Diagnostic Aids

Perform this 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 the following:

Spark.
Fuel system.
Ignition Control Module (ICM).
Wiring harness circuits (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.
Engine mechanical components.
Starter and battery circuits.
Ignition coil.

1) Starting System Check Ensure Inertia Fuel Shutoff (IFS) switch is closed (button pushed in). Try to start engine. If engine does not crank, check vehicle starting and charging systems. If engine cranks, go to next step.
2) Check For Spark At Plugs Disconnect any spark plug wire. Connect spark tester between spark plug wire and ground. Crank engine while checking for spark. If spark is okay, go to next step. If spark is not okay, go to CIRCUIT TEST JA.
3) Check VREF At TP Sensor Turn ignition off. Disconnect TP sensor. Turn ignition on. Measure voltage between terminal VREF and SIG RTN at TP sensor wiring harness connector. If voltage is between 4-6 volts, go to next step. If voltage is not 4-6 volts, go to CIRCUIT TEST C.
4) Check Fuel Pressure Turn ignition off. Release fuel pressure. Install fuel pressure gauge. Turn ignition on for one second, then turn key off. Wait 10 seconds, repeat procedure 5 times. If fuel pressure increases, go to next step. If fuel pressure does not increase, go to CIRCUIT TEST HC.
5) Idle Air Control Check Attempt to start engine at part throttle. If engine starts and runs okay at part throttle, go to CIRCUIT TEST KE. If engine will not start or runs poorly at part throttle, go to next step.
6) Check Basic Engine Condition Check engine compression, camshaft, valve train and timing belt. Repair as necessary. If engine mechanical condition is okay, go to TESTS W/O CODES article.