Refer to
MIL and Generator
Circuit Description
When the ignition is turned ON, the malfunction indicator lamp (MIL) will momentarily flash ON then OFF then remain ON until the engine is running, if no diagnostic trouble codes (DTCs) are stored. Battery voltage is supplied through the ignition switch directly to the MIL telltale. The powertrain control module (PCM) controls the MIL by providing a ground path through the MIL control circuit in order to turn ON the MIL.
Diagnostic Aids
An open ignition fuse causes the MIL to be inoperative.
An intermittent may be caused by any of the following conditions:
| • | A poor connection |
| • | Rubbed through wire insulation |
| • | A broken wire inside the insulation |
Thoroughly test any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Connections that are suspected of being malfunctioning should be thoroughly tested as described in the diagnostic aids.
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If the engine fails to start and the MIL is inoperative, then the malfunction can be isolated to one of the following items:
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Probing the MIL circuit with a test lamp to ground simulates the PCM's control of the MIL. If the MIL illuminates, then the malfunction can be isolated to the control of the MIL or a poor connection at the MIL terminal to the PCM.
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It takes very little resistance for the battery and the ignition 1 feed circuits to cause an intermittent condition. The battery and the ignition 1 feed circuits should also be inspected for a poor connection as described in diagnostic aids.
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The replacement PCM must be programmed and the Crankshaft Position System Variation Learn procedure must be performed.
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The PCM grounds will only cause a problem if all of the grounds are not making a good connection. If the PCM ground problem is suspected, the most probable place is where all of the grounds meet, at the engine block.
| • | Open PCM ignition feed (2) circuit |
| • | Open battery positive feed circuit |
| • | Poor ground at the engine block |
| • | Malfunctioning PCM |
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | ||||||||||
2 | Turn ON the ignition, with the engine OFF. Does the MIL illuminate? | -- | ||||||||||
Did you find and correct the condition? | -- | |||||||||||
Attempt to start the engine. Does the engine start? | -- | |||||||||||
5 |
Did you find and correct the condition? | -- | -- | |||||||||
Does the MIL illuminate? | -- | |||||||||||
7 | Inspect the following fuses:
Are the fuses OK? | -- | ||||||||||
Did you find and correct the condition? | -- | |||||||||||
9 | Did the test lamp illuminate? | -- | ||||||||||
10 |
Does the test lamp illuminate? | -- | ||||||||||
11 |
Did you find and correct the condition? | -- | -- | |||||||||
|
Important:: The replacement PCM must be programmed.
Did you complete the replacement? | -- | -- | ||||||||||
13 | Repair the short to voltage in the MIL control circuit. Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||||
14 |
Did you find and correct the condition? | -- | ||||||||||
15 |
Does the test lamp illuminate? | -- | ||||||||||
16 | Repair the open ignition positive voltage #2 circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||||
17 |
Did you find and correct the condition? | -- | ||||||||||
18 |
Did you find and correct the condition? | -- | ||||||||||
19 | Repair the open in the PCM battery positive feed circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||||||
20 | Replace the IPC. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console. Did you complete the replacement? | -- | -- | |||||||||
Did you find and correct the condition? | -- | |||||||||||
22 |
Does the MIL illuminate? | -- | System OK |
