GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2006 🢒 Vibe - FWD 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Malfunction Indicator Lamp (MIL) Inoperative

Circuit Description

There should always be a steady malfunction indicator lamp (MIL) when the ignition switch is in the ON position and the engine is not running. System voltage is applied to the indicator bulb and the powertrain control module (PCM) provides a path to ground. Once the engine starts, the PCM turns the OFF the MIL. When an engine control system malfunction occurs, the PCM turns ON the MIL, and a diagnostic trouble code is stored in memory.

Diagnostic Aids

An intermittent malfunction may be caused by a faulty electrical connection in the MIL circuit. Refer to Intermittent Conditions .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step checks whether there is communication between the PCM and a scan tool device. If the PCM is unable to provide serial data to the scan tool, there will be no MIL control.

    2.

  2. If other instrument panel cluster (IPC) functions are not working correctly, check for an open GAGE fuse, or for a lack of power and ground to the IPC.

    3.

  3. This step checks for an open MIL control circuit or for an internal PCM failure.

    4.

  4. An open fuse determines if a voltage is constantly being applied to the control circuit.

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Connect a scan tool.
  2. Turn ON the ignition, with the engine OFF.

Does the scan tool display any engine data?

Go to Step 3

Go to Scan Tool Does Not Communicate with Keyword Data Line in Computer/Integrating Systems

3

Observe the instrument panel cluster (IPC) assembly operation.

Do all other functions of the IPC function normally?

Go to Step 4

Go to Diagnostic Starting Point - Instrument Panel, Gages and Console in Instrument Panel, Gages, and Console

4

  1. Turn OFF the ignition.
  2. Disconnect the powertrain control module (PCM) electrical connector with the MIL control circuit.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the MIL control circuit on the harness side with a 3-amp fuse jumper wire to ground. Refer to Instrument Panel, Gages, and Console Connector End Views in Instrument Panel, Gages, and Console.

Does the MIL illuminate?

Go to Step 9

Go to Step 5

5

Did the fuse in the jumper wire open?

Go to Step 6

Go to Step 7

6

Repair the short to voltage in MIL control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 10

--

7
  1. Turn ON the ignition, with the engine OFF.
  2. Backprobe the MIL control circuit at the instrument panel cluster (IPC) assembly with a 3-amp fuse jumper wire to ground. Refer to Instrument Panel, Gages, and Console Connector End Views in Instrument Panel, Gages, and Console.

Does the MIL illuminate?

Go to Step 8

Go to Diagnostic Starting Point - Instrument Panel, Gages and Console in Instrument Panel, Gages, and Console

8

Repair the open in the MIL control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 10

--

9

Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 10

--

10

Turn ON the ignition, with the engine OFF.

Is the MIL illuminated?

Go to Step 11

Go to Step 2

11
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Observe the MIL operation.

Is the MIL illuminated?

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

System OK