Circuit Description
Battery positive voltage is supplied directly to the malfunction indicator lamp (MIL). The powertrain control module (PCM) turns the MIL ON by grounding the MIL control circuit. There should be a steady MIL with the ignition ON and the engine OFF.
MIL Operation
The MIL is located on the instrument panel cluster (IPC).
MIL Function
| • | The MIL informs the driver that a malfunction has occurred and the vehicle should be taken in for service as soon as possible. |
| • | The MIL illuminates during a bulb test and a system test. |
| • | A DTC will be stored if a MIL is requested by the PCM. |
MIL Illumination
| • | The MIL will illuminate with ignition switch ON and the engine not running. |
| • | The MIL will turn OFF when the engine is started. |
| • | The MIL will remain ON if the self-diagnostic system has detected a malfunction. |
| • | The MIL may turn OFF if the malfunction is not present. |
| • | If the MIL is illuminated and then the engine stalls, the MIL will remain illuminated so long as the ignition switch is ON. |
| • | If the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition switch is cycled OFF, then ON. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connect End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 |
Does the MIL turn ON and OFF when commanded with a scan tool? | -- | Go to Intermittent Conditions | Go to Step 3 |
3 | Inspect the fuse that supplies battery positive voltage to the MIL. Is the fuse open? | -- | Go to Step 10 | Go to Step 4 |
Is the voltage less than the specified value? | 0.3 V | Go to Step 5 | Go to Step 11 | |
5 |
Is the MIL illuminated? | -- | Go to Step 9 | Go to Step 6 |
6 |
Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 12 |
7 | Test the MIL control circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | -- | Go to Step 15 | Go to Step 8 |
8 | Test for an intermittent and for a poor connection at the IPC. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13 |
9 | Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 14 |
10 | Repair the short to ground in the battery positive voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 15 | -- |
11 | Repair the short to voltage in the MIL control circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 15 | -- |
12 | Repair the open in the MIL battery positive voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 15 | -- |
13 | Replace the IPC. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console. Did you complete the replacement? | -- | Go to Step 15 | -- |
14 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- |
15 |
Does the vehicle operate correctly, without any MIL illumination and without any stored DTCs? | -- | System OK | |
