP TESTS article in this section. If resistance 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. Scheme 116

TEST PIN NO. 17 (STO/MIL) WIRE COLOR I.D.

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

TEST PIN NO. 46 (SIG RTN) WIRE COLOR I.D.

TEST PIN NO. 48 (STI) WIRE COLOR I.D.

1) Check VREF Voltage At Data Link Connector (DLC) Turn ignition off. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. 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 step 2).

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 atbreakout box and Self-Test Input (STI) terminal at pigtail connector. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST. If reading is less than 5 ohms, go to step 4).

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 reading is less than 5 ohms, go to step 5). If resistance is 5 ohms or more, repair open circuit 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 pins No. 40 and 60 at breakout box. If any measurement is 2 volts or more, repair short to power in HO2S SIGNAL circuit, and repeat QUICK TEST. If voltage is less than 2 volts, replace right/rear HO2S sensor 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 more than 5 ohms, go to step 8). If resistance is 5 ohms or less, repair STO or MIL circuit for short to ground 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 pin No. 40 or 60 at breakout box. Turn ignition on and then off. Wait 10 seconds. If voltage changes from 10.5 volts (or more) to less than 1.0 volt, go to step 10). If voltage does not change from 10.5 volts (or more) to less than 1.0 volt, go to step 9).

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 and repeat QUICK TEST. If voltage is 1.0 volt or less, replace EEC power relay or CCRM 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. Scheme 117

TEST PIN NO. 1 (KAPWR) WIRE COLOR I.D.

Continuous Memory Code 15/512 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 15/512: Check KAPWR Circuit Voltage Code 15/512 indicates PCM power interruption in Keep-Alive Memory (KAM). Clear codes and repeat QUICK TEST. If Code 15/512 is repeated, 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. Measure voltage between test pin No. 1 and pin No. 40 or 60 at breakout box. Observe voltage reading while wiggling small sections of EEC wiring harness from PCM to dash. If reading is less than 10.5 volts, repair open circuit and repeat QUICK TEST. If reading is 10.5 volts or more, go to step 2).

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 15/512 is not repeated, 15/512 testing is complete. If Continuous Memory Code 15/512 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. Faulty Powertrain Control Module (PCM).
2. 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 SERVICE CODE-TO-TEST MENUS, and service codes as necessary. If Code 11/111 (pass code) is displayed, go to step 2). 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.
4. MAF system.

To prevent replacing good components, be aware the following non-EEC-IV areas may be at fault

1. Faulty power or ground connections.
2. Secondary ignition (distributor cap, rotor, wires, coil and plugs).
3. Engine mechanical components (compression, timing, valves, etc.).

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 step 2).

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 step 3). 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). Turn ignition off. Disconnect MAP/BARO sensor. Connect MAP/BARO tester between wiring harness and MAP/BARO sensor. (Scheme 118) Connect banana plugs of tester into DVOM. Turn ignition on. If Green light is on, go to step 4). If light is not on, repair open in VREF circuit and check system operation.

MAP/BARO Tester & Circuit. Scheme 118

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 step 5) (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 step 6). 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 step 7). 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 step 8). 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). Disconnect and plug vacuum line at EGR valve. Attempt to start engine. If vehicle did not start previously but starts now or if driveability symptoms are eliminated, go to CIRCUIT TEST DN, step 42) (vehicles with EVP) or CIRCUIT TEST DL, step 21) (all others). If vehicle could not start previously and still does not start or if vehicle driveability fault is still present, go to step 9).

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).

PNP Switch Circuit (Escort A/T & Tracer A/T). Scheme 119

TEST PIN NO. 30 (CPP/PNP) WIRE COLOR I.D.

TEST PIN NO. 46 (SIG RTN) WIRE COLOR I.D.

1) Code 67/522, 525 Or 528 Code 67/522, 525 or 528 is a result of voltage being high at either pin No. 10 (A/C input) or 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 1.9L A/T, go to step 10). On all other A/T models, go to step 8). For 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 terminals, and repair if damaged. 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. 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 step 3). If 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 step 4).

