Pinpoint Test T: The Malfunction Indicator Lamp (Mil) Is Never/Always On

WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

T1 RETRIEVE THE RECORDED DIAGNOSTIC TROUBLE CODES (DTCs) FROM BOTH CONTINUOUS AND ON-DEMAND PCM SELF-TESTS
- Retrieve the recorded PCM DTCs from the continuous and on-demand self-tests.
- Are any PCM DTCs recorded?
Yes : REFER to the INTRODUCTION - GASOLINE article to continue diagnosis of the DTCs.

No : GO to T2.
T2 CARRY OUT THE INSTRUMENT CLUSTER INDICATOR LAMP CONTROL ACTIVE COMMAND USING THE DIAGNOSTIC TOOL
- Key in ON position.
- Enter the following diagnostic mode on the scan tool: Instrument Cluster Active Command.
- Select the instrument cluster indicator lamp control active command. Trigger the MIL active command on and off. Observe the MIL.
- Does the MIL illuminate when triggered on, and turn off when triggered off?
Yes : GO to T4.

No : GO to T3.
T3 CHECK FOR CORRECT INSTRUMENT CLUSTER OPERATION
- Disconnect the instrument cluster connector.
- Check for:
  - corrosion
  - pushed-out pins
- Connect the instrument cluster connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes : INSTALL a new instrument cluster. REFER to INSTRUMENT CLUSTER . TEST the system for normal operation.

No : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
T4 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Check for:
  - corrosion
  - pushed-out pins
- Connect all the PCM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes : INSTALL a new PCM. REFER to ELECTRONIC ENGINE CONTROLS . TEST the system for normal operation.

No : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.