Pinpoint Test C: The Temperature Gauge Is Inoperative

Normal Operation 

The PCM receives the engine coolant temperature status through hardwired circuitry to the cylinder head temperature (CHT) sensor. 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 instrument cluster (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 instrument cluster (IC) does not receive the engine coolant temperature status message from the PCM for 5 seconds or less, the instrument cluster (IC) defaults the temperature gauge to the last setting, based upon the last known good temperature status message. If the instrument cluster (IC) does not receive the engine coolant temperature status message from the PCM for more than 5 seconds or if the data received is deemed invalid, the instrument cluster (IC) sets DTC U0100 in continuous memory and defaults the temperature gauge to cold (C).

This pinpoint test is intended to diagnose the following:

• PCM
• Instrument cluster (IC)

PINPOINT TEST C: THE TEMPERATURE GAUGE IS INOPERATIVE 

1. C1 CARRY OUT THE INSTRUMENT CLUSTER (IC) COOLANT TEMPERATURE GAUGE ACTIVE COMMAND USING THE SCAN TOOL 
   • Key in ON position.
   • Enter the following diagnostic mode on the diagnostic tool: Instrument Cluster (IC) DataLogger
   • Select the instrument cluster (IC) temperature gauge (ENGCOOLNT) active command and command the temperature gauge on then off. Observe the temperature gauge. The temperature gauge starts at cold (C) and moves to full hot (H).
   • Is the temperature gauge within specifications? 
   1. YES  : Go to  C2.
   2. NO  : Go to  C5.
2. C2 RETRIEVE THE RECORDED DTCs FROM BOTH THE CONTINUOUS AND ON-DEMAND PCM SELF-TESTS 
   • Check for recorded PCM DTCs from the continuous and on-demand self-tests.
   • Are any PCM DTCs recorded? 
   1. YES  : REFER to the Introduction - Gasoline Engines article.
   2. NO  : Go to  C3.
3. C3 RETRIEVE THE RECORDED DTCs FROM BOTH THE CONTINUOUS AND ON-DEMAND INSTRUMENT CLUSTER (IC) SELF-TESTS 
   • Check for recorded instrument cluster (IC) DTCs from the continuous and on-demand self-tests.
   • Is DTC U0100 recorded? 
   1. YES  : Go to Pinpoint Test AG  .
   2. NO  : Go to  C4.
4. C4 CHECK FOR CORRECT PCM OPERATION 
   • Disconnect all the PCM connectors.
   • Check for:
     • corrosion
     • damaged pins
     • pushed-out pins
   • Connect all the PCM connectors and make sure they seat correctly.
   • Operate the system and verify the concern is still present.
   • Is the concern still present? 
   1. YES  : INSTALL a new PCM. REFER to ELECTRONIC ENGINE CONTROLS article. TEST the system for normal operation.
   2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
5. C5 CHECK FOR CORRECT INSTRUMENT CLUSTER (IC) OPERATION 
   • Disconnect the instrument cluster (IC) connector.
   • Check for:
     • corrosion
     • damaged pins
     • pushed-out pins
   • Connect the instrument cluster (IC) connector and make sure it seats correctly.
   • Operate the system and verify the concern is still present.
   • Is the concern still present? 
   1. YES  : INSTALL a new instrument cluster (IC). REFER to Instrument Cluster (IC) . TEST the system for normal operation.
   2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.