Allison 3000 & 4000 Gen 4 Fault Code: P2763 TCC PCS Control Circuit High

DIAGNOSTIC RESPONSE:
Inhibit TCC operation

CIRCUIT DESCRIPTION:
The Torque Converter Clutch (TCC) Pressure Control Solenoid (PCS) is a normally closed solenoid used to apply the lockup clutch when specific engine and turbine speed conditions are met. The Transmission Control Module (TCM) commands the solenoid ON to produce hydraulic pressure in the lockup clutch apply circuit. When the TCC solenoid is commanded OFF, lockup clutch pressure is exhausted. The TCM sends control current to the TCC solenoid from High Driver 3 (HSD3) via wire 131. HSD3 is continuously ON unless the TCM detects a fault condition The TCM regulates the amount of current to the TCC solenoid by switching the TCC solenoid low side driver ON and OFF. Wire 137 completes the circuit between the TCC solenoid and its low side driver. DTC P2761 indicates that the DTC has detected a short-to-battery condition in the low side of the TCC solenoid electrical circuit.

CONDITIONS FOR RUNNING THE DTC:
TCM initialized normally and engine speed above 200 rpm.

CONDITIONS FOR SETTING THE DTC:
This DTC sets when the TCM detects the TCC solenoid low side driver in a failed high state.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P2763 is active:
1. The TCM inhibits TCC engagement.
2. DTC is stored in the TCM history.
3. The CHECK TRANS light illuminates.
4. The TCM freezes shift adapts (DNA).

CONDITONS FOR CLEARING THE DTC
Use diagnostic tool to clear the DTC from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without failure.

DIAGNOSTIC AIDS:
DTC P2763 can be cause by:
1. TCC solenoid circuit issues such as:
– W137 shorted to another wire in chassis harness.
– W137 (terminal 12 of 20-way) shorted to another wire internal transmission harness.
2. Broken or defective connector assemblies allowing pushed back pin to short together.
3. Unlocked connectors, missing seal plugs allowed moisture in connectors.
4. Defective TCM.

Review applicable information in Control System and Transmission Specifications to find additional circuit specifications, system and connector diagrams, and troubleshooting tips.