Pinpoint Test D: Incorrect Temperature Gauge Indication
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test D: Incorrect Temperature Gauge Indication
Normal Operation
The PCM uses the Cylinder Head Temperature (CHT) sensor to measure the engine coolant temperature. 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.
Fail-Safe Cooling
The PCM provides 2 modes or levels of fail-safe cooling for gasoline engines, which provides a visual indication to the driver that the engine is overheating while reducing the engine power to lower the engine temperature. When the PCM sends the IC a fail-safe mode 1 or 2 command, the IC drives the temperature gauge to the full hot (H) position.
If the engine coolant temperature data is missing for 5 seconds or less or if the IC receives invalid engine coolant temperature data 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 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 for 5 seconds or more, 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, speedometer or odometer.
This pinpoint test is intended to diagnose the following:
- PCM
- CHT sensor
- IC
PINPOINT TEST D: INCORRECT TEMPERATURE GAUGE INDICATION
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D1 CHECK FOR CORRECT OPERATION OF THE COOLING SYSTEM
- Verify that the engine cooling system and thermostat are functioning correctly.
- Does the engine cooling system and thermostat operate correctly?
Yes
GO to D2.
No
REFER to Cooling System.
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D2 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
DIAGNOSE all PCM DTCs first. REFER to Computers and Control Systems Information.
No
GO to D3.
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D3 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 AM. Pinpoint Tests AM: DTC U0100
For DTC U2023, RETRIEVE and REPAIR all non-network DTCs in the PCM and other modules on the network. REFER to Computers and Control Systems Information and Body Control Systems for a list of all DTCs.
For all other DTCs, REFER to DTC Charts. Instrumentation, Message Center and Warning Chimes
No
GO to D4.
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D4 CARRY OUT THE TEMPERATURE GAUGE ACTIVE COMMAND USING THE SCAN TOOL
NOTE: The coolant temperature should range between 0-59°C (32-138°F) with the gauge in the cold (C) range, between 60-120°C (140-248°F) with the gauge in the normal or mid-range and above 123°C (253°F) with the gauge in the hot (H) range.
- 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 instrument temperature gauge (ENGCOOLNT) active command. Command the temperature gauge according to the following table:
- Does the temperature gauge operate according to the above specifications?
Yes
GO to D5.
No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
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D5 CHECK THE COOLANT TEMPERATURE INPUT USING THE DEALER TEST MODE
- Ignition ON.
- Enter the IC dealer test mode.
- NOTE: The display below uses xxx's to represent a numeric or alpha-numeric value. The value may display the same amount of characters represented by the xxx's or there may be more/less depending on the type of display and that the minus symbol in parenthesis only appears if the temperature is below 0°C. For example: COOLANT TEMP xxx C may display COOLANT TEMP 20 C. Note that there were 3 x's in the display description but only 2 digits in the actual display.
- Scroll through the displays to COOLANT TEMP xxx C.
- Start the engine and run the engine through a variety of engine temperatures.
- NOTE: The coolant temperature should range between 0-59°C (32-138°F) with the gauge in the cold (C) range, between 60-120°C (140-248°F) with the gauge in the normal or mid-range and above 123°C (253°F) with the gauge in the hot (H) range.
- Monitor the engine coolant temperature input to the IC and the coolant temperature gauge indication.
- Does the engine coolant input agree with the position of the temperature gauge indication?
Yes
GO to D6.
No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
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D6 CHECK THE PCM TEMPERATURE PID
NOTE: The coolant temperature should range between 0-59°C (32-138°F) with the gauge in the cold (C) range, between 60-120°C (140-248°F) with the gauge in the normal or mid-range and above 123°C (253°F) with the gauge in the hot (H) range.
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- Ignition ON.
- Select the PCM temperature PID (CHT). With the engine running, monitor the PCM temperature PID.
- Does the PCM PID agree with the position of the temperature gauge indication?
Yes
INSTALL a new CHT sensor. TEST the system for normal operation.
No
INSTALL a new PCM. TEST the system for normal operation.
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