Part 1 of 3

Diagnostic Chart:

Wiring Schematic:

Circuit Description:

Before using this chart, battery condition, engine cranking speed, and fuel quantity should be checked and verified as being OK.


Test Description:

Numbers below refer to circled numbers on the diagnostic chart.

1. A malfunction indicator lamp "ON" is basic test to determine if there is battery positive voltage and ignition voltage supplied to the Engine Control Module (ECM). No data link connector data may be due to an ECM problem. CHART A-2 will diagnose the ECM. If throttle position sensor voltage is over 2.5 volts, the engine may be in the "clear flood" mode, which will cause starting problems. The engine will not start without reference pulses and, therefore, the "Scan tool" should indicate engine speed during cranking.

2. Because the electronic ignition system uses two plugs and wires to complete the circuit of each coil, the opposite spark should be left connected. If revolution per minute was indicated during crank, the ignition control module is receiving a crank signal, but no spark at this test indicates the Ignition Control Module (ICM) is not triggering the coils.

3. The test light should blink, indicating the ECM is in control of the injectors. How bright the light blinks is not important. However, the test light should be a J-34730-3 or equivalent.

4. This test will determine if the ignition control module is not generating the reference pules or if the wiring or ECM are at fault. By touching and removing a test light to 12 volts on YEL/RED wire, a reference pulse should be generated. If revolution per minute is indicated, the ECM and wiring are OK.

5. High resistance in the spark plug wire could cause a "no start" condition. If a spark plug wire is found to be faulty, replace it and retest system.