P0712

P0712-TRANSMISSION TEMPERATURE SENSOR LOW





For a complete wiring diagram Consult Diagrams/Electrical.

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.





Always perform the 45RFE/545RFE Pre-Diagnostic Troubleshooting procedure before proceeding. Testing and Inspection

Diagnostic Test

1. CHECK IF RELATED DTCS ARE PRESENT
With the scan tool, read DTCs.
Are there any line pressure or throttle position sensor DTCs present?

Yes

- Diagnose and repair the DTC(s).

No

- Go to 2

2. CHECK IF THE DTC IS CURRENT
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. CHECK THE TRANSMISSION TEMPERATURE SENSOR
Turn the ignition off to the lock position.
Remove the Starter Relay.

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.

Install the Transmission Simulator, Miller tool #8333.

NOTE: Check connectors - Clean/repair as necessary.

Ignition on, engine not running.
With the Transmission Simulator, turn the Input/Output switch to OFF.
With the scan tool, monitor the Transmission Temperature voltage while turning the Thermistor Voltage switch to all three positions on the Transmission Simulator.
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 45RFE/545RFE TRANSMISSION VERIFICATION TEST. Transmission Verification Test

No

- Go to 4

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




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

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.

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 Signal circuit for a short to ground.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. 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 and program the PCM. With the scan tool, perform Quick Learn.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST. Transmission Verification Test

5. CHECK WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
Wiggle the wires while checking for shorted and open circuits.
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 45RFE/545RFE TRANSMISSION VERIFICATION TEST. Transmission Verification Test

No

- Test Complete.