Neutral Gear/Clutch Input Circuit. Scheme 120

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 10,000 ohms or more, go to CIRCUIT TEST KM, step 40) (models with A/C) or replace PCM and repeat QUICK TEST (all others). If resistance is less than 10,000 ohms, 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. Measure resistance across CPP switch with clutch pedal down. If each resistance is 5 ohms or less, go to step 6). If resistance is more than 5 ohms, replace switch 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 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 terminals, and repair if damaged. 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 withA/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 terminals, and repair if damaged. 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 step 9).

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 and repeat QUICK TEST. If resistance is 5 ohms or more, replace PNP switch and repeat QUICK TEST.

10) Check PNP Input 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. Ensure transmission is in Neutral or Park. Disconnect 4EAT module 16-pin connector. Turn ignition on. Measure voltage between test pin No. 30 and chassis ground. If voltage is less than 1.0 volt, replace PCM. Reconnect all components, and repeat QUICK TEST. If voltage is 1.0 volt or more, go to step 11).

11) Check PNP Circuit Continuity Between PCM & 4EAT Module Turn ignition off. Leave PCM disconnected from breakout box. Disconnect 4EAT 16-pin connector. Measure resistance between test pin No. 30 at breakout box and PNP terminal at 4EAT module wiring harness connector. If resistance is less than 5 ohms, fault is in 4EAT system. If resistance is 5 ohms or more, repair open circuit and repeat QUICK

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

4EAT Solenoid Circuits (Escort & Tracer). Scheme 121

1) OUTPUT STATE CHECK Code 86/566, 89/629, 91/621, 92/622, 93/626, 94/627, 629, 641 or 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. see scheme 72 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 step 2). If voltage does not increase, depress throttle to WOT and release. If STO voltage goes high, go to step 2). If STO voltage does not go high, leave test equipment connected and go to CIRCUIT TEST QC, step 2).

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, go to step 3).

3) Check Solenoid & VPWR Circuit Continuity Turn ignition off. Leave transmission wiring harness disconnected. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between transmission wiring harness connector terminal and corresponding test terminal at breakout box. 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 step 4). If any resistance is 5 ohms or more, repair open circuit 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. Measure resistance between PCM output signal test pin and pins No. 40, 46 and 60 at breakout box. Measure resistance between PCM output signal test pin and chassis ground. If either resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If all resistances are 10,000 ohms or more, check solenoids. If solenoids are okay, replace PCM 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 99/624 Or 625: Check VPWR To Solenoid Code 99/624 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 resistance between VPWR and EPC PWR terminal at transmission wiring harness connector and chassis/battery ground. 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 step 11).

11) Check Solenoid Signal & VPWR Circuit Continuity 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. Measure resistance between VPWR/EPC PWR terminal at transmission wiring harness connector breakout box test pins No. 37 and 57. 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 and repeat QUICK TEST. If resistance is less than 5 ohms, go to step 12).

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. Measure resistance between test pins No. 40, 46 and 60 and suspect solenoid test pin at breakout box. If either resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If all resistances are 10,000 ohms or more, check solenoids. If solenoids are okay, replace PCM 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 step 21). If resistance is not 13-27 ohms, go to step 25).

21) Check Shift Solenoid For Short To Power Turn ignition off. Disconnect transmission wiring harness connector. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. Turn ignition on. Measure voltage between suspect shift solenoid at transmission wiring harness connector and chassis ground. If voltage is more than 0.5 volt, repair short to power and repeat QUICK TEST. If voltage is 0.5 volt or less, go to step 22).

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. Measure resistance between suspect shift solenoid and other circuits at transmission wiring harness connector. If any resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If all resistances are 10,000 ohms or more, go to step 23).

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 and repeat QUICK TEST. If resistance is less than 5 ohms, go to step 24).

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. If voltage is less than 0.5 volt, replace PCM 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 as necessary. If circuits are okay, go to step 31).

31) Check For Intermittent Short Or Open Turn ignition off. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. 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 step 32).

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. 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).

