Chart A-1, No Check Engine Light: Notes

The CHECK ENGINE light should stay on when ignition switch is in ON position and engine is not running. The ECM turns on CHECK ENGINE light by completing a ground circuit.

NOTE: Test numbers refer to test numbers on diagnostic chart.

Completing a ground circuit should illuminate the CHECK ENGINE light.
This checks for battery voltage from the control relay.
This verifies battery voltage to control relay from ignition switch.
This verifies a good ground circuit from ECM connector to ground.
If test light illuminates, this indicates a faulty control relay.