Malfunction Indicator Lamp (MIL) Inoperative

CIRCUIT DESCRIPTION
The malfunction indicator lamp (MIL) is illuminated when the ignition is on and the engine is off. Battery ignition voltage is supplied to the MIL. The powertrain control module (PCM) will turn the MIL on by grounding the lamp control circuit. The MIL is normally off when the engine is running.

DIAGNOSTIC AIDS
Check for any of the following conditions:
- Check for a faulty indicator bulb, or an open in the instrument cluster power circuit if the engine starts and runs OK.
- Check for a faulty main relay if there is no MIL and the engine cranks but will not start.
- A MIL that is dim or not illuminated steady can be caused by an inadequate PCM ground. Inspect G102 for a clean, tight connection.
- A faulty electrical connection to the PCM.

An intermittent malfunction may be caused by a fault in the MIL electrical circuit. Inspect the wiring harness and components for an intermittent condition. Refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Step 1-2:

Steps 3-8:

Steps 9-11:

The numbers below refer to the step numbers in the diagnostic table.
2. This step checks whether there is communication between the PCM and a scan tool device. If the PCM is unable to provide serial data to the scan tool, there will be no MIL control.
3. If other instrument panel cluster (IPC) functions are not working correctly check for an open GAUGE fuse or for a lack of power and ground to the IPC.
4. This step checks for an open MIL Control circuit or for an internal PCM failure.
5. An open fuse determines if a voltage is constantly being applied to the control circuit.