Identifying MLP Connector Terminals (4EAT). Scheme 122

1) Codes 522, 634 & 654 KOEO Codes 522, 634 and 654 indicate MLP sensor is out of self-test range (3770-4607 ohms) when gear selector is in Park position. 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 step 2).

2) Check MLP Sensor Circuit Continuity Turn ignition off. Disconnect MLP sensor wiring harness connector. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. 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. Measure resistance between SIG RTNterminal at MLP sensor wiring harness connector and test pin No. 46 at breakout box. If either resistance is more than 5 ohms, repair open circuit and repeat QUICK TEST. If both resistances are 5 ohms or less, go to step 3).

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. Measure resistance between test pin No. 30 and chassis ground. If any resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If resistance is 10,000 ohms or more, go to step 4).

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 step 11). 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 less than 10.5 volts, repair open circuit and repeat QUICK TEST. If voltage is 10.5 volts or more, go to step 12).

12) Check Transmission Select Switches Leave ignition off and 4EAT wiring harness connector disconnected. Check test pin and terminal values. If values are not correct, go to step 14). If connector terminal values are correct, go to step 13).

Identifying Inhibit Switch & 4EAT Module Terminals. Scheme 123

13) Check Transmission Switch Input Voltage Turn ignition off. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV) or 4EAT tester, leaving PCM disconnected. Reconnect inhibit switch and transmission switch. Turn ignition on. Check test pin and terminal values. 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.

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 terminals, and repair if damaged. 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. If test light stays on, fault cannot be duplicated at this time.

22) 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. 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. Step 20) and MAF RTN (pin No. 9 or 15) are 0.0-0.5 volt.

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 greater 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, go to TESTS W/O CODES article in this section for other possible causes of symptom.

4EAT Transmission Select Switch Specifications. Scheme 124

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. TOT sensor.
2. Wiring harness circuits TOT and SIG RTN.
3. Faulty Powertrain Control Module (PCM).

TOT Sensor Circuit (Escort & Tracer). Scheme 125

TOT SENSOR (4EAT) SPECIFICATIONS

1) KOEO Code 636 KOEO Code 636 indicate TOT 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 26/636 is present, go to step 2). If Code 26/636 is not present, test is complete.

2) Check VREF At Throttle Position (TP) Sensor Turn ignition off. Disconnect TPS wiring harness connector. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. 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 77 If voltage is 4-6 volts, go to step 3). If voltage is not 4-6 volts, go to CIRCUIT TEST C.

3) Check TOT Sensor Resistance Turn ignition off. Disconnect PCM from breakout box. Allow transmission to cool. Measure and record resistance between test pin No. 46 and TOT test pin at breakout box. Drive vehicle until transmission fluid is normal operating temperature. Disconnect PCM from breakout box. Measure resistance voltage between test pin No. 46 and TOT 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. If voltage is not as specified, go to step 25) (1.9L) or fault is in transmission (except 1.9L).

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 56 Or 637 KOEO Code 56 or 637 indicate TOT 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 TOT sensor.
4. Faulty PCM.

Turn ignition off. Disconnect TOT wiring harness connector. Inspect terminals, and repair if damaged. Connect jumper wire between TOT and SIG RTN terminals. Perform KOEO SELF-TEST. If Code 66/638 is present, go to step 25) (1.9L) or fault is in transmission (except 1.9L). If Code 66/638 is not present, go to step 11).

11) Check TOT & SIG RTN Circuit Continuity Turn ignition off. Leave TOT sensor disconnected. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box(T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between TOT circuit at TOT wiring harness connector and TOT test pin at breakout box. Measure resistance between SIG RTN circuit at TOT wiring harness connector and test pin No. 46 at breakout box. If either resistance is more than 5 ohms, repair open circuit and repeat QUICK TEST. If each resistance is 5 ohms or less, go to step 12).

12) Check TOT Sensor For Short To VPWR Turn ignition off. Leave PCM and TOT sensor disconnected. Measure resistance between TOT test pin and test pins No. 37 and 57 at breakout box. If resistance is more than 10,000 ohms, replace PCM and repeat QUICK TEST. If resistance is 10,000 ohms or less, repair short circuit 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 TOT sensor outputis lower than self-test minimum voltage. Possible causes for thesefaults are

1. Damaged TOT 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 56 or 637 is present, go to step 25) (1.9L) or fault is in transmission (except 1.9L). If Code 56 or 637 is not present, go to step 21).

