Preliminary Instructions (M/T) Ford Taurus II

Preliminary Instructions (M/T)

Record and clear continuous memory codes. Warm engine to normal operating temperature. Accelerate moderately to 40 MPH. Start in first gear, shifting no higher than second gear. 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 29/452 Code 29/452 indicates PCM detected incorrect output from VSS sometime during vehicle operation. Possible causes for this code are

1. Faulty VSS.
2. Open or shorted circuit.
3. Faulty PCM.

Perform appropriate drive cycle procedure. See PRELIMINARY INSTRUCTIONS (A/T) or PRELIMINARY INSTRUCTIONS (M/T). Ensure driveability complaint can be verified. If Code 29/452 is still present or driveability complaint can be verified, go to step 2). If code is not present or complaint cannot be verified, fault cannot be duplicated at this time. Clear codes, and see SYMPTOMS TESTS W/O CODES article in this section.

2) Check VSS Circuit Continuity Turn ignition off. Disconnect VSS sensor. Remove PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Measure resistance between VSS (+) terminal at VSS wiring harness connector and test pin No. 3 at breakout box. Measure resistance between VSS (-) terminal at VSS wiring harness connector and test pin No. 6 at breakout box. If any resistance reading is more than 5 ohms, service open circuit in VSS wiring harness and repeat step 1). If both resistance readings are 5 ohms or less, go to step 3).

3) Check VSS Circuits For Shorts To Power Or Ground Turn ignition off. Ensure PCM and VSS are disconnected. Measure resistance between test pin No. 3 and test pins No. 6, 37 and 40 at breakout box. If all readings are greater than 500 ohms, go to step 4). If any reading is less than 500 ohms, repair shorts in VSS wiring harness and repeat step 1).

4) Check VSS Resistance Turn ignition off, and wait 10 seconds. Disconnect VSS wiring harness connector. Measure resistance across VSS terminals. If reading is not 190-250 ohms, replace VSS and repeat step 1). If resistance is 190-250 ohms, replace PCM and repeat step 1).

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

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

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

CID Wiring Harness Circuits (3.0L SHO). Scheme 238

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

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

Start engine. If engine starts, go to next step. If engine does not start, go to step 10) for 2.0L or IGNITION SYSTEMS in I - EEC-IV SYS/COMP TESTS article in this section.

2) Attempt To Generate Code 214 Clear continuous memory codes. Start engine. Raise engine speed to 1500 RPM for 10 seconds. Return to idle speed. Raise speed to 1500 RPM for 10 seconds again. Turn ignition off. Perform KOEO SELF-TEST. If Continuous Memory Code 214 is not present, go to step 20). If Continuous Memory Code 214 is present, go to step 3).

3) Check Continuity Of CID Circuits Disconnect CMP sensor. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between CID or CID (+) test pin at breakout box and CID or CID (+) terminal at sensor wiring harness connector. If any resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST. If each resistance is less than 5 ohms, go to next step.

4) Check CID Circuit For Short To Power Turn ignition off. Ensure PCM and CKP/CMP sensor are disconnected. Ensure scan tester is not connected to vehicle. Disconnect ICM pins No. 1-6. On all models, turn ignition on. Measure voltage between CID or CID (+) test pin and test pin No. 40 at breakout box. If voltage is less than 1.0 volt, go to step 5). If voltage is 1.0 volt or more, repair circuit short to power.

5) Check CID Circuit For Short To Ground Turn ignition off. Ensure PCM and CKP/CMP sensor are disconnected. Ensure ICM pins No. 1-6 are disconnected. On all models, measure resistance between CID or CID (+) test pin and pins No. 16, 40 and 46 at breakout box. If resistance is less than 10,000 ohms, repair short circuit and repeat QUICK TEST. If resistance is more than 10,000 ohms, go to IGNITION SYSTEMS in I - EEC-IV SYS/COMP TESTS article in this section.

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

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

8) Check CKP/CMP Sensor Output Turn ignition off. Reconnect CKP/CMP sensor wiring harness connector. Set DVOM on AC scale. Start engine. Measure voltage between test pins No. 24 and 40 while varying engine RPM. If voltage varies more than 0.1 volt, replace PCM and repeat QUICK TEST. If voltage does not vary more than .1 volt, replace CKP/CMP sensor. Repeat QUICK TEST.

