Chart A-1 - No Check Engine Light: Notes

There should always be a steady CHECK ENGINE light when ignition is 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.

Test light provides a ground source to CHECK ENGINE light. If circuit is okay, CHECK ENGINE light should be on when circuit A5 is probed.
Battery voltage at terminals B1 and C16 is protected by a 30-amp fusible link in relay center, near battery. If terminals B1 and C16 have voltage, ECM or ECM grounds are faulty.
Using a test light connected to 12 volts, probe each system ground circuit to ensure a good ground is present.