21) Check VREF At Throttle Position (TP) Sensor Turn ignition off. Disconnect TPS wiring harness connector. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. 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 78 If voltage is 4-6 volts, go to step 22). If voltage is not 4-6 volts, go to CIRCUIT TEST C.

22) Check TOT Circuit For Short To Ground Turn ignition off. Disconnect PCM from breakout box. Measure resistance between TOT test pin at breakout box and test pins No. 40, 46 and 60. If resistance is more than 10,000 ohms, replace PCM and repeat QUICK TEST. If resistance is 10,000 ohms or less, repair short circuit 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 TOT 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 637/638 Continuous Memory Code 637/638 indicates a fault has been detected in TOT circuit during previous 80 warm-up cycles. Possible causes for these faults are

1. Incorrect fluid level.
2. Intermittent fault in TOT sensor.
3. Intermittent short or open in wiring harness.

Turn ignition off. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. 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 TOT 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 TOT sensor.
6. Intermittent short or open in wiring harness.

Turn ignition off. Disconnect transmission wiring harness connector. Inspect terminals, and repair if damaged. 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 (1.9L 4EAT). Scheme 126

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 terminals, and repair if damaged. 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. Measure resistance between SIG RTN terminal at TSS wiring harness connector and test pin No. 46 at breakout box. If either resistance is more than 5 ohms, repair open circuit and repeat QUICK TEST. If both resistances are 5 ohms or less, go to step 2).

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 resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If all resistances are 10,000 ohms or more, go to step 3).

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 2) to step 10). No test procedures have been omitted.

10) Code 639 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. If resistance is 200-600 ohms, go to step 11).

Identifying Transmission 12-Pin Connector Terminals. Scheme 127

11) Check TSS Circuit For Short To Power Leave ignition off and transmission 12-pin connector removed. Disconnect 60-pin PCM connector. Inspect terminals, and repair if damaged. Turn ignition on. Measure voltage between TSS (+) terminal at sensor wiring harness connector and chassis ground. Measure voltage between TSS (-) terminal at sensor wiring harness connector and chassis ground. If both voltages are less than 0.5 volt, go to step 12). If either voltage is 0.5 volt or more, repair short circuit 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. Measure resistance between TSS (+) terminal and TSS (-) terminal at 12-pin connector. If any resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If any resistance is 10,000 ohms or more, go to step 13).

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. Measure resistance between TSS (-) terminal at 12-pin connector and test pin No. 44 at breakout box. If either resistance is more than 5 ohms, repair open circuit and repeat QUICK TEST. If both resistances are 5 ohms or less, go to step 14).

14) Check PCM For Internal Shorts Turn ignition off. Connect PCM to breakout box. Leave transmission wiring harness connector removed. Measure resistance between test pin No. 24 and pins No. 37, 40, 44, 57 and 60 at breakout box. If any resistance is less than 500 ohms, replace PCM and repeat QUICK TEST. If each resistance is 500 ohms or more, go to step 15).

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 and repeat QUICK TEST. If AC voltage does not vary more than 0.5 volt, replace TSS 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 step 91).

91) Check TSS Circuit Continuity 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. Disconnect TSS wiring harness connector. Measure resistance at TSS terminal at TSS connector and test pin No. 5 at breakout box. Measure resistance at SIG RTN terminal at TSS connector and test pin No. 5 at breakout box. If either resistance is more than 5 ohms, repair short circuit and repeat QUICK TEST. If both resistances are 5 ohms or less, go to step 92).

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. Measure resistance between test pin No. 5 and test pins No. 40, 46 and 60 at breakout box. If either resistance is less than 500 ohms, repair short circuit and repeat QUICK TEST. If both resistances are 500 ohms or more, go to step 93).