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

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

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

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

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

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

BOO Switch Circuit. Scheme 239

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

TEST PIN NO. IDENTIFICATION

1) Code 74/536: Verify Brake Pedal Was Depressed Code 74/536 indicates that when brake pedal is applied during KOER SELF-TEST, BOO signal did not cycle high and low. Possible causes for this fault are

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

If brake was not applied during KOER SELF-TEST, repeat test. Depress and release brake pedal only once during test. If pedal was depressed, go to step 2).

2) Check Operation Of Brakelights With ignition on, check operation of brakelights. If brakelights operate normally, go to step 3). If brakelights do not operate, go to step 4). If brakelights are always on,go to step 5).

3) Check For BOO Switch Circuit Cycling Turn ignition off. Wait 10 seconds. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure voltage between BOO test pin (No. 2 or 5) and test pin No. 40 while applying and releasing brake. If voltage cycles, replace PCM and repeat QUICK TEST. If voltage does not cycle, repair open circuit in BOO switch circuit between PCM and BOO switch connection to brakelight circuit. Repeat QUICK TEST.

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

5) Verify Brake Switch Is Not Always Closed Turn ignition off. Disconnect brakelight switch (located on brake pedal). Turn ignition on. If brakelights are still on, go to step 6). If brakelights are not on, verify correct installation of brakelight switch. If installation is okay, replace brakelight switch and repeat QUICK TEST.

6) Check For Short To Power In PCM Turn ignition off. Disconnect PCM. Turn ignition on. Check brakelights. If brakelights are on, go to step 7). If brakelights are not on, replace PCM and repeat QUICK TEST.

7) Check For Short To Power In Shift Lock Actuator Turn ignition off. Ensure PCM and brakelight switch are disconnected. Disconnect shift lock actuator, cruise control module and ABS module (if equipped). Turn ignition on. If brakelights are still on, repair short to power in BOO or STOPLAMP circuit and repeat QUICK TEST. If brakelights are not on, repair short circuit in shift lock actuator circuit, cruise control system circuit or ABS circuit. Repeat QUICK TEST.

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

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

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

SWITCH CIRCUIT LOGIC

Electrical Load Input Circuit. Scheme 240

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

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

10) Check Blower Motor Switch (Low Speed) Turn ignition and all accessories off. Remove PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Turn climate control motor switch to low-speed position "1" or "2". Measure voltage between test pin No. 14 at breakout box and chassis ground. If voltage is not 10-17 volts, go to step 13). If voltage is 10-17 volts, go to step 11).

11) Check Blower Motor Switch (High Speed) Turn ignition and all accessories off. Turn climate control motor switch to high-speed position "3" or "4". Turn ignition on. Measure voltage between test pin No. 14 at breakout box and chassis ground. If voltage is less than 1.5 volts, replace PCM and confirm idle speed fault has been corrected. If voltage is 1.5 volts or more, go to step 12).

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

13) Check Blower Circuit Continuity Turn ignition off. Disconnect blower motor relay. Measure resistance between BLR terminal at power distributor box and test pin No. 14 at breakout box. If resistance is 5 ohms or more, repair open circuit. Repeat QUICK TEST. If resistance is less than 5 ohms, go to step 14).

14) Check Blower Circuit For Short To Power Turn ignition off. Disconnect blower motor relay. Measure resistance between test pin No. 14 and test pins No. 40, 46 and 60 at breakout box. If resistance is more than 10,000 ohms, check for damaged blower motor switch or relay. If resistance is 10,000 ohms or less, repair short circuit. Repeat QUICK TEST.

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

20) Check DRL Circuit Voltage (Headlights On) Turn ignition and all accessories off. Remove PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Apply parking brake. Turn ignition on. Turn headlights on. Turn accessories off. Measure voltage between test pin No. 42 at breakout box and chassis ground. If voltage is not 10-17 volts, go to step 23). If voltage is 10-17 volts, go to step 21).

21) Check DRL Circuit Voltage (Headlights Off) Turn headlights off. Release parking brake. Turn ignition on. Measure voltage between test pin No. 42 at breakout box and chassis ground. If voltage is less than 1.5 volts, replace PCM and confirm idle speed fault has been corrected. If voltage is 1.5 volts or more, go to step 22).

