Allison 3000 & 4000 Gen 4 Fault Code: P2739 Pressure Control Solenoid 5 (PCS5) Control Circuit High

DIAGNOSTIC RESPONSE:
Inhibit retarder operation

CIRCUIT DESCRIPTION:
Pressure Control Solenoid 5 (PCS5) is a normally closed solenoid used to apply the retarder solenoid or differential lock solenoid (3700 models). The Transmission Control Module (TCM) commands the solenoid ON to produce hydraulic pressure in the control circuit. When PCS5 is commanded OFF, the control circuit is deactivated. The TCM sends control current to PCS5 from High Side Driver 3 (HSD3) via wire 131. HSD3 is PCS5 by switching PCS5 low side driver ON and OFF. Wire 115 completes the circuit between PCS5 and its low side driver. DTC P2739 indicates that the TCM has detected a short-to-ground condition in the low side of the PCS5 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 PCS5 low side driver has been detected in a failed high state.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P2739 is active:
1. For 7-speed models, limit ranges to Reverse (R), Neutral (N) and ranges 2-6 operation.
2. TCM commands retarder OFF.
3. The TCM inhibits TCC engagement.
4. DTC is stored in the TCM history.
5. The CHECK TRANS light illuminates.
6. The TCM freezes shift adapts (DNA).

CONDITIONS FOR CLEARING THE DTC:
Use the 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 P2739 can be caused by:
1. PCS5 issues such as W115 shorted to another wire in the chassis harness.
2. Defective PCS5.
3. Broken or defective connector assemblies allowing pushed back pins to short together.
4. Unlocked connectors, missing seal plugs allowing moisture in connectors.
5. Defective TCM.

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