93) Measure Sensor Resistance Turn ignition off. Leave sensor disconnected. Measure resistance between sensor terminals. OSS terminal resistance should be 450-750 ohms. TSS circuit resistance should be 80-200 ohms. If resistance is correct, replace PCM and repeat step 90) to verify code elimination. If resistance is not correct, 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 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 terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Connect DVOM between test pins No. 24 and 44 at break-out 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 step 96).

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.

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.

Identifying PCM & CCRM Connectors. Scheme 128

1) Check Battery Supply Voltage 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 step 2).

2) Check Battery Ground Turn 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, and connect PCM. Turn ignition on (engine off). Measure voltage between negative battery terminal and test pins No. 40 and 60. If each 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. If voltage is more than 10.5 volts, go to step 7). If voltage is 10.5 volts or less, go to step 9).

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. If reading is 5 ohms or more, repair open in VPWR circuit and repeat QUICK TEST. If reading is less than 5 ohms, replace CCRM and repeat QUICK TEST.

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.

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 563: Check HFC Relay Resistance Code 563 indicates failed HFC circuit. Turn ignition off, and 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 step 16).

16) 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 test pin No. 31 and CCRM wiring harness connector terminal No. 17. 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.

17) Check HFC Circuit For Short To Power With ignition off andbreakout box installed, disconnect PCM and CCRM. Measure voltage between breakout box test pin No. 31 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 step 18).

18) Check HFC Circuit For Short To Ground With ignition off and breakout box installed, disconnect PCM and CCRM. Measure resistance between test pins No. 31 and 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.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 18) to step 20). No test procedures have been omitted.

20) Code 564 If cooling fan is always on when ignition is on, go to step 23). If cooling fan is not always on when ignition is on, go to next step.

21) 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 following test

Measure resistance between test pin No. 13 and test pin No. 40 or 60 at breakout box.

If reading is more than 10,000 ohms, go to step 22). If reading is 10,000 ohms or less, repair short to ground in FC/LFC circuit, and repeat QUICK TEST.

22) 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.

23) 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 following 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.

24) 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 following test

Measure resistance between breakout box test pin No. 13 and negative battery terminal.

If reading is less than one volt, go to step 25). 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.

25) FC/LFC Circuit Fault Isolation Check Turn ignition off. Install breakout box, leaving PCM disconnected. Connect CCRM to wiring harness connector. Turn ignition on. Using jumper wire, perform following test

Connect test pin No. 13 to test pin No. 40 or 60 at breakout box.

If fan continues to run, 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.

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) 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, repair short to power circuit between CCRM and fan.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 30) to step 35). No test procedures have been omitted.

35) No Fan Operation Turn ignition off. Disconnect CCRM. Connect negative probe of DVOM to negative battery terminal. Perform following test

Measure voltage between battery negative 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 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. 2 and 3 at CCRM wiring harness connector. If fan does not run, go to step 40). If fan runs, go to step 42).

38) Check Battery Voltage At Fan With CCRM By-Passed With ignition off, disconnect cooling fan and CCRM connectors. Perform following test

Install a jumper wire between CCRM harness connector terminals No. 3 and 6.

Set DVOM on 20-volt scale, and 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 following test

Install a jumper wire between CCRM harness connector terminals No. 3 and 6.

Set DVOM on 20-volt scale. Measure voltage between positive terminal at cooling fan harness connector and battery negative 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. Reconnect all components, and recheck system operation.

40) Check Battery 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. Set DVOM on 20-volt scale. Measure voltage at cooling fan wiring harness connector between power and ground terminals. If reading is more than 8 volts, replace fan motor. Reconnect CCRM, and recheck system operation. 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. Reconnect all components, and recheck system operation.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 40) to step 42). No test procedures have been omitted.

42) Check Fan Running Mode (Low Speed) Turn ignition off. Disconnect PCM. Reconnect CCRM. Turn ignition on (engine off). If fan runs, go to step 43). If fan does not run, replace CCRM. Reconnect PCM, and recheck system operation.

43) 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. 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. Remove breakout box, and reconnect PCM. Recheck system operation.