22) Check DRL Circuit For Short To Power Turn ignition off. Ensure PCM is disconnected. Disconnect daytime running lights relay. Measure resistance between test pin No. 42 and pins No. 37 and 57 at breakout box. If resistance is more than 10,000 ohms, check daytime running lights module for malfunction. If resistance is 10,000 ohms or less, repair short circuit and confirm idle speed fault has been corrected.

23) Check DRL Circuit Continuity Turn ignition off. Disconnect daytime running lights relay. Measure resistance between DRL relay connector and test pin No. 42 at breakout box. If resistance is 5 ohms or more, repair open circuit and confirm idle speed fault has been corrected. If resistance is less than 5 ohms, go to step 24).

24) Check DRL Circuit For Short To Power Turn ignition off. Measure resistance between test pin No. 42 and test pins No. 40, 46 and 60 at breakout box. If resistance is more than 10,000 ohms, check daytime running lights module for malfunction. If resistance is 10,000 ohms or less, repair short circuit and confirm idle speed fault has been corrected.

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

30) Check Headlight Circuit Voltage (Headlights Off) Turn ignition and all accessories off. Remove PCM 60-pin connector, and inspect it for damaged terminals. Repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn all accessories off. Turn ignition on. Measure voltage between test pin No. 45 at breakout box and chassis ground. If voltage is 1.5 volts or more, go to step 34). If voltage is less than 1.5 volts, go to step 31).

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

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

33) Check HDL Circuit For Short To Ground Turn ignition off. Disconnect headlight relay. Measure resistance between test pin No. 45 and test pins No. 40, 46 and 60 at breakout box. If each resistance is more than 10,000 ohms, check headlight switch for malfunction. If any circuit resistance is 10,000 ohms or less, repair short circuit and confirm idle speed fault has been corrected.

34) Check HDL Circuit For Short To Power Turn ignition off. Disconnect headlight relay. Measure resistance between test pin No. 45 and pins No. 37 and 57 at breakout box. If resistance is more than 10,000 ohms, check headlight switch for malfunction. If resistance is 10,000 ohms or less, repair short circuit and confirm idle speed fault has been corrected.

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

40) Check DEF Circuit Voltage (Defrost Off) Turn ignition off. Turn all accessories off. Remove PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Turn ignition on. Measure voltage between test pin No. 15 at breakout box and chassis ground. If voltage is 10-17 volts, go to step 41). If voltage is not 10-17 volts, go to step 43).

41) Check DEF Circuit Voltage (Defrost On) Turn ignition on. Turn rear window defroster on. Measure voltage between test pin No. 15 at breakout box and chassis ground. If voltage is less than 3 volts, replace PCM and confirm idle speed fault has been corrected. If voltage is 3 volts or more, go to step 42).

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

43) Check DEF Circuit Continuity Turn ignition off. Disconnect rear window defroster switch. Measure resistance between DEF terminal at power distribution box and test pin No. 15 at breakout box. If resistance is less than 5 ohms, go to step 44). If resistance is 5 ohms or more, repair open circuit and confirm idle speed fault has been corrected.

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

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

Perform this test when instructed during QUICK TEST or if directed by other test procedures. Some vehicles may not have power steering, but PCM may be equipped with PSP switch software strategy. If a KOEO Code 52/519 is displayed, check if vehicle is equipped with power steering. If vehicle is not equipped with power steering, disregard Code 52/519. This test is only intended to diagnose

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

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

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

Power Steering Pressure (PSP) Switch Circuit(Probe). Scheme 241

Power Steering Pressure (PSP) Switch Circuit (Except Probe). Scheme 242

PSP SWITCH TEST PIN NUMBER IDENTIFICATION

TEST PIN NO. 2, 24 OR 28 (PSP) WIRE COLOR I.D.

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

1) KOEO Code 52/519: Attempt To Eliminate Code Code 52/519 indicates PSP switch circuit is open. Possible causes for this fault are

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

Turn ignition off. Disconnect PSP switch. Install jumper wire between PSP terminal and SIG RTN terminal at wiring harness connector. Repeat KOEO SELF-TEST. If Code 52/519 is not displayed, replace PSP switch and repeat QUICK TEST. If Code 52/519 is displayed, remove jumper wire and go to step 2).

