Pinpoint Tests AC: The Engine Over-Temperature Warning Indicator Is Never/Always On

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests

Pinpoint Test AC: The Engine Over-Temperature Warning Indicator Is Never/Always On

Normal Operation

The Instrument Panel Cluster (IPC) receives the engine over-temperature command from the PCM over the High Speed Controller Area Network (HS-CAN) communication bus. If the PCM detects an engine over-temperature condition or has entered into the fail-safe cooling mode, the PCM sends a command to the IPC to turn the engine over-temperature warning indicator on. The PCM incorporates 2 strategies for fail-safe cooling in the event that the engine has reached an over-temperature condition. The first strategy is when the PCM provides engine operation but takes on the limp home strategy. The second strategy is when the PCM determines that the engine is sufficiently over-temperature and is about to be shut down by the PCM.

If the engine over-temperature status message is missing or invalid for less than 5 seconds, the engine over-temperature warning indicator remains in the last on/off state, based upon the last known good engine over-temperature status message received.

If the engine over-temperature status message is missing for more than 5 seconds, the IPC sets DTC U0100:00 in continuous memory and defaults the engine over-temperature warning indicator on.

NOTE: If DTC U0100:00 is set in the IPC, other observable symptoms may be an inoperative speedometer, tachometer or odometer.

This pinpoint test is intended to diagnose the following:

- PCM
- IPC


PINPOINT TEST AC: THE ENGINE OVER-TEMPERATURE WARNING INDICATOR IS NEVER/ALWAYS ON

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AC1 CARRY OUT THE IPC WARNING LAMPS AND CHIME ACTIVE COMMAND USING THE SCAN TOOL


- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC DataLogger .
- Select the engine over-temperature warning indicator (COOLANT_LMP) active command. Command the engine over-temperature warning indicator on and off while observing the engine over-temperature warning indicator.
- Does the over-temperature warning indicator illuminate when commanded on and turn off when commanded off?

Yes
GO to AC2.

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

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AC2 RETRIEVE THE RECORDED DTCs FROM THE PCM KEY ON ENGINE OFF (KOEO) SELF-TEST


- Check for recorded PCM DTCs from the KOEO self-test.
- Are any PCM DTCs recorded?

Yes
REFER to Computers and Control Systems.

No
GO to AC3.

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AC3 RETRIEVE THE RECORDED DTCs FROM THE IPC SELF-TEST


- Check for recorded DTCs from the IPC self-test.
- Is DTC U0100:00 recorded?

Yes
GO to Pinpoint Test AU. Pinpoint Tests AU: DTC U0100:00

No
INSTALL a new PCM. REFER to Electronic Engine Controls Service and Repair. TEST the system for normal operation.

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