Malfunction Indicator Lamp Circuit Check

Diagnostic Chart:

Electrical:

CIRCUIT DESCRIPTION

There should always be a steady Malfunction Indicator Lamp (MIL) when the ignition switch is on and the engine is not running. The ignition voltage is supplied directly to the indicator bulb. The Engine Control Module (ECM) controls the lamp by grounding the control circuit via an internal solid state device called a driver.

DIAGNOSTIC AIDS

^ Use the Connector Test Adapter Kit J 35616-A for any test that requires probing the ECM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.

^ An intermittent may be caused by the following:

- Corrosion

- A mis-routed harness

- A rubbed through wire insulation

- A broken wire inside the insulation

Refer to Symptoms / Intermittents. Testing and Inspection

TEST DESCRIPTION

The number(s) below refer to the step number(s) on the diagnostic table.

2. This step determines whether you were sent here because of an inoperative MIL, or because of a MIL that is always on with no DTCs set.

4. If the other indicator lamps in the instrument cluster are functioning, the feed circuit is OK.

7. This step verifies that the MIL is on with no DTCs set. If a DTC is displayed, return to the Powertrain On-Board Diagnostic (OBD) System Check. Testing and Inspection

8. If the MIL is on with the ECM connected and off with the ECM disconnected, and no DTCs are set, there is a problem in the ECM.

13. After the engine starts, the MIL should illuminate briefly and then go out. If the MIL remains on, go back to the Powertrain OBD System Check. Testing and Inspection