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 (ECT). The Instrument Cluster (IC) receives the ECT data from the PCM over the High Speed Controller Area Network (HS-CAN) communication bus. The IC monitors the ECT data received from the PCM and commands the temperature gauge indication with a corresponding movement of the pointer.
The PCM incorporates 2 strategies for failsafe cooling in the event that the engine has reached an over-temperature condition in order to protect the engine from severe damage. The first strategy is when the PCM provides engine operation but takes on the limp home strategy. The second strategy is when the PCM determines that the engine is sufficiently over-temperature and is about to be shut down by the PCM. In both strategies, the PCM provides the engine over-temperature information to the IC to illuminate the engine over-temperature warning indicator and send the temperature gauge to the full hot (H) position.
If the ECT data is missing or invalid 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 ECT status message from the PCM for more than 5 seconds, the IC sets DTC U0101 in continuous memory and defaults the temperature gauge to cold (C). If the ECT status message is invalid for more than 5 seconds, the IC sets DTC U2023 in continuous memory and defaults the temperature gauge to cold (C).
NOTE: If DTC U0101 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:
- CHT sensor
- PCM
- 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.
- Is the engine cooling system and thermostat operating 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
REFER to the 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 U0101, Go To Pinpoint Test AF. Pinpoint Tests AF: DTC U0101
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
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger.
- NOTE: The coolant temperature should range between [-]40-59°C (40-138°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.
- Select the IC temperature gauge (ECT_GAUGE) active command. Command the temperature gauge to the approximate values in the following table while monitoring the gauge.
- 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 IC 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 will only appear if the temperature is below 0°C. For example: TEMP GAUGE xxx DEG C may display TEMP GAUGE 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 TEMP GAUGE xxx DEG 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 ECT 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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