P0854

P0854-OVERDRIVE INPUT SWITCH CIRCUIT LOW

For a complete wiring diagram Refer to Diagrams/Electrical.

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 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. AS68RC - Pre-Diagnostic Troubleshooting Procedure


Diagnostic Test


1. CHECK IF THE DTC IS CURRENT
With the scan tool, check the STARTS SINCE SET counter for P0854.
Is the Starts Since Set counter set at 2 or less?

Yes


- Go to2


No


- Go to4



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




Turn the ignition off to the lock position.
Disconnect the Tow/Haul Overdrive Off Switch harness connector.
Disconnect the TCM C2 harness connector.
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 VERIFICATION TEST. AS68RC Transmission Verification Test


No


- Go to3



3. CHECK THE TOW/HAUL SWITCH




Reconnect the Tow/Haul Overdrive Off Switch harness connector.
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 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 VERIFICATION TEST. AS68RC Transmission Verification Test



4. INTERMITTENT 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.

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

Check for any Service bulletins that may apply.
Were there any problems found?

Yes


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


No


- Test Complete.