P0854

P0854-OVERDRIVE INPUT SWITCH CIRCUIT LOW

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

Theory of Operation

The overdrive switch circuit is used to input a momentary switch signal of the overdrive switch (normally open) to switch between Normal shift mode, Tow/Haul mode, and OD OFF modes.

- When Monitored:
Continuously with the ignition ON and the engine running

Output shaft speed is greater than 750 rpm.

- Set Condition:
The Transmission Control Module (TCM) detects the switch is stuck low when the switch remains closed (button pressed) for more than 60 seconds while the output shaft maintains speed above 750 rpm.





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

1. CHECK IF THE DTC IS CURRENT
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 4

2. CHECK THE (T6) TOW/HAUL OVERDRIVE OFF SWITCH SIGNAL CIRCUIT FOR A SHORT TO GROUND




1. Turn the ignition off to the lock position.
2. Disconnect the Tow/Haul Overdrive Off Switch harness connector.
3. Disconnect the TCM C2 harness connector.
4. Measure the resistance between ground an the (T6) Tow/Haul Overdrive Off Switch Signal circuit.

Is the resistance below 100k Ohms?

Yes

- Repair the (T6) Tow/Haul Overdrive Off Switch Signal circuit for a short to ground.
- Perform AS68RC TRANSMISSION VERIFICATION TEST AS68RC Transmission Verification Test.

No

- Go To 3

3. CHECK THE TOW/HAUL SWITCH




1. Reconnect the Tow/Haul Overdrive Off Switch harness connector.
2. Measure the resistance between ground and the (T6) Tow/Haul Overdrive Off Switch Signal circuit in the TCM C2 harness connector.

Is the resistance below 100k Ohms?

Yes

- Replace the Tow/Haul Overdrive Off Switch.
- Perform AS68RC TRANSMISSION VERIFICATION TEST AS68RC Transmission Verification Test.

No

- Using the schematics as a guide, check the Transmission Control Module (TCM) pins, terminals, and connectors 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 TCM.
- Perform AS68RC TRANSMISSION VERIFICATION TEST AS68RC Transmission Verification Test.

4. 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.

NOTE: It may be necessary to test drive the vehicle to enable or cause the DTC to set.

5. 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.