Chart A-1, No Check Engine Light: Notes

CHECK ENGINE light should always be on steady when ignition is on and engine is not running. Battery voltage is supplied directly to light bulb. ECM controls light and turns it on by providing a ground path through Purple/Yellow wire to ECM.

1. Checks to see if ECM is receiving power.
2. Checks to see if ECM is faulty.
3. Checks for an open in Blue/Black wire between main relay and ECM.
4. Checks for a good ECM ground.
5. Checks for an open in Black/White wire to instrument panel and Purple/Yellow wire to ECM.
6. Checks if main relay is receiving power.
7. Checks to see if main relay coil is receiving power.
8. Checks to see if main relay or ECM is faulty, or for an open in Blue wire between main relay and ECM.
9. Checks for a faulty ignition switch or an open in Black/Blue or Black/White wires to IG-COIL METER fuse.