Engine Controls - Tests W/codes - 3.0l Ford Probe I

INTRODUCTION

Ensure all steps in the BASIC TESTING article have been followed. If no faults were found while performing the BASIC TESTS, proceed with self-diagnostics. If no service codes and only pass codes are found during self-diagnostics, proceed to H - "Engine Type" TESTS W/O CODES article for diagnosis of intermittents or driveability symptoms.

DIAGNOSTIC FORMATS

There are 2 diagnostic formats used to test and service the EEC-IV system: QUICK TESTS and CIRCUIT TESTS. QUICK TEST procedures are designed to allow the technician to identify problems, retrieve and record service codes. The CIRCUIT TESTS give procedures for testing circuits and checking sensors and actuators. If a vehicle passes all QUICK TEST procedures, and there are no driveability symptoms or intermittent faults, the EEC-IV system is okay. Problem exists somewhere besides the EEC-IV system.

Always start with the QUICK TEST procedures before attempting any CIRCUIT TESTS. The QUICK TEST procedures allow the technician to retrieve and identify service codes which are used as a reference to find the correct CIRCUIT TEST.

SERVICE CODE DESCRIPTIONS

There are 3 types of service codes retrieved in the QUICK TEST procedures during Key On Engine Off (KOEO) and Key On Engine Running (KOER) Self-Test modes. They are KOEO, KOER, and Continuous Memory codes. Codes may be cleared from the ECA memory after they have been recorded or repaired. See CLEARING CODES.

KOEO & KOER CODES (HARD FAULTS)

These codes indicate a hard fault that is actually present at the time of testing. These hard faults may cause the CHECK ENGINE or SERVICE ENGINE SOON light to illuminate and remain on until the fault is repaired. If KOEO or KOER codes are retrieved during the Self-Test, the KOEO or KOER code charts must be used to select the correct CIRCUIT TEST for testing and repair.

CONTINUOUS MEMORY CODES (SOFT FAULTS)

These are soft fault codes that are used to diagnose intermittent problems. They indicate a fault that may or may not be present at the time of testing. Continuous Memory Codes are retrieved during the KOEO Self-Test. Some codes may illuminate the CHECK ENGINE or SERVICE ENGINE SOON light. The corresponding soft trouble code, will be retained in the ECA memory. If the fault does not reoccur within 40 warm-up cycles (80 cycles on some models), the code will automatically be cleared by the ECA.

Service codes may be cleared from memory by the technician. See CLEARING CODES. Intermittent faults may be caused by sensor, connector or wiring related problems. See INTERMITTENTS in H - "Engine Type" TESTS W/O CODES article.

RETRIEVING CODES

Service codes are retrieved from the EEC-IV system through the Self-Test connector. Various methods and test equipment may be used to access these codes. The following test equipment may be used

1. Analog Volt/Ohmmeter
2. Scan Tool
3. STAR Series Tester
4. In-Dash CHECK ENGINE or SERVICE ENGINE SOON Light

SELF-TEST CONNECTOR LOCATIONS

CLEARING CODES

To clear codes from the ECA memory, run the KOEO Self-Test, when service codes begin to appear on your test equipment or CHECK ENGINE light, disconnect the jumper wire from the Self-Test Input (STI) connector. If using a STAR series tester, unlatch the center button. This procedure erases Continuous Memory Codes from the ECA memory. If a problem has not been corrected, or the fault is still present, the hard code will be immediately reset into the ECA memory.

KOEO & KOER SELF-TEST CODES

All service codes are 2 digit numbers and are output by the ECA one digit at a time. These codes indicate a current fault in the system. They should be serviced in the order in which they appear. Use the appropriate code chart to find the correct CIRCUIT TEST. Codes are shown as voltage pulses (needle sweeps) on an analog Volt/Ohmmeter (VOM).

If a VOM is being used, pay careful attention to the length of the pauses in order to read the codes correctly. There will be a 1/2 second pause between the number of sweeps indicating a digit and a 2 second pause between each digit in a code. There will be a 4 second pause between each code. The KOEO Self-Test codes are separated from Continuous Memory codes by a 6 second delay, a single 1/2 second sweep (Separator), and another 6 second delay. Always record the codes in the order received.

If a Scan tool is used, it will count the pulses and display them as a digital code. The STAR tester will add a zero (0) to single digit Separator Code (10) and Dynamic Response (10) codes. The Dynamic Response code is displayed in the KOER Self-Test. (Scheme 30)

If the CHECK ENGINE light is used, service codes will be displayed as flashes.

SEPARATOR PULSE

A single 1/2 second separator pulse is issued 6-9 seconds after last functional KOEO Self-Test code. Then 6-9 seconds after the single 1/2 second separator pulse, the Continuous Memory Codes (soft faults) will be displayed. Some digital test equipment may display the separator code as a 10 instead of a one.

PASS CODES

A Code 11 is a pass code which indicates that there are no recorded service codes in that portion of the test and that the system passes that portion of the test. If a Code 11 is not received in the KOEO portion of the self-test, codes received during the KOER Self-Test may not be valid. It is very important that a Code 11 (pass code) be observed in KOEO. A Code 11-1-11 output during the KOEO Self-Test indicates that there are no KOEO or Continuous Memory Codes recorded. The separator code may appear as a 10 instead of a 1 on some test equipment.

CONTINUOUS MEMORY CODES

These codes are issued as a result of information stored by the ECA during continuous self-test monitoring. These codes are displayed during the KOEO Self-Test after the separator pulse code. These codes should be used for diagnosis, ONLY when KOEO and KOER Self-Tests result in a Code 11 (pass code) and all QUICK TEST steps have been successfully completed. There are a few exceptions which may be checked after the KOEO Self-Test codes have been repaired. These codes indicate a fault that has been recorded within the last 40 key starts. The fault may or may not be currently present.

FAST CODES

At the start of the KOEO testing and after the WOT request in the KOER test, there is an output from the ECA known as Fast Codes. These are short bursts of information that are used by the manufacturer during assembly. With most equipment these code bursts are not visible as the entire code sequence lasts less than 1/2 second. Ignore this fluctuation if noticed with your test equipment.

Scheme 30

Scheme 31

Scheme 32

"CHECK ENG"/"SERVICE ENG SOON" MIL ACTIVATING CODES

DESCRIPTION

The Quick Test diagnostic procedures are functional tests of the EEC-IV system. They consist of 7 basic test steps. These basic steps must be carefully followed in sequence, otherwise misdiagnosis, or replacement of non-faulty components may result.

1. Visual Check & Vehicle Preparation. See BASIC TESTING article in this section.
2. Equipment Hook-Up
3. Key On Engine Off (KOEO) Self-Test
4. Computed Timing Check
5. Key On Engine Running (KOER) Self-Test
6. Continuous Monitor Mode (Wiggle Test)
7. Intermittents & Diagnosis By Symptom. For more information, refer to the H - "Engine Type" TESTS W/O CODES article.

Note. After all tests, servicing, or repairs have been completed, repeat QUICK TEST procedures to ensure all EEC-IV systems work properly and service codes are no longer present.

VISUAL CHECK & VEHICLE PREPARATION

Complete all steps in BASIC TESTING article before you continue with this procedure. Ensure vacuum hoses are connected correctly and that EEC-IV wiring harnesses are connected.

EQUIPMENT HOOK-UP

Apply the vehicle parking brake, place shift lever in Park (A/T) or Neutral (M/T). Block drive wheels. Turn off all electrical loads. Connect appropriate test equipment to vehicle

ANALOG VOLT/OHMMETER (VOM)

1) Turn ignition switch to OFF position. Set VOM at 0-15V DC range and connect positive lead of VOM to positive battery terminal.

2) Connect negative VOM lead to Self-Test Output (STO) terminal on Self-Test connector. (Scheme 31) Connect timing light, and go to KOEO Self-Test. KOEO Self-Test is activated by connecting jumper wire from Self-Test Input (STI) pigtail to Signal Return terminal of Self-Test connector with the ignition on.

SCAN TOOL

Follow manufacturer's instructions to connect equipment and to record service codes.

STAR TESTER

Turn ignition switch to OFF position. Connect color coded adapter cable leads to diagnostic tester. Connect adapter cable's 2 service connectors to vehicle Self-Test connector and STI pigtail connector. Connect timing light. Go to KOEO SELF-TEST.

CHECK ENGINE OR SERVICE ENGINE SOON LIGHT (MIL)

With ignition on, connect a jumper wire between Self-Test Input (STI) pigtail and Signal Return terminal of Self-Test connector. No additional special equipment hook-up is required.

KOEO SELF-TEST

Start engine and idle until vehicle reaches operating temperature. If engine does not start or stalls after starting, continue to perform this KOEO Self-Test. DO NOT depress the throttle on gasoline engine vehicles. Turn key off and wait 10 seconds. Activate self-test procedure by using a jumper wire or with appropriate test equipment. Turn key on, leaving engine off. Record all KOEO and Continuous Memory Codes.

If a Code 11 (pass code) is not received in the KOEO portion of the test, service the KOEO codes. See KOEO, KOER or CONTINUOUS CODE/TEST MENUS. If ECA will not output codes, go to TEST QA, step 1). If service codes are received, check the following procedures

1. If CHECK ENGINE or SERVICE ENGINE SOON light was on when the vehicle arrived for service, use recorded Continuous Memory Codes and reference code charts before addressing any other symptoms.
2. If engine runs rough or idles rough, go to TEST A, step 1), except vehicles equipped with Distributorless Ignition System (DIS) or Electronic Distributorless Ignition System (EDIS) ignition systems. For vehicles equipped with DIS or EDIS ignition systems, use recorded Continuous Memory Codes and reference code charts.
3. On DIS and EDIS vehicles only do the following: if Continuous Memory Codes 45, 46 or 48 were received during KOEO Self-Test, go to TEST N, step 13), on (DIS vehicles). If Codes 45, 46 or 48 were not received, go to TEST S, step 2).
4. If vehicle is a no start, go to TEST A, step 1), except vehicles equipped with EDIS ignition. For EDIS vehicles, go to TEST AA, step 1).
5. If vehicle displays a Code 11 (pass code) and has no symptoms as described in the previous steps, go to COMPUTED TIMING CHECK.

COMPUTED TIMING CHECK

Turn key off and wait 10 seconds. Using jumper wire or test equipment, activate KOER Self-Test. Start engine. Check the following items

1. If engine starts and stalls, or stalls during self-test, go to TEST S, step 1).
2. If Code 98 is displayed, it indicates EEC-IV system is operating in Failure Mode Effects Management (FMEM). Vehicle cannot be diagnosed in KOER Self-Test, go to Code 98 reference in CONTINUOUS MEMORY CODE reference chart.
3. Check computed timing after the last service code has been displayed. The timing will remain fixed for 2 minutes after the last code has been received, unless self-test is deactivated.
4. Computed timing, at the crankshaft, should equal the base timing see vehicle emission decal) plus 20 degrees BTDC. This timing may vary 3 degrees (+/-). If computed timing is within specification, perform KOER Self-Test. If timing is not within specification, go to TEST P, step 2).

KOER SELF-TEST

Note. DO NOT enter this test sequence until a Code 11 (pass code) has been received in the KOEO portion of the self-test. If a system did not pass KOEO Self-Test, code recorded in KOER testing may not be valid.

Deactivate self-test by removing and reconnecting jumper wire or by procedure specified by test equipment in use. Start and run engine for 2 minutes at 2000 RPM to warm-up HEGO sensor. Turn engine off and wait 10 seconds. Activate KOER Self-Test by using a jumper wire or appropriate procedure for test equipment being used. Start engine. Record all service codes displayed. Check the following items

1. If engine starts and stalls, or stalls during self-test, go to TEST S, step 1).
2. If vehicle is equipped with a Brake On/Off (BOO) switch, the brake pedal MUST be depressed and released AFTER the ID code portion of test.
3. On vehicles equipped with Power Steering Pressure Switch (PSPS), the steering wheel must be turned at least one-half turn and released within 1-2 seconds after the ID code portion of test.
4. On vehicles equipped with E4OD transmissions, the Overdrive Cancel Switch (OCS) MUST be cycled after the ID code portion of the test.
5. When the Dynamic Response Code appears, perform a brief Wide Open Throttle (WOT). DO NOT perform a WOT unless requested.
6. If Code 98 is displayed, it indicates EEC-IV system is operating in Failure Management Effects Mode (FMEM). Vehicle DID NOT pass KOEO Self-Test. Vehicle cannot be diagnosed while in FMEM mode, go to Code 98 reference in Continuous Memory Code reference chart.
7. If a Code 11 (pass code) is received during KOER Self-Test, service Continuous Memory Codes which were received during KOEO SELF-TEST. Refer to the Continuous Memory Code reference chart.
8. If a Code 11 (pass code) was received during the Continuous Memory Code portion of the KOEO Self-Test (Code 11-1-11), and no driveability symptoms are present, EEC-IV testing is complete. If driveability symptoms are still present, go to H - "Engine Type" TESTS W/O CODES article in this section.
9. If KOER codes are present, refer to code reference charts. If system will not output codes, go to TEST QA, step 1).

CONTINUOUS MONITOR MODE (WIGGLE TEST)

The Continuous Monitor Mode allows a technician to attempt to recreate an intermittent fault while monitoring the system. This mode, also called the Wiggle Test, may be used in both KOEO and KOER modes. The CIRCUIT TESTS specify the use of this procedure to identify intermittent faults in specific circuits or components.

KOEO WIGGLE TEST PROCEDURE

Connect test equipment. (Scheme 31) Turn ignition on and activate self-test with jumper lead or diagnostic tester. Wait 10 seconds, deactivate, and then reactivate self-test. You are now in Wiggle Test mode. Tap, move, and wiggle the suspected sensor and/or harness area. If a fault is detected, a service code may be stored in memory and indicated at the diagnostic tester or Scan tool. Record or retrieve code and perform test indicated in Continuous Memory Codes chart.

KOER WIGGLE TEST PROCEDURE

Connect test equipment. (Scheme 31) Turn ignition off and wait 10 seconds. Start engine. Activate self-test with jumper lead or diagnostic tester. Wait 10 seconds, deactivate, and then reactivate self-test. DO NOT turn engine off. You are now in engine running Wiggle Test mode. Tap, move, and wiggle the suspected sensor and/or harness area. If a fault is detected, a service code may be stored in memory and indicated at the diagnostic tester or Scan tool. Record or retrieve code and perform test indicated in Continuous Memory Codes chart.

ADDITIONAL SYSTEM FUNCTIONS

A number of additional diagnostic system features are available to help technicians diagnose driveability problems and test EEC-IV systems.

CHECK ENG/SERVICE ENG SOON MALFUNCTION INDICATOR LIGHT (MIL)

The light is intended to alert the driver of certain malfunctions in the EEC-IV system.

The light may also be used to retrieve service codes stored in ECA. When hooked-up for KOEO or KOER Self-Test, the light will retrieve all codes, not just Continuous Memory Codes which turn the light on during vehicle operation.

If the light comes on during vehicle operation, it should be serviced and inspected as soon as possible. It is not necessary to immediately turn off the vehicle or have it towed to a service facility.

If the light comes on and then goes off while in operation, the code that caused the light to illuminate will be stored in ECA memory as a Continuous Memory Code.

The light should come on when the ignition is turned on and go out when the engine is started. The ECA turns out the light when the ECA receives an ignition PIP signal, if hard fault codes are not present.

If the light never comes on, see SYMPTOMS in H - "Engine Type" TESTS W/O CODES article.

OUTPUT STATE CHECK

The Output State Check is used as an aid in servicing output actuators associated with the EEC-IV system. It allows you to energize and de-energize most of the system output actuators on command. This mode is entered from the KOEO Self-Test after all codes have been received. At this time, leave self-test activated and depress throttle to initiate the test sequence. Each time throttle is depressed and released, the output actuators will change state (go from on to off, or off to on).

FAILURE MODE EFFECTS MANAGEMENT (FMEM), CODE 98

The FMEM mode allows system operation when one or more sensors fail or transmit signals which are out of their normal operating range. The ECA will substitute a mid-range signal for the defective sensor and continue to monitor the sensor. If the faulty sensor signals return to within the normal operating range, the ECA will use those signals. A Code 98 will be displayed when the FMEM mode is in effect.

HARDWARE LIMITED OPERATIONAL STRATEGY (HLOS)

If a number of system or sensor failures are present and the ECA is not receiving enough information to operate, the ECA will switch to the HLOS mode. ECA output will be fixed values to allow the vehicle to be driven. Driveability concerns will be present. ECA will not output service codes in this mode.

CYLINDER BALANCE TEST

The cylinder balance test is an aid in finding a weak or noncontributing cylinder in engines equipped with sequential PFI fuel systems. The ECA shuts off the fuel supply to each injector and measures the RPM drop. It computes the variation between the cylinders and identifies any weak ones. This test mode is entered during the KOER Self-Test after all codes have been displayed. Within 2 minutes after the 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, the ECA will activate the test procedure. The test will be repeated if the throttle is depressed within 2 minutes of the final code output. During the 2nd and 3rd test sequence, the percentage of allowable variation between cylinders will be reduced. Service codes displayed during this test correspond to cylinder number and indicate a weak or non-contributing cylinder. If Code 90 is displayed during this test, it indicates a pass. If Code 77 is displayed, repeat cylinder balance test. If throttle is moved during this test, Code 77 will appear, indicating that test was not completed. Total test time is about 3 minutes.

CYLINDER BALANCE TEST SERVICE CODES

FREQUENTLY USED EEC-IV ABBREVIATIONS

FREQUENTLY USED EEC-IV ABBREVIATIONS

SUMMARY

If no service codes (or pass code 11-1-11) are present, and a driveability problem still exists, proceed to H - "Engine Type" TESTS W/O CODES article for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.), or intermittent diagnosis procedures.

ALL PFI & MA PFI MODELS

PFI SERVICE CODE DEFINITIONS

KOEO CODE/TEST MENU - 3.0L

KOEO SELF-TEST - CKT TEST & STEP MENU

KOER CODE/TEST MENU - 3.0L

KOER SELF-TEST - CKT TEST & STEP MENU

CONTINUOUS CODE/TEST MENU - 3.0L

CONTINUOUS MEMORY - CKT TEST & STEP

CIRCUIT TESTS

Note. A breakout box, which connects to the vehicle harness at the ECA, is necessary to perform most circuit tests. References to Test Pin No. found in CIRCUIT TEST steps refer to test terminals on the manufacturer's breakout box. Circuit diagrams at the beginning of each test will identify circuit and wire colors.

HOW TO USE CIRCUIT TESTS (TESTS A TO X)

1) Ensure all non-EEC related faults that were found during BASIC DIAGNOSTIC PROCEDURES testing have been corrected. DO NOT perform any CIRCUIT TEST unless directed to do so by a QUICK TEST procedure. FOLLOW EACH TEST STEP IN ORDER UNTIL FAULT IS FOUND. Do not replace any part unless directed to do so. When more than one code is received, start with the first code displayed.

2) CIRCUIT TESTS require that you prove the electrical circuits are okay before you replace sensors or any other components. Always test circuits for continuity between the sensor and the ECA. Test all circuits for shorts to power, opens, or shorts to ground. Voltage Reference (VREF) and Voltage Power (VPWR) circuits should be tested with KOEO or as specified in CIRCUIT TESTS.

3) DO NOT measure voltage or resistance at ECA or connect any test light, unless specified in testing procedure. All measurements are made by probing REAR of connector. Isolate both ends of a circuit and turn key off whenever checking for shorts or continuity, unless specified.

4) Disconnect solenoids and switches from harness before measuring continuity, resistance, or applying voltage. After each repair, check all component connections and repeat CIRCUIT TEST.

5) An open is defined as any resistance reading greater than 5 ohms. This specification tolerance may be too high for some items in the EEC-IV system. If resistance approaches 5 ohms, always clean the suspected connector and coat with protective dielectric silicone grease. A short is defined as any resistance reading less than 10 k/ohms to ground, unless otherwise specified in CIRCUIT TEST.

6) On TESTS H, and J (Fuel Control), to prevent replacement of good components, be aware that the following non-EEC related areas may also be at fault. These areas include ignition coil, distributor cap and rotor, spark plug wires, fouled spark plugs, canister purge problems, EGR valve and gasket, air filter, poor power and ground circuits, fuel pressure, intake and exhaust manifold leaks, engine not at normal operating temperature, and problems with PCV valves or fuel contaminated engine oil.

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

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

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

Note. CIRCUIT TESTS are grouped in the following categories.

1. A-C: No Start & Voltage Tests
2. DA-DR: Input Sensor Tests
3. FA-FF: Additional Input Component Tests
4. H-J: Fuel Control Systems
5. KA-X: ECA (Processor) Output Tests

ECA SENSOR RESISTANCE & PIN VOLTAGE REFERENCE CHART

ECA SENSOR RESISTANCE & PIN VOLTAGE REFERENCE CHART

NO START

Note. Enter this CIRCUIT TEST only when QUICK TESTS have been successfully completed and the engine is still a no start, or when directed here from another test or chart.

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

1. Thick Film Ignition (TFI) Systems
2. TFI Systems With Closed Bowl Distributors (CBD) and Cowl Mounted TFI Modules
3. Distributorless Ignition Systems (DIS)
4. Spark (ECA Controlled)
5. Wiring Harness Circuits (PIP, SPOUT, IGN GND, VPWR)
6. ECA

TFI Module Circuits. Scheme 33

Scheme 34

TFI/DIS TEST PIN IDENTIFICATION

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

1. Fuel Quality & Quantity
2. Ignition (General System Condition)
3. Ignition (TFI or EDIS/DIS Module)
4. Engine Mechanical Components
5. Starter & Battery Circuits
6. Dual Hall Sensor
7. Distributor
8. Camshaft Sensor (CID)
9. Crankshaft Hall Sensor (PIP)
10. Ignition or EDIS/DIS Coil

1) Starting System Try to start engine. If vehicle is equipped with DIS, go to TEST N, step 1). If engine does not crank, check vehicle starting and charging systems. If engine cranks, go to next step.

2) Checking VREF Signal at TPS Ensure fuel pump inertia switch is set (button pushed in). Turn key off and wait 10 seconds. Set DVOM on 20-volt scale and disconnect Throttle Position Sensor (TPS). Turn key on, leaving engine off (KOEO). Measure voltage at TPS harness connector between VREF and SIG RTN. If reading is less than 4 volts or more than 6 volts, go to TEST C, step 1). If reading is between 4 and 6 volts, reconnect TPS and go to next step.

TPS Harness Connectors. Scheme 35

3) Check For Spark At Plugs Disconnect any spark plug wire and connect spark tester between plug wire and engine ground. Crank engine and check for spark. If spark was present and consistent, connect spark plug wire and go to step 12). If there is no spark, connect spark plug wire and go to next step or to step 5) for vehicles equipped with DIS.

4) Check For Spark at Coil Remove high tension coil wire from distributor and install spark tester. Check for spark while cranking engine. If spark exists, connect coil wire and service or repair TFI ignition system. If no spark exists, connect coil wire and go to next step.

5) Check Ignition Circuit Ground Continuity Turn key off and wait 10 seconds. Disconnect and inspect ECA 60-pin connector. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale and disconnect TFI module or DIS module (pins No. 7-12). Measure resistance between test pin No. 16 at the breakout box and TFI, Hall Sensor, or DIS harness connector IGN GND circuit. If reading is more than 5 ohms, repair open in circuit and repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

6) Isolating SPOUT Circuit Fault Install breakout box. Connect TFI module or DIS module (pins No. 7-12). Connect ECA to breakout box. Set breakout box timing switch to DISTRIBUTOR or DIST position. Try to start vehicle. If vehicle starts, move timing switch to COMPUTED position and go to step 10). If vehicle does not start, go to next step.

7) Check SPOUT Signal With KOEO, install breakout box and connect ECA. Move breakout box timing switch to COMPUTED position. Set DVOM on 20-volt scale and measure voltage between test pin No. 36 at the breakout box and battery negative post while cranking engine. If voltage is between 3 and 6 volts, EEC system is NOT at fault. Diagnose TFI or DIS ignition system. If voltage is less than 3 volts or more than 6 volts, go to next step.

8) Check SPOUT & PIP Circuits For Shorts Turn key off and wait 10 seconds. With breakout box installed, disconnect ECA. On 3.0L SHO, disconnect crankshaft sensor. Disconnect TFI module. Set DVOM on 200-k/ohm scale.

On SPOUT circuit, measure resistance between test pin No. 36 (SPOUT) and test pins No. 16, 20, 40, 46, and 60 for short to ground. Measure resistance between test pin No. 36 and test pins No. 26, 37 and 57 for short to power (VPWR). Measure resistance between test pins No. 36 and 56 for short to PIP.

On PIP circuit, measure resistance between test pin No. 56 (PIP) and test pins No. 16, 20, 40, 46, and 60 for short to ground. Measure the resistance between test pin No. 56 and test pins No. 26, 37 and 57 for short to power.

If any reading is less than 10 k/ohms, repair short in harness and repeat QUICK TEST. If engine still does not start, go to next step. If all readings are 10 k/ohms or more, go to next step.

9) Isolating Shorts In ECA Turn key off and wait 10 seconds. With breakout box installed, connect ECA, but leave TFI or DIS disconnected. Set DVOM on 200-k/ohm scale.

On SPOUT circuit, measure resistance between test pin No. 36 (SPOUT) and test pins No. 37 and 57 for short to power. Measure resistance between test pin No. 36 and test pins No. 40 and 60 for short to ground.

On PIP circuit, 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 reading is less than 500 ohms, replace ECA and repeat QUICK TEST. If all readings are greater than 500 ohms, connect TFI and go to next step.

10) Check PIP Signal With key off, install breakout box. Set DVOM on 20-volt scale. Measure voltage between test pins No. 56 and 16, while cranking engine. If reading is between 3 and 7 volts, remove breakout box. Replace ECA and repeat QUICK TEST. If reading is less than 3 volts or more than 7 volts, go to next step.

11) Check Continuity of PIP Circuit Install breakout box, turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Disconnect ECA and TFI. On 3.0L SHO, disconnect PIP sensor. Measure resistance between test pin No. 56 and TFI connector PIP circuit. If reading is 5 ohms or more, repair open PIP circuit and repeat QUICK TEST. If readings is less than 5 ohms, go to next step.

12) Verify SPOUT Signal Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector and inspect for damaged pins, corrosion, or loose wires. Repair as necessary. Install breakout box and connect ECA. Ensure breakout box timing switch is in COMPUTED position. Set DVOM on 20-volt scale and measure voltage between test pin No. 36 and test pins No. 40 and 60 while cranking engine. If reading is between 3 and 6 volts, go to step 20). If reading is less than 3 volts or more than 6 volts, return to step 8).

Note. There is a break in the step numbering sequence at this point, skipping from step 12) to step 20). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

20) Fuel Pump Check Connect pressure gauge to vehicle. Note initial pressure reading. Pressurize fuel system by turning key on for one second and observe pressure gauge. Turn key off, and wait 10 seconds. Repeat sequence 5 times. If pressure increased, go to TEST S, step 1) for PFI fuel injected engines. If pressure did not increase, go to next step.

21) Inertia Switch Resistance Check Turn key off. Locate fuel pump inertia switch and ensure push button on switch is pushed down in the ON or CLOSED position. Set DVOM on 200-ohm scale. Measure resistance of switch. If resistance is greater than 5 ohms, replace switch. If resistance is less than 5 ohms, go to TEST X, step 11) for 3.0L PFI engines. Go to TEST J, step 1) for all other engines.

TEST AA - NO START (EDIS IGNITION SYSTEMS)

Note. Enter this CIRCUIT TEST only when QUICK TESTS have been successfully completed and the engine is still a no start, or when directed here from another test or chart.

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

1. Spark (ECA Controlled)
2. Wiring Harness Circuits (PIP, IGN GND, VPWR)
3. ECA

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

1. Fuel Quality & Quantity
2. Ignition (General Condition)
3. Engine Mechanical Components
4. Starter & Battery Circuits
5. Variable Reluctance Sensor (VRS)
6. EDIS Module
7. Coil Packs

1) Starting System Ensure fuel pump inertia switch is pushed 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 Ensure fuel pump inertia switch is set (button pushed in). Turn key off and wait 10 seconds. Set DVOM on 20-volt scale and disconnect Throttle Position Sensor (TPS). Turn key on, leaving engine off (KOEO). Measure voltage at TPS harness connector between (VREF) and SIG RTN. If reading is less than 4 volts or more than 6 volts, go to TEST C, step 1). If reading is between 4 and 6 volts, reconnect TPS and go to next step.

3) Check For Spark At Plugs Disconnect any spark plug wire and connect spark tester between plug wire and engine ground. Crank engine and check for spark. If spark was present and consistent, connect spark plug wire and go to next step. If there is no spark, check ignition system. See SYSTEM & COMPONENT TESTING article.

4) Check Ignition Ground Continuity Turn key off, wait 10 seconds. Disconnect and inspect ECA 60-pin connector. Install breakout box, leaving ECA disconnected. Disconnect EDIS module. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 16 at breakout box and IGN GND circuit at EDIS module vehicle harness connector. If resistance is more than 5 ohms, repair open in circuit and repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

5) Check PIP Signal Turn key off and wait 10 seconds. With breakout box installed, disconnect ECA. Reconnect EDIS module. Set DVOM on 20-volt scale. Measure voltage between test pins No. 56 and 16 at the breakout box. Crank engine and record voltage. If voltage is between 3 and 7 volts, go to step 10). If not, go to next step.

6) Check PIP For Short To Power Turn key off and wait 10 seconds. With breakout box installed, disconnect ECA. Disconnect EDIS module. Set DVOM on 20-volt scale. Measure voltage between test pin No. 56 at the breakout box and the battery negative post. If voltage is greater than 7 volts, repair short to power. Remove breakout box and rerun QUICK TEST. If not, go to next step.

7) Check PIP Circuit Continuity Turn key off and wait 10 seconds. With breakout box installed, disconnect ECA. Disconnect EDIS module. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 56 at the breakout box and PIP circuit at the EDIS module vehicle harness connector. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open circuit. Remove breakout box, reconnect all components and rerun QUICK TEST.

8) Check PIP Circuit For Shorts to Power or Ground Turn key off and wait 10 seconds. With breakout box installed, disconnect ECA. Disconnect EDIS module. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 56 (PIP) and test pins No. 26, 37 and 57 for short to power. 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 k/ohms, repair short in harness and repeat QUICK TEST. If engine still does not start, go to next step. If all readings are 10 k/ohms or more, go to next step.

9) Isolate Shorts In ECA Turn key off and wait 10 seconds. With breakout box installed, connect ECA to breakout box. Disconnect EDIS module. Set DVOM on 200-k/ohm scale. 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 all readings are 90-150 k/ohms, problem is in EDIS system. See EDIS IGNITION SYSTEM in SYSTEMS & COMPONENT TESTING article. If any reading is less than 90 k/ohms or greater than 150 k/ohms, replace ECA and repeat QUICK TEST.

10) Fuel Pump Check Connect pressure gauge to vehicle. Note initial pressure reading. Pressurize fuel system by turning key on for one second and observe pressure gauge. Turn key off, and wait 10 seconds. Repeat sequence 5 times. If pressure increased, go to TEST S, step 1). If pressure did not increase, check fuel pump and system for mechanical problems.

TEST B - CHECKING VEHICLE BATTERY

Note. Enter this TEST only when directed here by TESTS C, J, or P.

Power Relay Circuits. Scheme 36

TEST PIN IDENTIFICATION

To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: battery cables and ground straps, voltage regulator, alternator, or ignition switch. This test is intended to diagnose the ECA, power relay, battery voltage and the following harness circuits

1. Signal Return
2. STO
3. STI
4. PWR GND
5. VPWR
6. KAPWR
7. VREF
8. Ignition

1) Battery Voltage Check Turn key on, leaving engine off. Set DVOM on 20-volt scale and measure voltage across battery terminals. If reading is less than 10.5 volts, service or replace discharged battery. If reading is 10.5 volts or more, go to next step.

2) Check Continuity of PWR GND Circuit Turn key off and wait 10 seconds. Inspect ECA connector and pins. Install breakout box, leave ECA connected. Set DVOM on 200-ohm scale and measure resistance between test pins No. 40 and 60 at the breakout box and battery negative post. If readings are greater than 5 ohms, repair open in PWR GND circuit. Remove breakout box, reconnect components and repeat QUICK TEST. If both readings are less than 5 ohms, go to next step.

3) Check For Open Between SIG RTN & PWR GND Circuits at ECA With breakout box installed and ECA connected, turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 46 and test pins No. 40 and 60 at breakout box. If both readings are less than 5 ohms, go to next step. If readings are greater than 5 ohms, disconnect ECA connector and inspect for corrosion or damaged pins. Repair if necessary. If fault is still present, replace ECA and repeat QUICK TEST.

4) Check Continuity of SIG RTN Circuit With breakout box installed and ECA connected, turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 46 at breakout box and SIG RTN circuit at the Self-Test connector. If resistance is greater than 5 ohms, repair open in SIG RTN circuit. Remove breakout box, reconnect components and repeat QUICK TEST. If reading is less than 5 ohms, remove breakout box, connect ECA and go to next step.

5) Check KAPWR Circuit Voltage at EEC Power Relay Turn key on, leaving engine off. With ECA connected, set DVOM on 20-volt scale. Measure voltage between battery negative post and KAPWR circuit at EEC power relay harness connector. If reading is less than 10.5 volts, check KAPWR circuit from EEC power relay to battery positive post for open circuit. If reading is 10.5 volts or more, go to next step.

6) Check Ignition Circuit Voltage at EEC Power Relay Turn key on, leaving engine off. Ensure ECA is connected, set DVOM on 20-volt scale. Measure voltage between battery negative post and IGNITION circuit at EEC power relay vehicle harness connector. If reading is less than 10.5 volts, check for open in ignition switch circuits. Repair wiring and repeat QUICK TEST. If reading is 10.5 volts or more, go to next step.

7) Check PWR GND Circuit Continuity Turn key off and wait 10 seconds. With ECA connected and DVOM on 200-ohm scale, measure resistance between battery negative post and PWR GND circuit at EEC power relay vehicle harness connector. If resistance is 5 ohms or more, repair wiring in ground circuit. Repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

8) Check VPWR Circuit at EEC Power Relay Turn key on, leaving engine off. With ECA connected and DVOM on 20-volt scale, measure voltage between battery negative post and VPWR circuit at EEC power relay vehicle harness connector. If reading is 10.5 volts or more, repair open or short to ground in VPWR circuit between ECA and EEC power relay. Reconnect components and repeat QUICK TEST. If reading is less than 10.5 volts, replace EEC power relay. Repeat QUICK TEST.

TEST C - REFERENCE VOLTAGE

Note. Perform this test when a check for VREF signal has failed in sensor input TESTS (DA-DR), or if directed here by TESTS A or QA.

Note. This TEST is intended to diagnose only the ECA, SIG RTN and VREF circuits.

Reference Voltage Ckts. Scheme 37

REFERENCE VOLTAGE TEST PIN ID

1) Check Battery Power Circuit Turn key off, wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA connected. Turn key on, leaving engine off. Set DVOM on 20-volt scale and measure voltage between test pin No. 37 and SIG RTN/PWR GND circuit in the Self-Test connector. If reading is less than 10.5 volts, reconnect sensor (if applicable) and go to TEST X, step 1) for 3.0L PFI, 3.0L SHO PFI engines. For all others, go to TEST B, step 1). If reading is 10.5 volts or more, go to next step.

2) Check VREF Voltage With breakout box installed and ECA connected, turn key on, leaving engine off. Set DVOM on 20-volt scale and measure voltage between test pins No. 26 and 46 at the breakout box. If reading is 6 volts or more, go to step 4). If reading is 4 volts or less, go to step 5). If reading is between 4 and 6 volts, go to next step.

3) Check VREF & SIG RTN Circuit Continuity With breakout box installed and ECA disconnected, turn key off. If directed here by a sensor test, ensure that sensor is disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 26 and VREF circuit terminal at the vehicle harness connector of the applicable sensor. Measure resistance between test pin No. 46 and SIG RTN circuit terminal at the vehicle harness connector of the applicable sensor. If both readings are less than 5 ohms, VREF voltage is okay. Remove breakout box, reconnect components and sensor, repeat QUICK TEST. Connect all sensors and repeat QUICK TEST. If any reading is 5 ohms or more, repair open in VREF or SIG RTN circuit. Remove breakout box, reconnect components and repeat QUICK TEST.

4) Check For Excess VREF Circuit Voltage Turn key off and wait 10 seconds. With breakout box installed, disconnect ECA and Scan tool or STAR tester (if applicable). Turn key on, leaving engine off. Set DVOM on 20-volt scale and measure voltage between test pin No. 26 and battery ground. If reading is less than 0.5 volt, replace ECA, remove breakout box, reconnect components and repeat QUICK TEST. If reading is 0.5 volt or more, repair short to battery power in EEC vehicle harness. Remove breakout box, reconnect components and repeat QUICK TEST. Replace ECA if fault still occurs.

5) Check For Shorted TPS Sensor Turn key off and wait for 10 seconds. With breakout box installed and ECA connected, disconnect Throttle Position Sensor (TPS) from vehicle harness. Turn key on, leaving engine off. Set DVOM on 20-volt scale and measure voltage between test pins No. 26 and 46. If reading is 4 volts or more, replace TPS, remove breakout box, reconnect components and repeat QUICK TEST. If voltage is less than 4 volts on models with EVP/PFE sensor, go to next step. If reading is less than 4 volts on all other models, go to step 7).

6) Check For Shorted EVP/PFE Sensor Turn key off and wait 10 seconds. With breakout box installed and ECA connected, disconnect the EVP/PFE sensor. Turn key on, leaving engine off. Set DVOM on 20-volt scale. Measure voltage between test pins No. 26 and 46. If reading is 4 volts or more, replace EVP/PFE sensor and repeat QUICK TEST. If reading is less than 4 volts, go to next step.

7) Check For Shorted MAP/BP Sensor If vehicle is not equipped with a MAP/BP sensor, go to step 10). Turn key off and wait 10 seconds. With breakout box installed and ECA connected, disconnect TPS, EVP/PFE (if equipped) and MAP/BP sensor. Set DVOM on 20-volt scale. With KOEO, measure voltage between test pins No. 26 and 46. If reading is 4 volts or more, replace MAP/BP sensor, remove breakout box, reconnect components and repeat QUICK TEST. If reading is less than 4 volts, go to next step. If reading is less than 4 volts on 3.0L Probe models with A/T, go to step 9). For all other vehicles, go to step 10).

Note. There is a break from step 7) to step 9). Step 8 did not apply to this engine. In order to maintain correct referencing from other articles, however, the remaining steps will not be re-numbered.

9) Check For Shorted (Models w/ 4EAT Transmission) With key off, disconnect the TPS, MAP/BP, and EVP/PFE sensors (if equipped). Install the breakout box and connect ECA. Disconnect both 4EAT module connectors. With KOEO, set DVOM on 20-volt scale. Measure voltage between test pins No. 26 and 46. If reading is less than 4.0 volts, go to next step. If reading is greater than 4.0 volts, remove breakout box, reconnect all components except 4EAT module and check for short in 4EAT system.

10) Check VREF Circuit For Short to Ground With breakout box installed and ECA disconnected, turn key off and wait 10 seconds. Disconnect TPS, MAP/BP, and EVP/PFE sensor. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 26 and test pins No. 20, 40, 46, and 60. If any resistance is less than 5 ohms, repair short to ground, connect all sensors and repeat QUICK TEST. If original problem still occurs, replace ECA and repeat QUICK TEST. If reading is 5 ohms or more, connect sensors, replace ECA and repeat QUICK TEST.

TEST DA - TEMPERATURE SENSOR TEST (ACT, ECT & VAT)

Note. Perform this test only when Codes 21, 24, 28, 51, 54, 58, 61, 64, or 68 are received in QUICK TEST. Ambient air temperature must be at least 50°F (10°C) to receive valid input from ACT and VAT sensors. Engine coolant temperature must be greater than 50°F to pass KOEO Self-Test and greater than 180°F 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. For test results to be valid, avoid performing test in unusually hot or cold conditions.

Note. This CIRCUIT TEST is intended to diagnose the following components and circuits

1. ACT Sensor
2. ECT Sensor
3. VAT Sensor
4. Vehicle Harness Circuits (ACT, ECT, VAT & SIG RTN)
5. ECA

Temperature Sensor Circuits. Scheme 38

Temperature Sensors Resistance & Voltage Charts. Scheme 39

To prevent the replacement of good components, ensure the following non-EEC areas or components are not at fault

1. Coolant Level Low
2. Cooling System, Water Pump, Fan
3. Engine Operating Temperature Low
4. Engine Oil Level Low
5. Faulty Thermostat
6. Faulty Heat Riser Duct Valve
7. Air Cleaner Duct
8. Ambient Temperature Too Low

TEST PIN ID

1) Code 21, 24 or 28: Check Installation & Operation of Temperature Sensor Codes 21 (ECT), 24 (ACT or VAT) and 28 (VAT) indicates that the corresponding sensor is out of Self-Test range. Correct range for measurement is .3 to 3.5 volts. Possible causes are

1. Low Ambient Temperature (Less Than 50°F)
2. Low Coolant Level
3. Faulty Harness Connector
4. Faulty Sensor

If vehicle is a no start, go to step 3). If vehicle stalls or starts and dies, go to TEST S, step 1). Run engine for 2 minutes at 2000 RPM. Ensure upper radiator hose is hot and pressurized. Repeat QUICK TEST. If Codes 21, 24 or 28 are present, go to next step. If not, service other codes as necessary.

