Malfunction Indicator Lamp (MIL) Inoperative

Malfunction Indicator Lamp (MIL) Inoperative

Refer to Engine Controls Schematics DLC, PCM Power and Ground .

Circuit Description

Ignition voltage is supplied directly to the malfunction indicator lamp (MIL). The powertrain control module (PCM) controls the lamp by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component ON, the voltage of the control circuit should be low (near 0 volts). When the PCM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high (near battery voltage). If the fault detection circuit senses a voltage other than what is expected, the fault line status will change causing a DTC to set.

Diagnostic Aids

* An open gauge fuse will cause the entire IP cluster to be inoperative.
* If the ignition feed circuit is suspected of being open, check if other bulbs on that circuit illuminate.
* Inspect for any circuitry that is suspected of causing an intermittent complaint for the following conditions:

- Backed out terminals
- Improper mating
- Broken locks
- Improperly formed or damaged terminals
- Poor terminal to wiring connections
- Physical damage to the wiring harness

Test Description

The numbers below refer to the step numbers on the diagnostic table.
2.
Important: If the I/P is completely inoperative, refer to Wiring Repairs Wiring Repairs in Wiring Systems for further diagnosis.


Command both the ON and the OFF states. Repeat the commands as necessary.
8. If you do not find trouble in the control circuit or the connection at the PCM, the PCM may be faulty. However, this is an extremely unlikely failure.