Pinpoint Test C: The Temperature Gauge Is Inoperative

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests

Pinpoint Test C: The Temperature Gauge Is Inoperative

Normal Operation

The PCM uses the Cylinder Head Temperature (CHT) sensor to measure the engine coolant temperature. The Instrument Panel Cluster (IPC) receives the engine coolant temperature data from the PCM over the High Speed Controller Area Network (HS-CAN) communication bus. The IPC monitors the engine coolant temperature data received from the PCM and commands the temperature gauge indication with a corresponding movement of the pointer.

If the engine coolant temperature data is missing or invalid for 5 seconds or less or if the IPC receives invalid engine coolant temperature data for 5 seconds or less, the IPC defaults the temperature gauge to the last setting, based upon the last known good temperature status message received.

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 temperature gauge to cold (C).

If the engine coolant temperature data is deemed invalid by the IPC for 5 seconds or more, the IPC sets DTC U0401:86 and defaults the temperature gauge to cold (C).

NOTE: If DTC U0100:00 is set 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 C: THE TEMPERATURE GAUGE IS INOPERATIVE

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C1 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO SELF-TEST


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

Yes
DIAGNOSE all PCM DTCs first. REFER to Computers and Control Systems.

No
GO to C2.

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C2 CARRY OUT THE TEMPERATURE GAUGE ACTIVE COMMAND USING THE SCAN TOOL


- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC DataLogger .
- Select the instrument temperature gauge (ENGCOOLNT) mode active command. Command the temperature gauge on and off while observing the temperature gauge.
- Does the temperature gauge begin at cold (C), sweep to hot (H) when commanded on then return to cold (C) when commanded off?

Yes
GO to C3.

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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C3 RETRIEVE THE RECORDED DTCs FROM THE IPC SELF-TEST


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

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

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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