2) Check VREF Circuit Voltage at TPS Turn key off and wait 10 seconds. Set DVOM on 20-volt scale. Disconnect Throttle Position Sensor (TPS). With KOEO, measure voltage at TPS vehicle harness connector between VREF and SIG RTN. If reading is less than 4 volts or more than 6 volts, go to TEST C, step 1). If reading is between 4 and 6 volts, reconnect TPS and go to next step.

3) Check Temperature Sensor Resistance With Engine Off Turn key off and wait 10 seconds. Disconnect suspect sensor. Set DVOM on 200-k/ohm scale. Measure resistance between sensor signal circuit and SIG RTN circuit at sensor. Refer to charts at the beginning of this CIRCUIT TEST for resistance specifications.

If resistance is within specifications, do the following

1. ECT sensor with a no start; go to TEST A, step 1).
2. ACT and ECT sensors; go to next step.
3. VAT sensor; replace ECA, reconnect components and repeat QUICK TEST.

If resistance is not within specifications, do the following

1. ACT sensor; check heat stove duct valve operation. If okay, replace ACT sensor, reconnect components and repeat QUICK TEST.
2. ECT sensor; replace ECT sensor, reconnect components and repeat QUICK TEST.
3. VAT sensor, refer to VAF component test in I - SYS/COMP TESTS article.

4) Check Resistance of Temperature Sensor With Engine Running If engine has cooled down, warm engine before measuring ECT sensor resistance. Check for an open thermostat. Turn key off and wait 10 seconds. Disconnect suspect sensor. Set DVOM on 200-k/ohm scale. Measure resistance between sensor signal circuit and SIG RTN circuit at temperature sensor. Refer to charts at the beginning of this CIRCUIT TEST for resistance specifications. If resistance is within specification, replace ECA, reconnect components and repeat QUICK TEST. If sensor is not within specifications, do the following

1. ACT sensor; check heat stove duct valve operation. If okay, replace ACT sensor, reconnect components and repeat QUICK TEST.
2. ECT sensor; replace ECT sensor, reconnect vehicle harness and rerun QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 4) to step 10). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

10) Code 51, 54 or 58: Induce Opposite Code (61, 64 or 68) Code 51 (ECT), 54 (ACT or VAT) and 58 (VAT) indicate that the corresponding sensor signal is greater than the Self-Test maximum. Maximum signal voltage for ECT and ACT sensors is 4.6 volts. Maximum signal voltage for VAT sensors is 3.5 volts. Possible causes for excess voltage signals are

1. Temperature too low (VAT)
2. Open circuit in vehicle harness (ACT or ECT)
3. Faulty connection
4. Faulty sensor
5. Faulty ECA

Turn key off and wait 10 seconds. Disconnect suspect temperature sensor. Connect a jumper wire between the sensor signal circuit and the SIG RTN circuit at the temperature sensor vehicle harness connector. Perform KOEO Self-Test. If Code 61, 64 or 68 is displayed, replace suspect sensor. Remove jumper wire, reconnect vehicle harness, and repeat QUICK TEST. If Code 61, 64 or 68 is not displayed, remove jumper wire and go to next step.

11) Check Continuity of Sensor Signal & SIG RTN Circuits Turn key off and wait 10 seconds. Ensure suspect temperature sensor is disconnected. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 7 (ECT sensor) or test pin No. 25 (ACT or VAT sensor), at the breakout box and sensor signal circuit at the sensor vehicle harness connector. Also measure resistance between test pin No. 46 and SIG RTN circuit at the sensor vehicle harness connector. If both readings are less than 5 ohms, replace ECA. Remove breakout box, reconnect components and rerun QUICK TEST. If either reading is 5 ohms or more, repair open circuits. Remove breakout box, reconnect components and rerun QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 11) to step 20). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

20) Code 61, 64 or 68: Induce Opposite Code (51, 54 or 58) Code 61 (ECT), 64 (ACT or VAT) or 68 (VAT) indicates that sensor signal is less than Self-Test minimum. Minimum signal for ACT and ECT sensor is 0.2 volt. Minimum signal for VAT sensor is 0.35 volt.

Possible causes for this fault are

1. Temperature too high (VAT)
2. Circuit grounded in vehicle harness (ACT or ECT)
3. Faulty sensor
4. Faulty ECA
5. Faulty connection

Turn key off and wait 10 seconds. Disconnect vehicle harness connector from suspect sensor. Inspect for and repair any damaged wiring. Repeat KOEO Self-Test. If code 51, 54 or 58 is displayed, replace sensor and connect harness. Repeat QUICK TEST. If code 51, 54 or 58 is not displayed, go to next step.

21) Check VREF Circuit Voltage at TPS Turn key off and wait 10 seconds. Set DVOM on 20-volt scale. Disconnect TPS. With KOEO, measure voltage between VREF and SIG RTN at TPS vehicle harness connector. If reading is less than 4 volts or more than 6 volts, go to TEST C, step 1). If reading is between 4 and 6 volts, connect TPS and go to next step.

22) Check Temperature Sensor Signal For Shorts to Ground Turn key off and wait 10 seconds. Disconnect suspect sensor. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 7 (ECT) or test pin No. 25 (ACT and VAT) and test pins No. 40, 46, and 60. If any reading is less than 10 k/ohms, repair short circuit. Remove breakout box, reconnect components, and repeat QUICK TEST. If all readings are 10 k/ohms or more, replace ECA. Remove breakout box and reconnect components. Repeat QUICK TEST.

TPS Connectors. Scheme 40

Note. There is a break in the step numbering sequence at this point, skipping from step 22) to step 90). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

90) Continuous Memory Code 51, 54, 58, 61, 64 or 68: Check Sensor A Continuous Memory Code 51, 54 or 58 indicates that sensor signal was greater than the Self-Test maximum of 4.6 volts. The code was set during normal driving conditions.

Continuous Memory Code 61, 64 or 68 indicates that sensor signal was less than the self-test minimum of 0.2 volt. The code was set during normal driving conditions.

Possible causes for these faults are

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

SENSOR CODES

ACT Sensor Circuit Fault. Scheme 41

Enter KOEO Continuous Monitor Mode (Wiggle Test), observe VOM or diagnostic 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 and repeat QUICK TEST. If a fault is not indicated, go to next step.

91) Check EEC-IV Vehicle Harness While in Continuous Monitor Mode (Wiggle Test), observe VOM or diagnostic tester while wiggling and bending EEC-IV harness from sensor to cowl, a small section at a time. Also check harness from cowl to ECA. If fault is indicated, isolate fault and repair as necessary. Repeat QUICK TEST. If no fault is found, go to next step.

92) Inspecting ECA & Vehicle Harness Connectors Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect both connector and connector terminals for obvious damage. If connectors and terminals are damaged, repair as necessary and repeat QUICK TEST. If connectors and terminals are okay, and you are unable to duplicate fault at this time, clear codes and repeat QUICK TEST. See to INTERMITTENTS in the TESTS W/O CODES article.

TEST DC - MASS AIRFLOW SENSOR (MAF)

Note. Perform this test when Code 26, 56, or 66 is displayed in the QUICK TESTS or when directed here by test charts. This test procedure is intended to diagnose only the MAF, ECA and vehicle harness circuits (VPWR, PWR GND, MAF and MAF RTN).

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

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

Mass Airflow Sensor (MAF) Circuits. Scheme 42

MAF SENSOR TEST PIN ID

MAF SIGNAL VOLTAGE

Note. MAF signal voltage is typical for an A/T equipped vehicle at normal operating temperature. Voltage signal may vary due to engine load and temperature.

1) Code 26: Check VPWR Circuit Voltage Code 26 indicates MAF sensor voltage is out of Self-Test. If code was received during KOEO Self-Test, voltage exceeded .70 volt test range. If Code 26 was received during KOER Self-Test, voltage was not within .20 to 1.50 volt operating range. Possible causes for this fault are a faulty MAF sensor or ECA.

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

Turn key off and disconnect MAF sensor. Set DVOM on 20-volt scale. Turn key on, leaving engine off. Measure voltage between VPWR circuit at the MAF sensor vehicle harness connector and the battery negative post. If voltage is greater than 10.5 volts, go to next step. If not, reconnect MAF sensor and go to TEST B, step 1).

2) Check MAF Sensor Ground With KOEO and MAF sensor disconnected, set DVOM on 20-volt scale. Measure voltage between VPWR circuit and PWR GND circuit at the MAF sensor connector. If voltage is greater than 10.5 volts, go to next step. If voltage is less than 10.5 volts repair open PWR GND circuit, reconnect MAF and rerun QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 2) to step 10). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

10) Code 66: Check Continuity of MAF Signal & VPWR Circuits Code 66 indicates that MAF signal was less than .40 volt during engine continuous operation or during KOER Self-Test. Possible causes for this fault are

1. Open MAF circuit
2. Open VPWR circuit to MAF sensor
3. Open PWR GND circuit to MAF sensor
4. MAF circuit shorted to ground
5. Faulty ECA or MAF sensor
6. Air leak before or after MAF sensor
7. MAF sensor disconnected

Ensure key is off. Disconnect and inspect 60-pin connector at ECA. Repair and service as necessary. Disconnect the MAF sensor and install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between VPWR circuit at the MAF sensor vehicle harness connector and test pins No. 37 and 57 at the breakout box. Measure resistance between MAF circuit at MAF sensor vehicle harness connector and test pin No. 50 at breakout box. If both resistances are less than 5 ohms, go to next step. If either resistance is greater than 5 ohms, remove breakout box, repair open circuit, reconnect all components and rerun QUICK TEST.

11) Check MAF Ckt For Shorts to Ground & MAF RTN Ckt With key off and MAF sensor disconnected, set DVOM on 200-k/ohm scale. Disconnect ECA 60-pin connector, inspect connector and terminals. Install breakout box leaving ECA disconnected. Measure resistance between test pin No. 50 and test pins No. 9, 40, and 60, at the breakout box. If all resistances are greater than 10 k/ohms, go to next step. If resistance in any circuit is less than 10 k/ohms, repair short circuit, remove breakout box, reconnect components and repeat QUICK TEST.

12) Check Continuity of PWR GND Circuit Ensure key is turned off and disconnect MAF sensor. Set DVOM on 200-ohm scale. Measure resistance between PWR GND circuit at MAF sensor vehicle harness connector and battery negative post. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open circuit, reconnect all components and repeat QUICK TEST. If resistance is 5 ohms or less, go to next step.

13) Check Continuity of MAF RTN Circuit With key off and MAF sensor disconnected, set DVOM on 200-ohm scale. Disconnect ECA 60-pin connector, inspect pins and install breakout box, leave ECA disconnected. Measure resistance between MAF RTN circuit at the MAF sensor vehicle harness connector, and test pin No. 9 at the breakout box.

If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, remove breakout box, reconnect components and repeat QUICK TEST.

14) Check MAF Signal For Short to Ground With key off, breakout box installed, and ECA connected, disconnect MAF sensor. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 50 and test pins No. 9, 40, and 60 at the breakout box. If all resistances are less than 10 k/ohms, remove breakout box. Replace ECA, remove breakout box, reconnect components and repeat QUICK TEST. If resistances are greater than 10 k/ohms, go to next step.

15) Check MAF Circuit Output With key off, install breakout box. Ensure ECA and MAF are connected. Set DVOM on 20-volt scale. Start engine. Measure voltage between test pin No. 50 at the breakout box and battery negative post. If voltage is between .2 and 1.5 volts replace ECA, remove breakout box, reconnect components and repeat QUICK TEST. If voltage is not between .2 and 1.5 volts, replace MAF sensor, remove breakout box, reconnect components and repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 15) to step 20). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

20) Code 56: Repeat Self-Test With MAF Sensor Disconnected With key off, disconnect MAF sensor from vehicle harness. Start engine and allow to idle for one minute. Turn key off. Repeat KOEO Self-Test. If Code 66 is present, replace MAF sensor and rerun QUICK TEST. If Code 66 is not present, go to next step.

21) Check MAF Circuit For Short to VPWR With key off, install the breakout box and disconnect MAF sensor and ECA. Disconnect ECA 60-pin connector, inspect for damaged or corroded terminals and repair as necessary. Set DVOM on 200-k/ohm scale. Measure resistance between MAF circuit and VPWR circuit at the MAF sensor vehicle harness connector. If resistance is greater than 10 k/ohms, replace ECA, remove breakout box, reconnect components and repeat QUICK TEST. If resistance is less than 10 k/ohms, repair circuit short, remove breakout box, reconnect components and repeat QUICK TEST.

EGR VALVE POSITION (EVP) SENSOR EGR CONTROL (EGRC) SOLENOID & EGR VENT (EGRV) SOLENOID

Note. Perform this test when Code 31, 32, 33, 34, 35, 83, or 84 is displayed during QUICK TESTS or when directed here by other test procedures.

EVP, EGRC & EGRV Solenoid Circuits. Scheme 43

EVP SENSOR SPECIFICATIONS

Note. Voltage values are calculated based on a VREF of 5.0 volts. Actual values may vary up to 15% due to sensor and VREF variations.

Note. To prevent replacement of good components, be aware that the following non-EEC related area may be at fault: Damaged EGR valve.

1) KOER Code 31: Repeat KOER Self-Test With EGR Vacuum Signal Line Disconnected at EGR Valve KOER Code 31 indicates that during the KOER Self-Test the EVP sensor signal to the ECA is out of range with the EGR valve in the closed position. Possible causes for this code are a faulty EGRC/EGRV solenoids or a clogged EGRV filter. Turn key off and wait 10 seconds. Disconnect vacuum line at EGR valve and plug end of vacuum line. Perform KOER Self-Test. If Code 31 is not displayed, reconnect EGR vacuum line and go to step 11). If Code 31 is displayed, go to next step. Ignore all other codes at this time.

2) KOEO Code 31: Checking EVP Sensor Resistance While Applying Vacuum to EGR Valve KOEO Code 31 displayed during the KOEO Self-Test indicates that the EVP sensor signal to the ECA was out of range with the EGR valve in the closed position. Possible causes for this code are

1. Open or shorted circuit
2. Faulty EGR valve
3. Faulty EVP sensor
4. Faulty ECA

Turn key off and wait 10 seconds. Disconnect and plug EGR vacuum line. Disconnect EVP sensor. Set DVOM on 200-k/ohm scale and connect vacuum pump to EGR valve. Measure resistance between EVP circuit and VREF circuit at EVP sensor connector while slowly increasing vacuum to 10 in. Hg. If reading is less than 100 ohms or more than 5500 ohms, replace EVP sensor. Reconnect EGR vacuum line and harness. Repeat QUICK TEST. If reading does not decrease or valve does not hold vacuum, go to step 14). If reading gradually decreases from a maximum of 5500 ohms to a minimum of 100 ohms, go to next step.

EVP Sensor. Scheme 44

3) Check VREF Circuity Voltage at EVP Sensor Vehicle Harness Connector With KOEO, disconnect harness from EVP sensor. Set DVOM on 20-volt scale. Measure voltage between VREF and SIG RTN at EVP sensor vehicle harness connector. If reading is less than 4 volts or more than 6 volts, go to TEST C, step 1). If reading is between 4 and 6 volts, go to next step.

EVP Sensor Vehicle Harness Connector. Scheme 45

4) Check EVP Circuit Continuity Turn key off and wait 10 seconds. Disconnect harness at EVP sensor and ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 27 and EVP circuit at EVP sensor vehicle harness connector. If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST. If resistance is less than 5 ohms, go to next step.

5) Checking EVP Circuit For Shorts to VREF Circuit & Ground Turn key off and disconnect harness at EVP sensor. Install breakout box, leaving ECA disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 27 and test pins No. 26, 40, 46, and 60 at the breakout box. If any reading is less than 10 k/ohms, repair short circuit. Remove breakout box, connect ECA and EVP sensor. Repeat QUICK TEST. If all readings are 10 k/ohms or more, go to next step.

6) Substitute EVP Sensor & EGR Valve Turn key off and wait 10 seconds. Electrically connect known good EVP sensor and EGR valve assembly to harness and vacuum lines. Connect ECA to breakout box. Perform KOEO Self-Test. If Code 31 is displayed, replace ECA. Connect original EVP sensor and EGR valve assembly. Repeat QUICK TEST. If Code 31 is not displayed, go to next step.

7) Check Original EVP Sensor on Substitute EGR Valve Turn key off. Ensure breakout box is installed and ECA is connected. Install original EVP sensor to known good EGR valve. Connect vehicle harness to EVP sensor and perform KOEO Self-Test. If Code 31 is displayed, replace EVP sensor and repeat QUICK TEST. If Code 31 is not displayed, service EGR system.

Note. There is a break in the step numbering sequence at this point, skipping from step 7) to step 11). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

11) Codes 32, 33, or 34 Displayed: Check For Vacuum Cycling at EGR Valve Codes 32, 33 or 34 indicate that the EGR valve did not open when instructed to by the ECA. Code 34 indicates the valve would not open. Code 32 indicates the valve is stuck open. Code 33 indicates the valve would not close correctly. Possible causes for these faults are as follows

1. Faulty vacuum lines
2. Clogged EGRV filter
3. Faulty EVP sensor
4. Faulty EGR valve
5. Faulty EGRC/EGRV solenoid
6. Faulty ECA

With key off, disconnect vacuum line at the EGR valve. Connect a vacuum gauge to the EGR vacuum line, leaving the EGR valve disconnected. Observe vacuum gauge while running KOER Self-Test. Disregard all other codes produced during this test. If vacuum reading increased from less than 1 in. Hg to greater than 5 in. Hg and, within 10 seconds, returned to less than 1 in. Hg, go to step 13). If vacuum did not increase, go to next step. If vacuum increased but did not return to less than 1 in. Hg, check EGRV filter for obstructions, replace filter or solenoid as necessary. Reconnect all vacuum lines and rerun QUICK TEST.

12) Check Vacuum Supply to EGRC/EGRV Solenoids With key off, disconnect vacuum source to EGRC/EGRV solenoids. Install a vacuum gauge at the source vacuum line. Start engine and check vacuum. If vacuum is greater than 10 in. Hg, check vacuum line from EGRC/EGRV solenoids to EGR valve for blockage, leaks or damage, replace as necessary. If supply line is okay, replace solenoid assembly and rerun QUICK TEST. If vacuum was less than specification, check vacuum line to EGRC/EGRV solenoids and repair as necessary. Reconnect all vacuum lines and repeat QUICK TEST.

13) Check EVP Sensor Resistance While Applying Vacuum to EGR Valve With key off, disconnect EVP sensor harness. Inspect for and repair any damaged wiring. Set DVOM on 200-k/ohm scale. Disconnect vacuum line at EGR valve and connect vacuum pump to valve. Measure resistance between EVP circuit and VREF circuit at the EVP sensor while increasing vacuum to 10 in. Hg. If reading slowly decreases from maximum of 5500 ohms to minimum of 100 ohms, replace ECA. Reconnect EVP sensor and EGR vacuum line. Repeat QUICK TEST. If reading does not slowly decrease, go to next step.

14) Manual Test of EVP Sensor With key off, disconnect EVP sensor harness. Remove EVP sensor and vacuum line from EGR valve. Measure resistance between EVP circuit and VREF circuit at the EVP sensor while sensor shaft is slowly pushed in and slowly released. If reading increases and decreases smoothly in range of 100-5500 ohms, service or replace EGR valve assembly. Connect EVP sensor and EGR vacuum line. Repeat QUICK TEST. If either reading changes abruptly during range of 100-5500 ohms, replace EVP sensor. Reconnect harness and EGR vacuum line. Repeat QUICK TEST.

Note. It is normal for EVP sensor total resistance to drop to less than 100 ohms when disconnected from EGR valve. A defective sensor will change resistance suddenly between 5500 and 100 ohms.

Note. There is a break in the step numbering sequence at this point, skipping from step 14) to step 17). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

17) Code 83 or 84 Displayed: Check EGRV/EGRC Solenoid Resistance Code 83 indicates an EGRC circuit failure. Code 84 indicates an EGRV circuit failure. Possible causes for these faults are an open or shorted circuit, a faulty EGRC/EGRV solenoid or a faulty ECA.

Turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Disconnect EGRC and EGRV solenoids from harness. Inspect for and repair any damaged wiring. Measure resistance between EGRV circuit and VPWR circuit at the EGRV solenoid. Measure resistance between EGRC circuit and VPWR circuit at the EGRC solenoid. If either reading is less than 30 ohms or more than 70 ohms, replace EGRC/EGRV solenoid assembly. Repeat QUICK TEST. If both readings are between 30 and 70 ohms, reconnect solenoids and go to next step.

18) Check VPWR Circuit Voltage at EGRC/EGRV Solenoids Disconnect EGRC and EGRV solenoids from harness. Turn key on, leaving engine off. Set DVOM on 20-volt scale. Measure voltage between battery negative terminal and VPWR circuit for both solenoids. If either reading is less than 10.5 volts, repair open circuit and repeat QUICK TEST. If both readings are 10.5 volts or more, go to next step.

EGRC & EGRV Vehicle Harness Connectors. Scheme 46

19) Check Continuity of EGRC & EGRV Circuits Turn key off and wait 10 seconds. Leave EGRC and EGRV solenoids disconnected. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 33 and EGRV circuit at the EGRC solenoid vehicle harness connector. Measure resistance between test pin No. 52 and EGRC circuit at EGRC solenoid vehicle harness connector. If either reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect ECA solenoids, and repeat QUICK TEST. If both readings are less than 5 ohms, go to next step.

20) Check EGRC & EGRV Circuits For Shorts To Ground Turn key off and wait 10 seconds. Set DVOM on 200-k/ohm scale. Install breakout box, leaving ECA disconnected. Disconnect EGRC and EGRV solenoids. Measure resistance between test pin No. 33 and test pins No. 40, 46, and 60. Measure resistance between test pin No. 52 and test pins No. 40, 46, and 60. If readings are less than 10 k/ohms, repair short to ground. Repeat QUICK TEST. If readings are 10 k/ohms or more, go to next step.

21) Check For Shorts to Power With key off, disconnect EGRC and EGRV solenoids from harness. Install breakout box, leaving ECA disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 33 and test pins No. 37 and 57. Measure resistance between test pin No. 52 and test pins No. 37 and 57. If any reading is less than 10 k/ohms, repair short in circuit. Remove breakout box and connect ECA. Repeat QUICK TEST. If all resistances are greater than 10 k/ohms, replace ECA. Remove breakout box and connect ECA. Repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 21) to step 30). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

30) Code 35: Check For Code 12 This code indicates that engine RPM is too low for EGR testing. Possible causes for this fault are a faulty ISC system or a faulty ECA. If Code 12 is also displayed go to TEST KE, step 1). If Code 12 is not displayed with Code 35, go to next step.

31) Retest at 1500 RPM Turn key off and wait 10 seconds. Install tachometer. Perform KOER Self-Test at 1500 RPM. Ignore all other codes at this time. Record KOER codes. If Code 35 is displayed, replace ECA. Clear codes and repeat QUICK TEST. If Code 35 is not displayed, clear codes and repeat QUICK TEST. Repair other codes as necessary.

Note. There is a break in the step numbering sequence at this point, skipping from step 31) to step 90). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

90) Continuous Memory Code 31: Exercise EVP Sensor Continuous Memory Code 31 indicates that sometime during vehicle operation the EVP signal was out of the Self-Test range. Possible causes for this fault are an open or shorted circuit or a faulty EVP sensor.

Using KOEO Continuous Monitor Mode (Wiggle Test), observe VOM or diagnostic tester for indication of fault while doing the following: connect vacuum pump to EGR valve. Very slowly apply 6 in. Hg vacuum to EGR valve. Bleed vacuum slowly and lightly tap on EVP sensor. Wiggle EVP sensor connector. This test should check vehicle harness for a short between the VREF, EVP SIG and SIG RTN circuits. If fault is indicated, go to next step. If no fault is indicated, go to step 92).

EVP Circuits. Scheme 47

91) Measure EVP Signal Voltage While Exercising EVP Sensor Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box and connect ECA. Stay in KOEO Continuous Monitor Mode (Wiggle Test).

Connect DVOM between test pins No. 27 and 46. Set DVOM on 20-volt scale. Turn key on, leaving engine off. While watching voltage, repeat test as in step 90). If fault occurs below 4.25 volts, disconnect EVP sensor from harness. Inspect for and repair any damaged wiring. If wiring is okay, replace EVP sensor. Clear codes and repeat QUICK TEST. If fault does not occur below 4.25 volts, EGR valve overshoot may have caused Continuous Memory Code 31. Sensor test is complete. Go to next step to check vehicle harness.

92) Check EEC-IV Harness While in KOEO Continuous Monitor Mode (Wiggle Test), bend, shake, and wiggle small sections of EEC-IV harness from sensor to firewall and from firewall to ECA. If fault is indicated, isolate fault and repair as necessary. Clear codes and repeat QUICK TEST. If no fault is indicated, go to next step.

93) Check ECA & Vehicle Harness Connectors Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect both connector and terminals for obvious damage. If connector and terminals are damaged, repair as necessary and repeat QUICK TEST. If connector and terminals are okay, fault cannot be duplicated at this time. Refer to INTERMITTENTS in TESTS W/O CODES article, in this section.

MANIFOLD ABSOLUTE PRESSURE (MAP)/BAROMETRIC PRESSURE (BP) SENSOR

Note. This test should be performed when Code 22 or 72 is displayed in QUICK TEST procedures, or when directed here by TEST S or symptom test. Barometric pressure sensor output is digital and must be measured with an oscilloscope or MAP/BP tester.

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

1. Unusually high or low atmospheric barometric pressure
2. Kinked or blocked vacuum lines
3. Engine mechanical condition (valves, vacuum leaks, valve timing, EGR valve, etc.) NOTE: This test is intended to diagnose the following
4. MAP/BP Sensor
5. Vehicle Harness Circuits (VREF, MAP/BP SIG, & SIG RTN)
6. MAP Vacuum Line
7. ECA

MAP/BP Circuits & Tester Hook-Up. Scheme 48

MAP SENSOR SPECS - MANIFOLD VACUUM

MAP/BP SENS SPECS-BAROMETRIC PRESSURE

1) Code 22: Check For Power to MAP/BP Sensor Code 22 indicates that the MAP/BP sensor is out of Self-Test voltage range (1.4-1.6 volts). Possible causes of this code are

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

Turn key off. Disconnect MAP/BP sensor from vehicle harness. Connect MAP/BP tester between wiring harness and MAP/BP sensor. Connect "banana plugs" of tester into DVOM and set DVOM on 20-volt scale.

Turn key on. If Red light, or no light is on, it indicates VREF is either to high or too low. Go to next step. If Green light is on, it indicates VREF is okay. Go to step 3).

2) Check For Power at Sensor Vehicle Harness Connector With MAP/BP tester connected, turn key on. If only Green light on tester is lit, VREF is correct, replace MAP/BP sensor and repeat QUICK TEST. If Green light is not on, remove MAP/BP tester. Reconnect MAP/BP sensor and go to TEST C, step 1).

3) Check MAP/BP Sensor Output With MAP/BP tester connected and key on, measure sensor output voltage. If voltage output is within range for altitude for vehicle being tested, remove MAP/BP tester and go to next step. If output reading is outside range, remove MAP/BP tester and go to step 5).

Note. If possible, measure several known good MAP/BP sensors on available vehicles. Average voltage reading will be typical for your location on date of testing.

MAP SENSOR VOLTAGE OUTPUT

4) Check Continuity of MAP/BP SIG Circuit Turn key off and wait 10 seconds. Disconnect MAP/BP sensor from vehicle harness. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between MAP/BP SIG circuit at sensor vehicle harness connector and test pin No. 45. If reading is less than 5 ohms, replace ECA. Reconnect components and repeat QUICK TEST. If reading is 5 ohms or higher, repair open circuit. Remove breakout box, reconnect components and repeat QUICK TEST.

5) Check MAP/BP SIG Circuit For Shorts to VREF, SIG RTN & Ground Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Disconnect harness at MAP/BP sensor. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 45 and test pins No. 26, 46, 40, and 60. If any reading is less than 10 k/ohms, repair short circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST. If all readings are 10 k/ohms or more, replace MAP/BP sensor. Remove breakout box and connect all wiring. Repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 5) to step 7). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

7) KOER Code 22: Check for EGR Related Codes KOER Code 22 indicates MAP/BP signal is out of self-test range during KOER Self-Test. Check for Codes 31, 32, 33, 34 or 35. If codes are present, go to KOER CODE CHART and perform appropriate CIRCUIT TEST. If codes are not present, go to next step.

8) Check MAP Sensor Operation Turn key off and wait 10 seconds. Disconnect vacuum hose from MAP sensor. Connect vacuum pump to MAP sensor and apply 18 in. Hg to sensor. If sensor does not hold vacuum, replace sensor, connect vacuum line and repeat QUICK TEST. If MAP sensor does hold vacuum, release vacuum and go to next step.

9) Attempt to Eliminate Code 22 Turn key off and wait 10 seconds. Plug vacuum hose going to MAP sensor. Start engine and run at 1400-1600 RPM. Slowly apply 15 in. Hg to MAP sensor. With engine operating under these conditions, perform KOER Self-Test. Check for Code 22, disregard any other codes at this time. If Code 22 is still present, replace MAP sensor. If Code 22 is no longer displayed, inspect vacuum hose going to MAP sensor. If okay, service other codes at this time. If no other codes are present, check engine mechanical condition for cause of low vacuum.

10) Code 72: Repeat Dynamic Response (Goose) Test Code 72 indicates that MAP sensor output did not change enough during dynamic response (Goose) test. Possible causes for this code are

1. System failed to detect partial Wide Open Throttle (WOT)
2. Incorrect MAP sensor vacuum line routing
3. Faulty MAP sensor

Repeat KOER Self-Test. Ensure complete WOT is performed during Dynamic Response portion of test. If KOER Code 72 is still present, go to next step. If not, service other codes as necessary.

11) Check Vacuum Hoses With key off, check vacuum lines for correct routing. Refer to Vehicle Emission Control Identification (VECI) decal. Check for disconnections, kinks or blockage. Repair vacuum lines as necessary and repeat QUICK TEST. If vacuum lines are okay, go to next step.

12) Check MAP Sensor Operation Turn key off and wait 10 seconds. Disconnect vacuum supply hose from MAP sensor. Install vacuum pump to MAP sensor. Apply 18 in. Hg to MAP sensor. If MAP sensor holds vacuum, release vacuum and go to next step. If not, replace MAP sensor, reconnect components and repeat QUICK TEST.

13) Check That Vacuum to MAP Sensor Decreases During Dynamic Response (Goose) Test Turn key off, wait 10 seconds. Use a "T" fitting to install a vacuum gauge in the intake manifold MAP sensor supply line. Run the KOER Self-Test while observing vacuum gauge. If vacuum decreased by more than 10 in. Hg during dynamic response (Goose) test, remove gauge, replace MAP sensor and rerun QUICK TEST. If vacuum did not decrease by 10 in. Hg or more, EEC-IV system is okay, repair engine mechanical components as necessary to increase engine vacuum.

Note. There is a break in the step numbering sequence at this point, skipping from step 13) to step 90). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

90) Continuous Memory Code 22: Operate MAP/BP Sensor Continuous Code 22 indicates the MAP/BP 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/BP sensor
2. Faulty wiring harness or connectors
3. Unusually high or low barometric pressure.

In KOEO Continuous Monitor Mode (Wiggle Test), observe test equipment while performing the following

1. Connect a vacuum pump to the MAP/BP 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 as necessary. If connectors are okay, replace MAP/BP sensor. If a fault is not indicated, go to next step.

91) Check EEC-IV Vehicle Harness Stay in KOEO Continuous Monitor Mode (Wiggle Test). Observe VOM or diagnostic tester for indication of fault while shaking, bending or wiggling small sections of harness from sensor connector to firewall. Check harness from firewall to ECA in same manner. If fault is indicated, isolate fault in harness and repair as necessary. Clear codes and repeat QUICK TEST. If no fault is indicated, go to next step.

92) Check ECA & Vehicle Harness Connectors Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect both connectors and terminals for obvious damage. If connectors and terminals are not okay, repair as necessary. Repeat QUICK TEST. If connectors and terminals are okay, fault cannot be duplicated at this time. Continuous Code 22 testing is complete. Refer to INTERMITTENTS in TESTS W/O CODES article.

TEST DG - KNOCK SENSOR (KS)

Note. Perform this test when Code 25 is received during QUICK TEST procedure or you are directed here by other diagnostic tests. Use DYNAMIC RESPONSE CHECK as specified in steps 1) and 6). There is no need to perform WOT during this test. For additional information see QUICK TEST DIAGNOSTIC AIDS and DYNAMIC RESPONSE CHECK.

Knock Sensor Circuits. Scheme 49

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

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

1) Code 25: Generate Knock Signal Manually Code 25 indicates that the Knock Sensor (KS) signal was not received by the ECA during the dynamic response (Goose) test after the engine ID code in the KOER Self-Test. Possible causes for this fault are

1. Faulty knock sensor
2. Open or shorted harness
3. Faulty ECA

Have 4 oz. hammer ready. Ensure engine is at normal operating temperature. Perform KOER Self-Test. Immediately after DYNAMIC RESPONSE CHECK request signal appears, lightly tap above knock sensor with 4 oz. hammer. DO NOT goose throttle. After 15 seconds, check for Code 25. Ignore all other codes at this time. If Code 25 is displayed, go to next step. If Code 25 is not displayed, knock system is okay. Repeat KOER Self-Test and service other codes.

2) Check KS Circuit Voltage Turn key off and wait 10 seconds. Disconnect knock sensor. Inspect for and repair any damaged wiring. Set DVOM on 20-volt scale. With KOEO, measure voltage between KS circuit and SIG RTN at sensor vehicle harness connector. If reading is greater than 4 volts, go to step 5). If reading is 1-4 volts, go to step 6). If reading is less than one volt, go to next step.

3) Check Continuity of KS & SIG RTN Circuits Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA and knock sensor disconnected. With DVOM on 200-ohm scale, measure resistance between SIG RTN circuit at KS harness connector and test pin No. 46. Measure resistance between KS circuit at the vehicle harness connector and test pin No. 23. If either reading is 5 ohms or more, service open circuit and repeat QUICK TEST. If both readings are less than 5 ohms, go to next step.

4) Check KS Circuit for Short to Ground Turn key off and wait 10 seconds. With breakout box installed, ECA and knock sensor disconnected, set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 23 and test pins No. 40, 46 and 60. If all readings are 10 k/ohms or more, remove breakout box, reconnect ECA and go to step 6). If any reading is less than 10 k/ohms, repair shorts in harness and repeat QUICK TEST.

5) Check KS Circuit for Short to Voltage Turn key off and wait 10 seconds. With breakout box installed, ECA and KS sensor disconnected, set DVOM on 20-volt scale. Turn key on, leaving engine off. Measure voltage between test pins No. 23 and 40. If reading is 0.5 volt or more, repair knock sensor harness short to power, and repeat QUICK TEST. If reading is less than 0.5 volt, remove breakout box, reconnect ECA and go to next step.

6) Test ECA With Substitute Knock Sensor Turn key off and wait 10 seconds. Remove breakout box and reconnect ECA. Connect substitute knock sensor into harness but do not install sensor on engine. Substitute sensor should be a known good unit with the same part number. Ensure engine is at normal operating temperature. Perform KOER Self-Test. When DYNAMIC RESPONSE CHECK signal appears, lightly tap knock sensor with 4 oz. hammer. DO NOT goose throttle. If Code 25 is displayed, replace ECA, reconnect original knock sensor and rerun QUICK TEST. Ignore all other codes at this time. If Code 25 does not appear, install new knock sensor and repeat QUICK TEST.

TEST DH - THROTTLE POSITION SENSOR (TPS)

Note. Perform this test when Code 23, 53, 63, or 73 is displayed during QUICK TEST.

TPS Circuits. Scheme 50

TPS Specification Charts. Scheme 51

THROTTLE POSITION SENSOR SPECIFICATIONS

Note. The normal range of throttle angle measurement for the TPS is 0 to 85 degrees. To pass QUICK TEST procedure, the range of throttle rotation (in degrees) must be within 3% of specification.

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

1. Idle speed
2. Throttle stop adjustment
3. Binding throttle shaft or linkage
4. Cruise control linkage

1) Code 23: Perform This Check Before Servicing This Code Code 23 indicates that the TPS rotational setting may be out of the Self-Test range. See specification chart. Possible causes for this fault are

1. Binding throttle linkage
2. TPS not seated correctly
3. Faulty TPS
4. Faulty ECA

If you are at this step to service a KOEO Code 23, check for a Code 68. If you are at this step to service a KOER Code 23, check for Codes 31 or 58. If any of these codes are present, return to the KOEO or KOER Code Charts and proceed as directed to Codes 68, 31 or 58. If these codes are not present, go to next step.

2) Check For Stuck Throttle Plate Inspect throttle body and linkage for binding or sticking. Ensure linkage is in the throttle closed position. If throttle plate or linkage is binding, check for binding throttle or cruise control linkage, vacuum line or harness interference, etc. Repair any problem and repeat QUICK TEST. If no mechanical problem is found, go to next step.

3) Code 53: Attempt to Generate Code 63 Code 53 indicates that TPS signal is greater than Self-Test maximum value. Possible causes for this fault are

1. TPS not seated properly
2. Faulty TPS sensor
3. VREF circuit shorted in vehicle harness
4. Faulty ECA

Turn key off and wait 10 seconds. Disconnect TPS from vehicle harness at throttle body. Inspect for and repair any damaged wiring or connector pins. Disconnect both 4EAT module vehicle harness connectors on 3.0L Probe A/T. Repeat KOEO Self-Test. Ignore all other codes at this time. If Code 63 is not displayed, go to step 6). If Code 63 is displayed, go to next step.

4) Check VREF Circuit Voltage Turn key off and wait 10 seconds. Set DVOM on 20-volt scale. Disconnect TPS and both 4EAT module vehicle harness connectors. With KOEO, measure voltage between VREF and SIG RTN at TPS vehicle harness connector. If reading is less than 4 volts or more than 6 volts, reconnect the sensor and go to TEST C, step 1). If reading is between 4 and 6 volts, go to next step (3.0L Probe) or replace TPS and repeat QUICK TEST (all others).

5) Check For Shorted 4EAT Transmission Module All 3.0L Probe vehicles that are equipped with automatic transmissions have a TP input circuit to the 4EAT module. This test is to verify that TP circuit is not shorted inside the 4EAT module. With key off, reconnect TP sensor. Ensure both 4EAT module vehicle harness connectors are disconnected. Repeat KOEO Self-Test. If Code 53 is present (ignore other codes at this time), replace TPS, and repeat QUICK TEST. If Code 53 is not present, service transmission components as necessary.

6) Checking TP Circuit For Short to Power Turn key off and wait 10 seconds. Disconnect TPS from harness. Set DVOM on 200-k/ohm scale. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Measure resistance between test pin No. 47 and test pins No. 26 and 57. If either reading is less than 10 k/ohms, repair short in harness, connect components and repeat QUICK TEST. If both readings are 10 k/ohms or more, replace ECA, reconnect components and repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 6) to step 10). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

10) Code 63: Attempt to Generate Code 53 or 23 Code 63 indicates that TP signal is less than minimum Self-Test value. Refer to specification chart at beginning of this CIRCUIT TEST. Possible causes for this fault are

1. TPS not seated correctly
2. Faulty TPS
3. Open circuit in vehicle harness
4. Grounded circuit in vehicle harness
5. Faulty ECA

Turn key off and wait 10 seconds. Disconnect TPS from harness. Install a jumper wire between VREF and TP circuit at TPS vehicle harness connector. Perform KOEO Self-Test. Check for Codes 53 or 23 (ignore all other codes at this time). If Codes 53 or 23 are not present, immediately remove jumper wire, and go to next step. If either Code 53 or 23 is displayed, replace TPS, remove jumper and repeat QUICK TEST.

11) Check VREF Circuit Voltage Turn key off and wait 10 seconds. Disconnect TPS from vehicle harness. Inspect for and repair any damaged wiring. Set DVOM on 20-volt scale. With KOEO, measure voltage between VREF and SIG RTN circuits at TPS vehicle harness connector. If reading is less than 4 volts or more than 6 volts, go to TEST C, step 1). If reading is between 4 and 6 volts, go to next step.

