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

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests

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

Normal Operation

The Malfunction Indicator Lamp (MIL) is controlled by the Instrument Cluster (IC) using data sent from the PCM over the High Speed Controller Area Network (HS-CAN) communication bus. If the MIL status message is missing for less than 5 seconds, the MIL remains in the last indication mode (on or off). If the MIL status message is missing for more than 5 seconds, the IC sets DTC U0100 in continuous memory and defaults the MIL on.

NOTE: If DTC U0100 is set in the IC, other observable symptoms may be an inoperative speedometer, tachometer or odometer.

This pinpoint test is intended to diagnose the following:

- PCM
- IC



PINPOINT TEST T: THE MIL IS NEVER/ALWAYS ON

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T1 CARRY OUT THE IC INDICATOR LAMP CONTROL ACTIVE COMMAND USING THE SCAN TOOL


- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger.
- Select the IC MIL (MIL_IC) active command mode and command the MIL on and off. Observe the MIL.
- Does the MIL illuminate when commanded on and turn off when commanded off?

Yes
GO to T2.

No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.

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T2 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO SELF-TEST


- Check for recorded PCM DTCs from the Key ON Engine OFF (KOEO) self-test.
- Are any PCM DTCs recorded?

Yes
REFER to Computers and Control Systems Information.

No
GO to T3.

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T3 RETRIEVE THE RECORDED DTCs FROM THE IC SELF-TEST


- Check for recorded IC DTCs from the self-test.
- Is DTC U0100 recorded?

Yes
GO to Pinpoint Test AU. Pinpoint Tests AU: DTC U0100

No
If the MIL is never on, the system is operating correctly at this time.

If the MIL is always on, INSTALL a new PCM. REFER to Computers and Control Systems. TEST the system for normal operation.

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