For 1990-2009 cars
Engine Controls Components
Power, Ground, MIL, and DLC
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

When the ignition is turned on, the Malfunction Indicator Lamp (MIL) will momentarily flash on and off and the remain on until the engine is running if no DTCs are stored. The Powertrain Control Module (PCM) controls the MIL by providing a ground path through the MIL control circuit to turn on the MIL.

### Diagnostic Aids

An open ignition positive voltage #2 fuse will cause the following conditions:

• | The entire cluster will be inoperative

• | DTC U1000 may set

• | A no-start condition

Inspect the B+ voltage and the ignition positive voltage #2 circuits for poor connections if the MIL is intermittent. It takes very little resistance in the B+ voltage and the ignition positive voltage #2 circuits to cause an intermittent condition.

Any circuitry that is suspected of causing an intermittent complaint should be inspected for the following conditions:

• | Any backed-out terminals

• | Any improper mating

• | Any broken locks

• | Any improperly formed terminals or damaged terminals

• | Faulty terminal-to-wire connections

• | Any physical damage to the wiring harness

### Test Description

The number below refers to step number on the diagnostic table.

1. The replacement PCM must be programmed and the Crankshaft Position System Variation Learn procedure must be performed.

#### No Malfunction Lamp (MIL)

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Test and inspect for an open and poor connections in the following circuits:

• | The battery positive voltage circuit

• | The ignition positive voltage #2 circuit

2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 3

3 |

1. Turn off the ignition.
2. Disconnect the PCM C2 connector.
3. Connect a test lamp to ground.
4. Turn on the ignition, leaving the engine off.
5. Probe the MIL driver circuit at the C2 connector.

Does the MIL illuminate?

--

Go to Step 6

Go to Step 4

4 | Did the test lamp illuminate? | -- | Go to Step 8 | Go to Step 5
5 |

1. Test and inspect the MIL control circuit for an open and a poor connection.
2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Instrument Cluster Inoperative in Instrument Panel, Gauges, and Console

6 |

1. Inspect for poor PCM ground connections.
2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 7

7 |

1. Inspect the MIL control circuit for a poor connection at the PCM connector.
2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

8 | 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 10 | --
9 | Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the repair? | -- | Go to Step 10 | --
10 | Turn on the ignition, leaving the engine off, while observing the MIL . Does the MIL illuminate? | -- | System OK | Go to Step 2