12) Check TPS Circuit Continuity Turn key off and wait 10 seconds. Leave TPS disconnected. Set DVOM on 200-ohm scale and disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box and connect ECA. Measure resistance between TP circuit at TPS vehicle harness connector and test pin No. 47. If reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components and repeat QUICK TEST. If reading is less than 5 ohms, go to step 14).

13) Check For Shorted 4EAT Module All 3.0L Probe vehicles that are equipped with automatic transmissions have a TP input circuit to the 4EAT module. This test is to verify that TP circuit is not shorted inside the 4EAT module. With key off, reconnect TP sensor. Ensure both 4EAT module vehicle harness connectors are disconnected. Repeat KOEO Self-Test. If Code 63 is present (ignore other codes at this time), disconnect TPS, and go to next step. If Code 63 is not present, service transmission components as necessary.

14) Check TP Circuit For Shorts to Ground Turn key off and wait 10 seconds. Leave TPS disconnected. Ensure both 4EAT module vehicle harness connectors are disconnected (if applicable). Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected and set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 47 and test pins No. 40, 46 and 60. If either reading is less than 10 k/ohms, repair short circuit, reconnect all components and repeat QUICK TEST. If both readings are 10 k/ohms or more, replace ECA. Remove breakout box, reconnect all components, and repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 14) to step 20). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

20) KOER Code 73: Perform Correct Dynamic Response (Goose) Test at Wide Open Throttle (WOT) KOER Code 73 indicates that TPS did not exceed 25% of its rotation during Dynamic Response (Goose) Test. A complete WOT must be performed during Dynamic Response portion of KOER Self-Test.

Run KOER Self-Test, ensure WOT is performed during Dynamic Response portion of test. If Code 73 is still present, go to next step. If not, system is unable to duplicate Code 73 at this time. Service any other KOER codes at this time. If no other KOER codes are present, testing is complete.

21) Check TPS Movement During Dynamic Response Test Turn key off and disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box and connect ECA. Set DVOM on 20-volt scale. Connect DVOM between test pins No. 46 and 47. Perform KOER Self-Test and ensure a proper WOT is performed. Monitor DVOM reading during Goose Check. If reading exceeds 3.5 volts, replace ECA, remove breakout box, reconnect all components and repeat QUICK TEST. If reading does not exceed 3.5 volts, ensure TPS is correctly installed and adjusted. If okay, replace TPS, and repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 21) to step 90). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

90) Continuous Memory Code 53: Monitor TPS Circuit Under Simulated Road Shock Conditions Using KOEO Continuous Monitor Mode (Wiggle Test), observe DVOM or diagnostic tester for indication of fault while slowly opening throttle to WOT. Slowly bring throttle to closed position, lightly tap TPS and wiggle harness connector. This test attempts to find an open or short in the TPS, connectors and vehicle harness. If no fault is indicated, go to step 92). If fault is indicated, go to next step.

91) Measure TP Circuit Voltage While Exercising TPS Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA connected. Stay in KOEO Continuous Monitor Mode (Wiggle Test) as in previous step. Connect DVOM between test pins No. 47 and 46. Set DVOM on 20-volt scale. With KOEO, observe DVOM and repeat step 90). If fault occurs at less than 4.25 volts, inspect TPS connectors and terminals. If okay, replace TPS, clear codes and repeat QUICK TEST. If fault does not occur at less than 4.25 volts, TPS over-travel may have caused Continuous Memory Code 53. TPS is okay, go to next step to check harness.

92) Check EEC-IV Vehicle Harness While in KOEO Continuous Monitor Mode, shake, bend and wiggle small sections of EEC-IV harness from TPS vehicle harness connector to firewall, and from firewall to ECA. If fault is indicated, isolate fault in wiring and repair as necessary. Clear codes and repeat QUICK TEST. If no fault is indicated, go to next step.

93) Check ECA & Harness Connectors Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect both connectors and terminals for obvious damage. If connectors and terminals are damaged, repair as necessary, clear Continuous Memory Codes and repeat QUICK TEST. If connectors and terminals are okay, fault cannot be duplicated at this time. Continuous Memory Code 53 testing is complete.

94) Continuous Memory Code 63: Monitor TP Circuit Under Simulated Road Shock Conditions Using KOEO Continuous Monitor Mode, observe VOM or diagnostic tester for indication of fault while doing the following

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

This test attempts to find an open or short in the TPS, connectors and vehicle harness. If fault is indicated, disconnect TPS. Inspect connectors and terminals. If connectors and terminals are okay, replace TPS. Clear Continuous Memory Codes and repeat QUICK TEST. If no fault is indicated, go to next step.

95) Check EEC-IV Vehicle Harness While in KOEO Continuous Monitor Mode, shake, bend and wiggle small sections of EEC-IV harness from TPS sensor vehicle harness connector to firewall, and from firewall to ECA. If fault is indicated, isolate fault in wiring and repair as necessary. Clear Continuous Memory Codes and repeat QUICK TEST. If no fault is indicated, go to next step.

96) Check ECA & Harness Connectors Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect both connectors and terminals for damage. If connectors and terminals are damaged, repair as necessary. Clear Continuous Memory Codes and repeat QUICK TEST. If connectors and terminals are okay, fault cannot be duplicated at this time. Continuous Memory Code 63 testing is complete.

PRESSURE FEEDBACK EGR (PFE) VALVE & EGR VACUUM REGULATOR (EVR) SOLENOID

Note. Perform this test when Service Code 31, 32, 33, 34, 35, or 84 is displayed during QUICK TEST or when directed here by other test procedures.

Note. This CIRCUIT TEST is intended to diagnose the following

1. VREF, PFE, SIG RTN, EVR and VPWR harness circuits
2. PFE sensor
3. EVR solenoid
4. EGR valve assembly
5. ECA
6. Vacuum lines and tubes of EVR and PFE

Pressure Feedback EGR (PFE) & EGR Valve Regulator (EVR) Ckts. Scheme 52

TEST PIN WIRE COLOR IDENTIFICATION

PFE SENSOR SPECIFICATIONS

To prevent replacement of good components, be aware that 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

1) Code 31: Generate Code 35 Code 31 indicates the PFE sensor signal is less than self-test minimum of 0.2 volt. Possible causes for this fault are: faulty PFE sensor, open harness circuits, shorted harness circuits, or a faulty ECA. Turn key off. Disconnect PFE harness at sensor. Install a jumper wire between VREF circuit and PFE circuit at PFE sensor vehicle harness connector. Perform KOEO Self-Test. Check for Code 35. Ignore all other codes at this time. If no codes are displayed, immediately remove jumper wire and go directly to step 4). If Code 35 is displayed, remove jumper wire and replace PFE sensor. Repeat QUICK TEST. If Code 35 is not displayed, remove jumper wire and go to next step.

2) Measure VREF Circuit Voltage With key off and PFE sensor disconnected, set DVOM on 20-volt scale. With KOEO, measure voltage at PFE sensor vehicle harness connector between VREF and SIG RTN circuits. If reading is less than 4 volts or more than 6 volts, go to TEST C, step 1). If reading is between 4 and 6 volts, go to next step.

3) Check PFE Circuit Continuity With key off and PFE sensor disconnected, set DVOM on 200-ohm scale. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Measure resistance between PFE circuit at PFE sensor vehicle harness connector and test pin No. 27. If resistance is 5 ohms or more, repair open circuit. Connect PFE sensor and remove breakout box. Repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

4) Check PFE Circuit For Shorts to Ground & SIG RTN With key off and PFE sensor disconnected, install breakout box leaving ECA disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between PFE circuit at vehicle harness connector and test pins No. 40 and 60 at the breakout box. Measure resistance between PFE circuit at the PFE sensor vehicle harness connector and test pin No. 46. If either reading is less than 10 k/ohms, repair short circuit. Connect PFE and remove breakout box. Repeat QUICK TEST. If both readings are 10 k/ohms or more, replace ECA. Reconnect all components and remove breakout box. Repeat QUICK TEST.

5) Code 35: Generate Code 31 Code 35 indicates the PFE sensor signal is greater than self-test maximum of 4.8 volts. Possible causes for this fault are: a faulty PFE sensor, shorted vehicle harness circuits, or faulty ECA. Turn key off and disconnect PFE sensor. Inspect for and repair any damaged wiring. Repeat KOEO Self-Test. Check for Code 31. Ignore all other codes at this time. If Code 31 is not displayed, proceed to step 7). If Code 31 is displayed, go to next step.

6) Measure VREF Circuit Voltage With key off and PFE sensor disconnected, set DVOM on 20-volt scale. Turn key on, leaving engine off. Measure voltage at PFE sensor vehicle harness connector between VREF circuit and SIG RTN circuit. If reading is between 4 and 6 volts, replace PFE sensor. Repeat QUICK TEST. If reading is less than 4 volts or more than 6 volts, go to TEST C, step 1).

7) Check PFE Circuit For Shorts to Power With key off and PFE harness disconnected, disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 27 and test pins No. 26, 37 and 57. If either reading is less than 10 k/ohms, repair short. Connect PFE and remove breakout box. Repeat QUICK TEST. If both readings are 10 k/ohms or more, replace ECA. Connect PFE and remove breakout box. Repeat QUICK TEST.

8) Code 34: Verify KOER Codes Code 34 indicates that PFE sensor is out of Self-Test range of 2.6-4.2 volts and that PFE sensor is probably faulty. The PFE system can detect lack of pressure in exhaust system. An efficient garage exhaust ventilation system, installed during KOEO Self-Test may cause PFE sensor to generate Code 34. Remove exhaust ventilation system and retest. If Code 34 is not displayed, service other codes displayed during KOEO Self-Test. If none are displayed, continue with QUICK TEST. If Code 34 is displayed, go to next step.

9) Check PFE Sensor Pressure Input Hose Remove pressure feed tube from PFE sensor. Inspect complete tube, including PFE inlet for blockage. If blockage is found, repair as necessary. Repeat QUICK TEST. If no blockage is found, go to next step.

10) Measure VREF Circuit Voltage Turn key off and disconnect PFE sensor. Inspect for and repair any damaged wiring. Set DVOM on 20-volt scale. Turn key on, leaving engine off. Measure voltage at PFE sensor vehicle harness connector between VREF and SIG RTN circuit. If reading is between 4 and 6 volts, replace PFE sensor. Repeat QUICK TEST. If reading is less than 4 volts or more than 6 volts, go to TEST C, step 1).

11) Code 84: Measure EVR Solenoid Resistance Code 84 indicates a failure in EVR solenoid circuit. Possible causes for this fault are: faulty EVR solenoid, open or shorted harness circuit, or faulty ECA. Turn key off. Set DVOM on 200-ohm scale. Disconnect EVR solenoid connector and measure solenoid resistance. If reading is less than 30 ohms or more than 70 ohms, replace EVR solenoid assembly. Repeat QUICK TEST. If reading is between 30 and 70 ohms, go to next step.

12) Check VPWR Circuit Voltage With KOEO and EVR solenoid disconnected from harness, set DVOM on 20-volt scale. Measure voltage between negative battery terminal and VPWR circuit at EVR solenoid vehicle harness connector. If reading is less than 10.5 volts, repair open circuit. Repeat QUICK TEST. If reading is 10.5 volts or more, go to next step.

13) Check Continuity of EVR Circuit Turn key off and disconnect EVR solenoid from harness. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 33 and EVR circuit at the EVR solenoid vehicle harness connector. If resistance is 5 ohms or more, repair open circuit. Connect EVR solenoid and remove breakout box. Repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

14) Check EVR Circuit For Shorts to Power or Ground Turn key off. Install breakout box, leaving ECA disconnected. Disconnect EVR solenoid. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 33 and test pins No. 37, 57, 40, and 60 at the breakout box. If any reading is less than 10 k/ohms, repair short circuit. Remove breakout box. Connect ECA and EVR solenoid. Repeat QUICK TEST. If code is repeated, replace ECA. If all readings are 10 k/ohms or more, replace ECA. Remove breakout box. Reconnect ECA and EVR solenoid. Repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 14) to step 20). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

20) Code 32: Verify KOER Codes Code 32 indicates EGR valve is not fully seated. Possible causes for this fault are: obstructed vacuum line, contaminated EVR filter, faulty EGR valve or faulty EVR solenoid. The PFE system can detect a lack of pressure in exhaust system. An efficient garage exhaust ventilation system, installed during KOER Self-Test may cause PFE sensor to generate Code 32. Temporarily remove exhaust ventilation system and retest. If Code 32 is not displayed, service other codes displayed during KOER Self-Test. If none, continue with QUICK TEST. If Code 32 is displayed, go to next step.

21) Code 31: Separate EVR From PFE Code 31 indicates PFE sensor signal is less than self-test minimum of 3.25 volts. Turn key off. Disconnect and plug EGR valve vacuum hose. Perform KOER Self-Test. If Codes 31 or 32 are present, go to next step. If not, EVR filter or solenoid is contaminated. Replace EVR solenoid. Reconnect all components and repeat QUICK TEST.

22) Check PFE Sensor Supply Tube For Blockage With key off, check PFE sensor supply tube for blockage or leaks. If these faults are found, repair as necessary. Connect all lines and repeat QUICK TEST. If no faults are found, service or diagnose faulty EGR system.

Note. There is a break in the step numbering sequence at this point, skipping from step 22) to step 25). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

25) Codes 34 or 35: Check For Excessive Backpressure Codes 34 and 35 in KOER Self-Test indicate excessive exhaust backpressure. There are 2 possible causes: the exhaust system is blocked, or PFE sensor is faulty. Turn key off. Substitute known good PFE sensor in place of original. Repeat KOER Self-Test. If Code 34 or 35 is not displayed, original sensor was faulty, replace it. Repeat QUICK TEST. If Code 34 or 35 is displayed, refit original PFE sensor and check exhaust system for restrictions.

Note. There is a break in the step numbering sequence at this point, skipping from step 25) to step 30). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

30) Code 33: Verify Vacuum at EGR Valve Code 33 indicates PFE sensor input did not change after EVR solenoid received signal from ECA to open the EGR valve. Possible causes for this fault are as follows

1. Vacuum hose leaks
2. Obstructed vacuum hose
3. Faulty EVR solenoid
4. Faulty PFE sensor
5. Faulty EGR valve

Turn key off and wait 10 seconds. 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 in. Hg, go to step 36). If vacuum reading is 1 in. Hg or less, remove vacuum gauge and go to next step.

31) Check Vacuum Hoses With key off, check vacuum hose from EVR solenoid to EGR valve and from vacuum source to EVR solenoid for loose connections, obstructions, cracks, etc. If vacuum hoses are damaged, repair or replace as necessary. Repeat QUICK TEST. If hoses are okay, go to step 34).

32) Check Source Line Vacuum Turn key off and wait 10 seconds. Attach vacuum gauge to supply line between throttle body and EVR solenoid at the solenoid. Start and run engine at 2000 RPM. If vacuum reading is greater than 10 in. Hg, go to step 35). If vacuum reading is less than 10 in. Hg, go to next step.

33) Check PCV Valve Operation With key off, disconnect vacuum hose at PCV valve from EVR solenoid. Connect vacuum pump to PCV valve. Slowly apply 10 in. Hg. If PCV valve opens and does not leak down, remove vacuum gauge, reconnect PCV valve, replace vacuum line to EGR solenoid. If PCV valve does not open, service or replace PCV valve.

34) Check Vacuum to EVR Solenoid Turn key off and wait 10 seconds. Attach vacuum gauge to source line from manifold. Start engine and run at idle. If vacuum is present, go to next step. If no vacuum is present, replace vacuum hose to EVR solenoid and repeat QUICK TEST.

35) Check EGR Valve Operation With KOEO, disconnect vacuum hose at EGR valve. Connect vacuum pump to EGR valve. While observing EGR valve, slowly apply 10 in. Hg. The EGR valve should begin to open with a very small amount of vacuum (1-1.5 in. Hg) and be fully open with about 4 in. Hg. If EGR opens freely and smoothly, replace EVR solenoid, remove vacuum pump and rerun QUICK TEST. If EGR valve does not open freely and smoothly, service or replace EGR valve.

36) Check PFE Sensor Control Pressure Input Tube With key off, check control pressure input tube to PFE sensor for cracks, obstructions or faulty connections. If supply tube is faulty, repair as necessary. If supply tube is okay, go to next step.

37) Substitute Known Good PFE Sensor Turn key off and wait 10 seconds. Substitute known good PFE sensor in place of original. Rerun KOER Self-Test. If Code 33 is present, reinstall original EGR valve and diagnose EGR system as necessary. If Code 33 is not present, original PFE sensor was the cause of the original Code 33. Replace PFE sensor and rerun QUICK-TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 37) to step 90). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

90) Continuous Memory Code 31 or 35: Testing PFE Sensor Code 31 or 35 indicates that PFE sensor signal was less than (Code 31) or greater than (Code 35) the self-test voltage sometime during vehicle operation. Possible causes for this fault are: damaged connectors or terminals, open or grounded vehicle harness, or faulty PFE sensor.

Using KOEO Continuous Monitor Mode (Wiggle Test), observe VOM or diagnostic tester for indication of fault while performing the following steps. Connect a vacuum pump to PFE sensor and slowly apply 5 in. Hg to sensor. Slowly bleed vacuum off PFE sensor. Lightly tap on PFE sensor and wiggle PFE connector. If fault is indicated, disconnect harness and inspect connector. If connector and terminals are okay, replace PFE sensor. Clear codes and repeat QUICK TEST. If no fault is indicated, go to next step.

PFE Harness Circuit. Scheme 53

91) Check EEC-IV Vehicle Harness With vehicle still in KOEO Continuous Monitor Mode, observe VOM or diagnostic tester for fault indication while grasping vehicle harness close to sensor connector, then wiggling, shaking or bending small sections of harness while working your way to firewall. Also wiggle, shake or bend harness from firewall to ECA. If fault is indicated, isolate fault and repair as necessary. Repeat QUICK TEST. If fault is not indicated, go to next step.

92) Check ECA & Vehicle Harness Connectors Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect both connector and terminals for damage. If connector and terminals are damaged, repair as necessary. Clear codes and repeat QUICK TEST. If connector and terminals are okay, fault is intermittent and cannot be duplicated at this time. Clear codes and repeat QUICK TEST.

93) Continuous Memory Code 34: Check PFE Supply Tube For Blockage Code 34 indicates that the PFE sensor was restricted sometime during vehicle operation. Turn key off. Remove PFE sensor and inspect sensor supply inlet for liquids or any type of blockage. Inspect PFE supply tube at EGR valve base for liquids or blockage. If supply tube is blocked, clean or service as necessary. Clear codes and repeat QUICK TEST. If supply tube is not blocked, fault is intermittent and cannot be duplicated at this time. Clear codes and repeat QUICK TEST.

94) Continuous Memory Code 32: Check EGR Valve Operation Code 32 indicates that the EGR valve did not seat itself fully sometime during vehicle operation. Possible causes for this fault are: obstructed vacuum hose, contaminated EVR filter, or faulty EGR valve. Turn key off. Connect vacuum pump to EGR valve and apply 10 in. Hg. While observing EGR valve, release vacuum, and repeat step if necessary. If EGR valve does not operate smoothly, service or replace EGR valve, clear codes and repeat QUICK TEST. If EGR valve works smoothly, go to next step.

95) Inspect Vacuum Lines Between EVR Solenoid & EGR Valve Inspect EGR valve vacuum supply line from EVR solenoid to EGR valve for kinks or obstructions. If vacuum supply line is blocked, repair as necessary. Clear codes and repeat QUICK TEST. If vacuum supply line is okay, go to next step.

96) Inspect EVR Solenoid Filter Carefully check EVR filter for contamination or obstructions. If EVR filter is contaminated, replace filter, clear codes and repeat QUICK TEST. If EVR filter is not contaminated, fault is intermittent and cannot be duplicated at this time. Continuous Memory Code 32 testing is complete.

97) Continuous Memory Code 33: Check EGR Valve Operation Code 33 indicates that EGR valve intermittently did not open, when required, during vehicle operation. Possible causes for this fault are a faulty EGR valve or a shorted or open harness circuit. Turn key off. Connect a vacuum pump to EGR valve. While observing EGR valve, slowly apply 10 in. Hg. EGR valve should begin to open at 1-1.5 in. Hg and be fully open at 4 in. Hg. If EGR valve does not move freely and smoothly, service exhaust gas recirculation system, clear codes and repeat QUICK TEST. If EGR valve moves freely and smoothly, go to next step.

98) Check EVR Harness With key off, disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box and connect ECA to box. Enter Output State Check mode, see ADDITIONAL SYSTEM FUNCTIONS,. Set DVOM on 20-volt scale. Connect DVOM negative test lead to test pin No. 40 at breakout box and DVOM positive test lead on test pin No. 33. Move throttle (if necessary), to indicate 10.5 volts or more and maintain position. While observing DVOM, grasp harness closest to EVR connector. Wiggle, shake or bend small sections of harness while working your way to firewall. Lightly tap EVR solenoid to simulate road vibration. If DVOM reads 10.5 volts or less, isolate fault and repair as necessary. Clear codes and repeat QUICK TEST. If DVOM reads 10.5 volts or more, fault cannot be duplicated at this time. Continuous Memory Code 33 testing is complete.

EGR VALVE POSITION (EVP) SENSOR & EGR VALVE REGULATOR (EVR) SOLENOID

Note. Perform this test when Code 31, 32, 33, 34, 35, 38 or 84 is displayed during QUICK TEST or when directed here by other test procedures.

Note. To prevent the replacement of good components, be aware that a damaged EGR valve may be at fault.

Note. This CIRCUIT TEST is intended to diagnose the following

1. EVP sensor
2. VREF, EVP, SIG RTN, EVR, and VPWR harness circuits
3. EVR solenoid
4. EGR valve assembly
5. ECA
6. EGR and EVR vacuum lines

EGR Valve Position (EVP) Sensor & EGR Valve Regulator (EVR) Solenoid Circuits. Scheme 54

TEST PIN WIRE COLOR IDENTIFICATION

1) Code 31: Generate Code 35 Code 31 indicates that EVP sensor signal is less than the self-test minimum of 0.2 volt. Possible causes for this fault are: a faulty EVP sensor, an open or grounded harness, or a faulty ECA. Turn key off and wait 10 seconds. Disconnect EVP harness at sensor. Install a jumper wire between VREF circuit and EVP circuit at the EVP sensor vehicle harness connector. Repeat KOEO Self-Test. Check for code 35. Ignore all other codes at this time. If Code 35 is displayed, remove jumper and replace EVP sensor. Repeat QUICK TEST. If Code 35 is not displayed, remove jumper wire and go to next step.

2) Check VREF Circuit Voltage With KOEO and EVP sensor disconnected, set DVOM on 20-volt scale. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Measure voltage at EVP sensor vehicle harness connector between VREF circuit and SIG RTN circuit. If reading is less than 4 or greater than 6 volts, go to TEST C, step 1). If reading is between 4 and 6 volts, go to next step.

3) Check EVP Circuit Continuity With key off, wait 10 seconds. Disconnect EVP sensor, set DVOM on 200-ohm scale. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, and connect ECA to box. Measure resistance between EVP circuit at EVP sensor vehicle harness connector and test pin No. 27. If reading is 5 ohms or more, repair open circuit. Connect EVP sensor and remove breakout box. Repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

4) Check EVP Circuit For Shorts to Ground With key off and EVP sensor disconnected, leave breakout box installed and ECA disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 27 and test pins No. 40, 46 and 60. If any reading is less than 10 k/ohms, repair short circuit. Reconnect all components and remove breakout box. Repeat QUICK TEST. If both readings are 10 k/ohms or more, replace ECA. Connect EVP and remove breakout box. Repeat QUICK TEST.

5) Code 35: Generate Code 31 Code 35 indicates EVP sensor signal is greater than the self-test maximum of 4.81 volts. Possible causes for this fault are a faulty EVP sensor or a short to power in the vehicle harness. Turn key off and wait 10 seconds. Disconnect EVP sensor. Inspect for and repair any damaged wiring. Perform KOEO Self-Test. Check for Code 31. Ignore all other codes at this time. If Code 31 is not displayed, go to step 7). If Code 31 is displayed, go to next step.

6) Check VREF Circuit Voltage With EVP harness disconnected, set DVOM on 20-volt scale. With KOEO, measure voltage at EVP sensor vehicle harness connector between VREF circuit and SIG RTN circuit. If reading is between 4 and 6 volts, replace EVP sensor. Repeat QUICK TEST. If reading is less than 4 volts or more than 6 volts, go to TEST C, step 1).

7) Check EVP Circuit For Short To Power Turn key off and disconnect EVP sensor. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 27 and test pins No. 26 and 57. If either reading is less than 10 k/ohms, repair short in harness. Connect EVP sensor and remove breakout box. Repeat QUICK TEST. If both readings are 10 k/ohms or more, replace ECA. Reconnect EVP sensor and remove breakout box. Repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 7) to step 10). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

10) Code 84: Check EVR Solenoid Resistance Code 84 indicates a fault in the EVR solenoid circuit. Possible causes for this fault are a faulty EVR solenoid or, shorted or open harness. Turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Disconnect EVR solenoid connector and measure solenoid resistance.

EVR SOLENOID RESISTANCE

If reading is not within specification, replace EVR solenoid assembly and repeat QUICK TEST. If reading is within specification, go to next step.

11) Check VPWR Circuit Voltage Leave EVR solenoid disconnected and set DVOM on 20-volt scale. Turn key on, leaving engine off. Measure voltage between negative battery terminal and VPWR circuit at EVR solenoid vehicle harness connector. If reading is less than 10.5 volts, repair VPWR open circuit. Reconnect components and repeat QUICK TEST. If reading is 10.5 volts or more, go to next step.

12) Check EVR Circuit Continuity With key off and EVR solenoid disconnected, disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 33 and EVR circuit at EVR solenoid vehicle harness connector. If reading is 5 ohms or more, repair open circuit. Reconnect all components and remove breakout box. Repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

13) Check EVR Circuit For Shorts to Power or Ground With key off, breakout box installed, and ECA disconnected. Disconnect EVR solenoid. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 33 and test pins No. 37 and 57, 40, 60, and 46 at breakout box. If any reading is less than 10 k/ohms, repair short circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST. If code is repeated, replace ECA. If all readings are 10 k/ohms or more, replace ECA. Remove breakout box, and reconnect all components. Repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 13) to step 20). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

20) KOEO Code 34: Check For Code 84 KOEO Code 34 indicates EGR valve and/or EVP is not fully seated in the closed position. EVP voltage signal, in the closed position, is greater than the self-test maximum of 0.67 volt. Because of the preload on the installed EVP sensor it is very difficult to determine if the EGR valve is seated or the EVP sensor is in contact with the EGR valve. Possible causes for this fault are: poor continuity at EVP sensor, non-seated EGR valve, faulty EGR valve or EVP sensor. Turn key off and wait 10 seconds. Check for Code 84 in KOEO Self-Test. If Code 84 is present, go to step 10) in this TEST. If Code 84 is not displayed, go to next step.

21) Check EVP Sensor & EGR Valve Operation Turn key off and wait 10 seconds. Disconnect EVP sensor. Inspect harness and connector, service as necessary. Remove vacuum line from EGR valve. Test EGR valve operation by applying and releasing vacuum to valve, using a vacuum pump or pressing and releasing the diaphragm manually. Reconnect vacuum line to EGR valve and connector to EVP sensor. Repeat KOEO and KOER Self-Test. If Code 34 is still displayed, go to next step. If Code 34 is not displayed, the original code was set by a faulty connection or a sticking EGR valve. Testing of EGR valve is complete.

22) Substitute EVP Sensor on Original EGR Valve Turn key off and wait 10 seconds. Install a known good EVP sensor on original EGR valve. Perform KOEO Self-Test. If Code 34 is present, check EGR valve for mechanical fault. If Code 34 is not present, service or replace original EVP sensor. Repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 22) to step 25). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

25) KOEO & KOER Code 32: Checking EVP Sensor & EGR Valve Operation Code 32 indicates that EGR valve and/or EVP sensor signal voltage is less than closed position minimum of 0.29 volt. Preload on EVP sensor makes it difficult to determine whether the EGR valve has malfunctioned or if the EVP sensor has abnormally high resistance. Possible causes for this fault are: poor continuity at EVP sensor connector, non-seated or faulty EGR valve or faulty EVP sensor.

Turn key off and wait 10 seconds. Disconnect EVP sensor. Inspect connector and harness for damage and service as necessary. Remove vacuum line from EGR valve. Test EGR valve operation by applying and releasing vacuum to valve, using a vacuum pump or manually depressing and releasing the diaphragm manually. Reconnect vacuum line to EGR valve and connector to EVP sensor. Repeat KOEO and KOER Self-Tests. If Code 32 is still present, go to next step. If Code 32 is not displayed, the original code was set by a faulty connection or a sticking EGR valve. Testing of EGR valve is complete.

26) Substitute EVP Sensor on Original EGR Valve Turn key off and wait 10 seconds. Install a known good EVP sensor on original EGR valve. Perform KOEO Self-Test. If Code 32 is present, check EGR valve for mechanical malfunction. If Code 32 is not present, replace original EVP sensor. Repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 26) to step 40). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

40) KOER Code 33: Check Vacuum at EGR KOER Code 33 indicates that EVP sensor input did not change after ECA signaled EGR operation. Because a Code 84 was not received in the KOEO Self-Test, the EVR solenoid electrical function is okay. The lack of Code 32 or 34 indicates the EVP sensor is within the closed position specifications. Possible causes for this fault are: leaking vacuum hose, restricted vacuum hose, restricted EVR solenoid filter, or a faulty EGR valve.

Turn key off. Disconnect vacuum line from EGR valve. Connect a vacuum gauge at open end of line. Perform KOER Self-Test and observe vacuum gauge. If reading is greater than 1.5 in. Hg, remove vacuum gauge and go to step 43). If not, remove vacuum gauge, reconnect EGR valve vacuum line and go to next step.

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

42) Check Vacuum Hose Between EVR Solenoid & EGR Valve Carefully check vacuum line for cracks, loose connections, blockage, kinks, and leaks. If vacuum hose is faulty, replace hose. Connect new vacuum hose. Repeat QUICK TEST. If vacuum hose is okay, check EVR solenoid filter for obstructions. Replace if needed. If filter is okay, replace EVR solenoid. Connect vacuum hoses. Repeat QUICK TEST.

43) Check EVP Sensor & EGR Valve Operation Turn key off and wait 10 seconds. Disconnect EVP sensor. Inspect connector and harness for damage and service as necessary. Remove vacuum line from EGR valve. Test EGR valve operation by applying vacuum or manually depressing and releasing the diaphragm. Reconnect vacuum line to EGR valve and connector to EVP sensor. Repeat KOEO and KOER Self-Test. If Code 33 is still present, go to next step. If Code 33 is not displayed, the original code was set by poor continuity at EVP sensor connector or a sticking EGR valve. Testing of EGR valve is complete.

44) Verify EGR Valve Vacuum Control With key off, disconnect EGR valve vacuum supply. Connect a vacuum gauge to EGR valve and apply 2-3 in. Hg for 2 minutes. If EGR holds vacuum, reconnect supply line and go to next step. If EGR valve will not hold vacuum, service or replace EGR valve.

45) Substitute Known Good EVP Sensor on Original EGR Valve Turn key off and wait 10 seconds. Install a known good EVP sensor on original EGR valve. Perform KOER Self-Test. If Code 33 is present, check EGR valve and/or system for mechanical malfunction. If Code 33 is not present, service or replace original EVP sensor. Repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 45) to step 50). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

50) Code 34: Check EGR Valve Operation in KOER Self-Test With EGR Vacuum Disconnected KOER Code 34 indicates that EVP voltage is greater than closed position self-test limit of 0.67 volt. Possible causes for this fault are: obstructed EVR solenoid filter, faulty EVR solenoid, faulty EGR valve, or faulty EVP sensor. Turn key off. Disconnect and plug EGR valve vacuum hose. Perform KOER Self-Test. If Code 34 is not present, check EVR solenoid filter for obstructions. Replace if necessary. If filter is okay, replace EVR solenoid. Connect all vacuum hoses and repeat QUICK TEST. If Code 34 is present, go to next step.

51) Check EVP Sensor Resistance While Applying Vacuum to EGR Valve Turn key off and wait 10 seconds. Disconnect harness from EVP sensor. Inspect connectors for damaged pins or corrosion. Repair if necessary. Set DVOM on 200-k/ohm scale. Disconnect vacuum hose to EGR valve and connect vacuum pump to valve. Measure resistance at EVP sensor between EVP circuit and VREF circuit while gradually increasing vacuum to 10 in. Hg. If reading decreases from no more than 5500 ohms to no less than 100 ohms, check EGR valve for mechanical malfunction and service or replace as necessary. If reading does not change as indicated, replace EVP sensor. Reconnect vacuum hose and rerun QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 51) to step 90). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

90) Continuous Memory Code 32: Check EVP Signal Voltage While Operating EVP Sensor Code 32 indicates that EGR valve closed further than normal with engine at idle and at normal operating temperature or that EVP sensor has failed with an intermittent low voltage spike symptom. Possible causes for this fault are an obstructed vacuum valve, a faulty EVP sensor or EGR valve. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box and connect ECA. Disconnect vacuum hose at EGR valve. Connect a vacuum pump to EGR valve. Set DVOM on 20-volt scale. With KOEO, measure voltage between test pins No. 27 and 46 while slowly applying 6 in. Hg to EGR valve. Slowly bleed vacuum off EGR valve and lightly tap on EVP sensor to simulate road shock. If voltage drops to less than .24 volt, the EGR valve may have caused Code 32. Clear Continuous Memory Codes. Check EGR valve for mechanical malfunction. If all readings are more than .24 volt, go to next step.

91) Continuous Memory Code 32/31: Check EVP Sensor While in Continuous Monitor Mode Code 31 indicates that sometime during vehicle operation, EVP signal was out of self-test range. Possible causes for this fault are a faulty EVP sensor or open or shorted circuit.

With DVOM connected as in previous step, enter KOEO Continuous Monitor Mode (Wiggle Test). Connect a vacuum pump to EGR valve. Observe DVOM while performing the following procedures. If a fault is indicated, go to next step. If not, go to step 93).

1. Very slowly apply 6 in. Hg to EGR valve.
2. Slowly bleed off vacuum from EGR valve, while tapping on EVP sensor to simulate road shock.
3. Wiggle EVP sensor connector.

Checking EVP Harness Circuit. Scheme 55

92) Measure EVP Signal Voltage While Exercising EVP Sensor Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector and terminals for obvious damage. If connector and terminals are damaged, repair as necessary. Install breakout box and reconnect ECA. Set DVOM on 20-volt scale and connect DVOM between test pins No. 27 and 46. Re-enter KOEO Continuous Monitor Mode (Wiggle Test). Observe DVOM while repeating test step 91). If the fault occurs at less than 4.25 volts, disconnect and inspect connector. If connector is okay, replace EVP sensor. Clear codes and repeat QUICK TEST. If fault does not occur at less than 4.25 volts, go to next step.

93) Continuous Memory Code 31 and/or 35: Check EEC-IV Harness Code 31 indicates an open in the EVP or VREF circuits, or a short to SIG RTN with the engine at idle and at normal operating temperature. Code 35 indicates a short to VREF and/or VPWR, or an open in SIG RTN with the engine at idle and at normal operating temperature.

Using KOEO Continuous Monitor Mode, observe VOM or diagnostic tester for fault indication while grasping harness close to sensor and wiggling, shaking, or bending a small section of EEC-IV harness while working toward dash panel. Wiggle, shake or bend harness from firewall to ECA. If fault is indicated, isolate fault and repair wiring harness as required. Clear codes and repeat QUICK TEST. If fault is not found, go to next step.

EVP Harness Faults. Scheme 56

94) Check ECA & Harness Connectors Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector and terminals for obvious damage. If connector and terminals are damaged, repair as necessary. Clear codes and repeat QUICK TEST. If connector and terminals are okay, fault cannot be duplicated at this time. Clear codes. Check EGR valve for mechanical fault.

95) Continuous Memory Code 33: Leak Test Code 33 indicates that EGR valve did not open with the engine at normal operating temperature and with the EVR solenoid signal present. Possible causes of this fault are: an obstructed or cracked vacuum line, an open circuit or a faulty EGR valve. Turn key off and wait 10 seconds. Disconnect vacuum hose at EGR valve and connect vacuum pump to valve. Apply 20 in. Hg to EGR valve. If EGR valve opens and holds vacuum, remove vacuum pump, reconnect EGR valve and go to next step. If not, remove pump and reconnect EGR valve. Clear codes and service or replace EGR valve as necessary.

96) EVR Solenoid Check Using Continuous Monitor Mode (Wiggle Test), observe VOM or diagnostic tester for fault indication. Grasp harness close to EVR solenoid connector and wiggle, shake, or bend a small section of harness while working toward ECA. Inspect connectors and terminals for obvious damage. If fault is indicated, isolate fault and repair as necessary. Clear codes and repeat QUICK TEST. If no fault is indicated, fault cannot be duplicated at this time. Clear codes and repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 96) to step 98). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

98) Continuous Memory Code 34: Check EVP Resistance While Applying Vacuum to EGR Valve Code 34 indicates EGR valve was open with the engine idling at normal operating temperature. Possible causes for this fault are: a faulty EVR filter, EVR solenoid or EGR valve.

Turn key off and disconnect EVP sensor. Inspect connector for obvious damage. Place DVOM on 200-k/ohm scale. Disconnect vacuum hose to EGR valve and connect vacuum pump to valve. Measure resistance at EVP sensor between EVP circuit and VREF circuit at the sensor while increasing vacuum to 10 in. Hg. If reading does not decrease gradually from up to 5500 ohms to not less than 100 ohms, remove vacuum pump and reconnect all components. Clear codes and check EGR valve for mechanical malfunction. If reading gradually decreases from no more than 5500 ohms to no less than 100 ohms, remove vacuum pump and reconnect all components. Go to next step.

99) EVR Check Turn key off. Disconnect vacuum hose from EGR valve and plug hose. Perform KOER Self-Test. If Code 34 is present, check EVR filter for obstructions. Replace if necessary. If filter is okay, replace EVR solenoid. Connect all vacuum hoses and repeat QUICK TEST. If Code 34 is not present, fault cannot be duplicated at this time. Clear codes and repeat QUICK TEST. Testing is complete.

TEST DP - VEHICLE SPEED SENSOR (VSS)

Note. Perform this test when Code 29 is displayed during QUICK TESTS or when directed here by TEST TC.

Note. This TEST is intended to diagnose the following

1. VSS harness circuits
2. Vehicle Speed Sensor (VSS)
3. ECA

Vehicle Speed Sensor Circuit. Scheme 57

TEST PIN WIRE COLOR IDENTIFICATION

PRELIMINARY INSTRUCTIONS - AUTO TRANS

Preliminary Instructions (Automatic Transmission Equipped Vehicles) - Record and clear Continuous Memory Codes. Warm engine to normal operating temperature. In Low gear, accelerate hard to 25 MPH and coast down to a stop. Shut off engine. Perform KOEO Self-Test. Go to step 1).

PRELIMINARY INSTRUCTIONS - MAN TRANS

Preliminary Instructions (Manual Transmission Equipped Vehicles) - Record and clear Continuous Memory Codes. Warm engine to normal operating temperature. Start in first gear, shift to second gear, and accelerate moderately to 40 MPH. Coast down to idle and stop. Shut engine off. Perform KOEO Self-Test and record Continuous Memory Codes. Go to step 1).

1) Continuous Memory Code 29 Code 29 indicates there is insufficient input to the ECA from the VSS. Possible causes for this code are a faulty VSS, open or shorted circuit or a faulty ECA. Perform drive cycle procedure applicable to the type of transmission fitted to the vehicle (except 3.0L PFI Aerostar). On 3.0L PFI Aerostar vehicles, ensure driveability complaint can be verified. If Code 29 is still present or driveability complaint can be verified (3.0L PFI Aerostar), go to next step. If not, fault cannot be duplicated at this time, clear codes and see INTERMITTENTS in TESTS W/O CODES article.

2) Checking VSS Resistance Turn key off and wait 10 seconds. Disconnect VSS. Set DVOM on 2-k/ohm scale. Measure resistance across vehicle speed sensor. If reading is 190-250 ohms, go to next step. If reading is incorrect, replace vehicle speed sensor and repeat drive cycle procedure.

3) Check VSS Circuit Continuity Turn key off and wait 10 seconds. Remove ECA 60-pin connector and inspect for damaged pins, corrosion, or loose wires. Repair as necessary. Install breakout box. With ECA and VSS disconnected, set DVOM on 200-ohm scale. Measure resistance between test pin No. 3 at breakout box and VSS DIF (+) circuit at VSS vehicle harness connector. Also measure resistance between test pin No. 6 at breakout box and VSS DIF (-) circuit vehicle harness connector. If both readings are 5 ohms or less, go to next step. If readings are 5 ohms or more, service open circuit in VSS wiring harness. After repairs, reconnect all components and repeat step 1).

