Chart A-2, Service Engine Soon Light Will Not Go Out Or Flash: Notes

The SERVICE ENGINE SOON (SES) light is located in the IPC. Light is powered by Ignition 1, circuit No. 39 and ECM completes system ground to turn light ON. With ignition ON, engine not running, light should be ON. If with engine running light is ON steady, this indicates an ECM code is set. When system diagnostics are entered, light should flash, indicating service mode of ECM has been entered. The system monitor button does not affect SERVICE ENGINE SOON light.

NOTE: Test numbers refer to numbers on diagnostic chart.

Test Number 1) This step verifies SERVICE ENGINE SOON light remains ON with engine running and no ECM codes displayed.

Test Number 2) Disconnecting ECM harness Yellow connector determines if short to ground is in ECM or elsewhere in circuit. If SERVICE ENGINE SOON light remains ON, fault is not in ECM.

Test Number 3) Check for short to ground in the IPC or in circuit No. 419. If test light illuminates when connected between IPC harness connector terminals C9 and D2, fault is a short to ground in circuit No. 419.