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. Remove breakout box, reconnect all connectors and recheck system operation. 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.

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) Check Voltage At A/C Clutch Disconnect A/C clutch connector. Turn ignition on (engine off). Set A/C demand switch to ON position. Check voltage at A/C clutch wiring harness connector. If reading is 10.5 volts or more, service A/C compressor and/or system. If reading is less than 10.5 volts, go to step 51).

51) Check Continuity Of CCRM To A/C Clutch Circuit Turn ignition off. Disconnect CCRM and A/C clutch. Measure resistance between CCRM wiring harness connector terminal No. 23 and power circuit terminal at A/C clutch harness connector. Also, measure resistance between CCRM wiring harness connector terminal No. 16 and ground circuit atA/C clutch harness connector. If readings are more than 5 ohms, repair open in power or ground circuit of A/C and recheck system operation. If readings are 5 ohms or less, reconnect A/C clutch connector and go to step 52).

52) Check A/C Demand Switch Voltage To CCRM Turn ignition off. Disconnect CCRM connector. Turn ignition on (engine off). Set A/C demand switch to ON position. Set DVOM to 20-volt scale. Check voltage between CCRM wiring harness connector terminal No. 21 and negative battery terminal. If reading is 10.5 volts or more, go to step 54). If reading is less than 10.5 volts, go to step 53).

53) Check Voltage To Cyclic Pressure Switch Turn ignition on (engine off). Disconnect cyclic pressure switch. Set A/C demand switch to ON position. Set DVOM to 20-volt scale. Measure voltage between cyclic pressure switch connector and battery negative terminal. If reading is 10.5 volts or more, repair open in A/C Cyclic Pressure (ACCS) circuit. Remove breakout box, reconnect all components and recheck system operation. If reading is less than 10.5 volts, EEC-IV system is okay. Remove breakout box, reconnect all components and diagnose A/C system.

54) Check A/C Demand Switch Voltage To PCM Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires, and repair as necessary. Install breakout box, leaving PCM disconnected. Disconnect CCRM connector. Set DVOM to 20-volt scale. Turn ignition on (engine off). Set A/C demand switch to ON position. Measure voltage between test pin No. 10 at breakout box and negative battery terminal. If reading is more than 10.5 volts, go to step 55). If reading is 10.5 volts or less, turn ignition off. Repair open between ACCS and PCM. Remove breakout box, reconnect all connectors and recheck system operation.

55) Check WAC Circuit For Short To Ground Turn ignition off. Install breakout box, leaving PCM disconnected. Disconnect CCRM connector. Measure resistance between breakout box test pin No. 54 and chassis ground. If any reading is less than 10,000 ohms, repair short to ground in Wide Open Throttle A/C Cut-Off (WAC) circuit. Remove breakout box, and reconnect all components. Recheck system operation. 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 55) to step 60). No test procedures have been omitted.

60) Check WAC Circuit Continuity Turn ignition off. Install breakout box. Disconnect PCM and CCRM. Turn ignition on (engine off). Set DVOM on 200-ohm scale, and 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. Remove breakout box, and reconnect all components. Recheck system operation.

61) Check WAC Circuit For Short To Power Turn ignition off. Leave breakout box installed and PCM disconnected. Disconnect CCRM connector. Set DVOM on 20-volt scale. Turn ignition on (engine off). 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. Remove break-out box, reconnect all components 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 (engine off). 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, replace PCM. Remove breakout box, reconnect all components 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.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 62) to step 70). No test procedures have been omitted.

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

Turn ignition off. Disconnect CCRM wiring harness connector. Perform following 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 72).

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 72). 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 Continuity Of Fuel Pump Circuit Turn ignition off. Disconnect PCM 60-pin connector. Inspect wiring, and repair if damaged. Install breakout box, leaving PCM disconnected. Perform following procedure

Measure resistance between terminal No. 18 at CCRM wiring harness connector and test pin No. 41 at breakout box.

If resistance is 5 ohms or more, repair open in fuel pump circuit and repeat QUICK TEST. If reading is less than 5 ohms, go to step 73).