Checking VSS Circuits. Scheme 58

4) Check VSS Circuits For Shorts to Power or Ground Turn key off. With ECA and VSS disconnected, install breakout box. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 3 and test pins No. 37, 40 and 6. Also measure resistance between test pin No. 6 and test pin No. 37. If all readings are greater than 10 k/ohms, remove breakout box, reconnect components and go to next step. If any reading is less than 10 k/ohms, repair short(s) in VSS wiring harness and reconnect components. After repairs, repeat step 1).

5) Repeat Drive Cycle Test With Substitute VSS Installed Substitute VSS with known good sensor and repeat drive cycle procedure (except and 3.0L PFI Aerostar) and return to this test step. If Code 29 is still present, replace ECA and repeat step 1). If no code is present, replace original VSS and repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 5) to step 10). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

10) Continuous Memory Code 29: Check For Battery Voltage Code 29 indicates that there is insufficient input to the ECA from the VSS. Possible causes for this fault are, a faulty VSS, an open or shorted circuit, or a faulty ECA. Turn ignition switch to RUN position. Raise vehicle on a hoist and disconnect VSS. Set DVOM on 20-volt scale. Measure voltage between pin No. 1 and pin No. 3 of the VSS vehicle harness connector. If voltage is greater than 10.5 volts, go to next step. If not, check fuse No. 20. If fuse is okay, repair open circuit, reconnect VSS and repeat QUICK TEST.

Checking VSS Voltage. Scheme 59

11) Check Ground to VSS With vehicle raised on hoist and key off, disconnect VSS. Set DVOM on 200-ohm scale. Measure resistance between pin No. 1 of VSS vehicle harness connector and engine block ground. If resistance is less than 5 ohms, go to next step. If not, repair open in VSS circuit. Reconnect VSS and repeat QUICK TEST.

Checking Resistance at VSS Harness Connector. Scheme 60

12) Check VSS Output Voltage With vehicle raised on hoist, turn ignition switch to the RUN position. Place transmission in Neutral. Disconnect VSS. Jumper pin No. 1 of the harness side of connector to pin No. 1 of the sensor side of connector. Jumper pin No. 2 of the harness side of the connector to pin No. 2 of the sensor side of connector. Jumper pin No. 3 of the harness side of the connector to pin No. 3 of the sensor side of connector. Connect positive lead of DVOM to pin No. 2 of the sensor side of connector and negative lead of DVOM to pin No. 1 of sensor side of connector. Set DVOM on 20-volt scale. Observe voltage while slowly rotating rear tire. If voltage rises to greater than 5.5 volts and falls to less than 1.5 volts in a regular cycle, replace ECA, reconnect VSS and repeat QUICK TEST. If not, replace VSS and repeat QUICK TEST.

Checking VSS Output Voltage. Scheme 61

TEST DR - CYLINDER IDENTIFICATION (CID) SENSOR

Note. You should enter this CIRCUIT TEST only when Code 19 is received during QUICK TEST. This test is intended to diagnose only the following

1. Harness circuit, CID (+) and CID (-)
2. CID sensor
3. ECA

CID Harness Circuits. Scheme 62

1) Continuous Memory Code 19: Check CID Sensor Resistance Code 19 indicates and error has been detected in the CID sensor input signal. The error could be due to a hard fault or intermittent condition. Possible causes for this fault are an open or shorted harness, a faulty CID sensor or a faulty ECA. With key off, disconnect CID sensor (located on back of cylinder head coil pack). Set DVOM on 200-k/ohm scale. Measure resistance of CID sensor. If resistance is 300-600 ohms, go to next step. If not, replace CID sensor and repeat QUICK TEST.

2) Check Continuity of CID Circuits With key off, and CID sensor disconnected, disconnect ECA 60-pin connector. Inspect and repair any corroded or damaged pins. Install breakout box, leaving ECA disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 41 and CID (+) circuit at the CID sensor vehicle harness connector. Measure resistance between test pin No. 42 and CID (-) at the CID sensor vehicle harness connector. If each resistance is less than 5 ohms, go to next step. If not, repair open circuit as necessary, remove breakout box and reconnect all components. Repeat QUICK TEST.

Checking CID Sensor Harness Circuit. Scheme 63

3) Check CID Circuit For Shorts With key off, and breakout box installed, ensure ECA and CID sensor are disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 41 and test pins No. 42, 37, 57, 40, and 60. Measure resistance between test pin No. 42 and test pins No. 37, 57, 40, and 60. If each resistance is greater than 10 k/ohms, go to next step. If not, repair short circuit, remove breakout box and reconnect all components. Repeat QUICK TEST.

4) Check For Shorts in ECA With key off, install breakout box and reconnect ECA. Disconnect CID sensor. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 41 and test pins No. 42, 37, 57, 40, and 60. Measure resistance between test pin No. 42 and test pins No. 37, 57, 40, and 60. If each resistance is greater than 500 ohms, go to next step. If not, replace ECA, remove breakout box and reconnect all components. Repeat QUICK TEST.

5) Check CID Sensor Output With key off, breakout box installed and ECA connected, reconnect CID sensor. Set DVOM on AC 5-volt scale. Start engine. Measure voltage between test pins No. 41 and 42 while varying engine RPM. If voltage varies, go to next step. If not, replace CID sensor, remove breakout box and reconnect components. Repeat QUICK TEST.

6) Attempt to Regenerate Code 19 With KOEO, clear Continuous Memory Codes. Start engine. Rev engine to 3100+ RPM, 2 or 3 times. Turn key off. Repeat KOEO Self-Test. If Continuous Memory Code 19 is still present, replace ECA, remove breakout box, reconnect all components and repeat QUICK TEST. If not, Code 19 is an intermittent fault. Check vehicle harness for intermittent opens or shorts. See INTERMITTENTS in TESTS W/O CODES article.

TEST FA - NEUTRAL DRIVE SWITCH (NDS) A/C INPUT CKT

Note. Perform this test when Service Code 67 or 79 is displayed during QUICK TESTS or when directed here by other test procedures. This test is designed to diagnose the following

1. A/C input to ECA
2. Clutch Engagement Switch (CES)
3. Neutral Clutch Switch (NCS)
4. Neutral Drive Switch (NDS)
5. Neutral Gear Switch (NGS)
6. ECA
7. Harness circuits (CES, NCS, NDS, NGS, ACC, ACCS & SIG RTN)

TEST PIN WIRE COLOR IDENTIFICATION

1) Code 67: System Identification Code 67 indicates that during engine cranking or KOEO Self-Test, signal voltage was greater than specification at test pin No. 10 (A/C input) or test pin No. 30 (NDS). Possible causes for this fault are: A/C circuit shorted to power, Neutral clutch/drive circuits open, Neutral clutch/drive switch open, faulty ECA, or a starter relay disconnected during self-test. See TEST STEP APPLICATION REFERENCE to enter this test at the correct step.

TEST STEP APPLICATION REFERENCE

2) Checking Neutral Gear/Clutch Circuit Input Turn key off and wait 10 seconds. Ensure A/C control is in OFF position (if equipped). Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leave ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pins No. 30 and 46 with transmission in Neutral and clutch pedal in the up position. Measure resistance with transmission in gear and clutch pedal depressed. If both resistances are less than 5 ohms, go to next step. If not, go to step 5).

Neutral Gear & Clutch Circuit Diagram. Scheme 64

3) Check Neutral Gear/Clutch Switch Input Circuit Turn key off and wait 10 seconds. Install breakout box, leave ECA disconnected and set DVOM to 200-ohm scale. Measure resistance between test pins No. 30 and 46 with transmission in any gear and the clutch pedal in the UP position. If resistance is less than 5 ohms, on vehicles equipped with A/C, go to step 10). If not equipped with A/C, replace ECA and remove breakout box. Repeat QUICK TEST. If any reading is greater than 5 ohms, go to next step.

4) Check For Short to Ground With key off and breakout box installed, leave ECA disconnected. Disconnect clutch interlock switch. Set DVOM on 200-k/ohm scale. Measure resistance between test pins No. 30 and 46. If resistance is greater than 10 k/ohms, for vehicles with A/C go to step 10). For all other vehicles, replace ECA, remove breakout box and repeat QUICK TEST. If resistance is not greater than 10 k/ohms, repair short circuit, remove breakout box and reconnect ECA. Repeat QUICK TEST.

5) Check Neutral Gear/Clutch Switch Turn key off and wait 10 seconds. Leave breakout box installed and ECA disconnected. Set DVOM on 200-ohm scale. Locate Neutral Gear Switch (NGS) on transmission and Clutch Switch (CS) at clutch pedal linkage. Disconnect harness at both switches and inspect connector for pins that are pushed back. Measure resistance across NGS terminals with transmission in Neutral, and across CS terminals with clutch pedal depressed. If both resistances are less than 5 ohms, go to next step. If all resistances are more than 5 ohms, replace open switches as necessary, remove test equipment, reconnect components and repeat QUICK TEST.

6) Check Neutral Gear/Clutch Harness With key off, set DVOM on 200-ohm scale. Install breakout box, leaving ECA disconnected. Disconnect vehicle harness at NGS and CS. Measure resistance between test pin No. 30 and NGS harness connector. Measure resistance between test pin No. 30 and CS harness connector. Measure resistance between test pin No. 46 and NGS harness connector. Measure resistance between test pin No. 46 and CS harness connector. If each resistance is less than 5 ohms, for vehicles with A/C, go to step 10). For all others, replace ECA. If resistance is not less than 5 ohms, repair open circuit, remove breakout box, reconnect all components and repeat QUICK TEST.

7) Check Clutch Engage Switch Turn key off. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box and leave ECA disconnected. Set DVOM on 200-ohm scale. Depress clutch pedal. Measure resistance between test pins No. 30 and 46. If both readings are less than 5 ohms, on vehicles equipped with air conditioning, go to step 10). If not equipped with A/C, replace ECA. If any reading is 5 ohms or more, repair open circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST.

Checking Clutch Switch Circuit. Scheme 65

8) Check Neutral Drive Input Turn key off and wait 10 seconds. Ensure heater control is in OFF position. Ensure transmission is in Neutral or Park position. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box and leave ECA disconnected. Set DVOM to 20-volt scale. Connect ECA to breakout box. With KOEO, measure voltage between test pin No. 30 at the breakout box and chassis ground. If voltage is less than one volt, on vehicles equipped with A/C, go to step 10). If not equipped with A/C, replace ECA. If reading is more than one volt, go to next step.

Checking NDS Switch Circuit. Scheme 66

9) Check Neutral Drive Switch Turn key off and wait 10 seconds. Install breakout box, leave ECA disconnected. Set DVOM on 200-ohm scale. Disconnect vehicle harness from NDS at transmission and measure resistance across switch. If resistance is less than 5 ohms, remove breakout box. Reconnect all components and service open in NDS circuit. If resistance is more than 5 ohms, replace NDS and rerun QUICK TEST.

10) Check A/C Input On vehicles equipped with E4OD transmissions, ensure transmission is in Park. Ensure A/C is turned off. If A/C was on, rerun QUICK TEST. If Code 67 or 79 is displayed, continue with this test.

Install breakout box and leave ECA disconnected. With KOEO, set DVOM on 20-volt scale. Measure voltage at test pin No. 10 at the breakout box and chassis ground. If reading is greater than one volt, remove breakout box and repair short to power in A/C clutch power circuit. If voltage is less than one volt, replace ECA, except on vehicles equipped with E4OD transmissions. Vehicles equipped with E4OD transmissions, go to TEST D25, step 1). Reconnect all components and rerun QUICK TEST.

Checking A/C Input. Scheme 67

11) Check A/C Input Circuit A low idle with A/C on could result in the ECA not receiving or recognizing A/C input on pin No. 10. Turn key off and wait 10 seconds. Disconnect ECA, inspect pins, and install breakout box. Leave ECA disconnected. Set DVOM on 20-volt scale. With KOEO, and A/C on, measure voltage between test pins No. 10 and 40. If voltage is greater than 10.5 volts, replace ECA. Remove breakout box. Reconnect all components and rerun QUICK TEST. If voltage is less than 10.5 volts, repair open in A/C circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST.

Checking A/C Clutch Circuit. Scheme 68

Note. There is a break in the step numbering sequence at this point, skipping from step 11) to step 13). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

13) Check Neutral Drive Input With key off, ensure transmission is in Park or Neutral. Disconnect ECA, inspect pins, and install breakout box. Reconnect ECA. Disconnect 16-pin connector from 4EAT transmission module. Set DVOM on 20-volt scale. With KOEO, measure voltage between test pin No. 30 at the breakout box and chassis ground. If voltage is less than one volt, replace ECA. Remove breakout box and reconnect all components. Repeat QUICK TEST. If voltage is not less than one volt, go to next step.

Checking NDS Input Circuit. Scheme 69

14) Check NDS Circuit Continuity Between ECA & 4EAT Module With key off, disconnect 4EAT module 16-pin connector. Install breakout box leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 30 and NDS pin at 4EAT module vehicle harness connector. If resistance is less than 5.0 ohms, EEC-IV system is not at fault, repair or replace transmission components as necessary. Remove breakout box and reconnect all components. If resistance is greater than 5 ohms, repair open circuit, remove breakout box and reconnect all components. Repeat QUICK TEST.

Checking 4EAT Module Circuits. Scheme 70

15) Check For Nonfunctioning A/C With High Idle A high idle when the A/C dash switch is on, but A/C is not functioning, may be the result of no signal being received at the A/C clutch. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for corroded or damaged connector pins and repair as necessary. Install breakout box, leaving ECA disconnected. Disconnect A/C clutch connector. Set DVOM on 20-volt scale. With KOEO and A/C on, measure voltage between input pin on fan connector and test pin No. 40 at the breakout box. If voltage is greater than 10.5 volts, go to next step. If not, repair open in A/C circuit. Remove breakout box, reconnect all components and repeat QUICK TEST.

Checking A/C Clutch Circuits. Scheme 71

16) Check Continuity of A/C Clutch With KOEO, install breakout box, leaving ECA disconnected. Disconnect A/C clutch harness connector. Set DVOM on the 200-ohm scale. Measure resistance across both pins of the A/C clutch. If resistance is within normal specification of 2.14-3.34 ohms, fault was probably due to faulty A/C clutch connection. Check for damaged or loose pins. Remove breakout box, reconnect all components and repeat QUICK TEST. If resistance was not within specification, repair or replace A/C clutch as necessary.

17) Check Continuity of A/C Cycle Pressure Switch Circuit Turn the key off and wait 10 seconds. Disconnect the ECA, inspect pins, and install breakout box. Leave ECA disconnected. Disconnect A/C cycle pressure switch. Turn A/C switch to ON position. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 10 at the breakout box and negative side of the A/C cycle pressure switch connector. If resistance is less than 5 ohms, EEC-IV system is not at fault. Repair or replace cycle pressure switch. If resistances are greater than 5 ohms, repair open circuit and remove breakout box. Reconnect all components and repeat QUICK TEST.

18) Check A/C Demand & A/C Cycle Pressure Switch For Short to Power Turn key off. Disconnect ECA, inspect pins, and install breakout box. Leave ECA disconnected. Ensure A/C switch is off. Set DVOM on 20-volt scale. With KOEO, measure voltage between test pin No. 43 and chassis ground. If voltage is greater than 1.0 volt, EEC-IV is okay. Check A/C switches, if okay, repair short circuit or re-evaluate symptom. Remove breakout box, reconnect all components and repeat QUICK TEST. If voltage is less than 1.0 volt, diagnose faulty A/C clutch. If clutch is okay, replace ECA.

Note. There is a break in the step numbering sequence at this point, skipping from step 18) to step 20). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

20) Check NDS Circuit For Short to Ground or Closed NDS Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector, inspect pins, and install breakout box, leaving ECA disconnected. Place transmission in Drive. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 30 and test pin No. 40 and 60 at breakout box. If resistance is greater than 10 k/ohms, service high idle condition. If resistance is less than 10 k/ohms, service circuit short or closed NDS. Remove breakout box, reconnect all components and repeat QUICK TEST.

TEST FD - BRAKE ON/OFF SWITCH (BOO)

Note. Perform this test when Service Code 74 or 75 is displayed during QUICK TEST.

Note. To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: brakelight bulb, brakelight switch, or brakelight fuse. This test is intended to diagnose a faulty BOO circuit or ECA.

Sable & Taurus (Except SHO) BOO Circuits. Scheme 72

Taurus SHO BOO Circuits. Scheme 73

Aerostar BOO Circuits. Scheme 74

1) Code 74: Verify Brake Pedal Was Depressed Code 74 indicates that when the brake pedal was depressed during the KOER Self-Test, the BOO signal did not cycle high. Possible causes for this fault are: brake pedal not depressed during self-test, open brakelight circuit (Batt + side of BOO splice), short to ground, faulty ECA. If brake was NOT depressed during KOER Self-Test, repeat test and depress and release brake pedal ONLY once during test. Depress and release brake pedal AFTER dynamic response code but before brief WOT. If pedal was depressed, go to next step.

2) Check For BOO Circuit Cycling Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, and loose wires. Install breakout box, leaving ECA disconnected. Set DVOM on 20-volt scale. Measure voltage between test pins No. 2 and 40 while applying and releasing brake. If voltage cycles, switch circuit is okay, replace ECA and repeat QUICK TEST. If voltage does not cycle, go to next step.

3) Checking BOO For Shorts To Ground Turn key off. Leave breakout box installed and ECA disconnected. Set DVOM on 200-k/ohm scale. Disconnect BOO circuit harness connector. Measure resistance between test pins No. 2 and 40 at the breakout box. If resistance is greater than 10 k/ohms, repair brakelight circuit as necessary. If resistance is less than 10 k/ohms, repair short, remove breakout box, reconnect all components and repeat KOER Self-Test.

Note. There is a break in the step numbering sequence at this point, skipping from step 3) to step 5). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

5) Code 75: Check For BOO Circuit Cycling Code 75 indicates that while brake pedal was released during KOER Self-Test, BOO signal was high. Possible causes for this fault are: brake pedal depressed during entire self-test, open BOO/brakelight circuit (between ECA and brakelight ground), short to POWER, or faulty ECA. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 20-volt scale. Measure voltage between test pins No. 2 and 40 while depressing and releasing brake pedal. If voltage cycles, replace ECA, remove breakout box and repeat QUICK TEST.

6) Check BOO Circuit For Short to Power Turn key off. With breakout box installed and ECA disconnected, set DVOM on 20-volt scale. Disconnect BOO circuit harness connector. Measure voltage between test pin No. 2 and an engine block ground. If voltage is greater than 1.0 volt, repair short circuit, Remove breakout box, reconnect all components and repeat KOER Self-Test. If not, go to next step.

7) Check Continuity of BOO Circuit Turn key off. Install breakout box, leaving ECA disconnected. Set DVOM on 20O-ohm scale. Disconnect BOO circuit harness connector. Measure resistance between test pin No. 2 at the breakout box and BOO circuit at the harness connector. If resistance is less than 5 ohms, check and repair brakelight system as necessary. If resistance is greater than 5 ohms, repair open circuit. Remove breakout box, reconnect all components and repeat KOER Self-Test.

Note. There is a break in the step numbering sequence at this point, skipping from step 7) to step 10). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

10) Code 74: Verify Brake Pedal Was Depressed Code 74 indicates that when brake pedal was depressed and released during KOER Self-Test, the BOO signal did not cycle high and low. Possible causes for this fault are: brake pedal was not depressed and released during the KOER Self-Test, brake pedal was depressed during entire KOER Self-Test, open in BOO/brakelight circuit, short to GROUND or POWER, or faulty ECA. If brake was NOT depressed during KOER Self-Test, repeat test and depress and release brake pedal ONLY once during test. Depress and release brake pedal AFTER dynamic response code but before brief WOT. If pedal was depressed, go to next step. If pedal was depressed correctly during self-test, go to next step.

11) Check Operation of Brake Lights Turn key on. Depress brake pedal and check brakelights. If brakelights operate normally, go to next step. If brakelights are never on, go to step 13). If brakelights are always on, go to step 14).

12) Check For BOO Circuit Cycling Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, and loose wires. Install breakout box, leaving ECA disconnected. Set DVOM on 20-volt scale. Measure voltage between test pin No. 2 or test pin No. 5 (as applicable per vehicle) and test pin No. 40 while applying and releasing brake. If voltage cycles, switch circuit is okay, replace ECA, remove breakout box, reconnect all components and repeat QUICK TEST. If voltage does not cycle, repair open BOO circuit between ECA and BOO connection to brakelight circuit. Repeat QUICK TEST.

13) Check For Brake Light Power to Harness Connector Turn key off. Disconnect BOO circuit harness connector. Set DVOM on 20-volt scale. Measure voltage between BOO circuit at harness connector and chassis ground while depressing brake pedal. If voltage is greater than 10 volts, repair open circuit between BOO connection to brakelight circuit and brakelight ground. If voltage is not greater than 10 volts, verify brake switch operation. If okay, repair open circuit between Batt (+) supply to circuit and BOO connection to brakelight circuit. Reconnect harness connector and repeat QUICK TEST.

14) Check BOO Circuit For Short to Power at Harness Connector Turn key off and wait 10 seconds. Disconnect BOO circuit harness connector. Set DVOM on 20-volt scale. With KOEO, measure voltage between BOO circuit at harness connector and chassis ground with brake pedal released. If voltage is less than 1.0 volt, go to next step. If not, verify operation of brake switch. If okay, repair short to power. Reconnect harness connector and repeat QUICK TEST.

15) Check For Short to Power in ECA Turn key off. Reconnect BOO circuit harness connector. Disconnect ECA. With KOEO, check to see if brakelights are on. If so, repair short to power between ECA and harness connector. Repeat QUICK TEST. If not, replace ECA and repeat QUICK TEST.

TEST FF - POWER STEERING PRESSURE SWITCH (PSPS)

Note. Perform this test when Service Code 52 is displayed during QUICK TESTS or when directed here by other test procedures. Some vehicles may not have power steering, but the ECA may be equipped with PSPS software strategy. If a KOEO Code 52 is displayed, check to see that vehicle is equipped with power steering. If not, disregard Code 52.

Note. This test is intended to diagnose only the following

1. Power Steering Pressure Switch (PSPS)
2. Harness circuits (PSPS and SIG RTN)
3. ECA

Power Steering Pressure Switch (PSPS) Circuit. Scheme 75

WIRE COLOR IDENTIFICATION

To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: idle speed/throttle stop adjustment, binding throttle shaft/linkage or cruise control linkage.

1) Code 52 Displayed, Attempt to Eliminate Code Code 52 indicates that PSPS circuit is open. Turn key off and wait 10 seconds. Disconnect PSPS. Install a jumper wire between PSPS circuit and SIG RTN at vehicle harness connector. Repeat KOEO Self-Test. If Code 52 is not displayed, replace PSPS and repeat QUICK TEST. If Code 52 is still displayed, go to next step.

2) Check Continuity of PSPS Circuits Turn key off and wait 10 seconds. Disconnect PSPS and ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale and measure resistance between test pin No. 46 and SIG RTN circuit at the PSPS vehicle harness connector. If both readings are less than 5 ohms, replace ECA. Remove breakout box, reconnect all components and repeat QUICK TEST. If readings are greater than 5 ohms, repair open in circuit. Remove breakout box, reconnect all components and repeat QUICK TEST.

3) Check PSPS Operation Connect tachometer and start engine. Allow engine to idle in Park or Neutral. Disconnect PSPS at switch. If RPM increases, replace PSPS. Recheck system. If RPM does not increase, go to next step.

4) Check PSPS Circuits For Shorts Turn key off and wait 10 seconds. Disconnect PSPS and ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 24 (test pin No. 2 on 3.0L SHO PFI) and test pin No. 46 at the breakout box. If resistance is 10 k/ohms or less, repair short in harness. Remove breakout box, reconnect all components and recheck symptom. If reading is greater than 10 k/ohms, replace ECA. Repeat QUICK TEST.

5) KOER Self-Test Code 52 Displayed Disregard this code if vehicle does not have power steering. Code 52 indicates that PSPS did not change states due to switch being either open or closed. If you turned steering wheel 1/2 turn within 1-2 seconds AFTER engine ID code, and front wheels are centered in a no load condition, go to next step. If not, repeat QUICK TEST.

6) Checking ECA Open Circuit Identifying Capabilities Turn key off and wait 10 seconds. Disconnect PSPS. Perform KOEO Self-Test. If Code 52 is present, go to step 8). If Code 52 is not present, go to next step.

7) Check PSPS Circuits For Shorts Turn key off and wait 10 seconds. Disconnect PSPS and ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Install breakout box, leaving ECA disconnected, and set DVOM on 200-k/ohm scale. Measure resistance between test pins No. 46 and 24 (test pin No. 2 on 3.0L SHO PFI) at breakout box. If reading is 10 k/ohms or less, repair short circuit. Remove breakout box, reconnect all components and repeat QUICK TEST. If reading is 10 k/ohms or more, replace ECA. Remove breakout box, reconnect all components and repeat QUICK TEST.

8) Check PSPS Position Comparison Turn key off and wait 10 seconds. Install breakout box, leaving ECA connected. With PSPS connected, set DVOM on 200-ohm scale. Turn key on and measure resistance between test pin No. 24 (test pin No. 2 on 3.0L SHO PFI) and test pin No. 46. Start engine. If reading remains less than 10 ohms between KOEO and KOER, go to next step. If not, go to step 11).

9) Check PSPS State With KOER: Load & No Load Install breakout box and connect ECA. Connect PSPS and set DVOM on 200-ohm scale. Start engine and allow it to idle. Ensure clutch is not depressed on 3.0L SHO PFI vehicles equipped with manual transmissions. Measure resistance between test pin No. 24 (test pin No. 2 on 3.0L SHO PFI) and test pin No. 46 at breakout box. Turn steering wheel 1/2 turn and return to center position. If resistance changes from less than 10 ohms to infinity (indicating PSPS opening) and then returns to 10 ohms or less (when steering wheel is centered), PSPS system is okay. Remove breakout box and return to QUICK TEST. If reading did not change as indicated, go to next step.

10) Check For PSPS Always Closed Compared to Hydraulic Pressure With Engine Running At this point, there are only 2 possible causes for the original KOER Code 52. They are a PSPS switch that will not open, or low available hydraulic pressure. Turn key off and wait 10 seconds. Substitute original switch with a known good PSPS switch. Perform KOER Self-Test and turn steering wheel at least 1/2 turn after engine ID code. If Code 52 is still present, check power steering system for hydraulic pressure. If Code 52 is not present, replace original PSPS switch. Service other codes if necessary.

11) Check For PSPS Always Open Compared to Hydraulic Pressure With Engine Running At this point, there are only 2 possible causes for original KOER Code 52. They are a PSPS switch that is always open, or excessively high hydraulic pressure. Turn key off and wait 10 seconds. Substitute original PSPS with a known good PSPS. Perform KOER Self-Test and turn steering wheel at least 1/2 turn after engine ID code. If Code 52 is still present, check power steering system for excessive hydraulic pressure. If Code 52 is not present, replace original PSPS switch. Service other codes if necessary.

TEST H - FUEL CONTROL

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

Note. Perform this test when Code 41, 91, 42, 92, 43, 65, 85, 86 or 93 is displayed during QUICK TESTS or when directed here by other test procedures.

Note. See HOW TO USE CIRCUIT TESTS, at beginning of circuit tests before performing this test. Fuel contaminated engine oil may affect Codes 41, 91, 42, or 92. If this is suspected, remove PCV valve from valve cover and repeat QUICK TEST. If problem is corrected, change engine oil and filter.

Note. Use this test to diagnose only the following components

1. HEGO sensor
2. HEGO signal and ground circuit
3. HEGO sensor connection
4. Vacuum systems
5. Fuel injector
6. ECA
7. Electrical circuits (HEGO GND, HEGO, INJ 1-8, VPWR and SIG RTN) NOTE: To prevent replacement of good components, be aware of the following non-EEC areas which may be the cause of driveability concerns
8. Ignition coil, distributor cap or rotor
9. Faulty or fouled spark plugs or wires
10. Faulty CANP system
11. Distributorless Ignition System (DIS)
12. EGR valve and gasket
13. Air filter
14. Fuel or engine oil contamination
15. Poor electrical ground
16. Faulty fuel pressure
17. Intake or exhaust system leaks
18. Engine below normal operating temperature

CAR - INDIVIDUAL INJECTOR RESISTANCE (1)

CAR - INJECTOR BANK RESISTANCE

3.0L SHO PFI Test Schematic. Scheme 76

TEST PIN WIRE COLOR IDENTIFICATION

Test Schematic For All PFI Engines. Scheme 77

Note. KOER Codes 41 and 91 are HEGO codes that indicate the system is always lean. KOER Codes 42 and 92 indicate the system is always rich. For vehicles equipped with dual HEGO's Codes 41 and 42 refer to Right (rear) HEGO sensors. Codes 91 and 92 refer to Left (front) HEGO sensors.

1) Check Fuel Pressure Turn ignition key off and wait 10 seconds. Install fuel pressure gauge. Verify that 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 key on and off several times. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. If vehicle is a no start, cycle key on and off several times. If fuel pressure is within specification, go to next step. If pressure is not to specification, remove fuel pressure gauge. Repair electric fuel pump or fuel pressure regulator.

2) Check Fuel Pressure Check Valve With KOEO, ensure that fuel pressure remains within specification for approximately 60 seconds. If system holds pressure, but vehicle runs rough or misses, or Codes 41, 42, 91 or 92 are present, go to step 9) for sequential PFI engines, or step 4) for all others. If vehicle is a no start, go to next step. If system does not hold pressure, go to step 6) for all engine applications except sequential PFI. For sequential PFI engines, go to step 9).

3) Fuel Delivery Test Ensure fuel is of good quality. With key off, install fuel pressure gauge and pressurize fuel system as in step 1). Disconnect inertia switch. Crank engine for 5 seconds. If fuel pressure drop is greater than 5 psi after 5 seconds of cranking, the EEC-IV system is not the cause of the no start condition. Check additional no start tests in TESTS W/O CODES article. If fuel pressure drop is less than 5 psi, remove fuel pressure gauge, reconnect inertia switch, and go to next step.

4) Check Injector & Harness Resistance Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect pins for damage. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Do the following

PFI ENGINES

Measure resistance of injector banks between test pins No. 37 and 58 (Right or rear) or 59 (Left or front) at breakout box. Record resistance. Refer to CAR - INJECTOR BANK RESISTANCE table.

SEQUENTIAL PFI ENGINES

Measure resistance between the suspect cylinder test pin (from the Cylinder Balance Test) and test pin No. 37 at the breakout box. Refer to CAR - INDIVIDUAL INJECTOR RESISTANCE table. For no starts, choose any injector and measure resistance between that injector circuit test pin and test pin No. 37 at breakout box. Record resistance. Refer to CAR - INDIVIDUAL INJECTOR RESISTANCE table.

Go to next step.

Remove breakout box and reconnect ECA. Service open/short in harness/connector. If okay, replace injector. Rerun QUICK TEST and Cylinder Balance Test.

For No Start: Service open in VPWR circuit.

5) Isolate Faulty Injector Circuit Turn key off. Install breakout box and disconnect ECA. Disconnect all injectors on suspect bank. With DVOM set on 200-ohm scale, connect one injector and measure resistance between test pins No. 37 and 58 or 59. Disconnect injector and repeat process for all other injectors. See CAR - INDIVIDUAL INJECTOR RESISTANCE table for specifications. If all injectors are within specifications, go to step 6). If injectors are not to specification, remove breakout box, reconnect ECA and injectors. Repair open or short in injector harness. If circuit is okay, replace injector. Rerun QUICK TEST.

6) Check Injector Drive Signal With key off and breakout box installed, connect ECA to breakout box. Use a non-powered 12-volt test light and the following connection procedure

Connect test light between test pins No. 37 and 58 at the breakout box. Connect light between test pins No. 37 and 59 at breakout box.

Connect test light between test pin No. 37 and the suspect injector(s) test pin at the breakout box.

Crank or start engine. A properly operating system is indicated by a test light that glows dimly. If light glows dimly, go to next step; except on sequential PFI engines. On sequential PFI engine, remove breakout box and reconnect ECA. Clean and test injectors. Rerun QUICK TEST and CYLINDER BALANCE TEST. If test light does not glow dimly, perform the following procedure

1. No Light - Check for 12 volts at test pins No. 37 and 57.
2. Bright Light - Check injector circuit for shorts to ground. If system is okay, remove breakout box and replace ECA. Remove breakout box, reconnect all components and repeat QUICK TEST.

7) Fuel Pressure Problems: External Sources Pressurize fuel system as per procedure in step 1) of this test. Examine fuel system using the following procedures as applicable

Visually inspect, fuel injector "O" rings, fuel pressure regulator, and fuel rails. If there is a visible leak, remove pressure gauge. Repair leak as necessary. Rerun QUICK TEST. If there is no leak, go to next step. Fuel delivery system is okay. Problem is in common area for all cylinders, such as, vacuum leak, fuel contamination, or EGR leak.

8) Injector Balance Test Connect tachometer to engine. Start and run engine at idle. Disconnect and reconnect injectors one at a time. Note RPM drop for each injector. Each injector should produce a momentary RPM drop of about 100 RPM. Note that ISC will attempt to re-establish correct RPM. If each injector does not produce at least 100 RPM drop when disconnected, service or replace faulty injector(s) and repeat QUICK TEST. If RPM drop is correct for all injectors, fuel delivery is okay. Problem is in area common to all cylinders such as a vacuum leak, fuel contamination, EGR, or HEGO ground. Check MAP frequency, etc.

9) Cylinder Balance Test: Sequential PFI Engines ONLY Perform KOER Self-Test. After last code is displayed, wait 5-10 seconds. Enter CYLINDER BALANCE TEST by briefly opening throttle for one second (not WOT). Test time is approximately 2-3 minutes. A Code 77 indicates that the throttle was touched when the test was running and that the test was not completed. Use table to interpret codes received from test. If balance test does not display Code 90, go to step 4). If balance test displays Code 90 (Pass), fuel delivery is okay, fault is in an area common to all cylinders (except vehicles with Codes 41/91 or 42/92). Vehicles with Code 41 or 91 displayed, go to next step. If a Code 42 or 92 is displayed, go to step 23)

CYLINDER BALANCE TEST SERVICE CODES

Note. There is a break in the step numbering sequence at this point, skipping from step 9) to step 11). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

11) Code 41 or 91: Fuel Control Always Lean If vehicle is equipped with dual HEGOs, Code 41 refers to the Right (rear) HEGO and Code 91 refers to the Left (front) HEGO. Run engine at 2000 RPM for 2 minutes. Turn key off and wait 10 seconds. Rerun KOER Self-Test. Check for Code 41 or 91. If Code 41 or 91 is not displayed, go to step 20). If Code 41 or 91 is displayed, go to appropriate step number as listed below.

1. Engines equipped with MAP sensors: Go to next step.
2. Engines equipped with MA meters: Go to step 14).

12) Checking HEGO Sensor on Engines With MAP Sensors Turn key off and set DVOM on 20-volt scale. Disconnect appropriate HEGO sensor from vehicle harness. Connect DVOM to HEGO SIGNAL lead at sensor and engine ground. Apply 10-14 in Hg to Manifold Absolute Pressure (MAP) sensor and start engine. Run engine at 2000 RPM for 2 minutes. If reading is greater than 0.5 volt, go to step 15). If reading is less than 0.5 volt, replace HEGO sensor, reconnect MAP, and rerun QUICK TEST.

Note. Vacuum or air leaks in non-EEC-IV related areas may cause Code 41 or 91. Check the following areas: leaking vacuum actuator (A/C control motor, etc.) engine seals, EGR system, PCV system and lead contamination of HEGO sensor.

Checking HEGO Sensor. Scheme 78

Note. Vacuum or air leaks in non-EEC-IV related areas may cause Code 41 or 91. Check the following areas: leaking vacuum actuator (A/C control motor, etc.) engine seals, EGR system, PCV system and lead contamination of HEGO sensor.

Checking HEGO Sensor & Circuit. Scheme 79

Note. There is a break in the step numbering sequence at this point, skipping from step 12) to step 14). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

14) Check HEGO Sensor on Engines With MA Sensor The purpose of this test is to verify HEGO sensor can generate a voltage signal of greater than 0.5 volt during KOER Self-Test. With key off and DVOM set on 20-volt scale and disconnect HEGO sensor from harness.

4-WIRE HEGO SENSORS

Connect DVOM between HEGO SIGNAL and HEGO GND at the HEGO sensor connector.

ALL OTHER HEGO SENSORS

Connect DVOM to HEGO SIGNAL at the sensor and battery negative post.

Rerun KOER Self-Test and monitor HEGO sensor voltage. If voltage is greater than 0.5 volt, go to next step. If voltage is less than 0.5 volt, replace HEGO sensor and rerun QUICK TEST.

Note. Vacuum or air leaks in non-EEC-IV related areas may cause Code 41 or 91. Check the following areas: leaking vacuum actuator (A/C control motor, etc.) engine seals, EGR system, PCV system and lead contamination of HEGO sensor.

15) Check Continuity of HEGO SIGNAL & POWER GROUND Circuits Turn key off. Install breakout box, leaving ECA and HEGO disconnected. Set DVOM on 200-ohm scale and use the following test

TRUCKS WITH 4-WIRE HEGO

Measure resistance between test pins No. 49 and 46 at breakout box and HEGO GND at the HEGO vehicle harness connector.

FOR ALL OTHERS

Measure resistance between test pin No. 49 at the breakout box and battery negative terminal.

On all above vehicles, measure resistance between test pin No. 29 at the breakout box and HEGO SIGNAL at the vehicle harness connector.

ALL VEHICLES WITH DUAL HEGO SENSORS

Measure resistance between test pin No. 43 at the breakout box and HEGO SIGNAL at the vehicle harness connector. If all resistances are less than 5 ohms, go to next step. If not, repair open circuit. Remove breakout box, reconnect all components and repeat QUICK TEST.

HEGO Sensor Connector. Scheme 80

16) Check HEGO Circuit For Short to Ground Turn key off. Leave breakout box installed and ECA disconnected. Disconnect HEGO sensor and set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 29 and test pins No. 40 and 49 at the breakout box. For trucks equipped with 4-wire sensors, measure resistance between test pin No. 29 and test pins No. 40 and 46 at the breakout box. For vehicles with dual sensors, measure resistance between test pin No. 43 and test pin No. 40. If any reading is less than 10 k/ohms, repair short to ground. Remove breakout box, reconnect all components and repeat QUICK TEST. If reading is 10 k/ohms or more, go to next step.

17) Check HEGO Sensor For Short to Ground With key off, breakout box installed, and ECA disconnected, set DVOM to 200-k/ohm scale. Disconnect HEGO sensor. Measure resistance between PWR GND and HEGO SIGNAL at the HEGO sensor connector. On trucks with 4-wire sensors, measure resistance between PWR GND, HEGO GND and HEGO SIG at the HEGO sensor connector. If resistance is less than 10 k/ohms, replace HEGO sensor, remove breakout box, reconnect all components and repeat QUICK TEST. If resistance is greater than 10 k/ohms, go to the appropriate following procedure.

1. Engines equipped with MAP sensor: Go to next step.
2. Engines equipped with MA (Mass Air Sensor): Remove breakout box, reconnect HEGO sensor, replace ECA and rerun QUICK TEST.

18) Attempt to Eliminate Code 41: Engines With MAP Sensor Turn key off. Install breakout box and reconnect ECA and HEGO sensor. Ensure MAP sensor vacuum hose is disconnected and plugged. Start and run engine at 2000 RPM for 2 minutes. Allow engine to return to idle. Apply 10-14 in. Hg to MAP sensor. Perform KOER Self-Test. If Code 41 is still present, remove breakout box. Reconnect ECA and MAP sensor vacuum line. If engine still runs rough, go to TEST S, step 2). If not, replace ECA and repeat QUICK TEST.

If Code 41 is not present, remove breakout box and reconnect ECA and MAP sensor vacuum hose. HEGO input circuit is okay. On sequential PFI engines, fuel delivery is okay, fault is in an area common to all areas. Service as necessary. On all other engines return to step 1) of this test.

Note. There is a break in the step numbering sequence at this point, skipping from step 18) to step 20). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

20) Check Resistance of HEGO Heating Element Turn key off, disconnect HEGO sensor, and set DVOM on 200-ohm scale. Measure resistance between KPWR circuit and PWR GND circuit at HEGO sensor connector. Hot to warm resistance should be 5.0-25.0 ohms. Room temperature resistance is 2.0-5.0 ohms. If resistance is within specification, go to next step. If not, replace HEGO sensor, and repeat QUICK TEST.

21) Check For Power at HEGO Harness Connector With KOEO, and HEGO disconnected, set DVOM on 20-volt scale. Measure voltage between KEY POWER circuit and PWR GND circuit at HEGO vehicle harness connector. If voltage is greater than 10.5 volts, HEGO system is okay, go to step 1) of this test (except sequential PFI engines). On vehicles equipped with sequential PFI engines, fuel delivery is okay, HEGO sensor may have cooled prior to KOER Self-Test. If a driveability symptom persists, fault is in an area common to all cylinders such as air or vacuum leaks, fuel contamination, EGR, MAP, etc. For all vehicles, if voltage is less than 10.5 volts, go to next step.