2) Check Continuity Of PSP Circuits Turn ignition off, and wait 10 seconds. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between test pin No. 46 and SIG RTN terminal at PSP switch wiring harness connector. Also measure resistance between PSP test pin at breakout box and PSP terminal at switch wiring harness connector. If both readings are less than 5 ohms, replace PCM and repeat QUICK TEST. If readings are 5 ohms or more, repair open circuit and repeat QUICK TEST.

3) Check PSP Switch Operation Turn ignition off. Connect tachometer, and start engine. Allow engine to idle in Park or Neutral. Disconnect PSP switch wiring harness connector. If RPM increases, replace PSP switch and recheck system. If RPM does not increase, go to step 4).

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

5) KOER Code 52/521 Disregard this code if vehicle does not have power steering. Code 52/521 indicates PSP switch did not change states due to open or closed switch. Possible causes for this fault are

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

If steering wheel was turned 1/2 turn within 2 seconds after engine ID code and then returned to center, go to step 6). If steering wheel was not turned, repeat QUICK TEST.

6) Check PCM Open Circuit Identifying Capabilities Turn ignition off. Disconnect PSP switch. Perform KOEO SELF-TEST. If Code 52/519 is present, go to step 8). If Code 52/519 is not present, go to step 7).

7) Check PSP Switch Circuits For Shorts Turn ignition off. Disconnect PSP switch. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between PSP test pin and test pin No. 46 at breakout box. If reading is 10,000 ohms or less, repair short circuit and repeat QUICK TEST. If reading is more than 10,000 ohms, replace PCM and repeat QUICK TEST.

8) Check PSP Switch Position Comparison Turn ignition off. With PSP switch connected, turn ignition on. Measure resistance between PSP test pin and test pin No. 46 at breakout box. Start engine. Measure resistance between PSP test pin and test pin No. 46 at breakout box. If reading shows less than 10 ohms difference between key on engine off and key on engine running, go to step 9). If reading is not as described, replace PSP switch and repeat QUICK TEST.

9) Check PSP Switch With Engine Running (Load & No Load) Connect PSP switch. Start engine, and allow it to idle. On Taurus 3.0L SHO, ensure clutch is not depressed. On all models, measure resistance between PSP test pin and test pin No. 46 at breakout box. Turn steering wheel 1/2 turn and return to center position. If resistance changes from less than 10 ohms to infinity and then returns to 10 ohms or less (when steering wheel is centered), PSP switch system is okay. Testing is complete. If reading does not change as indicated, replace PSP switch. Repeat QUICK TEST.

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

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

Turn ignition off. Disconnect PSP switch connector. Repeat KOEO SELF-TEST. Measure resistance between PSP test pin and test pin No. 46 at breakout box. If Code 519 is not present, replace PSP switch. If Code 519 is present, go to step 11).

11) Check PSP Circuit For Short Turn ignition off. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between PSP test pin and test pin No. 46 at breakout box. If reading is 10,000 ohms or less, repair short circuit and repeat QUICK TEST. If reading is more than 10,000 ohms, replace PCM and repeat QUICK TEST.

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

15) Check PSP Switch Operation Connect tachometer, and start engine. Allow engine to idle in Park or Neutral. Disconnect PSP switch connector. Using jumper wire, connect PSP switch wiring harness connector terminals. If RPM increases, replace PSP switch and recheck system. If RPM does not increase, go to step 16).

16) Check Continuity Of PSP Switch Circuits Turn ignition off, and wait 10 seconds. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Measure resistance between test pin No. 46 and SIG RTN terminal at PSP switch wiring harness connector. Also measure resistance between PSP switch test pin at breakout box and PSP terminal at PSP switch wiring harness connector. If both readings are less than 5 ohms, replace PCM and repeat QUICK TEST. If any reading is 5 ohms or more, repair open circuit and repeat QUICK TEST.

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

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

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

If steering wheel was turned 1/2 turn within 2 seconds after engine ID code and then returned to center, go to step 21). If steering wheel was not turned, repeat QUICK TEST.

