GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2008 🢒 Enclave 🢒 DTC 🢒 DTC P0796 or P0797

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0796:  Clutch Pressure Control (PC) Solenoid 3 - Stuck Off

DTC P0797:  Clutch Pressure Control (PC) Solenoid 3 - Stuck On

Circuit/System Description

The clutch pressure control (PC) solenoid 3 is part of the control solenoid (w/body and TCM) valve assembly and is not serviced separately. The clutch PC solenoid 3 flows fluid to the low and reverse/4-5-6 clutch when commanded OFF and exhausts fluid when commanded ON. The clutch PC solenoid 3 regulates the transmission fluid pressure to the low and reverse/4-5-6 clutch. The TCM calculates gear ratio based on data from the automatic transmission input speed sensor (ISS) and the output speed sensor (OSS). The TCM compares the known transmission gear ratio to a calculated gear ratio for each commanded gear.

Conditions for Running the DTC

P0796

    • No ISS DTCs P0716 or P0717.
    • No OSS DTCs P0722 or P0723.
    • No IMS DTCs P1825 or P1915.
    • The throttle position is 10 percent or greater.
    • The engine torque is greater than 120 N·m (88 lb ft).
    • The transmission input shaft speed is 60 RPM or greater.
    • Low and reverse/4-5-6 clutch is commanded ON.

P0797

    • No ISS DTCs P0716 or P0717.
    • No OSS DTCs P0722 or P0723.
    • No IMS DTCs P1825 or P1915.
    • The transmission output shaft speed is greater than 200 RPM.
    • Low and reverse/4-5-6 clutch is commanded OFF.

Conditions for Setting the DTC

P0796

The TCM detects an incorrect on-coming clutch gear ratio, or flare, when the low and reverse/4-5-6 clutch is commanded ON and the transmission input shaft speed is 100 RPM or greater from the anticipated input shaft speed for 2.25 seconds.

P0797

The TCM detects an incorrect off-going clutch gear ratio, or tie-up, when the low and reverse/4-5-6 clutch is commanded OFF and the transmission input shaft speed is 40 RPM or less from the anticipated input shaft speed for 1.2 seconds.

Action Taken When the DTC Sets
    • DTCs P0796 and P0797 are Type A DTCs.
    • The TCM commands maximum line pressure.
    • The TCM inhibits TCC.
    • The TCM freezes transmission adaptive functions.

Conditions for Clearing the DIC/DTC

DTCs P0796 and P0797 are Type A DTCs.

Reference Information

Description and Operation

Transmission General Description

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

    • DT-47825 Control Solenoid Test Plate
    • J 21867 Pressure Gage

Circuit/System Verification
  1. Perform the Transmission Fluid Check to verify correct fluid level and condition. The transmission fluid level should be within the crosshatch band and the transmission fluid should be red or dark brown.
    2. ⇒If the transmission fluid is low or discolored, refer to Transmission Fluid Replacement.
  2. Engine idling at operating temperature. Attempt to clean or free up a potential sticking valve with the scan tool Service Cleaning Procedure. Refer to Control Solenoid Valve and Transmission Control Module Assembly Cleaning for further instructions.
  3. Operate the vehicle in drive with the calculated throttle position greater than 15 percent to obtain 72 km/h (45 mph) and achieve 5th gear. Perform this maneuver 2 times. The DTCs should not set.
  4. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing
  1. Ignition OFF, remove the line pressure test hole plug and install the J 21867 to the transmission.
  2. Perform the Line Pressure Check. Verify the transmission line pressure gage is within the range specified in the Line PC Solenoid Valve Pressure table. Refer to Solenoid Valve Pressure.
    3. ⇒If not within the specified range, repair as necessary. Refer to Fluid Pressure High or Low for further diagnosis.
  3. Ignition OFF, remove the control solenoid (w/body and TCM) valve assembly.
  4. Install the DT-47825 to the control solenoid (w/body and TCM) valve assembly. Refer to Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test for detailed instructions.
  5. Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test. A pressure change should occur.
    6. ⇒If a pressure change does not occur, replace the control solenoid (w/body and TCM) valve assembly.
  6. Inspect for the following conditions and repair/replace as necessary:
    7. • The control valve lower body assembly for sticking valves, damage, scored bores, or debris
    • The low and reverse/4-5-6 clutch assembly for damage

Repair Instructions

Important: 

   • Perform the Service Fast Learn Adapts following all transmission related repairs.
   • Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Control Valve Lower Body and Upper Body Replacement
    •  Low and Reverse Clutch and 1-2-3-4 Clutch Plate Removal and 3-5-Reverse and 4-5-6 Clutch Housing Disassemble
    •  Control Module References for control solenoid (w/body and TCM) valve assembly replacement, setup, and programming