22) Check Continuity of Power Ground Circuit Turn key off and wait 10 seconds. Disconnect HEGO sensor and set DVOM on 200-ohm scale. Measure resistance between PWR GND circuit at HEGO vehicle harness connector and battery negative post. If resistance is less than 5 ohms, repair open in KEY POWER circuit. Reconnect HEGO and rerun QUICK TEST. If resistance is more than 5 ohms, reconnect HEGO sensor and repair open in PWR GND circuit. Reconnect HEGO sensor and rerun QUICK TEST.

23) Code 42 or 92: Fuel Control Always Rich, Check HEGO SIGNAL For Short To Power On dual HEGO systems, Code 42 refers to right (or rear) side HEGO, Code 92 refers to left (or front) side HEGO. Turn key off and wait 10 seconds. Disconnect appropriate HEGO sensor. Set DVOM on 20-volt scale. With KOEO, measure voltage between HEGO SIG and PWR GND at HEGO vehicle harness connector. If reading is more than .5 volt, repair short to power in HEGO circuit. Reconnect HEGO sensor and repeat QUICK TEST. If reading is less than 0.5 volt, go to next step.

24) Check HEGO Sensor For Short to KPWR Circuit Turn key off. Disconnect HEGO sensor. Set DVOM on 200-k/ohm scale. Measure resistance from KPWR circuit to HEGO SIG circuit at HEGO sensor connector. If reading is 10 k/ohms or less, replace HEGO sensor and repeat QUICK TEST. If reading is greater than 10 k/ohms, go to next step.

25) Attempt to Generate Code 41 or 91 The following non-EEC areas may cause these codes: fuel contaminated engine oil, ignition misfire and faulty CANP system. Turn key off and wait 10 seconds. Disconnect appropriate HEGO sensor. Using jumper wire, connect HEGO SIG circuit at HEGO vehicle harness connector to battery negative terminal. Repeat KOER Self-Test. If Code 41 or 91 is present, remove jumper wire and go to next step for engines with MAP. For all other engines, go to step 28). If Codes 41 and 91 are not present, remove jumper wire. Disconnect ECA connector and inspect for damage. If connector is okay, replace ECA. Repeat QUICK TEST.

Note. Because MAP sensor has a large influence on fuel control, a Code 42 or 92 may be the result of a faulty MAP sensor, even though a Code 22 has not been set. The next 2 test steps will verify the MAP vacuum circuit.

26) Check MAP Sensor For Vacuum Leaks Turn key off and wait 10 seconds. Disconnect vacuum hose from MAP sensor and connect vacuum pump to sensor. Apply 18 in Hg to MAP sensor. If sensor does not hold vacuum, replace MAP sensor. Remove vacuum pump. Connect vacuum hose and reconnect HEGO. Repeat QUICK TEST. If MAP holds vacuum, release vacuum and go to next step.

27) Check For Loss of Vacuum to MAP Sensor Using vacuum "T", connect vacuum gauge in intake manifold vacuum hose at MAP sensor. Start engine and note vacuum reading at a stable idle. Turn key off and wait 10 seconds. Remove "T" and vacuum gauge. Reconnect hose to MAP sensor. Connect vacuum gauge at a different intake manifold location. Start engine and note vacuum reading. If readings differ by more than 1 in. Hg, inspect vacuum hoses for leaks, kinks, or blockage. Repair as necessary. If readings are within 1 in. Hg of each other, go to next step.

28) HEGO Sensor Check Turn key off and wait 10 seconds. Disconnect HEGO sensor. Set DVOM on 20-volt scale and connect to HEGO SIGNAL at HEGO sensor connector and battery negative post. Remove a vacuum hose to create a vacuum leak, which will cause the HEGO sensor to go lean.

ALL MA PFI ENGINES

Disconnect any vacuum hose from manifold vacuum tree fitting.

ALL OTHER ENGINES

Disconnect the PCV valve hose from the PCV valve.

Start engine and run at approximately 2000 RPM. DVOM should indicate less than 0.4 volt within 30 seconds. If not, replace HEGO sensor. Reconnect vacuum hoses and repeat QUICK TEST. If voltage is to specification, HEGO sensor is okay. If engine has sequential PFI, fuel delivery is okay, problem is in an area common to all cylinders, such as a vacuum leak, fuel contamination, EGR system, MAP frequency, etc. Service as necessary. For all other engines, go to step 1) of this test.

29) Continuous Memory Code 41 or 91 (With Exhaust Odor or Smoke) Codes 41 or 91 indicate that a HEGO circuit has not switched during closed loop fuel control. In this situation a Code 41 or 91 may not indicate a lean condition. Diagnose all other driveability complaints (see SYMPTOMS in TESTS W/O CODES article) before attempting to service a Continuous Memory Code 41 or 91. Check the following areas

Circuits

1. HEGO SIG and GND circuits
2. HEGO harness insulation (near exhaust manifold)

Unmetered Air/Vacuum Leaks

1. Canister Purge (CANP) system
2. PCV system
3. Engine sealing
4. Crimped fuel lines
5. Plugged fuel filter
6. Fouled injectors
7. Air leaks between MAF and air outlet tube

HEGO Fuel Fouled

1. If an over-rich condition is suspected of fouling the HEGO sensor, run the vehicle at sustained high (legal) speeds followed by a few hard acceleration runs. This will allow the HEGO contamination to be burned off.

Ignition System

1. Check for DEFAULT base timing in QUICK TEST procedure.

Improper Fuel Used

1. Lead fouled HEGO sensor.

Fuel Pressure

1. Check pressure using steps 1) and 2) of this test.

TP Sensor

1. With KOEO, move throttle slowly to WOT. Measure voltage between test pins No. 47 and 46 at breakout box. If voltage does not increase with throttle opening, replace TP sensor or linkage as necessary.

If vehicle still has driveability problems, perform test steps 3) through 6).

30) Continuous Memory Codes 41, 42, 43, 65, 85 or 86 Diagnose all other driveability complaints such as rough idle, missing, etc. before servicing these codes

CODE 41

HEGO indication that the fuel system was lean for more than 15 seconds when the fuel system should have been in closed loop fuel control.

CODE 42

HEGO indication that the fuel system was rich for more than 15 seconds when the fuel system should have been in closed loop fuel control.

CODE 43

HEGO indicated that the fuel system was lean during WOT for more than 3 seconds.

CODE 65

Closed loop not activated on HEGO switching.

CODE 85

Excessive rich mixture condition corrected (made leaner) by adaptive fuel strategy.

CODE 86

Excessive lean fuel mixture condition corrected (made richer) by adaptive fuel strategy.

If an over-rich fuel condition is suspected or experienced, check ignition system. Burn off fuel deposits on HEGO by operating the vehicle at sustained high (legal) speeds followed by a few hard acceleration runs. This will allow the HEGO contamination to be burned off. Check the following areas

1. Intermittent HEGO circuit (SIG or GND circuit).
2. If Code 65 also present, repair faulty HEGO circuit (SIG or GND circuit).
3. If Code 43 also present, service Code 43 first.
4. Low fuel pressure at WOT, check fuel supply.
5. Low fuel flow at WOT (pressure okay), check clogged injectors or low battery voltage.

1. Intermittent HEGO signal (SIG or GND circuit).
2. Excessive fuel flow, pressure regulator vacuum supply disconnected or blocked fuel return line.
3. Excessive fuel flow, damaged or stuck open injector(s).

Codes 41 and 42

1. Intermittent HEGO circuit (SIG or GND circuit).
2. Contaminated HEGO sensor, lead or silicone fouled.

1. Low fuel pressure at WOT, fuel pump or restricted supply.
2. Low fuel flow at WOT, injectors plugged or low battery voltage (less than 11 volts).

1. Check for faulty HEGO signal (Signal or Ground circuit).

1. If Code 42 also displayed, service it first.
2. Excessive fuel pressure, check regulator vacuum line and fuel supply line.
3. Excessive fuel flow, check for damaged injector pintles or injector stuck open.

1. If Code 41 also displayed, service it first.
2. Low fuel pressure, low pressure pump or restricted fuel supply.
3. Low fuel flow, clogged injectors or low battery voltage.

TEST J - FUEL PUMP CKT (RELAY & INERTIA SWITCH)

Note. Perform this test when Service Code 87, 95, or 96 is displayed during QUICK TESTS or when directed here by other test procedures.

Note. This test is intended to diagnose only the following

1. Fuel Pump Relay
2. Inertia Switch
3. Harness Circuits (Batt +, VPWR, FUEL PUMP, GND, POWER-to-PUMP)
4. ECA

TEST PIN NO. 22 IDENTIFICATION

3.0L Fuel Pump Ckt Diagram. Scheme 81

1) No Fuel Pump Pressure: Check Fuel Pump Electrical Operation Turn key from OFF to RUN position several times (DO NOT turn to START position). If fuel pumps run briefly each time key is turned to RUN position, fuel pump circuit is okay. If not, go to next step.

2) Check For VPWR to ECA With key off, install breakout box and reconnect ECA. Set DVOM on 20-volt scale. Turn key on, leaving engine off. Measure voltage between test pins No. 37 and 40 at the breakout box. Measure voltage between test pins No. 57 and 60 at the breakout box. If both voltage readings are greater than 10.5 volts, go to step 5). If voltage is not greater than 10.5 volts, go to TEST B, step 1).

Note. There is a break in the step numbering sequence at this point, skipping from step 2) to step 5). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

5) Check Voltage to POWER-to-PUMP Circuit With KOEO, breakout box installed and ECA connected, set DVOM on 20-volt scale. Measure voltage between chassis ground and POWER-to-PUMP circuit at fuel pump relay while cranking engine. If reading is less than 8 volts, go to step 6). If reading is 8 volts or more, check the following: open in POWER-to-PUMP circuit, open in fuel pump and open fuel pump ground circuit.

6) Checking BATT (+) Circuit to Fuel Pump Relay Turn key on, leaving engine off. Leave breakout box installed and ECA connected. Locate fuel pump relay. Set DVOM on 20-volt scale. Measure voltage between chassis ground and BATT (+) circuit at fuel pump relay. If reading is less than 10.5 volts, repair open in BATT (+) circuit between fuel pump relay and battery positive post. Repeat QUICK TEST. If reading is 10.5 volts or greater, go to step 11).

7) Code 87: Checking VPWR Circuit to Fuel Pump Relay Code 87 indicates a fuel pump primary circuit failure. Possible causes for this fault are: inertia switch not reset or electrically open, faulty fuel pump relay or ECA. Open or shorted circuit. Turn key on, leaving engine off. Leave breakout box installed and ECA connected. Locate fuel pump relay. Set DVOM on 20-volt scale. Measure voltage between chassis ground and VPWR circuit at fuel pump relay. If reading is 10.5 volts or more, go to next step. If reading is less than 10.5 volts, ensure inertia switch is on. If inertia switch will not reset, replace switch. If switch is okay, repair open in VPWR circuit between EEC power relay and fuel pump relay. Repeat QUICK TEST.

8) Check FUEL PUMP Circuit Continuity Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for corroded or damaged connector pins and repair as necessary. Install breakout box, leaving ECA disconnected. With DVOM on 200-ohm scale, measure resistance between FUEL PUMP circuit at pump relay and test pin No. 22 at breakout box. If reading is 5 ohms or more, repair open in FUEL PUMP circuit. Repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

9) Check For Short to Power With key off, disconnect ECA and fuel pump relay. Install breakout box and set DVOM on 20-volt scale. Turn key on. Measure voltage between test pin No. 22 and battery negative terminal. If voltage is less than one volt, go to next step. If not, repair short circuit. Reconnect ECA and attempt to start vehicle. If vehicle fails to start, replace ECA. Rerun QUICK TEST.

10) Check For Shorts to Ground Turn key off and wait 10 seconds. Leave breakout box installed and ECA disconnected. Disconnect fuel pump relay. With DVOM on 200-k/ohm scale, measure resistance between test pin No. 22 and test pins No. 40 and 60. If reading is less than 10 k/ohms, repair short in FUEL PUMP circuit. Repeat QUICK TEST. If reading is 10 k/ohms or more, go to next step.

11) Check Voltage at POWER-to-PUMP Circuit Turn key off. Leave breakout box installed and ECA disconnected. Install a jumper wire between test pin No. 22 and test pins No. 40 or 60. Set DVOM on 20-volt scale. With KOEO, measure voltage between chassis ground and POWER-to-PUMP circuit at fuel pump relay. If reading is 10.5 volts or more, replace ECA and repeat QUICK TEST. If reading is less than 10.5 volts, replace fuel pump relay. Connect ECA and repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 11) to step 20). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

20) Code 95: Does Engine Start? A KOEO Code 95 indicates that one of the following has occurred

No Starts

1. Inertia switch not reset or electrically open.
2. Open circuit in or between ECA and fuel pump.
3. Faulty ground connection at fuel pump.

Vehicle Starts

1. Fuel pump secondary circuit shorted to power.
2. Fuel pump relay contacts always closed.
3. Open in Fuel Pump Monitor (FPM) circuit between ECA and connection to POWER-to-PUMP circuit.
4. Faulty ECA.

If engine starts, go to next step. If not, go to step 25).

21) Verify Fuel Pump is Off With key off, listen for fuel pump noise. If fuel pump is off, go to step 23). If fuel pump is on, go to next step.

22) Check For Fuel Pump Relay Always Closed Turn key off. Disconnect fuel pump relay. If fuel pump turns off when relay is disconnected, replace fuel pump relay. Repeat QUICK TEST. If fuel pump does not turn off, repair short in POWER-to-PUMP or FPM circuit. Repeat QUICK TEST.

23) Check Continuity of Fuel Pump Monitor (FPM) Circuit Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Install breakout box and leave ECA disconnected. Disconnect fuel pump relay. Set DVOM on 200-ohm scale and measure resistance between test pin No. 8 at the breakout box and POWER-to-PUMP circuit at the fuel pump relay vehicle harness connector. If resistance is less than 5 ohms, replace ECA, remove breakout box, reconnect fuel pump relay and repeat QUICK TEST. If resistance is greater than 5 ohms, repair open circuit, remove breakout box, reconnect all components and rerun QUICK TEST.

Fuel Pump Relay Vehicle Harness Connector. Scheme 82

24) Check Fuel Pump Primary Circuit For Short to Ground Turn key off and wait 10 seconds. Install breakout box and disconnect ECA. Disconnect fuel pump relay and set DVOM on 200-k/ohm scale. Measure resistance between test pins No. 22 and 40 at the breakout box. If resistance is greater than 10 k/ohms, remove test set-up. Replace ECA, reconnect components and rerun QUICK TEST. If resistance is less than 10 k/ohms, repair short circuit and reconnect components. Repeat QUICK TEST.

25) Check Inertia Switch Turn key off and wait 10 seconds. Locate and disconnect fuel pump inertia switch. Verify that switch is reset. Set DVOM on 200-ohm scale. Measure resistance of fuel pump inertia switch. If resistance is less than 5 ohms, reconnect switch and go to next step. If not, replace or reset inertia switch. Repeat QUICK TEST.

26) Check Continuity Between FPM Circuit & Ground Turn key off. Install breakout box and disconnect ECA. Disconnect fuel pump relay. Set DVOM on 200-ohm scale and measure resistance between test pin No. 8 at the breakout box and battery negative terminal. If resistance is less than 10 ohms, replace ECA, remove breakout box, reconnect fuel pump relay and repeat QUICK TEST. If resistance is more than 10 ohms, remove test set-up and check the following: open circuit in fuel pump, poor ground connection at fuel pump, or an open in POWER-to-PUMP circuit.

Note. There is a break in the step numbering sequence at this point, skipping from step 26) to step 30). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

30) Code 96: Checking BATT (+) to Fuel Pump Relay Code 96 indicates a fuel pump secondary circuit failure between the BATT (+) supply and the FPM connection to the POWER-to-PUMP circuit. Possible causes for this fault are: faulty fuel pump relay, ECA, or open circuit.

Turn key off and wait 10 seconds. Locate fuel pump relay. With the DVOM on 20-volt scale, measure voltage between BATT (+) circuit at fuel pump relay and battery negative post. If voltage is greater than 10.5 volts, go to next step. If voltage is less than 10.5 volts, repair open circuit in BATT (+) circuit and rerun QUICK TEST.

31) Check For Voltage at POWER-to-PUMP Circuit to Verify Fuel Pump Relay Operation With key off, set DVOM on 20-volt scale. Connect DVOM between POWER-to-PUMP circuit at fuel pump relay and battery negative post. Check voltage while turning key to ON position (for one second) and OFF position (10 seconds). Repeat cycle at least 5 times. If voltage is greater than 10.5 volts for approximately one second after key is turned to RUN position, replace ECA and rerun QUICK TEST. If voltage is not to specification, inspect relay harness connector. If okay, replace fuel pump relay. Rerun QUICK TEST.

32) Check Continuity of POWER-to-PUMP Circuit Turn key off and disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Service as necessary. Install breakout box and leave ECA disconnected. Disconnect fuel pump relay. With DVOM on 200-ohm scale, measure resistance between test pin No. 8 at breakout box and POWER-to-PUMP circuit at relay harness connector. If resistance is less than 5 ohms, remove test set-up, replace ECA, and rerun QUICK TEST. If resistance is greater than 5 ohms, repair open circuit between FPM connecting splice and fuel pump relay. Rerun QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 32) to step 90). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

90) Continuous Memory Code 95: Check EEC-IV Harness Code 95 indicates that one of the following conditions has occurred intermittently

1. Open circuit in or between the fuel pump and FPM circuit at the ECA.
2. Faulty ground circuit at the fuel pump.
3. FPM or POWER-to-PUMP circuit short to power.
4. Fuel pump relay contacts stuck open.
5. FUEL PUMP circuit activated when ECA expected circuit to be off.

Start engine and perform WIGGLE TEST on vehicle harness to fuel pump, and to pump ground circuit harness. Lightly tap inertia switch and pump to simulate road shock. Check for engine miss or stumble while performing test. With key off, check harness connectors for corrosion or damage. Isolate and repair any faults that are found, clear Code 95 and rerun QUICK TEST. If no fault is found, go to next step.

91) Check FPM Circuit Turn key off. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Install breakout box and leave ECA disconnected. With KOEO, connect a test light between test pin No. 8 and test pin No. 37 at the breakout box. With test light lit, perform WIGGLE test on FPM circuit between pump and monitor. Light should go out if fault is found during WIGGLE TEST. Isolate and repair any found faults, remove test set-up and rerun QUICK TEST. If no faults are found, go to next step.

92) Check For Shorts to Power With KOEO, breakout box installed and ECA disconnected, connect a test light between test pin No. 8 and test pin No. 40. Observe test light, perform WIGGLE test on FPM circuit and POWER-to-PUMP circuit. Lightly tap the fuel pump relay to simulate road shock. If light goes on to indicate a fault is found, isolate and repair as necessary. Remove test set-up and rerun QUICK TEST. If no faults are found, fault is intermittent and cannot be duplicated at this time. Clear Continuous Memory Codes and rerun QUICK TEST.

93) Continuous Memory Code 96: Check For Continuous Memory Code 87 If Code 87 is also present, go to step 26). If code 87 is not displayed, go to next step.

94) Check EEC-IV Harness A Continuous Memory Code 96, without an accompanying Continuous Memory Code 87 indicates that during vehicle operation, one of the following has occurred

1. An open in the BATT + circuit between the BATT + and the fuel pump relay
2. Fuel pump relay contacts opened
3. Open in the POWER-to-PUMP circuit from the fuel pump relay to the FPM splice, if applicable.

With engine running attempt to cause a miss or stumble while performing WIGGLE TEST on pump harness and connectors. With key off, inspect all fuel pump connectors and BATT + for damage or corrosion. If a fault is found, isolate and repair it as necessary. Clear Continuous Memory Codes and rerun QUICK TEST. If no fault is found, fault may not be duplicated at this time. Clear Continuous Memory Codes, Code 96 testing is complete.

95) Continuous Code 87: Check EEC-IV Harness A Continuous Memory Code 87 indicates the primary fuel pump circuit has failed during vehicle operation. Possible causes for this fault are

1. An open in the VPWR circuit between the EEC power relay and the fuel pump relay
2. Open coil in fuel pump relay
3. Open in fuel pump circuit
4. Faulty inertia switch

With engine running, attempt to cause a miss or stumble while performing WIGGLE TEST on VPWR circuit between EEC power relay and fuel pump relay. Wiggle fuel pump circuit harness (test pin No. 22) between ECA and the fuel pump relay. Lightly tap fuel pump relay to simulate road shock. With key off, inspect ECA 60-pin connector for damage or corrosion. If a fault is found, isolate and repair it. Rerun QUICK TEST. If no fault is found, fault may not be duplicated at this time.

TEST KA - EGR ON/OFF CONTROL

Note. Perform this test only when directed here by a driveability symptom.

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

1. Harness circuits (EGR and VPWR)
2. EGR solenoid
3. Presence of manifold vacuum
4. ECA NOTE: To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault
5. Air or vacuum leaks
6. EGR flow restrictions
7. EGR valve

EGR On/Off Circuit. Scheme 83

1) Enter Output State Check Possible causes for this fault are

1. Faulty EGR On/Off control solenoid
2. Faulty EGR solenoid
3. Faulty EGR vent solenoid
4. Faulty EVP sensor
5. Faulty wiring harness
6. Faulty ECA
7. Manifold vacuum line blocked or leaking

Use only VOM/DVOM, not diagnostic tester, for this step. Turn key off and wait 10 seconds. Disconnect electrical connector on speed control servo (if equipped). Set DVOM on 20-volt scale. Connect negative DVOM lead to STO at Self-Test connector and positive lead to positive battery terminal. Jumper STI to SIG RTN at Self-Test connector. Rerun KOEO Self-Test until end of Continuous Memory Codes display (DVOM will read less than one volt). Depress and release throttle and observe DVOM reading. If DVOM reading changes to a higher voltage, stay in OUTPUT STATE CHECK and go to next step. If DVOM did not show high voltage, depress throttle to WOT and release. If STO voltage does not increase, go to TEST QC, step 1). Leave test equipment hooked up.

2) Check EGR Solenoid Electrical Operation Disconnect EGR solenoid. Set DVOM on 20-volt scale. Connect DVOM positive lead to VPWR circuit at EGR solenoid and negative lead to EGR output circuit. While observing DVOM, depress and release throttle several times to cycle output on and off. If output does not cycle on and off, remove STI jumper wire and go to step 5). If output cycles on and off, go to next step.

3) Check EGR Solenoid For Vacuum Cycling Reconnect EGR solenoid. Connect vacuum pump to solenoid vacuum supply port and vacuum gauge to output port of solenoid. Apply minimum vacuum of 6 in. Hg. Depress and release throttle several times to cycle EGR solenoid output while maintaining vacuum at supply port. Note gauge reading. If vacuum output does not cycle, replace EGR solenoid and repeat QUICK TEST. If vacuum output cycles, go to next step.

4) Check Manifold Vacuum Lines For Blockage or Leaks With vacuum lines disconnected at EGR solenoid, start engine. If vacuum is present, EEC-IV system is not cause of problem. Check EGR system for mechanical faults. If vacuum is not present, correct vacuum source blockage or leak and repeat QUICK TEST.

5) Measure EGR Solenoid Resistance Turn key off and wait 10 seconds. Disconnect EGR solenoid. Set DVOM on 200-ohm scale. Measure resistance between EGR circuit and VPWR circuit at the EGR solenoid. If reading is less than 65 ohms or more than 110 ohms, replace EGR solenoid and repeat QUICK TEST. If reading is between 65 and 110 ohms, go to next step.

6) Check VPWR Circuit Voltage With KOEO and EGR solenoid disconnected, set DVOM on 20-volt scale. Measure voltage between VPWR circuit at EGR solenoid vehicle harness connector and battery ground. If reading is less than 10.5 volts, repair open in harness, reconnect EGR solenoid and repeat QUICK TEST. If reading is 10.5 volts or more, go to next step.

7) Check Continuity of EGR Circuit Turn key off and wait 10 seconds. Disconnect EGR solenoid. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 35 at the breakout box and EGR circuit at EGR solenoid vehicle harness connector. If reading is 5 ohms or more, repair open circuit and repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

8) Check EGR Circuit For Short to Ground Turn key off and wait 10 seconds. Leave breakout box installed and ECA disconnected. Disconnect EGR solenoid. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 35 and test pins No. 40, 46, and 60. If any reading is less than 10 k/ohms, repair short to ground and reconnect all components. Repeat QUICK TEST. If all readings are 10 k/ohms or more, go to next step.

9) Check EGR Circuit For Short to Power Turn key off and wait 10 seconds. Leave breakout box installed. Disconnect ECA and EGR solenoid. With DVOM on 200-k/ohm scale, measure resistance between test pin No. 35 and test pins No. 37 and 57. If any reading is less than 10 k/ohms, repair short to power and repeat QUICK TEST. If fault is still present, replace ECA. If all readings are 10 k/ohms or more, replace ECA and repeat QUICK TEST.

TEST KD - CANISTER PURGE (CANP)

Note. Perform this test when Service Code 85 is displayed during QUICK TESTS or when directed here by other test procedures. This test is intended to diagnose only the following

1. CANP solenoid
2. Harness circuits (CANP, VPWR)
3. ECA

Canister Purge (CANP) Circuit. Scheme 84

TEST PIN WIRE COLOR IDENTIFICATION

1) Check System Function Enter Output State Check. See OUTPUT STATE CHECK, under ADDITIONAL SYSTEM FUNCTIONS. Use only VOM or DVOM, not diagnostic tester, for this step. Turn key off and wait 10 seconds. Set DVOM on 20-volt scale. Connect DVOM negative test lead to STO and positive test lead to positive battery terminal. Using jumper wire, connect STI circuit to SIG RTN at Self-Test connector. Perform KOEO Self-Test until end of Continuous Memory Codes (DVOM reads zero volts). Depress and release throttle. DVOM should change to a high voltage reading. If reading did not change, depress throttle to WOT and release. If STO voltage does not increase, go to TEST QC, step 1). Leave test equipment hooked up. If reading changed, remain in Output State Check and go to next step.

2) Check CANP Solenoid Electrical Function With KOEO, set DVOM on 20-volt scale. Disconnect CANP solenoid. Connect DVOM positive test lead to VPWR circuit and negative test lead to CANP output circuit on harness connector. While observing DVOM, depress and release throttle several times to cycle output on and off. If CANP circuit does not cycle on and off, remove jumper wire and go to step 6). If CANP circuit cycles, go to next step.

3) Check Solenoid For Vacuum Leaks Turn key 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. If CANP holds vacuum for 20 seconds, leave vacuum pump attached and go to next step.

4) Check Solenoid Mechanical Operation While still in Output State Check, cycle CANP circuit off (no voltage). Reconnect CANP solenoid connector. Apply 16 in. Hg vacuum to CANP solenoid as in step 3). Depress and release throttle. If vacuum is released, check hose from CANP solenoid to canister for leaks or cracks. If okay, remove jumper wire from STI to SIG RTN and go to next step. If vacuum is not released, check hose from CANP solenoid to canister for leaks or cracks, if hose is okay, replace CANP solenoid. Repeat QUICK TEST.

5) Check Vacuum Supply to CANP Solenoid Disconnect vacuum hose from CANP solenoid on manifold vacuum (PCV) side. Start engine. If vacuum is present at vacuum hose, EEC system is okay. Check evaporative canister. If vacuum is not present at hose, check vacuum hose for proper routing, kinks, or blockage, If hose is okay, check engine for cause of low vacuum.

6) Measure CANP Solenoid Resistance Code 85 indicates a fault in the CANP solenoid circuit. Possible causes for this fault are

1. Faulty CANP solenoid
2. Open in harness circuit
3. Shorted harness circuit (power to ground)

Turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Disconnect CANP solenoid connector and measure CANP solenoid resistance. If resistance is 40-90 ohms, go to next step. If reading is incorrect, replace CANP solenoid and repeat QUICK TEST.

7) Check Voltage of VPWR Circuit With KOEO, and CANP solenoid disconnected, set DVOM on 20-volt scale. Measure voltage between VPWR circuit at CANP solenoid harness connector and battery negative terminal. If reading is 10.5 volts or greater, go to next step. If reading is less than 10.5 volts, repair open in circuit and repeat QUICK TEST.

8) Check Continuity of CANP Circuit Turn key off and wait 10 seconds. Disconnect CANP solenoid and ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Connect breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 31 and CANP harness connector. If reading is less than 5 ohms, go to next step. If reading is 5 ohms or more, repair open circuit, remove breakout box and reconnect components. Repeat QUICK TEST.

9) Check CANP Circuit For Short to Ground Turn key off and wait 10 seconds. Install breakout box, leaving ECA disconnected. Set DVOM on 200-k/ohm scale and disconnect CANP solenoid. Measure resistance between test pin No. 31 and test pins No. 40, 46, and 60. If all readings are 10 k/ohms or more, go to next step. If any reading is less than 10 k/ohms, repair short to ground. Remove breakout box, reconnect components and repeat QUICK TEST.

10) Check CANP Circuit For Short to Power Turn key off and wait 10 seconds. Disconnect CANP solenoid. Install breakout box, leaving ECA disconnected. Set DVOM on 200-k/ohm scale and disconnect CANP solenoid. Measure resistance between test pin No. 31 and test pins No. 37 and 57. If all reading are 10 k/ohms or more, remove breakout box. Replace ECA and repeat QUICK TEST. If any reading is less than 10 k/ohms, repair short to power, remove breakout box and reconnect components. Repeat QUICK TEST. If any resistance is greater than 10 k/ohms, replace ECA. Remove breakout box and reconnect components. Repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 10) to step 15). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

15) Check If CANP Caused Codes 16 or 26 With key off, disconnect vacuum hose at CANP solenoid on canister side. Start engine and allow to idle. If vacuum is present on canister side of CANP solenoid, go to step 1), in this test. If vacuum is not present, and a Code 26 is displayed, check for vacuum leaks or lack of vacuum. If Code 16 is present, check for vacuum leaks at injector "O" rings, vacuum lines and fittings, or between air meter and throttle body. Service as necessary and rerun QUICK TEST.

TEST KE - IDLE SPEED CONTROL (AIR BY-PASS)

Note. Perform this test when Code 12, 13, 16, 17, 19, 47 or 48 is displayed during QUICK TESTS or when directed here by other test procedures. If engine is running rough or has rough idle, correct these conditions before performing test. Causes may be in ignition system, fuel system or EGR system. This test is intended to diagnose only the following

1. RPM during Self-Test mode
2. ISC solenoid
3. Harness circuits (ISC and VPWR)
4. Faulty ECA NOTE: To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault
5. Engine temperature not up to operating temperature
6. Engine over operating temperature
7. A/C input (electrical problem)
8. Incorrect idle speed or throttle stop adjustment
9. Faulty cruise control linkage

Idle Speed Control (Air By-Pass) Circuit. Scheme 85

1) Code 12: Check For RPM Drop On 1.9 PFI engine, Code 12 indicates that during KOER Self-Test, engine was unable to reach maximum self-test RPM.

On all other models, Code 12 indicates that during KOER Self-Test engine RPM could not be controlled within self-test upper RPM limit.

Possible causes for this fault are

1. Open or shorted circuit
2. Sticking or binding throttle linkage
3. Incorrect idle adjustment
4. Throttle body or ISC solenoid contaminated
5. Faulty ISC solenoid
6. Faulty ECA
7. Non-ECC mechanical faults that could affect RPM

Turn key off. Connect engine tachometer and start engine. Disconnect Idle Speed Control (ISC) harness. If RPM drops or if engine stalls, go to next step. If not, go to step 3).

2) Check For EGR Codes If EGR service codes 31, 32, 33 or 34 are displayed, reconnect ISC solenoid and go to KOER CODE CHART and perform appropriate CIRCUIT TEST. If these codes are not displayed, go to next step.

3) Check For Other EEC-IV Codes If Codes 22, 41, 42, 91, or 92 are displayed, reconnect ISC solenoid, go to KOER CODE/TEST MENU to determine and then perform appropriate CIRCUIT TEST. If these codes are not displayed, go to next step.

4) Measure ISC Solenoid Resistance Turn key off. Disconnect ISC solenoid. Set DVOM on 200-ohm scale, and measure resistance of ISC solenoid. Connect DVOM positive (+) lead to VPWR terminal and DVOM negative lead to ISC terminal as ISC solenoid is equipped with a diode. If resistance is between 7 and 13 ohms, go to next step. If resistance is less than 7 ohms or greater than 13 ohms, replace ISC solenoid and repeat QUICK TEST.

ISC Solenoid Connector. Scheme 86

5) Check For Internal Short to ISC Solenoid Case With key off and ISC solenoid disconnected, set DVOM on 200-k/ohm scale. Measure resistance from either ISC terminal pin to ISC solenoid housing. If reading is greater than 10 k/ohms, go to next step. If reading is 10 k/ohms or less, replace ISC solenoid. Repeat QUICK TEST.

6) Check VPWR Circuit Voltage Leave ISC harness disconnected. With KOEO, set DVOM on 20-volt scale. Measure voltage between VPWR circuit at ISC harness connector and battery ground terminal. If reading is less than 10.5 volts, repair open in circuit and repeat QUICK TEST. If reading is 10.5 volts or more, go to next step.

7) Check ISC Circuit Continuity Turn key off and wait 10 seconds. Leave ISC solenoid disconnected. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA disconnected. With DVOM on 200-ohm scale, measure resistance between test pin No. 21 and ISC circuit at ISC vehicle harness connector. If reading is greater than 5 ohms, repair open circuit, remove breakout box and reconnect all components. Repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

8) Check ISC Circuit For Short to Ground Turn key off and wait 10 seconds. Leave ISC solenoid disconnected. Install breakout box, leaving ECA disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 21 and test pins No. 40, 46, and 60. If any reading is less than 10 k/ohms, repair short to ground and repeat QUICK TEST. If all readings are 10 k/ohms or more, go to next step.

9) Check ISC Circuit For Short to Power Turn key off and wait 10 seconds. Leave breakout box installed. Leave ECA and ISC solenoid disconnected. Set DVOM on 200-k/ohm scale. Measure resistance by connecting DVOM negative lead to test pin No. 21 and positive lead to test pin No. 37. If reading is greater than 10 k/ohms, go to next step. If reading is 10 k/ohms or less, repair short circuit and remove breakout box. Reconnect all components and repeat QUICK TEST. If code or symptom is still present, replace ECA.

10) Check ISC Signal From ECA With key off, reconnect ECA and ISC. Leave breakout box installed and set DVOM on 20-volt scale. Connect DVOM between test pins No. 21 and 40. Start engine and observe DVOM while slowly increasing and decreasing engine RPM. If DVOM voltage reading varies, go to next step. If DVOM voltage reading does not vary, replace ECA and repeat QUICK TEST.

11) Check Base Idle Verify base idle speed, see ON-VEHICLE ADJUSTMENTS article. If base idle speed is within specifications, remove ISC solenoid and inspect for contamination, service as necessary. Rerun QUICK TEST. If code or symptom is still present, replace ISC solenoid. If curb idle speed is incorrect, reset idle speed to specification. Rerun QUICK TEST. If unable to set idle to specification, go to next step.

12) Check Faults Which Affect Idle Speed Check the following mechanical items for faults

1. Throttle linkage and/or cruise control linkage for sticking or binding
2. Throttle body for contamination
3. Vacuum hoses (check emission decal)
4. Check for leaks around ISC solenoid (gaskets, etc.)

If all of the above items are okay, remove ISC solenoid and inspect for contamination. Service as necessary and rerun QUICK TEST. If code or symptom is still present, replace ISC. If any of the above items are faulty, service as needed. Remove breakout box. Reconnect components. Rerun QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 12) to step 15). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

15) Code 13: Verify Idle Speed is Within Specification Code 13 indicates engine could not be controlled within lower RPM range during self-test. Possible causes for this fault are

1. Incorrect idle setting
2. Vacuum leaks
3. Sticking or binding throttle linkage
4. Throttle plates open
5. Incorrect ignition timing (TFI ignition only)
6. Throttle body or ISC solenoid contamination
7. ISC circuit shorted to ground
8. Faulty ISC solenoid

If all of the above components are okay and idle is set to specification, remove ISC solenoid and inspect for contamination. Service as necessary and rerun QUICK TEST. If code or symptom is still present, replace ISC solenoid. If idle speed is not set to specification, reset and rerun QUICK TEST. If idle speed cannot be reset to specification, go to next step.

16) Check For Conditions Affecting Idle Speed Check the following mechanical components for faults

1. Engine vacuum hoses (refer to emission decal)
2. Throttle linkage and/or cruise control linkage for sticking or binding
3. Ensure throttle plates are fully closed
4. Check for vacuum leaks in induction system
5. Check throttle body for contamination
6. Ensure base ignition timing is to specification on emission decal (TFI vehicles only)

If all above checks are okay, go to next step. If a fault has been found, service as necessary and rerun QUICK TEST.

17) Check For Internal Short to ISC Solenoid Case With key off and ISC solenoid disconnected, set DVOM on 200-k/ohm scale. Measure resistance from either ISC terminal pin to ISC solenoid housing. If reading is greater than 10 k/ohms, go to next step. If reading is 10 k/ohms or less, replace ISC solenoid. Repeat QUICK TEST.

18) Check ISC Circuit For Short to Ground Turn key off and wait 10 seconds. Leave ISC solenoid disconnected. Disconnect ECA 60-pin connector. Inspect for damaged or corroded terminal pins. Service as necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 21 and test pins No. 40, 46, and 60. If any reading is less than 10 k/ohms, repair short to ground and remove breakout box. Reconnect components and repeat QUICK TEST. If all readings are 10 k/ohms or more, go to next step.

19) Check ISC Signal From ECA With key off, connect ECA and ISC. Leave breakout box installed and set DVOM on 20-volt scale. Connect DVOM between test pins No. 21 and 40. Start engine and observe DVOM while slowly increasing and decreasing engine RPM. If DVOM voltage reading varies, remove ISC solenoid and inspect for contamination, service as necessary. Rerun QUICK TEST. If code or symptom is still present, replace ISC solenoid. If DVOM voltage does not vary, replace ECA and rerun QUICK TEST.

20) Code 47: Check For Low Flow of Unmetered Air Code 47 indicates that measured airflow at base idle was lower than ECA specification. Possible causes for this fault are: air/vacuum leaks in fuel charging system or faulty or leaking purge solenoid and/or leaking injector "O" rings. Check for holes, cracks and or disconnections in fuel charging assembly. Check for a stuck open purge solenoid or injector "O" rings. Service any faults as necessary and rerun QUICK TEST. If no faults are present, EEC-IV system is okay. Service other codes as necessary.

21) Code 48: Check For High Flow of Unmetered Air Code 48 indicates that measured airflow at base idle was higher than ECA specification. Possible causes for this fault are: air/vacuum leaks in fuel charging system or loss of ignition or fuel.

Check for and repair holes, cracks, and/or bad connections at air cleaner outlet tube (between vane airflow meter and fuel charging assembly). Check for loss of ignition or injection on one or more cylinders. If any faults are found, service as necessary. Rerun QUICK TEST. If no faults are found, EEC-IV system control of metered airflow is okay. Service other codes as necessary.

22) Code 16: High ISC RPM Code 16 indicates that with ISC off, engine RPM was greater than self-test specification limit. Possible causes for this fault are

1. Incorrect idle adjustment
2. Faulty purge solenoid
3. Air or vacuum leaks

If Code 48 is also present, reset throttle plate. Refer to Vehicle Emission Control Decal for curb idle set procedure. Rerun QUICK TEST. If Code 48 is still present, go back to step 21) of this test. If Code 48 is not present, go to TEST KD, step 15).

Note. There is a break in the step numbering sequence at this point, skipping from step 22) to step 25). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

25) Code 19: ISC RPM Low Code 19 indicates that with ISC off, engine RPM dropped below self-test limit (about 600 RPM). Possible causes for this fault are

1. Engine below normal operating temperature
2. Throttle body/air inlet contamination
3. Incorrect idle speed adjustment

Turn key off and wait 10 seconds. Deactivate KOER Self-Test. Start and run engine at 2000 RPM for 2 minutes or until top radiator hose is hot and pressurized. Turn key off and wait 10 seconds. Rerun KOER Self-Test. If engine stumbles and/or Code 19 is still displayed, inspect throttle body and air inlet for contamination, service as necessary and adjust base idle. Rerun QUICK TEST. If Code 19 has been cleared, service other codes as necessary.

