Diagnostic Aids
Enter this CIRCUIT TEST only when all steps under QUICK TEST have been successfully completed and engine still does not start or if directed here from another test or chart. This test is only intended to diagnose:
- Ignition Control Module (ICM).
- Powertrain Control Module (PCM).
- Spark (PCM-controlled).
- Wiring harness circuits (PIP, IGN GND and VPWR).
To prevent replacement of good components, be aware the following non-EEC related areas and components may be cause of problem:
- Fuel quality and quantity.
- Ignition (general condition).
- Engine mechanical components.
- Starter and battery circuits.
- Crankshaft Position (CKP) sensor.
- Ignition Control Module (ICM).
- Coil packs.
1) Starting System Check
Ensure fuel pump inertia switch is closed (button pushed in). Try to start engine. If engine does not crank, check vehicle starting and charging systems. If engine cranks, go to next step.
2) Attempt to start engine. If engine now starts, go to CIRCUIT TEST Z. step 50). If engine does not start, go to next step.
3) Check For Malfunction Indicator Light (MIL) During Cranking -Turn ignition off. Turn ignition on and observe MIL. If MIL is off, go to CIRCUIT TEST NB, step 1). If MIL is on, turn ignition switch to the START position. If MIL goes off, PIP circuit is okay; go to next step. If MIL stays on while engine is cranking, go to step 8).
4) Check Fuel Pressure
Turn ignition off. Install fuel pressure gauge. While observing gauge, turn ignition on; wait one second and turn ignition off for 10 seconds. Repeat procedure 5 times. If fuel pressure increases, go to next step. If fuel pressure does not increase, go to appropriate step as follows:
5) Check Idle Air Control
Attempt to start engine at part throttle. If engine will not start and run smoothly, go to next step. If engine will start and run smoothly, go to CIRCUIT TEST KE, step 2).
6) Check VREF At TP Sensor
Turn ignition off. Disconnect TP sensor. Measure resistance between terminal VREF and SIG RTN at TP sensor wiring harness connector. If resistance is 4-6 ohms, go to next step. If resistance is not 4-6 ohms, go to CIRCUIT TEST C.
7) Check Flash EPROM (FEPS) Circuit For Short To Power
With ignition on, measure voltage between negative battery terminal and DLC terminal No. 13. See Figure . If voltage is less than 9 volts, go to next step. If voltage is 9 volts or more, repair circuit for a short to power and repeat QUICK TEST .
8) Check For Spark At Plugs
Disconnect any spark plug wire. Connect spark tester between spark plug wire and ground. Connect Spark Plug Firing Indicator (D89P-6666-A). Crank engine while checking for spark. If spark is okay and MIL turned off on step 3), EEC-V system is okay and testing is complete. If spark is okay and MIL stayed on in step 3), go to next step. If spark is not okay and MIL turned off on step 3), check spark plugs and wires. Repair or replace as necessary.
9) Check Continuity Of Ignition Ground Circuit
Ensure ignition is turned off. Disconnect PCM 104-pin connector and inspect for damage. Repair as necessary. Install Breakout Box (014-00950) leaving PCM disconnected. Install EI Diagnostic Harness (007-00059) leaving ICM disconnected. Install ICM overlay. Measure resistance between test pin No. 23 at breakout box and IGN GND terminal at the EI Diagnostic Harness. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST .
10) Check Continuity Of PIP Circuit
Ensure ignition is off and PCM is disconnected. Measure resistance between test pin No. 49 at breakout and PIP circuit at EI Diagnostic Harness. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit and repeat QUICK TEST .
11) Check PIP Circuit For Short To Power
Turn ignition on. Leave PCM and ICM disconnected. Measure voltage between test pin No. 49 and negative battery terminal. If voltage is less than one volt, go to next step. If voltage is one volt or more, repair short to power and repeat QUICK TEST .
12) Check PIP Circuit For Short To Ground
Ensure ignition is off. Measure resistance between breakout box test pin No. 49 and test pins No. 23, 51, 91 and 103. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short circuit and repeat QUICK TEST . If vehicle will not start, go to next step.
13) Check PIP Signal
Ensure ignition is off. Reconnect ICM wiring harness connector. While cranking engine, measure voltage between test pins No. 23 and 49 at breakout box. If voltage is 3-7 volts, replace PCM and repeat QUICK TEST . If voltage is not 3-7 volts, replace PCM and repeat QUICK TEST .