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 (Instrument Panel Cluster) 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 (Instrument Panel Cluster) receives an invalid engine temperature status message for 5 seconds or less, the IPC (Instrument Panel Cluster) 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 (Instrument Panel Cluster) does not receive the engine coolant temperature status message from the PCM for more than 5 seconds, the IPC (Instrument Panel Cluster) 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 (Instrument Panel Cluster) for 5 seconds or more, the IPC (Instrument Panel Cluster) sets DTC U0401:68 and defaults the engine over-temperature warning indicator on.

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

This pinpoint test is intended to diagnose the following:

- PCM

- IPC (Instrument Panel Cluster)

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

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 (Instrument Panel Cluster) DataLogger.

- Select the IPC (Instrument Panel Cluster) 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 (Instrument Panel Cluster). REFER to Instrument Panel Cluster (IPC) Service and Repair. TEST the system for normal operation.

I2 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO (Key ON Engine OFF) 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 Information.

No
GO to I3.

I3 RETRIEVE THE RECORDED DTCs FROM THE IPC (Instrument Panel Cluster) SELF-TEST

- Check for recorded IPC (Instrument Panel Cluster) DTCs from the self-test.

Are any DTCs recorded?

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

For all other DTCs, REFER to DTC Charts Instrumentation, Message Center and Warning Chimes.

No
INSTALL a new PCM. TEST the system for normal operation.