26) Code 17: ISC RPM Low Code 17 indicates that with the ISC off, engine RPM was below self-test limit. Possible causes for this fault are

1. Excessive engine accessory load
2. Engine temperature below normal operating temperature
3. Throttle body/air inlet contamination
4. Incorrect idle adjustment

Check and correct excessive engine load conditions, cooling fans, lights, etc. Run engine at 2000 RPM for 2 minutes, or until top radiator hose is hot and pressurized. Turn key off and wait 10 seconds. Rerun KOER Self-Test. If Code 17 is displayed, inspect throttle body and air inlet for contamination and clean as necessary. If okay, adjust base/curb idle speed and repeat QUICK TEST. If Code 17 is not displayed, service other codes as necessary.

ELECTRO DRIVE FAN (EDF)/HIGH ELECTRO DRIVE FAN (HEDF)

Note. Perform this test only when Code 83 or 88, is displayed during QUICK TEST or directed here by a driveability symptom. This test is intended to diagnose only the following components or circuits

1. Harness circuits (EDF, HEDF, EDF POWER-TO-FAN, HEDF POWER-TO-FAN IGN START/RUN, GND))
2. EDF and HEDF relays
3. Cooling fan
4. ECA

EDF/HEDF Circuit. Scheme 87

TEST PIN IDENTIFICATION

1) Code 83 or 88: Check For IGNITION START/RUN Voltage at EDF/HEDF Relay Code 83 indicates a faulty HEDF primary circuit. Code 88 indicates a faulty EDF primary circuit. Possible causes for these faults are

1. Open or shorted circuit
2. Faulty fan relay
3. Faulty ECA
4. Faulty A/C high pressure switch (Code 83)

With key off, disconnect EDF and HEDF relays. Set DVOM on 20-volt scale. With KOEO, measure voltage between IGN START/RUN circuit at the EDF/HEDF relay vehicle harness connector and chassis ground. If voltage is greater than 10.5 volts, go to next step. If not, repair open circuit. Reconnect relays and rerun QUICK TEST.

2) Enter Output State Check Use a VOM or DVOM for this test. Turn key off and wait 10 seconds. Set DVOM on 20-volt scale. Disconnect electrical connector on speed control servo (if equipped). Connect DVOM negative test lead to STO at the self-test connector and positive test lead to the battery positive post. Jumper STI or SIG RTN at the self-test connector. Perform KOEO Self-Test until completion of Continuous Memory Code output. When DVOM indicates less than one volt, depress and release throttle. If voltage increases to greater than 10.5 volts, remain in Output State Check and go to next step. If voltage does not increase to at least 10.5 volts, depress throttle to WOT and release. If STO voltage does increase to specification, leave equipment connected and go to TEST QC, step 2).

3) Check For EDF/HEDF Circuit Cycling With vehicle still in Output State Check, disconnect EDF or HEDF relay. Set DVOM on 20-volt scale. Connect DVOM positive test lead to IGN START/RUN circuit and negative test lead to EDF or HEDF circuit at relay vehicle harness connector. Observe DVOM and depress throttle. For EDF, wait until CHECK ENGINE light flashes once (about 10 seconds). For HEDF, wait until CHECK ENGINE light flashes twice (about 15 seconds). Release throttle. EDF/HDF output is now ON. To cycle output OFF, depress and release throttle. If voltage cycles (about a 1-volt change), replace EDF or HEDF relay. Remove jumper and repeat QUICK TEST. If voltage does not cycle, remove jumper and go to next step.

4) Check Continuity of EDF/HEDF Circuit Turn key off and disconnect EDF or HEDF relay. Disconnect ECA 60-pin connector. Inspect for corroded or damaged connector pins and repair as necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Perform the following appropriate check

CODE 83

Measure resistance between test pin No. 31 at the breakout box and HEDF circuit at HEDF relay vehicle harness connector.

CODE 88

Measure resistance between test pin No. 35 at the breakout box and EDF circuit at EDF relay vehicle harness connector. If resistance is less than 5 ohms, go to next step. If not, repair open circuit. Remove breakout box and reconnect all components. Rerun QUICK TEST.

5) Check EDF/HEDF Circuit For Short To Power With breakout box installed, leave ECA disconnected. Disconnect EDF or HEDF relay. Set DVOM on 20-volt scale. Turn key on. Measure voltage between test pin No. 31 (HEDF) or 32 (EDF) at the breakout box and battery negative terminal. If voltage is less than one volt, go to next step. If not, repair short circuit. Remove breakout box and reconnect all components. Rerun QUICK TEST. If code is still present, replace ECA.

6) Check EDF/HEDF Circuit For Short To Ground With key off, install breakout box, leaving ECA disconnected. Disconnect EDF or HEDF relay. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 31 (HEDF) or 35 (EDF) and test pins No. 40 and 60 at the breakout box. If resistance is greater than 10 k/ohms, replace the ECA. Remove breakout box, reconnect all components and repeat QUICK TEST. If resistance is less than 10 k/ohms, repair short circuit. If Code 83 is present, ensure A/C high pressure switch is open. Remove breakout box, reconnect all components and repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 6) to step 10). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

10) Low Speed (EDF) And/Or High Speed (HEDF) Cooling Fan Does Not Operate: Check For Voltage To EDF Relay With key off, disconnect EDF relay. Set DVOM on 20-volt scale. With KOEO, measure voltage between SHORT CONNECTOR (shorted for non-A/C) input pin at the EDF relay vehicle harness connector and battery negative terminal. If voltage is greater than 10.5 volts, go to step 13). If not, for A/C equipped vehicles, go next step. For non-A/C vehicles, verify condition of jumper at SHORT CONNECTOR and operation of ignition relay. If these are okay, repair open circuit. Reconnect EDF relay. Recheck the system or re-evaluate the driveability symptom.

EDF Vehicle Harness Connector. Scheme 88

11) Check For Voltage To HEDF Relay With key off, disconnect EDF and HEDF relays. Set DVOM on 20-volt scale. With KOEO, measure voltage between ignition relay input terminal at the HEDF relay vehicle harness connector and battery negative terminal. If voltage is greater than 10.5 volts, go to next step. If not, check operation of ignition relay. If relay is okay, repair open circuit. Reconnect EDF and HEDF relays. Re-evaluate symptoms.

HEDF Relay Harness Connector. Scheme 89

12) Check Continuity Between EDF & HEDF Relays With key off, disconnect EDF and HEDF relays. Set DVOM on 200-ohm scale. Measure resistance between HEDF input terminal at the EDF relay vehicle harness connector and the output to the EDF terminal at the HEDF relay vehicle harness connector. If resistance is less than 5 ohms, replace HEDF relay. Reconnect all components. Re-evaluate symptom.

EDF & HEDF Relay Harness Connectors. Scheme 90

13) Check Circuits From EDF Relay To Fan With key off, disconnect EDF relay. Install a jumper wire from SHORT CONNECTOR input terminal to POWER-TO-FAN terminal at the EDF relay vehicle harness connector. Turn key on. If fan operates, remove jumper and go to step 16) for vehicles equipped with A/C. For non-A/C vehicles, replace EDF relay. Recheck system. If fan does not operate, remove jumper wire and go to next step.

EDF Relay Harness Connector. Scheme 91

14) Check EDF POWER-TO-FAN Circuit Continuity With key off, disconnect EDF relay and cooling fan. Set DVOM on 200-ohm scale. Measure resistance between EDF POWER-TO-FAN output terminal at the EDF vehicle harness connector and the EDF POWER-TO-FAN input pin at the cooling fan vehicle harness connector. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open circuit. Reconnect all components. Re-evaluate driveability symptoms.

EDF & Cooling Fan Vehicle Harness Connector. Scheme 92

15) Check Cooling Fan Ground Circuit With key off, disconnect EDF relay. Disconnect cooling fan. Set DVOM 200-ohm scale. Measure resistance between GND circuit at the cooling fan vehicle harness connector and battery negative terminal. If resistance is less than 5 ohms, replace cooling fan. Reconnect all components. Recheck symptom. If resistance is greater than 5 ohms, repair open circuit. Reconnect all components and recheck symptom.

16) Check Circuits From HEDF Relay To Fan With key off, disconnect EDF relay. Disconnect A/C high pressure (A/C HP) switch. Install a jumper wire between the 2 terminals of the A/C HP switch vehicle harness connector. Turn key on. If fan runs at high speed, replace EDF relay. Remove jumper wire. Reconnect A/C HP switch. Recheck symptom. If fan does not run at high speed, remove jumper wire and reconnect ERDF relay. Go to next step.

17) Check Continuity of Circuits From A/C High Pressure Switch With key off, disconnect A/C HP switch and HEDF relay. Set DVOM on 200-ohm scale. Measure continuity from GND circuit at A/C HP switch vehicle harness connector and battery negative terminal. Measure continuity between signal output terminal (to HEDF relay) at A/C HP switch vehicle harness connector and A/C HP switch signal input terminal at HEDF relay vehicle harness connector. If each resistance is less than 5 ohms, go to next step. If not, repair open circuit. Reconnect all components and recheck symptoms. If symptom is still present, return to step 16) in this test.

HEDF & AC HP Switch Vehicle Harness Connector. Scheme 93

18) Check HEDF POWER-TO-FAN Voltage at Fan With A/C HP Switch Grounded With key off, disconnect A/C HP switch and cooling fan. Reconnect HEDF relay. Set DVOM on 20-volt scale. Install a jumper wire between the 2 terminals of the A/C HP switch vehicle harness connector. Turn key on, measure voltage between HEDF POWER-TO-FAN circuit at the cooling fan vehicle harness connector and the battery negative terminal. If voltage is greater than 10.5 volts, replace cooling fan. Remove jumper wire and reconnect all components. Recheck system operation. If voltage is not greater than 10.5 volts, remove jumper wire. Reconnect A/C HP switch and go to next step.

Cooling Fan Vehicle Harness Connector. Scheme 94

19) Check HEDF POWER-TO-FAN Circuit Continuity Turn key off. Disconnect cooling fan and HEDF relay. Set DVOM on 200-ohm scale. Measure resistance between the HEDF POWER-TO-FAN output terminal at the HEDF vehicle harness connector and the HEDF POWER-TO-FAN input terminal at the cooling fan vehicle harness connector. If resistance is less than 5 ohms, replace HEDF relay. Reconnect all components. Recheck system operation. If resistance is greater than 5 ohms, repair open circuit. Reconnect all components and recheck system operation.

HEDF Relay Vehicle Harness Connector. Scheme 95

Note. There is a break in the step numbering sequence at this point, skipping from step 19) to step 25). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

25) Low Speed (EDF) or High Speed (HEDF) Cooling Fan Always On: Ensure Ignition Relay is Opening Turn A/C off during this test. Check cooling fan with key in OFF and ON positions. If cooling fan is always on with key off, but operates normally with key on, ensure IGNITION relay contacts are always closed. If relay is okay, check circuit from IGNITION relay to fan relays for a short to BATT (+). If system does not operate as described, go to next step.

26) Check For Relay Always Closed Turn key off and disconnect EDF relay. Turn key on. If fan continues to run, go to next step for vehicles equipped with A/C. For non-A/C vehicles, repair short to power in EDF POWER-TO-FAN circuit. Reconnect EDF relay. Recheck system operation. If vehicle does not continue to run, replace EDF relay and recheck system operation.

27) Check HEDF Relay Turn key off. Disconnect EDF and HEDF relay. Turn key on. If fan continues to run, go to next step. If not, replace HEDF relay. Reconnect EDF relay. Recheck system operation.

28) Check EDF POWER-TO-FAN Circuit For Short to Power Turn key off. Disconnect EDF and HEDF relays. Disconnect cooling fan. Set DVOM on 20-volt scale. Turn key on. Measure voltage between EDF POWER-TO-FAN circuit at the cooling fan vehicle harness connector and battery negative terminal. If voltage is greater than 1.0 volt, repair short-to-power in EDF POWER-TO-FAN circuit. Reconnect all components. Recheck system operation. If voltage is not greater than 1.0 volt, repair short-to-power in HEDF POWER-TO-FAN circuit. Reconnect all components. Recheck system operation.

Cooling Fan Vehicle Harness Connector. Scheme 96

TEST KH - SERVICE PIN ADJUSTMENT

Note. Perform this test only when Code 57 OR 59 is displayed during QUICK TEST procedure or directed here by a driveability symptom. This test is intended to diagnose only the following components or circuits

1. Harness circuits (OCTANE ADJUST, IDLE ADJUST)
2. Service pin connector shell (jumper wire)

Service Pin Circuit. Scheme 97

1) Check if Octane Adjust Jumper Wire is Installed If the service pin connector is installed in the vehicle harness connector, then Code 57 is not a fault code but an information code, indicating that the service pin jumper wire is installed or circuit No. 23 is shorted to ground. For additional information on the octane adjust circuit, go to step 3). Locate the 3-pin service connector. If jumper wire is installed, Code 57 indicates service pin in use. Do not remove, testing is complete. If jumper is not installed, go to next step.

2) Check For Short To Ground Turn key off. Disconnect ECA 60-pin connector. Inspect for corroded or damaged connector pins and repair as necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 23 and test pins No. 20, 40 and 60. If each resistance is greater than 10 k/ohms, replace ECA. Remove breakout box and rerun QUICK TEST. If each resistance is not greater than 10 k/ohms, repair short to ground. Remove breakout box and rerun QUICK TEST.

3) Octane Adjust Pin The purpose of the octane adjust pin is to provide optimum spark advance. If the vehicle spark knocks, install the service pin connector (jumper wire) to the vehicle harness connector. This will retard ignition timing 4 degrees. A Code 57 will be displayed to indicate service pin is in use. If vehicle continues to spark detonate, use gasoline with a higher octane rating.

Service Pin Connector (Jumper Wire). Scheme 98

Note. There is a break in the step numbering sequence at this point, skipping from step 3) to step 10). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

10) Check If Idle Adjust Wire is Installed If the service pin connector is installed in the vehicle harness connector, Code 59 is not a fault code but an information code, indicating that the jumper wire is installed or circuit No. 28 is shorted to ground. For additional information on the idle adjust circuit, go to step 12). Locate the 3-pin connector. If jumper wire is installed in circuit 28 of the service pin connector, Code 59 indicates service pin in use. Do not remove, testing is complete. If jumper is not installed, go to next step.

11) Check For Short To Ground Turn key off. Disconnect ECA 60-pin connector. Inspect for corroded or damaged connector pins and repair as necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 28 and test pins No. 20, 40 and 60. If each resistance is greater than 10 k/ohms, replace ECA. Remove breakout box and rerun QUICK TEST. If each resistance is not greater than 10 k/ohms, repair short to ground. Remove breakout box and rerun QUICK TEST.

12) Idle Adjust Pin The purpose of the idle adjust pin is to increase engine RPM due to additional engine loads. If the vehicle's curb idle appears to be low during parking maneuvers or vehicle stalls with A/C on, connect grounded jumper wire to IDLE ADJUST circuit No. 28 at the 3-pin service pin connector. This will retard ignition timing 4 degrees. A Code 59 will be displayed to indicate service pin is in use. If vehicle continues to exhibit driveability concerns, adjust idle speed.

TEST KL - SHIFT INDICATOR LIGHT (SIL)

Note. Perform this test only when directed here by a driveability symptom or from TEST QA, step 9). This test is intended to diagnose only the following

1. Harness circuits (SIL and STO)
2. Top gear switch
3. SIL dimmer relay
4. SIL bulb and SIL circuit fuse

Shift Indicator Light (SIL) Circuits. Scheme 99

1) Check SIL Operation Inspect SIL while driving vehicle. SIL should turn on when optimum shift RPM is reached in each gear. Light should be off in highest gear. If SIL light is always on, check for a short in SIL circuit. If light is always off, check for an open in SIL circuit. If light is always on, go to step 6). If light is NOT always on, go to next step.

2) Check SIL Circuit Fuse Turn key off and wait 10 seconds. Remove and inspect SIL fuse (fuse No. 18. If fuse is okay, reconnect and go to next step. If fuse is blown, repair short to ground between fuse and SIL bulb. Replace the fuse and check SIL operation.

3) Check SIL Bulb With key off, remove and inspect SIL bulb. If bulb is okay, go to next step. If bulb has failed, replace bulb and check SIL operation.

4) Check Continuity of SIL Dimmer Relay With key 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 next step. If resistance is more than 5 ohms, replace SIL dimmer relay and check operation.

5) Check SIL Dimmer Relay Function With key off, disconnect SIL dimmer relay. Apply 12 volts across pins No. 1 and 2 of SIL dimmer relay. With DVOM on 200-ohm scale, measure resistance between pins No. 3 and 5 on SIL dimmer relay. If resistance is between 40 and 55 ohms, go to next step. If resistance is not 40-55 ohms, replace SIL dimmer relay and retest operation.

6) Check Voltage at SIL Dimmer Relay With KOEO, disconnect SIL dimmer relay. Set DVOM on 20-volt scale. Measure voltage between test pin No. 5 of the SIL dimmer relay harness connector and the battery negative post. If voltage is greater than 5 volts, reconnect relay and go to next step. If voltage is less than 5 volts, repair circuit between top gear switch and SIL dimmer relay. Recheck SIL operation.

7) Check Voltage at Top Gear Switch With KOEO, disconnect top gear switch. Set DVOM on 20-volt scale. Measure voltage between the SIL dimmer relay side of the top gear switch vehicle harness connector and battery negative post. If voltage is greater than 5 volts, go to next step. If voltage is less than 5 volts, repair circuit between high gear switch and dimmer relay. Check SIL operation.

8) Check Operation of Top Gear Switch Turn key off and wait 10 seconds. Disconnect top gear switch. Set DVOM on 200-ohm scale. Measure resistance of top gear switch while shifting transmission from highest gear to the next lower gear. If switch opens and closes, go to next step. If circuit does not open and close, replace switch and check operation.

9) Check Continuity of SIL Circuit Turn key off, and disconnect top gear switch. Disconnect ECA 60-pin connector. Inspect for corroded or damaged connector pins and repair as necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale, and measure resistance between test pin No. 53 and the ECA side of the top gear switch vehicle harness connector. If resistance is less than 5 ohms, reconnect top gear switch, shift transmission into high gear and go to next step. If resistance is more than 5 ohms, repair open circuit between high gear switch and ECA. Remove breakout box, reconnect all components and verify operation of SIL.

10) Check SIL Circuit For Short to Ground Turn key off, and place transmission in highest gear. Set DVOM on 200-k/ohm scale, and install breakout box, leaving ECA disconnected. Measure resistance between test pin No. 53 and test pin No. 60. If resistance is less than 10 k/ohms, repair short between high gear switch and ECA. If resistance is greater than 10 k/ohms, replace ECA. Remove breakout box and rerun QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 10) to step 15). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

15) Check For Voltage to SIL Socket Turn key off and remove SIL bulb. Place transmission in any gear except top gear. Set DVOM on 20-volt scale. With KOEO, measure voltage between power contact at SIL socket and chassis ground. If voltage is greater than 10.5 volts, go to step 17). If not, reconnect SIL bulb and go to next step.

16) Check Operation of Top Gear Switch Top gear switch is a normally closed switch and is in the IGNITION RUN circuit to the SIL bulb. The top gear switch should be open only when the vehicle is shifted into top gear. With key off and transmission in any gear except top gear, disconnect top gear switch. Set DVOM on 200-ohm scale. Measure resistance of top gear switch. If resistance is less than 5 ohms, repair open in IGNITION RUN circuit to SIL bulb socket and verify SIL operation. If resistance is not less than 5 ohms, replace top gear switch and verify SIL operation.

17) Check Continuity of SIL Circuit Turn key off and remove SIL bulb. Disconnect ECA 60-pin connector. Inspect for corroded or damaged connector pins and repair as necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 53 and SIL circuit contact at the SIL bulb socket. If resistance is less than 5 ohms, replace ECA. Remove breakout box and reconnect SIL bulb. Verify SIL operation. If resistance is not less than 5 ohms, repair open circuit and remove breakout box. Reconnect all components and verify SIL operation.

WIDE OPEN THROTTLE A/C CUT-OUT (WAC) & A/C DEMAND SWITCH

Note. Perform this test when diagnosing a symptom. To prevent the replacement of good components, the following non-EEC components and systems should be checked

1. Refrigerant charge
2. Low ambient temperature (less than 45°F) NOTE: This test is intended to diagnose only the following
3. Harness circuits (WAC, VPWR, GND, POWER-to-CLUTCH, ACD)
4. WAC relay
5. A/C fan controller
6. ECA

3.0L Aerostar WOT A/C Cut-Out Ckts. Scheme 100

TEST PIN WIRE COLOR IDENTIFICATION

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. Use only DVOM, not diagnostic tester, for this step. With key off, disconnect A/C clutch harness connector. Turn A/C switch to A/C position. Set DVOM on 20-volt scale. Start engine and wait 10 seconds. Measure voltage between the power side of the A/C clutch vehicle harness connector and negative battery terminal. If voltage is greater than 10.5 volts, EEC-IV system is okay, diagnose A/C system. If voltage is less than 10.5 volts, go to next step.

2) Check Continuity of POWER-to-CLUTCH Circuit Turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Disconnect A/C clutch harness and harness from WAC relay or A/C fan controller. Measure resistance between power side of A/C clutch vehicle harness connector and POWER-to-CLUTCH circuit terminal pin at WAC relay or A/C fan controller vehicle harness connector. If resistance is less than 5 ohms, reconnect A/C clutch and go to next step. If resistance is more than 5 ohms, service open circuit and retest system. System application is as follows

1. WAC Relay: 3.0L PFI (Aerostar)

3) Check For Power on A/C Demand Circuit With KOEO and WAC relay or A/C fan controller disconnected, turn on A/C switch. Set DVOM to 20-volt scale. Measure voltage between A/C demand input terminal pin at WAC relay or A/C fan controller vehicle harness connector and chassis ground. If voltage is greater than 10.5 volts, go to step 6). If voltage is less than 10.5 volts, verify operation of A/C clutch cyclic pressure switch and A/C demand switch. If components are okay, repair open circuit and reconnect all components. Recheck system.

4) Check Continuity Between WAC Relay & A/C De-Icing Switch Turn key off, and disconnect WAC relay. Set DVOM on 200-ohm scale. Measure resistance between A/C deicing switch output to the WAC relay at the A/C deicing switch vehicle harness connector and the A/C deicing switch input at the WAC relay vehicle harness connector. If resistance is less than 5 ohms, reconnect WAC relay and diagnose A/C system (A/C deicing switch voltage circuit and operation). If resistance is not less than 5 ohms, repair open circuit and reconnect components. Recheck system.

WAC Relay Harness Connector. Scheme 101

5) Check Continuity Between WAC Relay & A/C Relay With key off, disconnect WAC and A/C relays. Set DVOM on 200-ohm scale. Measure resistance between A/C relay output to WAC relay circuit at the A/C relay vehicle harness connector and A/C relay input at the WAC relay vehicle harness connector. If resistance is less than 5 ohms, reconnect WAC relay. Diagnose A/C system. If resistance is greater than 5 ohms, repair open circuit, reconnect relays and recheck system operation.

6) Check WAC Circuit For Short to Ground Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector and WAC relay or A/C fan controller. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between WAC circuit at WAC relay or A/C fan controller and chassis ground. If resistance is greater than 10 k/ohms, go to next step for A/C fan controller systems or step 9) for WAC relay systems. If resistance is less than 10 k/ohms, repair short, reconnect all components and recheck system operation.

7) Check A/C Fan Controller Ground Circuit With key off and A/C fan controller disconnected, set DVOM on 200-ohm scale. Disconnect ECA. Measure resistance between ground circuit at A/C fan controller harness connector and chassis ground. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open circuit and retest system.

8) Check For Voltage to A/C Fan Controller With key on, ECA and the A/C fan controller disconnected, set DVOM on 20-volt scale. Measure voltage between ignition switch RUN circuit at the A/C fan controller vehicle harness connector and chassis ground. Measure voltage between BATT (+) circuit at the A/C fan controller vehicle harness connector and chassis ground. If voltage is greater than 10.5 volts, go to next step. If voltage is less than 10.5 volts, repair open circuit. Reconnect ECA and A/C controller. Recheck system operation.

9) Check WAC Relay or A/C Fan Controller Turn key off and wait 10 seconds. Leave ECA disconnected and reconnect WAC relay or A/C fan controller. Disconnect A/C clutch. Set DVOM on 20-volt scale. With KOEO and the A/C on, measure voltage between power side of A/C clutch vehicle harness connector and battery negative terminal. If voltage is greater than 10.5 volts, replace ECA. Reconnect A/C clutch and retest system. If voltage is less than 10.5 volts, replace WAC relay or fan controller. Reconnect all components and recheck system.

Note. There is a break in the step numbering sequence at this point, skipping from step 9) to step 15). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

15) No A/C Output at WOT Enter Output State Check, see OUTPUT STATE CHECK under ADDITIONAL SYSTEM FUNCTIONS. Use a VOM or DVOM meter for this test. Turn key off and wait 10 seconds. Set DVOM on 20-volt scale. Connect DVOM negative (-) test lead to STO at Self-Test connector and positive lead to positive (+) battery terminal. Jumper STI to SIGNAL RETURN at Self-Test connector. Perform KOEO Self-Test until completion of Continuous Memory Code sequence. Meter will indicate less than one volt when test is complete. Depress and release throttle. If voltage increases to greater than 10.5 volts, remain in Output State Check and go to next step. If voltage does not increase to 10.5 volts, leave test equipment connected and go to TEST QC, step 2).

16) System Identification If vehicle is equipped with WAC relay, go to next step. If vehicle is equipped with A/C fan controller, go to step 22).

1. WAC Relay: 3.0L PFI (Aerostar)

17) Check For VPWR to Relay With vehicle in Output State Check, disconnect harness from WAC relay and set DVOM on 20-volt scale. Measure voltage between VPWR circuit at the WAC relay vehicle harness connector and chassis ground. If voltage is greater than 10.5 volts, go to next step. If voltage is less than 10.5 volts, repair open circuit between power relay and WAC relay. Remove test equipment and retest system.

18) Check WAC System For Cycling With vehicle in Output State Check, reconnect WAC relay and set DVOM on 20-volt scale. Connect positive test lead to VPWR circuit and negative test lead to WAC circuit at WAC relay vehicle harness connector. Check DVOM while depressing and releasing throttle several times, to cycle output on and off. If voltage cycles from high to low, replace WAC relay, remove jumper and retest system. If voltage does not cycle, remove test leads and go to next step.

19) Check Continuity of WAC Circuit Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA and WAC relay disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 54 and WAC circuit at WAC relay vehicle harness connector. If reading is 5 ohms or more, repair open circuit and remove breakout box. Reconnect all components and repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

20) Check WAC Circuit For Short to Power Turn key off and wait 10 seconds. Leave breakout box installed, ECA and WAC relay disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 54 and test pins No. 37 and 57. If any reading is less than 10 k/ohms, repair short circuit and repeat QUICK TEST. If all readings are 10 k/ohms or more, replace ECA and reconnect WAC relay. Retest system.

Note. There is a break in the step numbering sequence at this point, skipping from step 20) to step 22). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

22) Check WAC Cycling With vehicle in Output State Check, disconnect A/C fan controller and set DVOM on 20-volt scale. Connect DVOM positive test lead to ignition run circuit and negative test lead to WAC circuit at A/C fan controller harness connector. Check DVOM while depressing and releasing throttle several times, to cycle system. If voltage cycles from high to low, replace A/C fan controller. Reconnect components and retest system. If voltage does not cycle, remove jumper and reconnect components. Go to next step.

23) Check Continuity of WAC Circuit Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA and fan controller disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 54 and WAC circuit at WAC relay vehicle harness connector. If reading is 5 ohms or more, repair open in harness, remove breakout box and reconnect all components. Repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

24) Check WAC Circuit For Short to Power Turn key off and wait 10 seconds. Install breakout box, leaving ECA and A/C fan controller disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 54 and test pins No. 37 and 57 at the breakout box. If all readings are greater than 10 k/ohms, replace ECA. Reconnect A/C fan controller and retest system. If any reading is 10 k/ohms or less, repair short to power and repeat QUICK TEST. If symptom is still present, replace ECA.

Note. There is a break in the step numbering sequence at this point, skipping from step 24) to step 30). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

30) Cycle A/C Demand Switch Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for corroded or damaged connector pins and repair as necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 20-volt scale. With KOEO, connect DVOM positive test lead to test pin No. 43 and negative test lead to test pin No. 40. If voltage goes high and low as switch is cycled, replace ECA and remove breakout box. Retest system. If voltage does not cycle, go to next step.

31) Check Continuity of A/C Demand (ACD) Circuit Turn key off and wait 10 seconds. Install breakout box leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 43 at the breakout box and A/C demand switch. If resistance is greater than 5 ohms, repair open in ACD circuit and rerun QUICK TEST. If resistance is less than 5 ohms, EEC-IV system is okay. Remove breakout box and reconnect components. Diagnose A/C system.

Note. There is a break in the step numbering sequence at this point, skipping from step 31) to step 35). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

35) Check A/C Demand (ACD) Circuit For Short to Power With key off, disconnect WAC relay or A/C fan controller. Disconnect ECA 60-pin connector. Inspect for corroded or damaged connector pins and repair as necessary. Install breakout box, leaving ECA disconnected. With the A/C demand switch in OFF position, set DVOM on 20-volt scale. With KOEO, measure voltage between test pin No. 24 at breakout box and chassis ground. If voltage is less than one volt, EEC-IV system is okay. Remove breakout box, reconnect all components and diagnose A/C system. If voltage is greater than one volt, check operation of A/C demand switch, if okay, repair short circuit. Remove breakout box, reconnect all components. Retest system.

TEST KP - OCTANE ADJUST

Note. Enter this test when directed here by a driveability symptom. This test is intended to diagnose only the following systems or components

1. Harness circuits (VPWR, SIG RTN, OCT ADJ)
2. Octane shorting bar connector

Octane Adjust Circuit. Scheme 102

OCTANE ADJUST SHORTING BAR LOCATIONS

TEST PIN WIRE COLOR IDENTIFICATION

The purpose of the Octane Adjust Shorting Bar is to provide optimum spark advance for the fuel being used. If the vehicle engine detonates (spark knock), REMOVE the Octane Shorting Bar. This retards spark advance about 3 to 4 degrees. If the vehicle continues to detonate, use fuel with a higher octane rating.

INTAKE AIR CONTROL VALVE (IAC) - TAURUS 3.0L SHO PFI ONLY

Note. Perform this test only when Code 81, is displayed during KOEO Self-Test or directed here by a driveability symptom. This test is intended to diagnose only the following components or circuits

1. Harness circuits (VPWR and IAC)
2. IAC solenoid
3. ECA NOTE: To prevent replacement of good components, be aware that the following non-EEC areas may be at fault
4. Vacuum tank leaks
5. Vacuum hose leaks

IAC Circuit. Scheme 103

1) Code 81: Check IAC Solenoid Resistance Code 81 indicates IAC solenoid output voltage did not change when IAC was activated during KOEO Self-Test. Possible causes for this fault are: IAC circuit open, shorted or disconnected or ECA output driver open or grounded.

Turn key off and wait 10 seconds. Set DVOM on 200-ohm scale and disconnect IAC solenoid connector from harness. Measure resistance between IAC and VPWR circuits of solenoid at solenoid terminals. If resistance is 50-100 ohms, go to next step. If resistance is not 50-100 ohms, replace solenoid and rerun QUICK TEST.

IAC Solenoid. Scheme 104

2) Check Voltage of VPWR Circuit With KOEO, disconnect IAC solenoid. Set DVOM on 20-volt scale. Measure voltage between VPWR circuit of IAC solenoid vehicle harness connector and battery negative post. If voltage is greater than 10.5 volts, go to next step. If voltage is less than 10.5 volts, reconnect IAC solenoid, repair open circuit in harness and rerun QUICK TEST.

3) Check Continuity of IAC Solenoid Circuit Turn key off and wait 10 seconds. Disconnect 60-pin ECA connector. Inspect pins for corrosion or damage and service as necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 32 at the breakout box and IAC solenoid vehicle harness connector. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open circuit. Remove breakout box, reconnect all components and repeat QUICK TEST.

4) Check For Short to Ground Turn key off and wait 10 seconds. With breakout box installed and ECA disconnected, set DVOM on 200-k/ohm scale. Disconnect IAC solenoid. Measure resistance between test pin No. 32 and test pins No. 40, 46 and 60 at the breakout box. If resistance is greater than 100 k/ohms, go to next step. If resistance is less than 100 k/ohms, repair short circuit, reconnect components and repeat QUICK TEST.

5) Check IAC Circuit For Short to Power Turn key off and wait 10 seconds. With breakout box installed and ECA disconnected, set DVOM on 200-k/ohm scale. Disconnect IAC solenoid. Measure resistance between test pin No. 32 and test pins No. 37 and 57 at the breakout box. If resistance is greater than 100 k/ohms, replace ECA. Remove breakout box, reconnect components and repeat QUICK TEST. If resistance is less than 100 k/ohms, repair short circuit, reconnect components and retest. If fault is still present, replace ECA.

6) Check Front & Rear Intake Air Valves With key off, disconnect vacuum lines from both intake air valves. Check each air valve with a vacuum pump. Apply 10 in. Hg vacuum. If both valves hold vacuum, go to next step. If not, replace valve(s) as necessary. Reconnect all components and rerun QUICK TEST.

7) Check Operation of Both Intake Air Valve Systems With key off, apply 10 in. Hg to each air valve. If both valves and mechanical linkage move in response to the applied vacuum, go to next step. If valves and linkage are faulty, service as necessary and rerun QUICK TEST.

8) Check Vacuum to Both Intake Air Valves With key off, check vacuum lines from air valves to IAC solenoid. Inspect for damage or blockage. If vacuum lines are okay, go to next step. If vacuum lines are faulty, service as necessary and retest.

Vacuum Line Routing. Scheme 105

9) Check Vacuum Source to IAC Solenoid Disconnect IAC solenoid vacuum supply hose from intake manifold. Start engine and check vacuum at the disconnected manifold hose. If vacuum is present at hose, replace IAC solenoid and rerun QUICK TEST. If vacuum is not present, check supply hose to IAC solenoid. Service as necessary and rerun QUICK TEST.

IAC Solenoid Vacuum Hose. Scheme 106

TEST M, CODE 77 - DYNAMIC RESPONSE TEST

Note. You should perform this test only when a Code 77 is received during QUICK TEST.

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

1. Technician testing EEC system did not perform brief Wide Open Throttle (WOT) after Dynamic Response code.
2. Faulty mechanical engine components
3. Engine did not go over 2000 RPM during WOT NOTE: This test is intended to diagnose only the following
4. Throttle movement (Minimum 3/4 throttle).
5. RPM increase greater than 2000 RPM.

Note. If throttle is snapped open briefly, it may not be sufficient to pass the WOT test. Ensure that the throttle is depressed fully to WOT and that engine exceeds 2000 RPM.

Code 77 Displayed: System Failed to Recognize WOT Test Rerun KOER Self-Test as follows

1. Start engine
2. Activate KOER Self-Test
3. Observe ID Code "2" (Code "0" with STAR tester)
4. Observe Dynamic Response Code "1" (Code "0" with STAR tester)
5. Perform brief WOT
6. Testing is complete, KOER code output begins

If Code 77 is still displayed, replace ECA and rerun QUICK TEST. If Code 77 is no longer present, vehicle has passed Dynamic Response test, service other codes as necessary.

"CHECK ENG", "CHECK DCL", OR "SERVICE ENG SOON" LIGHT/MESSAGE (MALFUNCTION INDICATOR)

Note. You should perform this test only when Code 70, 71 or 72 is displayed, or when directed here by other test procedure or driveability symptom.

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

1. Fuse, bulb, or socket NOTE: This test is intended to diagnose only the following
2. ECA
3. Data Communications Link (DCL)

"CHECK ENGINE" Indicator Ckt. Scheme 107

TEST PIN WIRE COLOR IDENTIFICATION

Data Communication Link (DCL) Circuit (If Equipped). Scheme 108

TEST PIN WIRE COLOR IDENTIFICATION

1) CHECK ENGINE or SERVICE ENGINE SOON Light Always On If vehicle will not start, go to TEST A, step 1). Service all other KOEO and Continuous Memory Codes before proceeding with this test. Turn key off. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Connect DVOM between test pins No. 17 and No. 40 at the breakout box. If resistance is greater than 5 ohms, replace ECA, remove breakout box and rerun QUICK TEST. If reading is less than 5 ohms, repair short between test pin No. 17 and Self-Test connector or CHECK ENGINE light. Remove breakout box, reconnect all components and repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 1) to step 5). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

5) CHECK ENGINE or SERVICE ENGINE SOON Light Never On: Check Continuity of STO/MIL Circuit If vehicle will not start, go to TEST A, step 1). Turn key off. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 17 and CHECK ENGINE or SERVICE ENGINE SOON light. If resistance is less than 5 ohms, go to next step. If not, repair open circuit in wiring harness. Remove breakout box, reconnect all components and repeat QUICK TEST.

6) Check For Voltage to Bulb Turn key off. Set DVOM on 20-volt scale. With KOEO, measure voltage from battery negative post to the hot side of the CHECK ENGINE or SERVICE ENGINE SOON bulb. If voltage is greater than 10.5 volts, go to next step. If not, go to step 8).

7) Check For Faulty Bulb or Socket Install a known good bulb and socket. Turn key to RUN position. If bulb is ON, reconnect all components, bulb was cause of fault. If bulb is not ON, replace ECA. Verify repair by turning key to RUN position.

8) Check For Voltage at Fuse Set DVOM on 20-volt scale. With KOEO, measure voltage from battery negative post to hot side of the fuse. If voltage is greater than 10.5 volts, repair fuse or open circuit. Reconnect ECA and verify repair by turning key to RUN position. If voltage is not greater than 10.5 volts, repair VBAT circuit. Reconnect ECA and verify repair by turning key to RUN position.

Note. There is a break in the step numbering sequence at this point, skipping from step 8) to step 10). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

10) CHECK ENGINE or SERVICE ENGINE SOON Intermittent, Check For Intermittent Short From STO to Ground If vehicle does not start, go to TEST A, step 1). The light will come on when a Continuous Memory Code is present. Service all Continuous Memory Codes before proceeding. If no codes are outputted, proceed with this test. Enter KOEO Continuous Monitor Mode (WIGGLE TEST). Observe DVOM for indication of fault while performing WIGGLE TEST on the harness in the following areas

1. From Self-Test connector to dash panel
2. Dash panel to ECA
3. Dash panel to CHECK ENGINE or SERVICE ENGINE SOON light

If a fault is indicated, repair as necessary and rerun QUICK TEST. If a fault is not indicated, fault cannot be duplicated at this time. Testing for this fault is complete.

Note. There is a break in the step numbering sequence at this point, skipping from step 10) to step 15). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

15) CHECK ENGINE or SERVICE ENGINE SOON Light Flashes With Erratic Idle: Check STI Circuit For Short to Ground Vehicle symptoms indicate STI is grounded and ECA is performing Self-Test without tester installed. With key off, disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Set DVOM on 200-k/ohm scale. Measure resistance between STI connector and engine block ground. If resistance is less than 10 k/ohms, repair short circuit. Reconnect ECA and retest. If resistance is not less than 10 k/ohms, reconnect ECA. Verify symptom and test for other rough idle symptoms.

Note. There is a break in the step numbering sequence at this point, skipping from step 15) to step 20). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

20) CHECK ENGINE Message Displayed If vehicle will not start, go to TEST A, step 1). Perform KOEO Self-Test, if the result is a Pass Code (11-10-11), repair fault in electronic message center Data Communications Link (DCL). If Pass Code is not displayed, service codes as required in Self-Test procedures.

Note. There is a break in the step numbering sequence at this point, skipping from step 20) to step 25). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

25) Continuous Memory Code 70, 71 and 72: CHECK ENGINE or CHECK DCL Message Displayed Codes 70, 71 and 72 indicate a circuit failure has occurred on the Data Communications Link (DCL). These codes can occur alone or in conjunction with another code. CHECK ENGINE or CHECK DCL message will be displayed when

1. Code 70 indicates ECA is unable to transmit data
2. Code 71 indicates Cluster Control Assembly (CCA) is unable to transmit data
3. Code 72 indicates that Message Center Control Assembly (MCCA) is unable to transmit data

If vehicle is a NO START, go to TEST A, step 1). Perform KOEO Self-Test, if the result is a Pass Code (11-10-11), repair fault in electronic message center Data Communications Link (DCL). If Pass Code is not displayed, service codes as described in Self-Test procedures.

TEST N - IGNITION DIAGNOSTIC MONITOR (IDM)

Note. Perform this test when Code 14, 18, 19, 28, 45, 46, 48 or 88 is displayed during QUICK TESTS or when directed here by other test procedure or driveability symptom. This test is intended to diagnose only the EEC-IV portion of the ignition system. For additional information on ignition system and component testing, see SYSTEMS & COMPONENT TESTING article.

