Chart A-1 No Check Engine Light

CIRCUIT DESCRIPTION
There should always be a steady "Check Engine" light when the ignition is "ON" and the engine is "OFF." Battery voltage is supplied directly to the light bulb. The electronic control module (ECM) controls the light and turns it "ON" by providing a ground path through CKT 419 to the ECM.

TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.
1. Probing CKT 419 to ground creates an alternate ground. If the "Check Engine" light illuminates, this verifies that the trouble is not in the lamp portion of the circuit.

DIAGNOSTIC AIDS
If engine runs OK, check the following:
^ Faulty light bulb.
^ CKT 419 open.
^ Gage fuse blown. This will result in no oil or generator lights, seat belt reminder, etc.

If "Engine Cranks But Won't Run," use CHART A-3. Related Tests, Information and Procedures