P0712-TRANSMISSION TEMPERATURE SENSOR LOW





For a complete wiring diagram Refer to Section 8W.

Theory of Operation


The Transmission Temperature Sensor is a variable resistor that changes with temperature, or otherwise known as a thermister. The temperature of the transmission fluid can affect a variety of electronically controlled transmission operations such as shift quality, torque converter lock-up, and when and/or if certain OBDII or system self-diagnostic test are performed. The Powertrain Control Module (PCM) substitutes a calculated transmission temperature value if a fault is detected in the Transmission Temperature Sensor circuit.


  • When Monitored:

    Continuously with the ignition on and engine running.

  • Set Condition:

    The DTC will set when the monitored Temperature Sensor voltage drops below 0.078 volts for the period of 0.45 seconds.


Possible Causes
  
RELATED DTC'S PRESENT
  
(T54) TRANSMISSION TEMPERATURE SENSOR SIGNAL CIRCUIT SHORT TO GROUND
  
TRANSMISSION TEMPERATURE SENSOR
  
POWERTRAIN CONTROL MODULE
  

Always perform the 45RFE/545RFE Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)



Diagnostic Test

1.CHECK IF RELATED DTCS ARE PRESENT



Are there any line pressure or throttle position sensor DTCs present?

Yes


No
  • Go To 2

2.CHECK IF DTC IS CURRENT


NOTE: This counter only applies to the last DTC set.



Is the STARTS SINCE SET counter 2 or less?

Yes
  • Go To 3


No
  • Go To 5

3.CHECK THE TRANSMISSION TEMPERATURE SENSOR



CAUTION: Removal of the Starter Relay will prevent the vehicle from being started in gear.


WARNING: The Starter Relay must be removed from the PDC. Failure to do so can result in personal injury or death.


NOTE: Failure to remove the Starter Relay can cause a Transmission - No Response condition.



NOTE: Check connectors - Clean/repair as necessary.







Do the readings on the Transmission Simulator match the scan tool readings ± 0.2 volts?

Yes


No
  • Go To 4

4.CHECK THE (T54) TRANSMISSION TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND






CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller tool #8815 to perform diagnosis.




Is the resistance below 5.0 ohms?

Yes


No
  • Using the schematics as a guide, check the Powertrain Control Module (PCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the PCM per the Service Information. With the scan tool, perform QUICK LEARN.
  • Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 45RFE/545RFE - STANDARD PROCEDURE)

5.CHECK WIRING AND CONNECTORS






Were there any problems found?

Yes


No
  • Test Complete.