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

1. TFI or DIS ignition module
2. Ignition coil or DIS coil packs
3. Spark plugs and/or high tension cables
4. Distributor and PIP sensor
5. Secondary ignition component arcing NOTE: This test is intended to diagnose the following circuits and components.
6. Harness circuits (IGN GND, SPOUT, PIP, IDM, DPI & SAW)
7. ECA assembly

All Other TFI Applications. Scheme 109

3.0L SHO (DIS) IDM Circuit. Scheme 110

TEST PIN WIRE COLOR IDENTIFICATION

There are 4 types of ignition system connections used with EEC-IV. They are configured as follows

DISTRIBUTORLESS IGNITION SYSTEM (DIS)

Two 6-pin connectors located at top and bottom of DIS module. Pins No. 1-6 are located on the top of the module. Pins No. 7-12 are located in the connector on the bottom of the module.

ELECTRONIC DISTRIBUTORLESS IGNITION SYSTEM (EDIS)

The EDIS system consists of a Variable Reluctance Sensor (VRS) mounted at the front crankshaft pulley, an engine mounted coil pack, and a fender mounted EDIS control module. A 12-pin connector is used at the control module to link it to the ECA and ignition components.

CLOSED BOWL DISTRIBUTOR (CBD)

TFI module is located on the cowl, away from the distributor. The previous mounting window in the bowl of the distributor is closed. Two connectors are used, one connecting the harness to the vehicle Hall sensor, located in the distributor, and another connecting the harness to the TFI module.

TFI MODULE DISTRIBUTOR

This is the most common system. The TFI module is mounted in the distributor and a single module connector is used.

IGNITION SYSTEM APPLICATIONS

1) Continuous Memory Code 14: Erratic Ignition Code 14 indicates 2 successive erratic Profile Ignition Pickup (PIP) pulses occurred, resulting in a possible engine miss or stall. If vehicle is a NO START and has a Code 14, go directly to TEST AA, step 1). Possible causes for this fault are

1. Loose wires or connectors
2. Arcing secondary ignition components
3. On-board transmitter equipment (2-way radio)

If any of the above are present, service as necessary, clear code and rerun QUICK TEST. If the items listed are not present, go to step 4).

2) Code 16: IDM Circuit Failure (EDIS) If engine does not start, see EDIS ignition system in the I - SYS/COMP TESTS article. If engine starts, go to step 4).

3) Continuous Memory Code 18: Check For Other Codes A Code 18 indicates a loss of IDM input signal to the ECA. Possible causes for this fault are

1. Open or shorted harness
2. Faulty DIS module
3. Faulty ECA

If Continuous Memory Codes 45, 46 or 48 are present, see DIS or EDIS testing in I - SYS/COMP TESTS. If Codes 45, 46 or 48 are not present, go to next step.

4) Continuous Memory Codes 18, 28 or 48: Check IDM Circuit Continuity Code 18 indicates a loss of IDM input signal. Possible causes are

1. Open harness circuit
2. Shorted harness
3. Faulty TFI or DIS module
4. Faulty ECA

Code 28 indicates the IDM input signal is always low. Possible causes are

1. Open or shorted harness
2. Faulty CID sensor
3. VBAT (battery voltage) low at DIS
4. Faulty DIS module
5. Faulty ECA

Code 48 indicates IDM input signal always high. Possible causes are

1. Open signal in harness
2. VBAT open at secondary coil
3. VBAT low at secondary coil

Note. On TFI vehicles the IDM circuit has a 22 k/ohm-resistor between Test Pin No. 4 and the ignition coil negative terminal (except 3.0L CALIFORNIA vehicles).

Turn key off an wait 10 seconds. Disconnect E-core ignition coil on TFI vehicles and DIS module connector (pins No. 7-12) on DIS equipped vehicles. Disconnect EDIS module (if equipped). Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leave ECA connected and set DVOM on 200-k/ohm scale.

On TFI equipped vehicles, measure resistance between Test Pin No. 4 at breakout box and negative terminal of ignition coil harness connector.

On DIS and EDIS equipped vehicles, measure resistance between Test Pin No. 4 at breakout box and DIS module harness connector pin No. 12.

If resistance is 20-24 k/ohms (on DIS and 3.0L CALIFORNIA vehicles, resistance should be less than 5 ohms), go to step 6) for EDIS vehicles or next step for all others. If resistance is not to specification, repair open circuit, clear codes, retest and reconnect "E" core coil.

5) Check IDM Circuit For Short to Ground Turn key off and wait 10 seconds. Disconnect "E" core ignition coil on TFI vehicles and DIS module connector (pins No. 7-12) on DIS equipped vehicles. Disconnect EDIS module on EDIS equipped vehicles. Install breakout box and leave ECA disconnected. With DVOM on 200-k/ohm scale, measure resistance between Test Pin No. 4 and test pins No. 40, 46, and 60. If any reading is less than 10 k/ohms, remove breakout box, repair short to ground in IDM circuit, reconnect all components and rerun QUICK TEST. If any readings is 10 k/ohms or more, go to step 8).

6) Check IDM Circuit For Shorts To Power (Except VREF Circuit) With key off, install breakout box. Disconnect ECA and EDIS module. Measure voltage between Test Pin No. 4 and test pins No. 40 and 60. To check for a short to VBAT, leave key off. To check for a short to KEYPOWER or VPWR, turn key on, leaving engine off. If any voltage reading is greater than 10.5 volts, repair short circuit. Remove breakout box and reconnect all components. Rerun QUICK TEST. If voltage is less than 10.5 volts, go to next step.

7) Check IDM Circuit For Short To VREF, GROUND & PIP Turn key off. Install breakout box, leaving ECA disconnected. Disconnect EDIS module (if equipped). For shorts to ground, measure resistance between Test Pin No. 4 and test pins No. 16, 20, 40, 46 and 60.

On vehicles equipped with EDIS, a short to SIG RTN (Pin No. 46) may be indicated in conjunction with an actual PWR GND short when the 4-wire HEGO sensor is connected.

To test for shorts to VREF, measure resistance between test pins No. 36 and 26, at the breakout box.

To test for shorts to PIP, measure resistance between test pins No. 36 and 56, at the breakout box.

If each resistance is greater than 10 k/ohms, go to next step. If not, repair short circuit. Remove breakout box, reconnect all components and repeat QUICK TEST.

8) Check ECA For Short to Ground Turn key off and wait 10 seconds. Disconnect "E" core ignition coil on TFI vehicles and DIS module connector (pins No. 7-12) on DIS equipped vehicles. Disconnect EDIS module on EDIS vehicles. Install breakout box and connect ECA. With DVOM on 200-k/ohm scale, measure resistance between Test Pin No. 4 and test pins No. 40, 46, and 60. If any reading is less than 10 k/ohms, replace ECA, reconnect all components and rerun QUICK TEST. If all readings are 10 k/ohms or more, reconnect components and go to next step.

9) Check Ignition Module Turn key off and wait 10 seconds. Deactivate Self-Test. Using Continuous Monitor Mode (WIGGLE TEST), observe VOM or diagnostic tester for indication of fault while lightly tapping on TFI or DIS/EDIS module to simulate road shock. Wiggle all TFI or DIS harness connectors. On Closed Bowl Distributor (CBD) models, wiggle TFI and distributor hall connectors. If fault is indicated, go to next step. If not, disconnect and inspect TFI harness connectors and terminals for damage. If connector and terminals are okay, check ignition system, see SYSTEMS & COMPONENT TESTING. If ignition is okay, replace ECA.

10) Check EEC-IV Harness While still in Continuous Monitor Mode (WIGGLE TEST), observe VOM or diagnostic tester for indication of fault while wiggling, shaking, or bending small sections of harness while working from TFI or DIS connectors toward firewall. Repeat process from firewall to ECA. On CBD systems also test distributor Hall connector. Perform this test to check for faults in the following circuits

CONDITION-TO-CIRCUIT/TEST PIN NO. MENU

Perform Continuous Monitor Mode (WIGGLE TEST) on these circuits one at a time in order to isolate fault. If fault is indicated, isolate fault and repair harness. Repeat QUICK TEST. If no fault is indicated, go to next step.

11) Check ECA & Harness Connectors Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion or loose wires. If connector is damaged, repair as necessary, clear codes and repeat QUICK TEST. If connector is okay, perform the following procedure based on the Continuous Memory Code displayed

1. Code 14: Unable to duplicate erratic ignition fault in EEC system. Remove breakout box, reconnect all components. Diagnosis DIS ignition system.
2. Code 18: Replace ECA, remove breakout box and reconnect all components. Start and run engine for about one minute and rerun QUICK TEST.
3. Codes 28 & 48: Remove breakout box and reconnect all components. Diagnose ignition system. If ignition system is okay, replace the ECA.

12) Continuous Memory Code 19: Check Camshaft Sensor Output Code 19 indicates one of the 2 Cylinder Identification (CID) sensor output signals has failed. One of the outputs is a signal sent to the DIS and the second output is the signal to the ECA. Both outputs have a 50 percent duty cycle of 0.4 volt to battery voltage (VBAT). Possible causes for this fault are; open or short in CID-to-ECA circuit.

With key off, disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion or loose wires. If connector is damaged, repair as necessary. Install breakout box and connect ECA. With KOER, and DVOM set on AC scale, measure voltage between Test Pin No. 24 and GROUND. If voltage varies, replace ECA, remove breakout box, reconnect all components and rerun QUICK TEST. If voltage does not vary, go to next step.

13) Check CID Harness For Continuity With key off and breakout box installed, disconnect ECA. Disconnect DIS module. Set DVOM on 200-ohm scale. Measure resistance between Test Pin No. 24 at the breakout box and pin No. 2 (CID signal) at the DIS module connector. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open circuit, remove breakout box, reconnect all components and rerun QUICK TEST.

14) Check CID Circuit For Shorts Turn key off, Install breakout box, leaving ECA disconnected. Disconnect DIS module. Set DVOM on 200-k/ohm scale. Measure resistance between Test Pin No. 24 and test pins No. 16, 37 and 40 at the breakout box. If all resistances are not greater than 10 k/ohms, repair CID circuit for short to GROUND or POWER. Remove breakout box, reconnect all components and rerun QUICK TEST. If all resistances are greater than 10 k/ohms, remove breakout box, reconnect all components and diagnose TFI or DIS system. See I - SYS/COMP TESTS article.

Note. There is a break in the step numbering sequence at this point, skipping from step 14) to step 20). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

20) Continuous Memory Code 88: Check Continuity of DPI Circuit Code 88 indicates an open in the Dual Plug Inhibit (DPI) circuit or an open or short to ground in coil No. 4. Possible causes for this fault are

1. Open or short circuit in harness
2. Faulty ECA
3. Faulty DIS module
4. Faulty coil No. 4

Turn key off and wait 10 seconds. Disconnect DIS connector (pins No. 1-6). Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion or loose wires. If connector is damaged, repair as necessary. Install breakout box and leave ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between pin No. 6 at the DIS vehicle harness connector and Test Pin No. 32 at the breakout box. If resistance is less than 5 ohms, remove breakout box, reconnect all components. Diagnose DIS ignition system. If system is okay, replace ECA. If resistance is not less than 5 ohms, repair open circuit, remove breakout box, reconnect all components and rerun QUICK TEST.

TEST P - SPARK TIMING CHECK

Note. Perform this test when Code 18 or 49 is displayed during QUICK TEST or when directed here by other test procedures. This test is intended to diagnose the following

1. Harness circuits (SPOUT, SAW)
2. Base timing
3. Faulty ECA NOTE: To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault
4. Basic engine condition (valves, vacuum leaks, valve timing, EGR valve, etc.)
5. Distributor
6. TFI, DIS or EDIS module
7. Camshaft sensor (CID)
8. Single Hall Crankshaft Sensor (PIP signal)
9. Dual Hall Sensor

TFI Applications Spark Timing Check Circuit. Scheme 111

1) KOER Code 18: Check Computed Spark Timing On TFI vehicles, Code 18 indicates SPOUT circuit is open. Possible causes for this fault are: open harness circuit or faulty ECA or TFI module.

On DIS vehicles, Code 18 indicates: SPOUT circuit is open or shorted to ground. Possible causes for this fault are: an open or shorted harness or faulty ECA or DIS module.

On EDIS vehicles, Code 18 indicates SAW circuit is either open or shorted to ground or VBAT. Possible causes for this fault are: an open or shorted harness or faulty ECA or EDIS module.

Perform KOER Self-Test and verify that Self-Test is activated. Check and record timing while in KOER Self-Test. Self-Test mode locks timing during testing and for a period of 2 minutes after last code is displayed. Computed timing during these 2 minutes is equal to base timing plus 20 degrees (+/- 3 degrees). If computed timing is correct, go to KOER Self-Test. If timing is not to specification, go to next step.

2) Check Base Timing Locate in-line Spark Output (SPOUT) connector or Spark Angle Word (SAW) connector and open the connection. Start engine and check for 10 degrees BTDC base timing +/- 3 degrees. Use specification on VECI decal. If base timing is correct, reconnect SPOUT and go to next step. If base timing is incorrect, on TFI equipped vehicles adjust base timing as necessary. See the appropriate ADJUSTMENTS article. After timing is reset, reconnect SPOUT and perform Computed Timing Check. On DIS and EDIS equipped vehicles, base timing is not adjustable, diagnose ignition system. See I - SYS/COMP TESTS article in this section.

3) Check For Power to ECA Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box. With KOEO, and DVOM set on 20-volt scale, measure voltage between test pins No. 37 and 40, and between test pins No. 57 and 60 at the breakout box. If either reading is less than 10.5 volts, go to TEST X, step 1) on 3.0L PFI or 3.0L SHO PFI. If either reading is less than 10.5 volts, go to TEST A2, step 1) for all other engines. If both readings are 10.5 volts or more, go to next step.

4) Check SPOUT/SAW Circuit For Continuity Turn key off and wait 10 seconds. Install breakout box. Disconnect ECA and TFI, EDIS or DIS (pins No. 1-6) module. With DVOM set on 200-ohm scale, measure resistance between Test Pin No. 36 at breakout box and SPOUT/SAW terminal at TFI, DIS or EDIS module vehicle harness connector. If resistance is greater than 5 ohms, repair open circuit. Reconnect all components and check timing as described in step 1). If resistance is 5 ohms or less, go to next step for DIS/EDIS equipped vehicles, or step 6) for TFI vehicles.

View of Module Connectors. Scheme 112

5) Check SPOUT/SAW Circuit For Shorts To Power (Except VREF) Turn key off and wait 10 seconds, Install breakout box and disconnect ECA and EDIS or DIS module (pins No. 1-6). Set DVOM on 20-volt scale. Perform the following measurements

1. Shorts to VBAT - With key off, measure voltage between Test Pin No. 36 and test pins No. 4 or 60.
2. Shorts to KEYPOWER or VPWR - With key on engine off, measure voltage between Test Pin No. 36 and test pins No. 40, or 60.

If any voltage is less than 10.5 volts, go to next step. If any voltage is greater than 10.5 volts, service short circuit, remove breakout box, reconnect components and rerun QUICK TEST.

6) Check SPOUT/SAW Circuit For Short To VREF, GROUND, or PIP Turn key off and wait 10 seconds. Install breakout box. Disconnect ECA and EDIS or DIS module (pins No. 1-6). Set DVOM on 200-k/ohm scale. For shorts to ground, measure resistance between Test Pin No. 36 and test pins No. 16, 20, 40, 46 and 60.

On vehicles equipped with EDIS, a short to SIG RTN (pin No. 46) may be indicated in conjunction with an actual PWR GND short when the 4-wire HEGO sensor is connected.

To test for shorts to VREF, measure resistance between test pins No. 36 and 26, at the breakout box.

To test for shorts to PIP, measure resistance between test pins No. 36 and 56, at the breakout box.

If each resistance is greater than 10 k/ohms, go to next step. If not, repair short circuit. Remove breakout box, reconnect all components and repeat QUICK TEST.

7) Check SPOUT/SAW Voltage at ECA With key off, and breakout box installed, connect ECA to breakout box. Reconnect TFI, DIS or EDIS module. Ensure timing switch on breakout box is in DIST position. Set DVOM on 20-volt AC scale. With KOEO, measure voltage between Test Pin No. 36 and battery negative post. If voltage is not to specification, replace ECA, remove breakout box and repeat QUICK TEST. If voltage is within specification, EEC-IV system is okay, remove breakout box, reconnect ECA and check ignition system. See I - SYS/COMP TESTS article in this section.

SPOUT/SAW VOLTAGE SPECIFICATIONS

TEST QA - NO CODES/CODES NOT LISTED

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

1. ECA
2. EEC power relay
3. Harness circuits (SIG RTN, STO, STI, VPWR, VREF, PWR GND)

No Codes/Codes Not Listed Circuits. Scheme 113

TEST PIN WIRE COLOR IDENTIFICATION

1) Check VREF Voltage at Self-Test Connector Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, and connect ECA. Set DVOM on 20-volt scale. With KOEO, measure voltage between Test Pin No. 26 and SIG RTN at Self-Test connector. If reading is less than 4 volts or more than 6 volts, go to TEST C, step 1). If reading is between 4 and 6 volts, go to next step.

2) Check STI Circuit Continuity Turn key off and wait 10 seconds. With breakout box installed and ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between Test Pin No. 48 at the breakout box and Self-Test Input (STI) at Self-Test connector pigtail. If resistance is 5 ohms or more, repair open in circuit, remove breakout box and reconnect ECA. Rerun QUICK TEST. If reading is less than 5 ohms, go to next step.

3) Check STO Circuit Continuity With breakout box installed and ECA disconnected, set DVOM on 200-ohm scale. Measure resistance between Test Pin No. 17 at the breakout box and Self-Test Output (STO) at Self-Test connector. If reading is 5 ohms or more, repair open circuit, remove breakout box and reconnect ECA. Rerun QUICK TEST. If reading is less than 5 ohms, go to step 5).

4) Check EGO GND Circuit Continuity Turn key off. With breakout box installed and DVOM on 200-ohm scale, measure resistance between Test Pin No. 49 and EGO GND on engine block. If resistance is greater than 5 ohms, repair EGO sensor ground wire or open circuit. If resistance is less than 5 ohms, go to next step.

5) Check STO Circuit For Short to Ground With breakout box installed and ECA disconnected, set DVOM on 200-ohm scale. Measure resistance between STO at Self-Test connector and engine block ground. If resistance is less than 5 ohms, repair STO or MIL/SIL circuit for short to ground. Reconnect ECA and repeat QUICK TEST. If reading is greater than 5 ohms, go to next step.

6) Check If Power Relay Always On With key off, install breakout box leaving ECA disconnected. Set DVOM on 20-volt scale. Connect DVOM between test pins No. 37 or 57 and pins No. 40 or 60. Turn key on and then off. Wait 10 seconds. If reading does not change from 10.5 volts (or more) to zero volts, go to next step. If reading changes from 10.5 volts (or more) to zero volts, go to step 8) only if vehicle is equipped with Malfunction Indicator Light (MIL) or Shift Indicator Light (SIL). If vehicle is NOT equipped with either of these lights, replace ECA and repeat QUICK TEST.

Note. Malfunction Indicator Light (MIL) is displayed as CHECK ENGINE or SERVICE ENGINE SOON light on instrument cluster.

7) Check VPWR Circuit For Short to Power With key off, breakout box installed and EEC power relay or Integrated Relay Controller Module (IRCM) disconnected, set DVOM on 20-volt scale. Ensure ECA is disconnected. Connect DVOM to Test Pin No. 37 or 57 and to Test Pin No. 40 or 46 at the breakout box. If voltage is greater than 10.5 volts, repair short to VPWR circuit. Remove breakout box, reconnect ECA and rerun QUICK TEST. If voltage is less than 10.5 volts, replace EEC-IV power relay or IRCM. Remove breakout box, reconnect ECA and rerun QUICK TEST.

8) Malfunction Indicator Light (MIL) or Shift Indicator Light (SIL) Equipped Vehicles If shift indicator light is always on or off, go to TEST KL, step 1). If malfunction indicator light is always on, go to TEST ML, step 1). If malfunction indicator light is always off, go to TEST ML, step 5). If MIL or SIL is working normally, replace ECA and repeat QUICK TEST.

TEST QB, CODE 15 - KOEO OR CONTINUOUS MEMORY CODE

Note. Perform this test when directed by other test procedures. This test is intended to diagnose only the following components or systems

1. ECA
2. Harness circuits (PWR GND, VPWR, KAPWR, IGNITION)

EEC Power Relay Circuit. Scheme 114

TEST PIN WIRE COLOR IDENTIFICATION

1) Continuous Memory Code 15 Displayed Clear Continuous Memory Codes using procedure described. Repeat KOEO Self-Test through Continuous Memory Code output. If Continuous Memory Code 15 is not displayed, Continuous Memory Code 15 testing is complete. Service other codes as necessary. If Continuous Memory Code 15 is displayed during retest, go to next step.

Note. Continuous Memory Code 15 may be displayed when power to Keep Alive Memory (KAM) Test Pin No. 1 at ECA is interrupted. This code may be set when installing a breakout box and displayed the first time Self-Test is performed and power is restored to ECA. Repeat Self-Test to ensure correct diagnosis.

2) Inspect Engine Compartment Wire Routing Ensure that EEC-IV components and wiring are not close to high tension secondary voltage wires or ignition components. If EEC-IV wiring is close to high tension wires, reroute EEC wiring. Repeat KOEO Self-Test. If Continuous Memory Code 15 is no longer displayed, Continuous Memory Code 15 testing is complete, service other codes as necessary. If Continuous Memory Code 15 is still displayed, go to next step.

3) Check KAPWR Circuit Voltage Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector and inspect for damaged pins and loose wires. Service as necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 20-volt scale. Connect DVOM positive test lead to Test Pin No. 1 and negative test lead to pins No. 40 or 60 at the breakout box. With KOEO, observe voltage reading. If reading is less than 10.5 volts, repair open circuit. Reconnect ECA and repeat QUICK TEST. If reading is 10.5 volts or more, replace ECA and remove breakout box. Repeat QUICK TEST.

TEST QC - OUTPUT STATE CHECK NOT FUNCTIONING

Note. Perform this CIRCUIT TEST when directed by other test procedures. This test is intended to diagnose only the following

1. ECA
2. Harness circuits (SIG RTN, STO, STI, GND, VPWR, & VREF)

1) Check For Codes 23,53,63 or 68 If vehicle is equipped with a speed control, speed control servo must be electrically disconnected. This prevents the speed control system from affecting throttle plate movement during Output State Check. Rerun QUICK TEST or Output State Check.

Turn key off and wait 10 seconds. Perform KOEO Self-Test. If Codes 23, 53, 63 or 68 are displayed, go to KOEO Self-Test table and service code(s) as necessary. If no codes are displayed, go to TEST QA, step 1). If Code 11 (Pass) is displayed, go to next step.

2) Check Throttle Linkage Check throttle and linkage for sticking or binding. If throttle and linkage are okay, replace TPS and repeat QUICK TEST. If throttle and linkage are binding, repair as necessary and repeat QUICK TEST.

TEST QD - RE-INITIALIZATION CHECK

Note. Perform this test when Codes 71, 72 or 78 is displayed or when directed by other test procedure or driveability symptoms. This test is intended to diagnose only the following

1. ECA
2. EEC Power Relay
3. Harness circuits (GND, VPWR, IGNITION)

Note. The electrical signatures of some aftermarket components may affect driveability of the vehicle.

EEC Power Relay Circuit. Scheme 115

TEST PIN WIRE COLOR IDENTIFICATION

1) Codes 71 or 72: Check For Electrical Noise Sources Continuous Memory Code 72 indicates that power to the ECA was interrupted sometime during the last 40 warm-up cycle. A Continuous Code 71 indicates that sometime during the past 40 warm-up cycles, the ECA software requested a re-initialization or review of previous drive sequence data. This process could result in a driveability complaint. Possible causes for this fault or complaint are

1. Vehicle power interrupted to ECA
2. Spark plug wires incorrectly routed too close to ignition
3. High tension wire shielding removed
4. Electrical, radio, or motor static noise
5. Test Pin No. 20 (case ground) not grounded to chassis
6. Open diodes on A/C or ISC relay

Turn key off. Ensure that EEC-IV wiring and components are more than 2" (50 mm) away from secondary ignition wires and ignition coil. Make sure that EEC-IV wiring and components are more than 4" (100 mm) away from distributor, ignition coil, and starter motor and its wiring. If these items are correct, go to next step. If not, correct as necessary and repeat QUICK TEST.

2) Check CASE GND Circuit Continuity Turn key off. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between Test Pin No. 20 and chassis ground. If reading is less than 5 ohms, go to next step. If not, repair wiring harness. Remove breakout box, reconnect components and repeat QUICK TEST.

3) Check Case Ground Check With Harness Disconnected Turn key off. Connect ECA to breakout box, but disconnect vehicle harness from breakout box. Set DVOM on 200-ohm scale. Measure resistance between Test Pin No. 20 and ECA metal case. If resistance is less than 5 ohms, go to next step. If reading is more than 5 ohms, replace ECA. Remove breakout box and repeat QUICK TEST.

4) WIGGLE TEST VPWR Circuit With KOEO, connect DVOM to Self-Test connector. Deactivate Self-Test. Using Continuous Monitor Mode, perform WIGGLE TEST on EEC-IV harness from ECA to EEC Power Relay. If a fault is indicated or a Code 71 is displayed, repair intermittent in VPWR circuit. If no fault is indicated, inspect harness connections and pins. Repair as necessary. If harness is okay, replace EEC Power Relay and rerun QUICK TEST.

5) Code 19: Internal Voltage Code 19 indicates the ECA voltage regulator does not have the ability to maintain correct internal voltage. Run KOEO Self-Test, if Code 19-10-11 is present, replace ECA and rerun QUICK TEST. If Code 19-10-11 is not present, service other codes as indicated. If no other codes are present, testing is complete.

TEST S - SYSTEM CHECK

Perform this test only after Code 11 is displayed in KOEO Self-Test and you have been directed here from TEST A, step 20) or by a driveability symptom.

Note. This test is intended to diagnose the following components or systems

1. ISC by-pass air system
2. MAP system
3. EGR system
4. MAP system

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

1. Faulty power or ground connections
2. Ignition system (distributor cap, rotor, wires, coil, plugs)
3. Basic mechanical engine components (cam timing, compression, etc.)

System Check Block Diagram. Scheme 116

1) ISC-BPA Check This step is for PFI vehicles with stall or no start faults. If engine stalls or if it does not start, attempt to start engine at part throttle. If engine will start and run smoothly at part throttle, go to TEST KE, step 4). If not, proceed to step 3).

2) Check For RPM Drop Turn key off. Connect a tachometer. Start engine and disconnect ISC solenoid. If RPM drops or engine stalls, reconnect ISC solenoid and go to next step. If not, go to step 4).

3) Power to MAP/BP Sensor If vehicle is not equipped with a MAP/BP sensor, go directly to step 8). Use Ford Motor Co. MAP/BP tester for this test. If Green light is on, VREF circuit voltage is okay. If Red light (or no light) is on, VREF circuit voltage is too low or too high. Turn key off and disconnect MAP/BP sensor from vehicle harness. Connect MAP/BP tester between vehicle harness and MAP/BP sensor. Connect banana plugs of tester into DVOM and set DVOM on 20-volt scale. With tester connected, turn key on. If Green light is on, go to next step. If light is not on, repair open in VREF circuit, remove MAP/BP tester. Reconnect components and retest symptom.

MAP/BP Tester & Circuit. Scheme 117

4) MAP/BP Tester Output Reading Measure several known good MAP sensors to obtain average measured voltage for specific location and date of testing. With MAP/BP tester and DVOM connected. Turn key on and measure MAP/BP SIG voltage at MAP sensor. If voltage is in the correct range for altitude, go to next step, except vehicles equipped with MA sensors, go to step 8). If voltage is not in the correct range for altitude, replace MAP/BP sensor.

MAP VOLTAGE OUTPUT

5) Check MAP/BP Sensor Turn key off and wait 10 seconds. Disconnect vacuum line from MAP sensor. Install vacuum pump to MAP sensor. Apply 18 in. Hg vacuum to MAP sensor. If MAP sensor holds vacuum, release vacuum and remove vacuum pump. Reconnect vacuum line to MAP sensor and go to next step.

6) MAP Engine Running Response Test Turn key on. Ensure MAP/BP tester and DVOM are connected. Set DVOM on 20-volt scale. Crank engine. If MAP output voltage changes while engine is being cranked, go to step 8). If not, go to next step.

7) Check Vacuum Lines Check vacuum lines for correct routing. Refer to VECI decal. Check MAP sensor vacuum line for leaks or blockage. If vacuum lines are okay, replace MAP sensor. Remove MAP/BP tester. Recheck system operation. If vacuum lines are not okay, repair as necessary. Rerun QUICK TEST.

8) Check EGR Vacuum If vehicle is not equipped with EGR system hardware, go directly to TEST H, step 1). Steps No. 8 and 9 attempt to determine if EGR system is cause of driveability symptom or NO START. Disconnect vacuum line at EGR valve. DO NOT plug vacuum line. Start engine. If vehicle was a NO START, and still does not start, or if vehicle had a driveability fault, and vacuum is NOT present at EGR vacuum line, go to next step. If vehicle still a NO START, or vacuum is not present, go to the following appropriate CIRCUIT TEST

1. 3.0L SHO PFI: Go to TEST DL, step 21)

9) Check EGR Valve Inspect EGR valve for leaks. If valve is fully closed, go to TEST H, step 1). If EGR valve is leaking or not fully seated, replace or repair valve.

TEST T - AXOD TRANSAXLE

Note. Perform this test only when Codes 29, 39, 57, 59, 62, 67, 68, 69 or 89 are displayed. Ensure all basic transmission mechanical faults are serviced before continuing with this test. This test is intended to diagnose only the following circuits or systems

Scheme 118

1. Harness circuits (THS 4/3, THS 3/2, TTS, LUS, NPS, VSS DIF (+), VSS DIF (-), VPWR)
2. Vehicle Speed Sensor (VSS)
3. ECA (Scheme 118): AXOD Transaxle Circuits NOTE: All components must be connected for this test and the following AXOD DRIVE CYCLE TEST must be performed
4. Record and clear Continuous Memory Codes.
5. Warm engine to operating temperature.
6. With transaxle in Drive range, lightly accelerate from a stop to 40 MPH to allow transaxle to shift into 3rd gear. Hold speed and throttle opening steady for a minimum of 15 seconds (30 seconds above 4000 feet altitude).
7. Shift transaxle into overdrive and accelerate lightly from 40 to 50 MPH to allow transaxle to shift into 4th gear. Hold speed and throttle opening steady, in 4th gear, for a minimum of 15 seconds.
8. With transaxle in 4th gear, throttle open and speed steady, lightly apply and release brakes (enough to turn on brake lights). Hold speed and throttle opening steady for an additional 15 seconds.
9. Brake to a stop and remain stopped for a minimum of 20 seconds with transaxle in overdrive range.
10. Turn engine off. Perform KOEO Self-Test and record Continuous Memory Codes.

1) Continuous Memory Code 29 Displayed Code 29 indicates insufficient input to the ECA from the Vehicle Speed Sensor (VSS). Possible causes for this fault are: faulty VSS, open or shorted circuit or faulty ECA. For 3.0L Probe vehicles, go to TEST DP, step 1). For all other vehicles, perform AXOD DRIVE CYCLE TEST and return to this step. If Continuous Memory Code 29 is not displayed, fault cannot be duplicated at this time. If any other codes are present, return to QUICK TEST for instructions. If there are none, test is complete. If Continuous Memory Code 29 is displayed, go to next step.

2) Check Continuity of Vehicle Speed Sensor (VSS) Circuits Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA and VSS disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 3 at the breakout box and VSS DIF (+) circuit at VSS vehicle harness connector. Measure resistance between test pin No. 6 and VSS DIF (-) circuit at VSS vehicle harness connector. If both readings are 5 ohms or more, repair open circuit(s) in VSS harness, then repeat step 1). If both readings are less than 5 ohms, go to next step.

VSS Harness Connector. Scheme 119

3) Check VSS Circuit For Shorts to Power or Ground With key off, ECA and VSS disconnected, set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 3 and test pins No. 37, 40, and 6 at the breakout box. Measure resistance between test pin No. 6 and test pin No. 37 at the breakout box. If all readings are less than 10 k/ohms, repair short(s) in VSS harness. Remove breakout box and reconnect all components. Repeat step 1). If all readings are more than 10 k/ohms, remove breakout box. Reconnect all components and go to next step.

4) Repeat Drive Cycle With Substitute VSS Installed Substitute original VSS with a good known VSS. With ECA and VSS connected, perform AXOD DRIVE CYCLE TEST and return to this step. If Continuous Memory Code 29 is displayed, replace ECA then repeat step 1). If Code 29 is not displayed, replace original VSS then repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 4) to step 10). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

10) Continuous Memory Code 69 Displayed Code 69 indicates that THS 3/2 pressure switch circuit is faulty. Possible causes for this fault are

1. Open or shorted THS 3/2 circuit
2. Faulty ECA
3. Faulty THS 3/2 pressure switch

Perform AXOD DRIVE CYCLE TEST and return to this step. If Code 69 did not repeat, fault cannot be duplicated at this time. If any other codes are present, return to QUICK TEST for instructions. If no codes are displayed, test is complete. If Continuous Memory Code 69 is still displayed, go to next step.

11) Check Continuity of THS 3/2 Circuit Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA and AXOD harness disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 19 at the breakout box and THS 3/2 circuit at AXOD vehicle harness connector. If resistance is more than 5 ohms, repair open in THS 3/2 circuit and repeat step 10). If reading is 5 ohms or less, go to next step.

AXOD Harness Connector (THS 3/2 Circuit). Scheme 120

12) Check THS 3/2 Circuit For Short to Power With key off, breakout box installed, and ECA and AXOD harness disconnected, set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 19 and test pin No. 37. If reading is less than 10 k/ohms, repair short to power in THS 3/2 circuit. Remove breakout box and reconnect all components. Repeat step 10). If reading is more than 10 k/ohms, go to next step.

13) Check ECA Operation With key off and breakout box installed, connect ECA and AXOD harness. Install a jumper wire between test pins No. 19 and No. 40 at the breakout box. Perform KOEO Self-Test. If Code 62 or 69 is displayed, remove jumper wire. Remove breakout box and reconnect ECA. Repair internal transmission electrical fault. If Code 62 or 69 is not displayed, remove jumper wire and replace ECA. Remove breakout box and repeat step 10).

Note. There is a break in the step numbering sequence at this point, skipping from step 13) to step 20). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

20) Continuous Memory Code 59 Displayed Code 59 indicates THS 4/3 pressure switch circuit is open. Possible causes for this fault are

1. Open or shorted THS 4/3 circuit
2. Faulty ECA
3. Faulty THS 4/3 pressure switch

Perform AXOD DRIVE CYCLE TEST and return to this step. If Code 59 is not displayed, fault cannot be duplicated at this time. If any other codes are present, return to QUICK TEST for instructions. If no codes are present, test is complete. If Code 59 is displayed, go to next step.

21) Check Continuity of THS 4/3 Circuit Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA and AXOD harness disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 18 and THS 4/3 circuit at AXOD vehicle harness connector. If reading is more than 5 ohms, repair open in THS 4/3 harness. Remove breakout box and reconnect all components. Repeat test step 20). If reading is 5 ohms or less, go to next step.

AXOD Harness Connector (THS 4/3 Circuit). Scheme 121

22) Check THS 4/3 Circuit For Short to Power With key off, breakout box installed, and ECA and AXOD harness disconnected, set DVOM on 200-k/ohm scale. Measure resistance between pin No. 18 and test pin No. 37 at the breakout box. If reading is less than 10 k/ohms, repair short to power in THS 4/3 circuit. Remove breakout box and reconnect all components. Repeat step 20). If reading is greater than 10 k/ohms, go to next step.

23) ECA Verification With key off and breakout box installed, reconnect ECA and AXOD harness. Install a jumper wire between test pins No. 18 and 40. Perform KOEO Self-Test. If Code 62 or 59 is displayed, remove jumper wire and repair internal transmission electrical faults. If Code 59 or 62 is not displayed, remove jumper wire, and replace ECA. Repeat step 20).

Note. There is a break in the step numbering sequence at this point, skipping from step 23) to step 30). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

30) Continuous Memory Code 39 Displayed Code 39 indicates AXOD converter by-pass clutch (lock-up) is not operating correctly. If Continuous Memory Code 59 is also present, go directly to step 20). Perform AXOD DRIVE CYCLE TEST then return to this step. If Continuous Memory Code 39 is still displayed, repair internal transmission electrical fault. If Continuous Memory Code 39 is not displayed, fault cannot be duplicated at this time. If any other codes are present, return to QUICK TEST for instructions. If no codes are displayed, test is completed.

Note. There is a break in the step numbering sequence at this point, skipping from step 30) to step 40). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

40) Continuous Memory Code 57 Displayed Code 57 indicates Neutral Pressure Switch (NPS) has failed in the open position. Possible causes for this fault are

1. Open or short in NPS circuit
2. Faulty ECA
3. Faulty NPS

Perform AXOD DRIVE CYCLE TEST and then return to this step. If Continuous Memory Code 57 is not displayed, fault cannot be duplicated at this time. If any other codes are present, return to QUICK TEST for instructions. If no codes are displayed, test is completed. If Continuous Memory Code 57 is still displayed, go to next step.

41) Check Continuity of NPS Harness Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA and AXOD harness disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 30 and NPS circuit at AXOD vehicle harness connector. If resistance is more than 5 ohms, repair open in NPS circuit. Remove breakout box and reconnect all components. Repeat step 40). If reading is 5 ohms or less, go to next step.

AXOD Harness Connector (NPS Circuit). Scheme 122

42) Check NPS Circuit For Short to Power With key off, install breakout box and disconnect ECA. Disconnect AXOD harness connector and set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 30 and test pin No. 37 at the breakout box. If resistance is greater than 10 k/ohms, go to next step. If resistance is less than 10 k/ohms, repair short to power in NPS circuit. Remove breakout box, reconnect all components and retest.

43) ECA Verification With key off, install breakout box and connect ECA. Ensure AXOD harness is connected. Jumper test pin No. 30 to test pin No. 40 at the breakout box. Run KOEO Self-Test. If Code 67 is present, remove breakout box and go to TEST D25, AXOD TRANSAXLE ELECTRICAL SYSTEM DIAGNOSIS. If Code 67 is not present, replace ECA, reconnect components and repeat step 14).

Note. There is a break in the step numbering sequence at this point, skipping from step 43) to step 50). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

50) Code 89 Displayed: Check Continuity of VPWR Circuit Code 89 indicates the Lock-Up Solenoid (LUS) signal indicates solenoid is always open or always closed. Possible causes for this fault are

1. Open or shorted circuit
2. Faulty ECA
3. Faulty LUS

Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA and AXOD harness disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 37 and VPWR circuit at AXOD harness connector. If reading is more than 5 ohms, repair open in VPWR circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST. If reading is 5 ohms or less, go to next step.

AXOD Harness Connector (VPWR Circuit). Scheme 123

51) Check Continuity of LUS Circuit With key off, breakout box installed, and ECA and AXOD harness disconnected, set DVOM on 200-ohm scale. Measure resistance between test pin No. 53 and LUS circuit at AXOD harness connector. If reading is more than 5 ohms, repair open in LUS circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST. If reading is 5 ohms or less, go to next step.

AXOD Harness Connector (LUS Circuit). Scheme 124

52) Check LUS Circuit For Shorts to Power or Ground With key off, breakout box installed, and ECA and AXOD harness disconnected, set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 53 and test pins No. 37 and 40 at the breakout box. If both resistances are less than 10 k/ohms, repair shorts in LUS circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST. If Code 89 is still displayed, replace ECA and repeat QUICK TEST. If both readings are greater than 10 k/ohms, go to next step.

53) Check Total Circuit Resistance With key off and breakout box installed, disconnect ECA. Ensure AXOD harness is connected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 53 and test pin No. 57. If resistance is 20-40 ohms replace ECA, remove breakout box. Repeat QUICK TEST. If resistance is not 20-40 ohms, repair internal transmission electrical fault.

Note. There is a break in the step numbering sequence at this point, skipping from step 53) to step 60). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

60) Code 62: AXOD Harness Verification Code 62 indicates THS 4/3 or 3/2 pressure switch has failed in the closed position. Possible causes for this fault are

1. Short in THS 4/3 or THS 3/2 circuit
2. Faulty ECA
3. Faulty THS 4/3 or 3/2 pressure switch

Turn key off and disconnect AXOD harness. Perform KOEO Self-Test and record codes. If Code 62 is still displayed, fault is in THS 4/3 circuit. Go to next step. If Code 62 is not displayed, remove test equipment. Repair internal transmission electrical fault.

