Part 1 of 3

Chart A-3:

Ignition Circuit:

CIRCUIT DESCRIPTION:
This chart assumes that battery condition and engine cranking speed are OK, and there is adequate fuel in the tank.

TEST DESCRIPTION: Number(s) below refer to circled number(s) on the diagnostic chart.

1. A MIL (Service Engine Soon) "ON" is a basic test to determine if there is a 12 volt supply and ignition 12 volts to ECM. No DLC may be due to an ECM problem and CHART A-2 will diagnose the ECM. If TP sensor is over 62%, 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 Tech 1 scan tool should read RPM (reference) during crank.

2. For the first two seconds with ignition "ON" or whenever reference pulses are being received, PPSW should indicate fuel pump circuit voltage (8 to 12 volts).

3. Because the direct ignition system uses two plugs and wires to complete the circuit of each coil, the opposite spark should be left connected. If RPM was indicated during crank, the ignition control module is receiving a crank signal, but no spark at this test indicates the ignition module is not triggering the coils.

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

5. Use fuel pressure gauge J 34730-1 or equivalent Wrap a shop towel around the fuel pressure tap to absorb any small amount of fuel leakage that may occur when installing the gauge.

6. This test will determine if the ignition control module is not generating the reference pulse or if the wiring or ECM are at fault. By touching and removing a test light to 12 volts on CKT 430, a reference pulse should be generated. If RPM is indicated, the ECM and wiring are OK.

7. This test will determine if the ignition control module is not triggering the problem coil or if the tested coil is at fault. This test could also be performed by using another known good coil.