No Malfunction Indicator Lamp (MIL)

Diagnostic Chart:

Connector View:

CIRCUIT DESCRIPTION

When the ignition is turned ON, the Malfunction Indicator Lamp (MIL) will momentarily flash ON then OFF and remain ON until the engine is running, it no Diagnostic Trouble Codes (DTC) 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 to turn ON the MIL.

DIAGNOSTIC AIDS

An open ignition #1 fuse will cause the entire cluster to be inoperational, as well as setting DTC's P1601 and P1629.

Any circuitry, that is suspected as causing an intermittent complaint, should be thoroughly checked for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminals to wiring connections or physical damage to wiring harness.

TEST DESCRIPTION

Number(s) below refer to step number(s) on the Diagnostic Table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool, if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is stored in the scan tool for later reference.

3. If the engine fails to start and the MIL is inoperational, then the fault can be isolated to either the PCM Ignition Positive Voltage #2, the Battery Positive Voltage B+, a poor PCM ground at the engine block, or the PCM.

4. A MIL that responds correctly to the scan tool commands indicates that the fault is not present at this time or conditions has been corrected.

5. Probing the MIL circuit with a test light to ground simulates the PCM's control of the MIL. If the MIL illuminates, then the fault can be isolated to the control of the MIL.

6. Locate and repair any shorts that may have caused the fuse to open before replacing the fuse.

7. If the Ignition Positive Voltage #3 is open, DTC's P0748 and P0753 may also be set (electronic automatic transmission only).

11. Before replacing the PCM, check for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminals to wiring connections or physical damaged to the wiring harness. Replacement PCM's must be reprogrammed. Refer to the latest Techline information for programming procedures.

13. A shorted MIL circuit can be diagnosed with a scan tool. Refer to PCM Outputs Diagnosis.

14. An open MIL circuit can be diagnosed with a scan tool. Refer to PCM Outputs Diagnosis.

16. For MIL bulb replacement procedures, refer to Instrument Panel.

17. For IPC replacement procedures, refer to Instrument Panel.

20. PCM grounds will only cause a problem if all of the grounds are not making a good connection. If a PCM ground problem is suspected, the most probable place to check is where all the grounds meet, at the engine block.