61) Check THS 3/2 and 4/3 Circuits For Short to Ground With key off, disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box and leave ECA disconnected. Leave AXOD harnesses disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 18 and test pins No. 40 and 60. Also measure resistance between test pin No. 19 and test pins No. 40 and 60. If all readings are less than 10 k/ohms, repair short(s) to ground. Remove breakout box and reconnect all components. Repeat QUICK TEST. If all readings are greater than 10 k/ohms, replace ECA and remove breakout box. Reconnect all components and repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 61) to step 70). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

70) Code 59: AXOD Harness Verification Code 59 indicates THS 4/3 pressure switch circuit has failed in the closed position. Possible causes for this fault are

1. Short in THS 4/3 circuit
2. Faulty ECA
3. Faulty THS 4/3 pressure switch

Turn key off and disconnect AXOD Harness. Run KOEO Self-Test. If Code 59 is displayed, go to next step. If Code 59 is not displayed, reconnect AXOD vehicle harness. Repair internal transmission electrical fault.

71) Check THS 4/3 Circuit For Short to Ground With key off, disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA and AXOD harness connector disconnected. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 18 and test pins No. 40 and 60. If readings are greater than 10 k/ohms, remove breakout box, replace ECA and rerun QUICK TEST. If reading is less than 10 k/ohms, repair short to ground. Remove breakout box and reconnect all components. Rerun QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 71) to step 75). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

75) Code 69: Check AXOD Harness Code 69 indicates THS 3/2 pressure switch circuit is failed in the closed position. Possible causes for this fault are

1. Short in THS 3/2 circuit
2. Faulty ECA
3. Faulty 3/2 pressure switch

With key off, disconnect AXOD vehicle harness. Perform KOEO Self-Test. If Code 69 is still displayed, go to next step. If Code 69 is not displayed, repair internal transmission electrical fault.

76) Check THS 3/2 Circuit For Short to Ground With key off, disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box and leave ECA disconnected. Disconnect AXOD harness and set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 19 and test pins No. 40 and 60 at the breakout box. If all readings are less than 10 k/ohms, repair short to ground and remove breakout box. Reconnect all components and repeat QUICK TEST. If all readings are greater than 10 k/ohms, replace ECA and rerun QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 76) to step 80). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

80) Code 67: Check Voltage at NPS Input to ECA Code 67 indicates that NPS circuit has failed closed or input to A/C clutch circuit is closed. For 3.0L Probe vehicles, go to TEST FA, step 1), at this time. Possible causes for this fault are

1. Short in NPS circuit
2. Short in A/C clutch circuit (3.0L PFI only)
3. A/C ON during self-test (3.0L PFI only)
4. Faulty ECA or NPS

With KOEO, disconnect ECA and inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box and reconnect ECA. Set DVOM on 20-volt scale. Measure voltage between test pins No. 30 and 46 at breakout box. If voltage is less than 4 volts, go to next step. If voltage is more than 4 volts, go to TEST FA, step 10).

81) Check NPS Harness Circuit For Shorts to Ground Turn key off. Install breakout box and disconnect ECA and AXOD vehicle harness. Set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 30 and test pins No. 40 and 60 at the breakout box. If each resistance is greater than 10 k/ohms, go to next step. If resistances are less than 10 k/ohms, repair short to ground in NPS circuit. Remove breakout box, reconnect all components and rerun QUICK TEST.

82) Check ECA Turn key off and install breakout box. Reconnect ECA. Disconnect AXOD harness and run KOEO Self-Test. If Code 67 is displayed, replace ECA. Remove breakout box, reconnect all components and rerun QUICK TEST. If Code 67 is not displayed, repair internal transmission electrical fault.

Note. There is a break in the step numbering sequence at this point, skipping from step 82) to step 90). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

90) Code 68: Check Continuity of TTS Harness Circuit Code 68 indicates Transmission Temperature Switch (TTS) circuit is failed open. Possible causes for this fault are

1. Open or shorted TTS circuit
2. Faulty ECA
3. Faulty TTS

Turn key off and wait 10 seconds. Disconnect AXOD harness. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 9, at the breakout box, and TTS terminal of AXOD vehicle harness connector. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open circuit in TTS circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST.

AXOD Harness Connector (TTS Circuit). Scheme 125

91) Check TTS Circuit For Short to Power Turn key off and wait 10 seconds. Disconnect ECA and AXOD harness. Install breakout box and set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 9 and test pin No. 37 at the breakout box. If resistance is greater than 10 k/ohms, go to next step. If resistance is less than 10 k/ohms, repair short in TTS circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST.

92) Check ECA Operation With key off and breakout box installed, reconnect ECA and AXOD harness. Connect a jumper wire between test pins No. 9 and No. 40 at the breakout box. Perform KOEO Self-Test. If Code 68 is still present, replace ECA. Remove jumper wire. Remove breakout box and reconnect all components. Repeat QUICK TEST. If Code 68 is not present, remove jumper wire. Remove breakout box and reconnect all components. Repair internal transmission electrical fault.

TEST TB - A4LD TRANSMISSION

Note. Perform this test only when Code 86 or 89 is displayed or referred here by other chart or test procedure. To prevent replacement of good components be aware that the following non-EEC areas may be at fault

1. Hydraulic or emergency brake system
2. Transmission linkage
3. Internal transmission components

This test is intended to diagnose only the following components or circuits

1. Harness circuits (CCO, SS 3/4-4/3, VPWR)
2. CCO solenoid
3. Shift solenoid 3/4-4/3
4. ECA

A4LD Transmission Circuits. Scheme 126

TEST PIN NO. 53 WIRE COLOR IDENTIFICATION

1) Code 86 or 89: Check Solenoid Resistance Code 86 indicates ECA did not see a voltage drop when the Shift Solenoid (SS) was activated. Code 89 indicates ECA did not see a voltage drop when the CCO solenoid was activated. Possible causes for this fault are

1. CCO/SS resistance out of limits
2. CCO/SS circuit open or grounded
3. Faulty ECA

Verify codes match appropriate transmission solenoid circuit.

TRANSMISSION SOLENOID CIRCUITS

Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pins No. 37 and 57 and ECA signal output pin at the breakout box. If the resistance is 26 to 40 ohms, go to step 4). If resistance is not 26-40 ohms, go to next step.

2) Check Continuity of Vehicle Harness Circuits With key off, install breakout box. Leave ECA and transmission bulkhead connector (A4LD solenoids) disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pins No. 37 and 57 at the breakout box and VPWR circuit pin of the vehicle harness connector at the transmission. Measure resistance between the appropriate ECA signal output pin (No. 52 or 53) at the breakout box and same circuit at the transmission vehicle harness connector.

3) Check Transmission Vehicle Harness Circuits With key off, install breakout box, leaving ECA disconnected. Disconnect transmission bulkhead connector. Set DVOM on 200-k/ohm scale. Measure resistance between the appropriate ECA signal output pin and test pins No. 37 and 57 at the breakout box. Measure resistance between the appropriate ECA signal output pin and test pins No. 40, 60 and 46 at the breakout box and at chassis ground. If all resistances are greater than 10 k/ohms, go to next step. If any resistance is less than 10 k/ohms, repair short circuit. Remove breakout box and reconnect components. Rerun QUICK TEST.

4) Check VPWR Voltage to Transmission Solenoids With key off, breakout box installed and ECA connected, set DVOM on 20-volt scale. Disconnect transmission bulkhead connector. Turn key on, leaving engine off. Measure voltage between test pins No. 37 and 57 at the bulkhead connector and chassis ground. If voltage is greater than 10.5 volts, go to next step. If voltage is less than 10.5 volts, replace ECA. Remove breakout box and reconnect all components. Rerun QUICK TEST.

5) Check Output Driver Signal Turn key off. Install breakout box, leaving ECA connected. Disconnect A4LD transmission bulkhead connector. Connect a test light between test pin No. 37 or 57 and appropriate signal output pin at the breakout box. Enter KOEO Self-Test. If test light flashes momentarily and then stays off, fault is internal in transmission. Repair internal electrical fault as necessary. If light does not flash momentarily and then stay off, replace ECA. Remove breakout box and reconnect all components. Repeat QUICK TEST.

TEST X - INTEGRAL RELAY CONTROL MODULE (IRCM)

Note. Perform this test only when Codes 72, 78, 82, 83, 87, 88, 95 or 96 are displayed, or when you are directed here by TEST A, TEST C, or by a driveability symptom.

Note. This test is intended to diagnose only the following systems or components

1. IRCM (Battery voltage and all relays)
2. Harness circuits (VBAT, VPWR, F.P., GND & PWR to Fuel Pumps, WAC, ACC, ACCS, Cooling Fan Power, A/C Clutch, Key Power, VPWR)
3. ECA
4. A/C Demand Switch Input NOTE: To prevent replacement of good components, be aware that the following non-EEC related components or systems may be at fault
5. Fuel lines or fuel filters
6. Contaminated fuel
7. Fuel pump
8. Ignition switch, battery cables and ground straps
9. Alternator and voltage regulator
10. A/C clutch or A/C demand switch
11. Cooling fan motor

ECA & IRCM Connectors. Scheme 127

3.0L PFI (AXOD) IRCM Circuits. Scheme 128

3.0L PFI (Probe) IRCM Circuits. Scheme 129

IRCM Circuits. Scheme 130

1) Check Battery Supply Voltage With KOEO, set DVOM on 20-volt scale. Measure voltage across battery terminals. If reading is less than 10.5 volts, service or replace discharged battery. If reading is 10.5 volts or more, go to next step.

2) Check Battery Ground With KOEO, set DVOM on 20-volt scale. Measure voltage between negative battery terminal and SIG RTN circuit in Self-Test connector. If reading is less than .5 volt, go to step 6). If reading is .5 volt or more, go to next step.

3) Isolating Ground Fault Turn key off. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box and connect ECA. Turn key on, leaving engine off. Set DVOM on 20-volt scale. 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 next step.

4) ECA Ground Fault Isolation Turn key off and wait 10 seconds. With breakout box installed and ECA connected, set DVOM on 200-ohm scale. Measure resistance between test pins No. 46 and test pins No. 40 and 60. If each resistance is 5 ohms or more, replace ECA. Remove breakout box and repeat QUICK TEST. If both readings are less than 5 ohms, go to next step.

5) Check Continuity of SIG RTN Circuit Turn key off and wait 10 seconds. With breakout box and ECA connected, set DVOM on 200-ohm scale. Measure resistance between test pin No. 46 and SIG RTN circuit at Self-Test connector. If reading is less than 5 ohms, system is okay. Remove breakout box and reconnect ECA. Repeat QUICK TEST. If reading is 5 ohms or more, repair open SIG RTN circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST.

6) Measure Voltage & Ground to IRCM Turn key off and disconnect IRCM. Set DVOM on 20-volt scale. Measure voltage between pin No. 8 and pin No. 15 at the IRCM vehicle harness connector. If voltage is greater than 10.5 volts, go to next step. If not, go to step 9).

7) Check Key Power to IRCM With key off, disconnect IRCM and set DVOM on 20-volt scale. With KOEO, measure voltage between pins No. 13 (+) and 15 (-) at IRCM vehicle harness connector. If reading is less than 10.5 volts, repair open between pin No. 13 and ignition switch. Reconnect IRCM and repeat QUICK TEST. If reading is 10.5 volts or more, go to next step.

8) Check Continuity of VPWR Circuit Turn key off. Disconnect IRCM and ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pins No. 37 and 57 at the breakout box to pin No. 24 at the IRCM vehicle harness connector. If reading is 5 ohms or more, repair open in VPWR circuit. Remove breakout box. Reconnect IRCM and repeat QUICK TEST. If reading is less than 5 ohms, replace IRCM. Remove breakout box and reconnect all components. Repeat QUICK TEST.

9) Check Continuity of Power Ground to IRCM With key off and IRCM disconnected, set DVOM on 200-ohm scale. Measure resistance between negative battery terminal to IRCM harness connector pin No. 15. If resistance is 5 ohms or more, repair open in ground circuit to IRCM harness connector pin No. 15. Remove breakout box and reconnect all components. Repeat QUICK TEST. If reading is less than 5 ohms, repair open in battery positive to pin No. 8 of IRCM harness connector. Reconnect IRCM and repeat QUICK TEST.

10) Code 72: Intermittent Open in VPWR Circuit Code 72 indicates that while key power was present VPWR (voltage) to the IRCM was interrupted, or electrical noise caused the ECA to reset. Driveability problems such as, stalling, high idle, lack of power on acceleration or other drive symptoms could result. Possible causes for this fault are

1. Intermittent open in VPWR circuit between IRCM and ECA
2. Intermittent fault in EEC power relay
3. Intermittent open in VBAT circuit of IRCM
4. Intermittent open in KEY POWER circuit
5. EEC-IV harness too close to spark plug wires

Using KOER Continuous Monitor Mode (WIGGLE TEST), observe VOM or diagnostic tester for indication of fault while wiggling, bending, or twisting harness from IRCM to ECA and from ignition switch to battery positive terminal. If fault is indicated or if Code 72 reappears, repair intermittent fault in VPWR circuit. Check for correct routing of harness. Repeat QUICK TEST. If fault is not found or if codes do not reappear, inspect all component and harness connectors for damaged pins, corrosion, or loose wires. Repair if necessary. If okay, replace IRCM and repeat QUICK TEST.

11) Check POWER-to-PUMPS Circuit Voltage With KOEO, locate and disconnect fuel pump(s). Set DVOM on 20-volt scale. Measure voltage between CHASSIS GROUND and POWER-to-PUMP circuit at fuel pump vehicle harness connector while cranking engine. If reading is 8.0 volts or more, service electric fuel pump system. If reading is less than 8.0 volts, go to next step.

12) Check POWER-to-PUMP Circuit Continuity With key off and DVOM on 200-ohm scale, disconnect IRCM and fuel pump(s). Measure resistance between IRCM harness connector pin No. 5 and POWER-to-PUMP circuit at harness connector at fuel pump(s). If reading is less than 5 ohms, replace IRCM. Reconnect all components and repeat QUICK TEST. If reading is 5 ohms or more, repair open in POWER-to-PUMP circuit. Reconnect all components and repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 12) to step 14). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

14) Check POWER-to-PUMP Circuit For Shorts to Power With key off and DVOM on 200-k/ohm scale, disconnect IRCM and fuel pump(s). Measure resistance between pin No. 5 and pin No. 24 at IRCM harness connector. Measure resistance between pin No. 5 at the IRCM harness connector and battery positive terminal. If any reading is less than 10 k/ohms, repair short circuit. Reconnect all components and attempt to start vehicle. If vehicle runs, repeat QUICK TEST. If vehicle does not run, replace IRCM and repeat QUICK TEST. If all readings are 10 k/ohms or more, replace IRCM. Reconnect fuel pump and repeat QUICK TEST.

15) Code 83 or 87: Check Continuity of Fuel Pump Circuit Code 83 or 87 indicates voltage output for the high or low fuel pump circuit did not change when activated during KOEO Self-Test. Possible causes for this fault are

1. Open or grounded fuel pump circuit
2. Open or grounded ECA driver
3. Disconnected or open solenoid

Turn key off. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Disconnect IRCM and set DVOM on 200-ohm scale. Perform the following appropriate procedure

1. Code 83 (3.0L SHO Only) - Measure resistance of fuel pump(s) circuit, between test pin No. 22 at the breakout box and IRCM vehicle harness connector pin No. 18.
2. Code 87 (All Models Except 3.0L SHO) - Measure resistance between test pin No. 22 at the breakout box and pin No. 18 at the IRCM vehicle harness connector.
3. Code 87 (3.0L SHO)

Measure resistance between test pin No. 41 at the breakout box and pin No. 11 at the IRCM vehicle harness connector. If resistance is 5 ohms or more, repair open in fuel pump circuit. Remove breakout box. Reconnect all components and repeat QUICK TEST. If reading is less than 5 ohms, go to next step.

16) Check Fuel Pump Circuit For Shorts to Power & Ground With key off, install breakout box. Disconnect ECA and IRCM. Set DVOM on 200-k/ohm scale.

1. Code 83 (3.0L SHO Only) - Measure resistance between test pin No. 22 at the breakout box and pin No. 18 at the IRCM vehicle harness connector.
2. Code 87 (All Models Except 3.0L SHO) - Measure resistance between test pin No. 22 and test pins No. 37, 57, and battery positive terminal. Measure resistance between test pins No. 22, and test pins No. 40, 60, and battery negative terminal.
3. Code 87 (3.0L SHO) - Measure resistance between test pin No. 22 and pin No. 18 at the IRCM vehicle harness connector.

If any reading is less than 10 k/ohms, repair fuel pump(s) circuit shorts to power or ground. Remove breakout box and reconnect all components. Repeat QUICK TEST. If Code 83 or 87 is still present, go to next step. If all readings are 10 k/ohms or more, go to next step.

17) Check Fuel Pump Relay Coil Resistance Turn key off. Disconnect IRCM and set DVOM on 200-ohm scale. Disconnect ECA and install breakout box. Measure resistance of IRCM between pins No. 18 and 24 or pins No. 11 and 24. If resistance is 65-100 ohms, replace ECA. Remove breakout box and reconnect all components. Repeat QUICK TEST. If resistance is not 65-100 ohms, replace IRCM. Remove breakout box and reconnect all components and repeat QUICK TEST.

18) No Fan Operation Turn key off. Disconnect IRCM and set DVOM on 20-volt scale. Measure voltage between battery negative terminal and IRCM vehicle harness connector pins No. 1, 2, 6, and 7 (pins No. 3 and 4 on 3.0L Probe). If any reading is less than 10.5 volts, service open in battery power circuit. Reconnect IRCM and recheck system operation. If all readings are 10.5 volts or more, go to next step.

19) Check Fan Motor Operation Turn key off and disconnect IRCM connector. Install a jumper wire between IRCM harness connector pins No. 3 and 6. If cooling fan does not run, go to step 21). If cooling fan runs, go to next step for 3.0L (Probe) or step 25) for all other engines.

20) Check Fan Motor Operation Turn key off. Disconnect IRCM. Install a jumper between pins No. 3 and 2 at the IRCM vehicle harness connector. If fan does not run, go to step 23). If fan runs, go to step 25).

21) Measuring Battery Voltage Supply at Fan With IRCM By-Passed With key off, disconnect cooling fan and IRCM. Install a jumper wire between IRCM vehicle harness connector pins No. 3 and 6. Set DVOM on 20-volt scale and measure voltage at cooling fan harness connector. If reading is 8.0 volts or more, replace cooling fan motor. Reconnect IRCM and re-evaluate symptom. If reading is less than 8.0 volts, go to next step.

22) Check Cooling Fan Ground Circuit Turn key off. Disconnect cooling fan and IRCM. Install a jumper wire between IRCM harness connector pins 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 IRCM and re-evaluate symptom. If reading is less than 8 volts, repair open in POWER-to-FAN circuit from pins No. 3 and 4 (pins No. 6 and 7 on 3.0L Probe) of IRCM vehicle harness connector to cooling fan vehicle harness connector. Reconnect all components and recheck system operation.

23) Measure Battery Voltage Supply at Fan With IRCM By-Passed Turn key off. Disconnect cooling fan and IRCM. Install a jumper wire between pins No. 2 and 3 at the IRCM vehicle harness connector. Set DVOM on 20-volt scale. Measure voltage at cooling fan vehicle harness connector. If voltage is greater than 8 volts, replace fan motor. Reconnect IRCM and recheck system operation. If voltage is less than 8 volts, go to next step.

24) Check Cooling Fan Ground Circuit Turn key off. Disconnect cooling fan and IRCM. Install a jumper wire between IRCM vehicle harness connector pins No. 2 and 3. Set DVOM on 20-volt scale. Measure voltage between positive terminal at cooling fan harness connector and battery negative terminal. If reading is greater than 8 volts, repair open in ground circuit to fan. After repairs, reconnect IRCM and re-evaluate symptom. If reading is less than 8 volts, repair open in POWER-to-FAN circuit from pins No. 1 and 2 of IRCM vehicle harness connector to cooling fan vehicle harness connector. Reconnect all components and recheck system operation.

25) Check Fan Running Mode (Low Speed) Turn key off. Disconnect ECA. Reconnect IRCM. With KOEO, if fan runs at low speed, replace IRCM. Reconnect ECA and recheck system operation. If not, go to next step.

26) Jumper High Speed Electric-Drive Fan Signal (HEDF) to Ground Turn key off. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Ensure IRCM is connected. With KOEO, install a jumper wire between test pins No. 52 and 40 at the breakout box. If fan speed changes from low to high, go to next step. If not, replace IRCM. Remove breakout box and reconnect ECA. Recheck system operation.

27) Check ECT Sensor Turn key off and wait 10 seconds. With breakout box installed, connect ECA and check engine coolant level. Warm engine to normal operating temperature. Turn key off and wait 10 seconds. Disconnect Engine Coolant Temperature (ECT) sensor harness. Set DVOM on 200-k/ohm scale. Measure resistance of ECT sensor. If reading is 1500-2000 ohms, replace ECA. Remove breakout box and reconnect all components. recheck system operation. If reading is not 1500-2000 ohms, replace ECT sensor. Remove breakout box. Reconnect all components and re-evaluate symptom.

28) Check A/C Pressure Switch Harness Continuity With key off, install breakout box and connect ECA. Disconnect A/C pressure switch. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 2 at the breakout box and A/C pressure switch circuit at the harness connector. Measure resistance between test pin No. 46 at the breakout box and SIG RTN at the A/C pressure switch vehicle harness connector. If both resistances are less than 5 ohms, go to next step. If resistances are greater than 5 ohms, remove breakout box and reconnect all components. Repair open circuit and rerun QUICK TEST.

29) Check HEDF Operation With key off, install breakout box and reconnect ECA. Disconnect A/C pressure switch. Jumper A/C pressure circuit to SIG RTN at the switch vehicle harness connector. Turn key on. If HEDF is on, replace A/C pressure switch and retest system. If HEDF is not on, replace ECA, reconnect components and rerun QUICK TEST.

30) Code 83 Displayed: Check HEDF Controller Resistance Code 83 indicates a failed HEDF circuit. Turn key off and disconnect IRCM. Set DVOM on 200-ohm scale. Measure resistance of IRCM between pins No. 17 and 24. If reading is not between 50 and 100 ohms, replace IRCM and repeat QUICK TEST. If reading is between 50 and 100 ohms, go to next step.

31) Check HEDF Circuit Continuity Turn key off. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Disconnect IRCM connector. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 52 and IRCM vehicle harness connector pin No. 17. If resistance is greater than 5 ohms, repair open in HEDF circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST. If reading is 5 ohms or less, go to next step.

32) Check HEDF Circuit For Shorts to Ground With key off and breakout box installed. Disconnect ECA and IRCM. Set DVOM on 200-k/ohm scale. Measure resistance between test pins No. 52 and 40 at the breakout box. If resistance is 10 k/ohms or less, repair short to ground in HEDF circuit. Reconnect components and repeat QUICK TEST. If reading is greater than 10 k/ohms, go to next step.

33) Check HEDF Circuit For Short to Power With key off and breakout box installed, disconnect ECA and IRCM. Set DVOM on 200-k/ohm scale. Measure resistance between test pins No. 52 and 37 at the breakout box.

If resistance is greater than 10 k/ohms, replace ECA. Remove breakout box and reconnect all components. Repeat QUICK TEST. If reading is 10 k/ohms or less, repair short to power. Remove breakout box and reconnect all components. Repeat QUICK TEST. If Code 83 is still present, replace ECA and repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 33) to step 35). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

35) Low Speed Fan Always On Turn key off. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Disconnect IRCM and set DVOM on 200-ohm scale. Measure resistance between test pins No. 55 at the breakout box and test pin No. 14 at the IRCM vehicle harness connector. If resistance is greater than 5 ohms, repair open in EDF circuit. Remove breakout box. Reconnect all components and re-evaluate symptom. If reading is 5 ohms or less, go to next step.

36) Check EDF Circuit For Shorts to Power With key off, install breakout box. Disconnect ECA and IRCM. Set DVOM on 200-k/ohm scale. Measure resistance between test pins No. 55 and 37, and between test pin No. 55 and battery positive terminal. If each resistance is 10 k/ohms or less, repair short to power in EDF circuit, and then go to next step. If reading is more than 10 k/ohms, go to next step.

37) Check EDF Circuit For Short to Ground With KOEO, breakout box installed and ECA disconnected, connect IRCM. Install a jumper wire between test pin No. 55 and test pins No. 40 or 60 (ground). If cooling fan continues to run, replace IRCM. Remove breakout box and reconnect components. Recheck system operation. If cooling fan stops running, replace ECA. Remove breakout box and reconnect all components. Recheck system operation.

38) Check A/C Pressure Switch Input With key off, disconnect vehicle harness at A/C pressure switch. Turn key on, leaving engine off. If fan still runs, reconnect components and go to next step. If fan does not run, replace A/C pressure switch and re-evaluate symptom.

39) Check A/C Pressure Switch Circuit For Short to Ground With key on, disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Disconnect IRCM and set DVOM on 200-k/ohm scale. Measure resistance between test pin No. 2 and test pins No. 40, 46 and 60. If resistance is less than 10 k/ohms, repair short circuit, remove breakout box and reconnect components. Re-evaluate system. If resistance is greater than 10 k/ohms, go back to step 35), of this test.

40) Check Fan Voltage Turn key off. Disconnect IRCM and set DVOM on 20-volt scale. Measure voltage between battery negative terminal and pins No. 1 and 2 at IRCM harness connector. If readings are less than 10.5 volts, repair open in battery power circuit. Reconnect IRCM and re-evaluate symptom. If reading is 10.5 volts or more, go to next step.

41) Check Fan Motor Turn key off and disconnect IRCM. Install a jumper wire between IRCM vehicle harness connector pins No. 1 and 3. Turn key on. If cooling fan does not run, go to step 43). If cooling fan runs, go to next step.

42) Check Fan Run Mode With key off and ECA disconnected, connect IRCM. Turn key on. If cooling fan does not run, go to step 46). If cooling fan runs, go to step 44).

43) Measure Battery Voltage at Fan: By-Pass IRCM Turn key off. Disconnect cooling fan harness and IRCM connector. Install a jumper wire between IRCM vehicle harness connector pins No. 1 and 3. Set DVOM on 20-volt scale and measure voltage at cooling fan vehicle harness connector. If reading is 8.0 volts or more, replace cooling fan. Reconnect all components and re-evaluate symptom. If reading is less than 8.0 volts, go to step 45).

44) Check EDF Circuit For Short to Ground Turn key off. Disconnect ECA and IRCM. Set DVOM on 200-k/ohm scale and measure resistance between IRCM vehicle harness connector pins No. 14 and 15. If resistance is 10 k/ohms or more, replace IRCM. Reconnect all components and re-evaluate symptom. If reading is less than 10 k/ohms, repair short to ground in EDF circuit. Reconnect all components and re-evaluate symptom.

45) Check Cooling Fan Ground Circuit Turn key off and disconnect cooling fan. Disconnect IRCM connector. Install a jumper wire between IRCM harness connector pins No. 1 and 3. Set DVOM on 20-volt scale and measure voltage between cooling fan harness connector (+) and battery negative terminal (-). If reading is 8.0 volts or more, repair open in fan ground circuit. Reconnect all components and re-evaluate symptom. If reading is less than 8.0 volts, repair open in POWER-to-FAN circuit from IRCM harness connector pins No. 3 and 4 to cooling fan connector. Connect IRCM and re-evaluate symptom.

46) Check ECT Sensor With key off, reconnect ECA. Check engine coolant level. Warm engine to normal operating temperature. Turn key off and wait 10 seconds. Disconnect ECT sensor. Set DVOM on 200-k/ohm scale and measure resistance of ECT sensor. If resistance is 1500-2000 ohms, replace ECA. Reconnect all components and re-evaluate symptom. If reading is not 1500-2000 ohms, replace ECT sensor. Connect all components and re-evaluate symptom.

Note. There is a break in the step numbering sequence at this point, skipping from step 46) to step 50). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

50) Check Voltage at A/C Clutch Disconnect A/C clutch. Turn key on, leaving engine off. Place A/C demand switch to A/C ON position. Set DVOM on 20-volt scale and check voltage at A/C clutch vehicle harness connector. If voltage reading is 10.5 volts or more, service A/C compressor and/or system. If voltage is less than 10.5 volts, go to next step.

51) Check Continuity of IRCM to A/C Clutch Circuit Turn key off. Disconnect IRCM and A/C clutch. Set DVOM on 200-ohm scale. Measure resistance between IRCM vehicle harness connector pin No. 23 and power circuit terminal pin at A/C clutch harness connector. Also measure resistance between IRCM vehicle harness connector pin No. 16 and ground circuit at A/C clutch harness connector. If readings are more than 5 ohms, repair open in power or ground A/C circuit(s) and re-evaluate symptom. If readings are 5 ohms or less, go to next step.

Note. Do not use diagnostic tester in step 52), use VOM/DVOM only. Enter Output State Check as specified in test. For additional information see ADDITIONAL SYSTEM FUNCTIONS, OUTPUT STATE CHECK at beginning of this article.

52) Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged electrical wiring. After inspection, reconnect breakout box and ECA. Disconnect vehicle harness connector to speed control servo (if equipped). Set DVOM on 20-volt scale. Connect DVOM negative test lead to Self-Test Output (STO) and positive lead to battery positive terminal. Using jumper wire, connect Self-Test Input (STI) to SIG RTN at Self-Test connector. Perform KOEO Self-Test until completion of Continuous Memory Code output (DVOM will read zero volts). Depress and release throttle. DVOM voltage reading should increase. If DVOM did not change, depress throttle to WOT and release. If STO voltage still does not increase, leave equipment hooked up and go to TEST QC, step 1). If DVOM reading changes, remain in Output State Check and go to next step.

53) Check WAC Output Operation With KOEO, place A/C demand switch to A/C ON position. Set DVOM on 20-volt scale. Connect DVOM positive test lead to pin No. 37 and negative test lead to test pin No. 54. While observing DVOM, depress and release throttle several times (to cycle output on and off). If voltage output does not change, go to step 57). If voltage output changes, go to next step.

54) Check Voltage at A/C Clutch Switch With key on, engine off and A/C demand switch in A/C ON position, verify that breakout box is installed and that ECA and IRCM are connected. Set DVOM on 20-volt scale and measure voltage between test pins No. 10 and 40. If reading is less than 10.5 volts, go to step 56). If reading is 10.5 volts or more, go to next step.

55) Check Continuity of ACCS Circuit to IRCM Turn key off and wait 10 seconds. Install breakout box. Disconnect ECA and IRCM connectors. Set DVOM on 200-ohm scale and measure resistance between test pin No. 10 and IRCM harness connector pin No. 21. If reading is more than 5 ohms, service open in ACCS circuit. Remove breakout box and reconnect all components. Re-evaluate symptom. If reading is 5 ohms or less, replace IRCM. Remove breakout box and reconnect all components. Re-evaluate symptom.

56) Check ACCS Circuit Continuity Turn key off and wait 10 seconds. Install breakout box and reconnect ECA. Place A/C demand switch to A/C ON position. Set DVOM on 200-ohm scale and measure resistance between test pin No. 10 and A/C demand switch. If reading is 5 ohms or less, EEC-IV system is okay. Service or repair A/C system. If reading is more than 5 ohms, repair open in switch circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST.

57) Check Continuity in WAC to IRCM Circuit Turn key off and wait 10 seconds. Install breakout box. Disconnect ECA and IRCM. Set DVOM on 200-ohm scale and measure resistance between test pin No. 54 and IRCM vehicle harness connector pin No. 22. If reading is more than 50 ohms, repair open in WAC circuit. Remove breakout box and reconnect all components. Re-evaluate symptom. If reading is 50 ohms or less, go to next step.

58) Check WAC Circuit For Shorts to Ground Turn key off and wait 10 seconds. Leave breakout box installed, and ECA disconnected. Disconnect IRCM connector. Set DVOM on 200-k/ohm scale. Measure resistance between test pins No. 54 and 40, and between test pins No. 54 and 46, and between test pin No. 54 and battery negative terminal. If any reading is less than 10 k/ohms, repair shorts to ground in WAC circuit. Remove breakout box and reconnect all components. Re-evaluate symptom. If all readings are 10 k/ohms or more, go to next step.

59) Check WAC Circuit For Short to Power Turn key off and wait 10 seconds. Leave breakout box installed, and ECA disconnected. Disconnect IRCM connector. Set DVOM on 200-k/ohm scale. Measure resistance between test pins No. 54 and 37, and between test pin No. 54 and battery positive terminal. If any reading is less than 10 k/ohms, repair shorts to power in WAC circuit. Remove breakout box, reconnect all components and go to next step. If all readings are 10 k/ohms or more, go to next step.

60) Check Voltage at A/C Clutch Turn key off and wait 10 seconds. Leave breakout box installed, and ECA disconnected. Connect IRCM connector and disconnect A/C clutch. Place A/C demand switch to A/C ON position. With KOEO, set DVOM on 20-volt scale and measure voltage at A/C clutch harness connector. If voltage is greater than 10.5 volts, replace ECA. Remove breakout box and reconnect all components. Re-evaluate symptom. If reading is less than 10.5 volts, replace IRCM. Remove breakout box and reconnect all components. Re-evaluate symptom.

Note. There is a break in the step numbering sequence at this point, skipping from step 60) to step 80). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

80) Code 88: Check EDF Signal to IRCM For Short to Ground If fan is always on with Code 88, go to step 82). With key off, disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Disconnect IRCM connector. Set DVOM on 200-k/ohm scale and measure resistance between test pins No. 40 and 55. If reading is 10 k/ohms or less, repair short to ground in EDF circuit. Reconnect all components and repeat QUICK TEST. If reading is more than 10 k/ohms, go to next step.

81) Check Fan Running Mode With key off and breakout box installed, disconnect ECA and connect IRCM connector. Turn key on. If fan runs at low speed, replace ECA. Remove breakout box and reconnect all components. Repeat QUICK TEST. If fan does not run as indicated, replace IRCM. Remove breakout box. Reconnect all components and repeat QUICK TEST.

82) Fan Always On With Code 88: Check EDF Signal Circuit to IRCM Continuity Turn key off. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA disconnected. Disconnect IRCM connector. Set DVOM on 200-ohm scale and measure resistance between breakout box test pin No. 55 and pin No. 14 at IRCM harness connector. If reading is 5 ohms or less, go to next step. If not, repair open in EDF circuit. Remove breakout box and reconnect all components. Repeat QUICK TEST.

83) Check EDF Circuit For Short to Power Turn key off. Install breakout box, leaving ECA disconnected. Disconnect IRCM connector. Set DVOM on 200-k/ohm scale. Measure resistance between test pins No. 55 and 37, and from test pin No. 55 to battery positive terminal. If readings are 10 k/ohms or less, repair short to power in EDF circuit. After repairs, go to next step. If readings are greater than 10 k/ohms, go to next step.

84) Check EDF For Shorts to Ground Turn key off. Install breakout box, leaving ECA disconnected. Ensure IRCM is properly connected. Turn key on. Using jumper wire, connect test pin No. 55 to test pins No. 40 or 60. If fan continues to run, replace IRCM. Remove breakout box and reconnect all components. Repeat QUICK TEST. If fan does not run, replace ECA. Remove breakout box. Reconnect all components and repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 84) to step 90). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

90) Code 95: Check Inertia Switch A KOEO Code 95 indicates one of the following

1. Open circuit in fuel pump or between fuel pump and FPM circuit
2. Poor fuel pump ground connection
3. FUEL PUMP circuit shorted to power
4. Fuel pump relay contacts always closed

Turn key off and wait 10 seconds. Locate and disconnect fuel pump inertia switch. Set DVOM on 200-ohm scale. Measure resistance of fuel pump inertia switch. If resistance is less than 5 ohms, reconnect inertia switch and go to next step. If resistance is more than 5 ohms, replace or reset inertia switch, rerun QUICK TEST.

91) Verify That Fuel Pump is Off Turn key off. Listen for fuel pump. If pump is still running go to next step. If pump is off, go to step 93).

92) Check For Closed Fuel Pump Relay With key off, locate and disconnect IRCM. If fuel pump shuts off when controller is disconnected, replace IRCM and rerun QUICK TEST. If pump does not shut off, repair short to power in POWER-to-PUMP (FPM) circuit. Reconnect IRCM and rerun QUICK TEST.

93) Check Continuity of FPM Circuit With key off, disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA disconnected. Disconnect IRCM. Set DVOM on 200-ohm scale and measure resistance between FPM circuit at the breakout box and pin No. 5 of IRCM vehicle harness connector. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open circuit. Remove breakout box and reconnect all components. Rerun QUICK TEST.

94) Check For Continuity Between FPM Circuit & Ground With key off, install breakout box, leaving ECA disconnected. Disconnect IRCM connector. Set DVOM on 200-ohm scale and measure resistance between FPM circuit at breakout box and battery negative terminal. If resistance is less than 5 ohms, replace ECA. Remove breakout box and reconnect all components. Retest system. If resistance is greater than 5 ohms, repair fuel pump circuit or replace fuel pump and rerun QUICK TEST.

95) Code 96: Check POWER-to-PUMP Circuit Continuity Code 96 indicates that when fuel pump is activated, no power is supplied to pump. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA disconnected. Disconnect IRCM. Set DVOM on 200-ohm scale and measure resistance between FPM circuit at breakout box and pin No. 5 at IRCM vehicle harness connector. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open in POWER-to-PUMP circuit between FPM splice and IRCM. Remove breakout box and reconnect all components. Rerun QUICK TEST.

96) Check Fuel Pump Operation With key off, disconnect ECA 60-pin connector. Install breakout box, reconnect ECA and IRCM. Set DVOM on 20-volt scale. Connect DVOM between FPM circuit and test pin No. 40, at the breakout box. Observe DVOM and turn key to ON position. If voltage is greater than 9.8 volts, for approximately one second after key is turned on, replace ECA. Remove breakout box and rerun QUICK TEST. If voltage does not increase to specification, replace IRCM. Remove breakout box and reconnect all components. Rerun QUICK TEST.

97) Code 59: Measure Idle Fuel Pump Relay Power Circuit Continuity Code 59 indicates idle fuel pump is not receiving the correct supplied voltage through the circuit. Turn key off. Disconnect IRCM. Set DVOM on 200-ohm scale. Measure resistance between pin No. 10 at the IRCM vehicle harness connector and battery positive terminal. If resistance is 1.0-1.2 ohms, go to next step. If not, repair idle fuel pump circuit. Reconnect IRCM and repeat QUICK TEST.

Note. There is a break in the step numbering sequence at this point, skipping from step 97) to step 100). Break is due to previous chart references to these testing procedures. No test procedures have been omitted.

100) Continuous Memory Code 95: Check EEC-IV Harness Code 95 indicates that there is an open circuit in the fuel pump or between the fuel pump and FPM circuit in the ECA. The fuel pump ground circuit is poor.

Start engine and test for stalling or stumble while performing WIGGLE TEST on fuel pump and ECA harness. Perform WIGGLE TEST on fuel pump ground circuit. Lightly tap on fuel pump to duplicate road shock. Turn key off and inspect connections for corrosion or damage. If no fault is found, go to next step. If fault is found, repair it, clear codes, and rerun QUICK TEST.

101) Check FPM Circuit Turn key off. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box, leaving ECA disconnected. With KOEO, connect a test light between FPM circuit and test pin No. 37. Observe test light while performing WIGGLE TEST on the fuel pump monitor circuit (pin No. 8) between the ECA and the connection at the POWER-to-PUMP circuit. If a fault is found, isolate and repair. Clear codes and rerun QUICK TEST. If no fault is found, fault cannot be duplicated at this time. Clear memory codes for future testing.

102) Continuous Memory Code 59 or 96: Check For Continuous Memory Code 83 or 87 Also Displayed If Code 83 or 87 is also present, go to step 104). If a Code 83 or 87 is not present, proceed to the next step.

103) Check EEC-IV Harness A Continuous Memory Code 59 or 96, without the presence of a Continuous Memory Code 83 or 87, indicates that during vehicle operation the fuel pump relay contacts have opened or that there is an open in the POWER-to-PUMP circuit from the IRCM pin No. 5 to the FPM splice. Start engine and listen for fuel pump stopping, stall or stumble while performing WIGGLE TEST on PUMP-to-POWER circuit from IRCM to FPM splice. With key off, inspect IRCM 24-pin connector and harness. If a fault is found, isolate and repair, clear codes and retest. If no fault is found, problem cannot be duplicated at this time. Clear codes and rerun QUICK TEST.

104) Continuous Memory Code 83 or 87: Check EEC-IV Harness A Continuous Memory Code 83 or 87 indicates that during vehicle operation there has been an open condition in the VPWR circuit of the IRCM, an open coil in the fuel pump relay, or an open in the fuel pump primary circuit.

Start engine and listen for fuel pump stopping, stall or stumble while performing WIGGLE TEST on EEC-IV harness fuel pump circuit (pin No. 22 or 41) between the ECA and IRCM (pin No. 18 or 11). With key off, inspect harness and connectors. If a fault is found, isolate and repair, clear codes and retest. If no fault is found, problem cannot be duplicated at this time. Clear codes and rerun QUICK TEST.

See also:
• FUEL PRESSURE SPECIFICATIONS
• TEST STEP APPLICATION REFERENCE