Pinpoint Test G: The Temperature Gauge Is Inoperative

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests

Pinpoint Test G: The Temperature Gauge Is Inoperative

Normal Operation

The PCM uses the Engine Coolant Temperature (ECT) sensor to measure the engine coolant temperature on the 6.4L diesel engine and the Cylinder Head Temperature (CHT) sensor on the 5.4L and 6.8L gasoline engines. The Instrument Cluster (IC) receives the engine coolant temperature data from the PCM over the High Speed Controller Area Network (HS-CAN) communication bus. The IC 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 IC receives invalid engine coolant temperature data from the PCM for 5 seconds or less, the IC defaults the temperature gauge to the last setting, based upon the last known good temperature status message. If the IC does not receive the engine coolant temperature status message from the PCM or if the data received is deemed invalid for more than 5 seconds, the IC sets DTC U0100 in continuous memory and defaults the temperature gauge to cold (C). If the engine coolant temperature data is deemed invalid by the IC, the IC sets DTC U2023 and defaults the temperature gauge to cold (C).

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

This pinpoint test is intended to diagnose the following:

- PCM
- IC



PINPOINT TEST G: THE TEMPERATURE GAUGE IS INOPERATIVE

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G1 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 Information.

No
GO to G2.

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G2 CARRY OUT THE TEMPERATURE GAUGE ACTIVE COMMAND USING THE SCAN TOOL


- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger .
- NOTE: Make sure to set the scan tool to 0 or full cold before beginning this step.
- Select the IC temperature gauge (ENGCOOLNT) active command. Command the temperature gauge on and off while monitoring the gauge.
- Does the temperature gauge start at cold (C), move to full hot (H) and return to cold (C)?

Yes
GO to G3.

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

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G3 RETRIEVE THE RECORDED DTCs FROM THE IC SELF-TEST


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

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

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

No
INSTALL a new PCM. REFER to Computers and Control Systems. TEST the system for normal operation.

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