73) Check Fuel Pump Circuit For Short To Power Leave PCM and CCRM disconnected. Turn ignition on. Perform following procedure

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 74). If voltage is 1.0 volt or more, repeat short to power and repeat QUICK TEST.

74) Check Fuel Pump Circuit For Short To Ground Leave PCM and CCRM disconnected. Perform following procedure

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.

75) Code 557: Check VPWR At Low Speed Fuel Pump (LFP) Codes 557 indicates LFP circuit failure. Following are possible causes.

1. Open Or Grounded Fuel Pump Circuit
2. Faulty LFP Relay
3. Faulty PCM

Turn ignition off. Disconnect LFP relay. Turn ignition on. Measure voltage between VPWR terminal at LFP wiring harness connector and negative battery cable. If voltage is less than 10.5 volts, repair open in VPWR circuit between LFP relay and CCRM. If voltage is 10.5 volts or more, go to step 76).

76) Check LFP Relay Turn ignition off. Disconnect fuel pump relay wiring harness connector. Leave LFP relay disconnected. Measure resistance between LFP terminal and VPWR terminal at fuel pump relay wiring harness connector. Measure resistance between LFP terminal and B+ terminal at fuel pump relay wiring harness connector. Measure resistance between LFP terminal and POWER-TO-PUMP terminal at fuel pump relay wiring harness connector. If any resistance is less than 10,000 ohms, replace LFP relay and repeat QUICK TEST. If all resistance checks are 10,000 ohms or more, go to step 77).

Identifying LFP Relay Connector Terminals. Scheme 129

77) Check LFP Circuit For Short To Power Turn ignition off. Leave LFP relay disconnected. Disconnect PCM 60-pin connector. Inspect wiring, and repair if damaged. Install breakout box, leaving PCM disconnected. Turn ignition on. Measure voltage between test pin No. 32 at breakout box and negative battery terminal. If voltage is less than one volt, go to step 78). If voltage is one volt or more, repair short circuit and repeat QUICK TEST.

78) Check LFP Circuit For Short To Ground Turn ignition off. Leave LFP relay and PCM disconnected. Measure resistance between test pin No. 32 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 more than 10,000 ohms, go to step 79).

79) Check LFP Circuit Continuity Leave LFP relay and PCM disconnected. Measure resistance between test pin No. 32 and LFP terminal at LFP relay wiring harness connector. If resistance is 5 ohms or less, replace PCM and repeat QUICK TEST. If resistance is more than 5 ohms, repair open circuit and repeat QUICK TEST.

80) Code 542 Code 542 indicates one of the following conditions.

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. VCRM And Power Control Module (PCM)
2. Harness Circuits Associated With VCRM

Refer to illustration for VCRM connector terminal identification. (Scheme 130) For VCRM terminals and wiring identification, see WIRING DIAGRAMS at the end of this article. 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

Identifying VCRM Connector Terminals. Scheme 130

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 step 2).

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 step 4). 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 step 5). 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 break-out 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 step 11). 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 step 12). 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 step 16). 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 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 step 19).

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. Defective Cooling Fan Motor
3. Defective 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 step 21). 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 step 22). 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 Ground In Cooling Fan Circuit Turn ignition off. Visually inspect power-to-cooling fan circuit between terminal No. 2 (Light Blue wire) at 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 step 25).

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 turn on, 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. Defective 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 step 31).

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 step 32).

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 step 33). 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. Defective ACP Sensor
3. Defective 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 step 41). 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 step 42). 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 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. Defective ACP Sensor
3. Defective 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, 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 579 is present, go to step 51). If Code 579 is not present, ACP sensor is functioning properly and is now able to detect an A/C pressure change. Either an intermittent ACP sensor fault or anA/C system intermittent or marginal mechanical condition exists. Go to step 64).

51) Check ACP VREF & ACP SIG RTN Circuits 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 131) If voltage is more than 6 volts, go to step 58). If voltage is less than 4 volts, go to step 60). If voltage is 4-6 volts, go to step 52).