21) Check PCM Closed Circuit Identifying Capabilities Turn ignition off. Disconnect PSP switch. Connect jumper wire between PSP terminal and SIG RTN terminal at PSP switch wiring harness connector. Perform KOEO SELF-TEST. If Code 519 is present, remove jumper wire and go to step 23). If Code 519 is not present, go to step 22).

22) Check Continuity Of PSP Switch Circuits Turn ignition off, and wait 10 seconds. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Measure resistance between PSP test pin at breakout box and PSP terminal at PSP switch wiring harness connector. Also measure resistance between test pin No. 46 at breakout box and SIG RTN terminal at PSP switch wiring harness connector. If both readings are less than 5 ohms, replace PCM and repeat QUICK TEST. If either reading is 5 ohms or more, repair open circuit and repeat QUICK TEST.

23) Check PSP Switch Position Comparison Turn ignition off. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM connected. Reconnect PSP switch. Turn ignition on. Measure resistance between PSP switch test pin and test pin No. 46 at breakout box. Start engine. If reading shows less than 10 ohms difference between key on engine off and key on engine running, go to step 24). If reading is not as described, replace PSP switch and repeat QUICK TEST.

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

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

1. Excessive blow-by.
2. PCV malfunction.
3. Vacuum leaks.
4. Incorrect fuel pressure.
5. Throttle binding.

This test is only intended to diagnose

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

1) Continuous Memory Code 121, 124 Or 125: TPS Integrity Code 121 indicates TPS is inconsistent with MAF value. Code 124 indicates TPS value is higher than expected. Code 125 indicates TPS value is lower than expected.

Turn ignition off. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Connect DVOM to test pins No. 46 and 47. Slowly apply throttle to WOT, and release to closed position. Voltage should change smoothly from 0.4-4.5 volts. See CIRCUIT TEST DH for schematics and specific engine values. If voltage change is incorrect or erratic, ensure TPS is properly installed. If TPS is properly installed, replace TPS and repeat QUICK TEST. If voltage is okay, go to step 7) for Code 121 or step 2) for all other codes.

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

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

4) Check MAP/BARO Sensor Output Refer to CIRCUIT TEST DF for MAP/BARO sensor output check. (Scheme 243)for connector terminal identification and MAP/BARO tester hookup. With tester connected and ignition on, measure sensor output voltage. If output voltage is within range for specified altitude, remove MAP/BARO tester and go to step 5). See MAP SENSOR VOLTAGE OUTPUT table for specification. If output voltage is not within range, replace MAP/BARO sensor and repeat QUICK TEST.

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

MAP SENSOR VOLTAGE OUTPUT

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

6) Continuous Memory Code 184 & 185: Inspect MAF Sensor Code 184 indicates MAF sensor signal is higher than expected. Code 185 indicates MAF sensor signal is lower than expected. Turn ignition off. Check for air leaks between Idle Air Control (IAC) solenoid and MAF sensor. Inspect MAF sensor for oil contamination caused by excessive blow-by or malfunctioning PCV. If problems are found, repair as necessary. Clear codes, and repeat QUICK TEST. If all checks are okay, go to step 9).

7) Check MAF Sensor Circuit Voltage Turn ignition off. Disconnect PCM 60-pin connector. Inspect and repair any damaged terminals. Install EEC-IV Breakout Box (T83L-50-EEC-IV). Connect PCM to breakout box. Start engine, and warm it to normal operating temperature. Measure voltage between test pins No. 40 and 60 and MAF test pin at breakout box. See MAF TEST PIN NO. IDENTIFICATION table. If voltage is not within specification, replace MAF sensor and repeat QUICK TEST. See MAF SENSOR DATA table. If voltage is within acceptable range, system is operating normally at this time. See SYMPTOMS in TESTS W/O CODES article in this section.

MAF TEST PIN NO. IDENTIFICATION

MAF SENSOR DATA

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

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

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

11) Cylinder Balance Test Perform KOER SELF-TEST. After last code, wait 5-10 seconds, and then goose throttle lightly (not wide open throttle). This will activate cylinder balance test. If Code 90 is present after test, go back to step 6). If Code 90 is not present after test, go to CIRCUIT TEST H, step 4).