68RFE

P0712-TRANSMISSION TEMPERATURE SENSOR LOW





For a complete wiring diagram refer to the Wiring Information Electrical Diagrams.

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 clutch engagement, 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.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Testing and Inspection

1. CHECK FOR RELATED DTCS
1. With the scan tool, read DTCs.

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

Yes

- Perform the appropriate diagnostics.

No

- Go to 2

2. CHECK IF THE DTC IS CURRENT
1. With the scan tool, read DTCs.

Is the status Active or is the Starts Since Set counter 2 or less for this DTC?

Yes

- Go to 3

No

- Go to 5

3. TRANSMISSION TEMPERATURE SENSOR
1. Turn the ignition off to the lock position.
2. Remove the Ignition Switch Feed fuse from the TIPM.

CAUTION: Removal of the Ignition Switch Feed fuse from the TIPM will prevent the vehicle from being started in gear.

WARNING: The Ignition Switch Feed fuse must be removed from the TIPM. Failure to do so can result in possible serious or fatal injury.

3. Install the Transmission Simulator, Miller tool #8333.
4. Ignition on, engine not running.
5. With the Transmission Simulator, turn the Input/Output switch to OFF.
6. With the scan tool, monitor the Transmission Temperature voltage while turning the Thermistor Voltage switch to all three positions on the Transmission Simulator.
7. Compare the scan tool readings with the numbers listed on the Transmission Simulator.

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

Yes

- Replace Transmission Solenoid/TRS Assembly.
- Perform 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Transmission Verification Test

No

- Go to 4

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




1. Turn the ignition off to the lock position.
2. Disconnect the Transmission Simulator, Miller tool #8333.
3. Disconnect the PCM C4 harness connector and connect Miller tool #8815.

NOTE: Check connectors - Clean/repair as necessary.

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 the PCM Pinout Box 8815 to perform diagnosis.

4. Measure the resistance between ground and the (T54) Transmission Temperature Sensor Signal circuit.

Is the resistance below 5.0 ohms?

Yes

- Repair the (T54) Transmission Temperature Sensor Signal circuit for a short to ground.
- Perform 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Transmission Verification Test

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. With the scan tool, perform Quick Learn. Programming and Relearning
- Perform 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Transmission Verification Test

5. CHECK THE WIRING AND CONNECTORS
1. The conditions necessary to set this DTC are not present at this time.
2. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
3. Wiggle the wires while checking for shorted and open circuits.
4. With the scan tool, check the Event Data to help identify the conditions in which the DTC was set.

Were there any problems found?

Yes

- Repair as necessary.
- Perform 68RFE TRANSMISSION VERIFICATION TEST. 68RFE Transmission Verification Test

No

- Test Complete.