Transmission Control Module (TCM)

P0708-TRANSMISSION RANGE SENSOR CIRCUIT HIGH







Theory of Operation

The Transmission Range Sensor (TRS) is a multiple position selector switch which changes the signal path by redirecting a 12-volt signal source to seven different TRS signal circuits (P, R, N, D, 3, 2, 1) and also houses a Park/Neutral (P/N) switch circuit. These circuits are monitored by the Transmission Control Module and used in conjunction with various pressure switches to validate proper operation of the transmission and diagnose any possible problem. In a normal operating mode, pressure switch 8, is in an "Open" state in P, R, or N. and in an "Closed" state in any forward gear (engine running).

When Monitored:
- Ignition on in the run position.

Set Condition:
- When the Transmission Control Module (TCM) detects two or more Shift Lever positions registering "CLOSED" for the period of 500 msec.






Always perform the AS68RC Pre-Diagnostic Troubleshooting procedure before proceeding. Testing and Inspection.

1. CHECK IF DTC IS CURRENT

NOTE: This DTC may set if the Transmission Range Sensor has been replaced or reinstalled and not properly adjusted (calibrated). Make sure the TRS is properly adjusted before attempting to perform this diagnostic procedure. If the TRS was improperly adjusted, adjust as necessary and perform AS68RC TRANSMISSION VERIFICATION TEST AS68RC Transmission Verification Test .

1. Using the scan tool, read TCM DTCs.
2. Record the Environmental Data and any DTCs.
3. Clear DTCs.
4. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
5. Read TCM DTCs.

Did the DTC reset?

Yes

- Go To 2

No

- Go To 6

2. CHECK THE TRANSMISSION RANGE SENSOR STATES
1. Ignition on, engine not running.
2. With the scan tool, monitor the TRS states (Open-Closed) in the following steps:
3. Slowly move the shift lever to all positions (P, R, N, D, 3, 2, 1) while noting the TRS states.

Is there a shift position that shows more than one TRS position as "Closed"?

Yes

- Go To 4

No

- Go To 3

3. CHECK THE CONNECTORS
1. Turn the ignition off to the lock position.
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.

Was there any problems found?

Yes

- Repair as necessary.
- Perform AS68RC TRANSMISSION VERIFICATION TEST AS68RC Transmission Verification Test.

No

- Using the schematics as a guide, check the Transmission Control Module (TCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. Check for Service Information Tune-ups or Service Bulletins for any possible causes that may apply. If no problems are found, replace and program the TCM.
- Perform AS68RC TRANSMISSION VERIFICATION TEST AS68RC Transmission Verification Test.

4. CHECK THE TRANSMISSION RANGE SENSOR
1. Turn the ignition off to the lock position.
2. Disconnect the TRS harness connector.
3. Ignition on, engine not running.
4. With the scan tool read the TRS states (P, R, N, D, 3, 2, 1).

Did any of the TRS positions show as "Closed"?

Yes

- Repair the identified (P, R, N, D, 3, 2, 1) TRS Signal circuit for a short to voltage.
- Perform AS68RC TRANSMISSION VERIFICATION TEST AS68RC Transmission Verification Test.

No

- Go To 5

5. CHECK THE TRS SIGNAL CIRCUIT FOR A SHORT TO ANOTHER TRS SIGNAL CIRCUIT
1. Turn the ignition off to the lock position.
2. Disconnect the TCM C3 harness connector.
3. Measure the resistance between the two identified TRS signal circuits (P, R, N, D, 3, 2, 1) confirmed earlier.

Is the resistance below 100k ohms?

Yes

- Repair the identified TRS Signal circuit for a short to another TRS Signal circuit.
- Perform AS68RC TRANSMISSION VERIFICATION TEST AS68RC Transmission Verification Test.

No

- Replace and adjust the Transmission Range Sensor.
- Perform AS68RC TRANSMISSION VERIFICATION TEST AS68RC Transmission Verification Test.

6. CHECK WIRING AND CONNECTORS
1. The conditions necessary to set the 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. Check for any Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform AS68RC TRANSMISSION VERIFICATION TEST AS68RC Transmission Verification Test.

No

- Test Complete.