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

Instrumentation, Message Center and Warning Chimes

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

Normal Operation

The PCM uses the Engine Coolant Temperature (ECT) sensor to measure the engine coolant temperature. The Instrument Panel Cluster (IPC) receives the engine over-temperature request from the PCM over the High Speed Controller Area Network (HS-CAN) communication bus. When the PCM detects high engine coolant temperature, the PCM sends a request to the IPC to illuminate the engine over-temperature warning indicator.

If the engine coolant temperature status message is missing for 5 seconds or less or if the IPC receives an invalid engine temperature status message for 5 seconds or less, the IPC defaults the engine over-temperature warning indicator to the last setting (on or off), based upon the last known good request message.

If the IPC does not receive the engine coolant temperature status message from the PCM for more than 5 seconds, the IPC sets DTC U0100:00 in continuous memory and defaults the engine over-temperature warning indicator on. If the engine coolant temperature status message is deemed invalid by the IPC for 5 seconds or more, the IPC sets DTC U0401:68 and defaults the engine over-temperature warning indicator on.

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

This pinpoint test is intended to diagnose the following:

- PCM
- IPC

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

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I1 CARRY OUT THE ENGINE OVER-TEMPERATURE WARNING INDICATOR ACTIVE COMMAND USING THE SCAN TOOL

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

Yes
GO to I2.

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

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I2 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO SELF-TEST

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

Yes
REFER to Computers and Control Systems.

No
GO to I3.

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I3 RETRIEVE THE RECORDED DTCs FROM THE IPC SELF-TEST

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

Yes
For DTC U0100:00, GO to Pinpoint Test AM. Pinpoint Tests AM: DTC U0100:00 and P1607:87

For all other DTCs, REFER to DTC Charts.

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

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