Chart A-1 - No Check Engine Light: Notes

There should always be a steady CHECK ENGINE light with ignition on and engine off. Electronic Control Module (ECM) will also turn on light if ECM senses a malfunction or ECM fails.

NOTE: Test numbers refer to numbers on diagnostic chart.

Battery voltage at circuits No. B1 and C16 is protected by an 80-amp MAIN fuse.
Using a test light connected to 12 volts, probe each system ground circuit to ensure a good ground is present.