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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 battery and ignition voltage to the ECM. The injector 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. The scan tool can be used to verify that the ECM recognizes the reference signal. If it does, the scan tool should read RPM during crank.

2. If test light is "OFF," the 20 amp fuse could be blown or CKT 1149 open or shorted to ground.

3. 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.

4. 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 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 or the coil cannot generate spark.

5. 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.