Identifying ACP Sensor Connector Terminals. Scheme 131

52) 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 5 seconds, note pressure reading. High pressure should increase. If A/C high pressure gauge reading changes by more than 25 psi within 5 seconds of turning A/C on, turn A/C and ignition off and go to step 53). If A/C high pressure gauge reading does not change by more than 25 psi within 5 seconds of turning A/C on, check A/C system for mechanical fault. Service A/C system as necessary. Clear continuous memory. Start engine. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

53) Check ACP Sensor Output Turn ignition off. Ensure ACP sensor is disconnected. Install A/C system manifold gauge set. Connect jumper wire between SIG RTN terminal at ACP sensor and SIG RTN terminal (Light Blue/Red wire) at ACP sensor connector. (Scheme 131) Connect jumper wire between VREF terminal at ACP sensor and VREF terminal (Orange/Light Blue wire) at ACP sensor connector. Connect DVOM between ACP signal terminal at ACP sensor connector and jumper wire at SIG RTN terminal. Observe DVOM and turn A/C on. After 5 seconds, read voltage.

Note. Listen to A/C clutch to ensure clutch does not disengage during 5 seconds of testing. If clutch disengages, retest.

If ACP sensor voltage changes by more than .3 volt within 5 seconds of turning A/C on, sensor is operational. Remove jumper wires and go to step 54). If ACP sensor voltage does not change by more than .3 volt within 5 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.

54) 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.

55) 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 step 56). 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.

56) Check For Short To Ground In ACP Circuit Turn ignition off. Ensure ACP sensor and VCRM are disconnected. Measure resistance between ACP signal terminal (Dark Green/White wire) at ACP sensor connector and negative battery terminal. If resistance is more than 10,000 ohms, replace VCRM. 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. If resistance is 10,000 ohms or less, repair short to ground 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.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 56) to step 58). No test procedures have been omitted.

58) 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.

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 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 step 61). 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. Turn A/C on and wait 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST.

61) 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 step 62). 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. TurnA/C and ignition off. Repeat QUICK TEST.

62) 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. 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 62) to step 64). No test procedures have been omitted.

64) Check A/C Cooling Performance Check A/C system performance. If A/C system cools properly, go to step 65). If A/C system does not cool properly, service A/C system. Go to step 65).

65) 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 light 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 15 seconds. TurnA/C and ignition off. Repeat QUICK TEST. If open circuit is not detected, go to step 66).

66) 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 15 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 15 seconds. Turn A/C and ignition off. Repeat QUICK TEST. If short to power is not detected, go to step 67).

67) 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 15 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 15 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.

Note. A break in step numbering sequence occurs at this point. Procedure skips from step 67) to step 70). No test procedures have been omitted.

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. Defective A/C Clutch
3. Defective 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 step 71). 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 step 72). 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 Pink 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 Pink 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 turnA/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 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. If a short to ground is not detected, go to step 75).

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 Right 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 betweenA/C clutch terminals. If resistance is less than 10 ohms, replace VCRM. Reconnect all components. Clear continuous memory. WithA/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. WithA/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 right 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 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 step 86).

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.

90) No A/C (With Code 111); Check Power At A/C Clutch Ensure all A/C-related fuses in fuse block are okay. Turn ignition off. DisconnectA/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 is on, EEC-VI system is okay. Reconnect A/C clutch connector. Check A/C system for mechanical problems. If test light is off, go to step 91).

91) Check If PCM Is Receiving & Recognizing A/C Cyclic Pressure (ACCS) Input Turn ignition off. Remove test light, and reconnectA/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 step 92). 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 step 93). 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. 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 step 94). 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 step 97). 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 betweenA/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 andA/C cyclic pressure switch operation. See AUTOMATIC A/C-HEATER SYSTEMS article in the AIR CONDITIONING & HEAT Section.

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 atA/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. TurnA/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 step 101).

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 step 102). 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 and PCM is disconnected. Turn ignition on. Measure voltage between test pins No. 40 and 54 at break-out box. If voltage is less than one volt, go to step 103). 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. Disconnect 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 step 111).

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 step 112). 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 step 113). 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 step 116). 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