GM Service Manual Online
For 1990-2009 cars only

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 Descriptor

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 DTCs P0716 or P0717.
    • No DTCs P0722 or P0723.
    • No DTCs P1825 or P1915.
    • The transmission input shaft speed is greater than 60 RPM.
    • Low and reverse/4-5-6 clutch is commanded ON.

P0797

    • No DTCs P0716 or P0717.
    • No DTCs P0722 or P0723.
    • No 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

P0776

The TCM detects an incorrect on-coming clutch gear ratio, or flare, when the low and reverse/4-5-6 clutch is commanded OFF for 0.5 seconds and the transmission input shaft speed is greater than 75 RPM from the anticipated input shaft speed.

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 ON for 0.5 seconds and the transmission input shaft speed is greater than 40 RPM from the anticipated input shaft speed.

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.

Diagnostic Aids

When attempting to set transmission performance DTCs, observe the Freeze Frame and Failure Records to assist in duplicating the failure conditions.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing.
    •  Connector Repairs.
    •  Testing for Intermittent Conditions and Poor Connections.
    •  Wiring Repairs.

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Perform the Transmission Fluid Check.
  2. Turn ON the ignition, with the engine OFF.
  3. Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records.

  4. Record the DTC Freeze Frame and Failure Records.
  5. Clear the DTC.
  6. Operate the vehicle in DRIVE with the calculated throttle position greater than 15% to obtain 72 km/h (45 mph) and achieve 5th gear. Perform this manoeuvre 2 times.
  7. If the DTC resets, go to Circuit/System Testing.

Circuit/System Testing

  1. Perform the Line Pressure Check.
  2. If the pressure is out of specification, correct this concern first.
  3. Perform the Control Solenoid Valve and Transmission Control Module Assembly Cleaning and retest the DTC as outlined in the Circuit/System Verification steps.
  4. If the DTC resets, continue on with testing.
  5. Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection.
  6. If a concern is found, repair or replace the control solenoid (w/body and TCM) valve assembly.
  7. Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test.
  8. If the solenoid is found to be leaking or stuck closed, replace the control solenoid (w/body and TCM) valve assembly.
  9. Inspect the control valve lower body assembly for sticking valves, damage, scored bores, or debris.
  10. If a concern if found in the valve body, repair or replace the valve body as necessary.
  11. Inspect the low and reverse/4-5-6 clutch assembly for damage.
  12. If a concern is found in the low and reverse/4-5-6 clutch assembly, repair or replace as necessary.

Component Testing

Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection.

PC Sol 3 Operation

Exercise

Normal Operation

Stuck OFF

Stuck ON

 

Steady State Gears 1st Braking 4, 5, 6

1st Braking, 4, 5, 6

1st Free Wheel, Neutral

1st Braking, 4, 5, 6

Steady State Gears, 1 Free Wheel 2, 3

1st Free Wheel, 2, 3

1st Free Wheel, 2, 3

1st Braking, 4, 5, 6

Garage Shift

Park/Neutral to Reverse/Drive

Neutral 1st Free Wheel

Drive Gear

Downshift from gears 4, 5, 6 to 1, 2, 3

1st Free Wheel, 2, 3

1st Free Wheel, 2, 3

1st Braking, 4, 5, 6

Upshift from gears 1, 2, 3 to 4, 5, 6

4, 5, 6

Neutral

4, 5, 6

Repair Instructions

       Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    • Control valve body replacement. Refer to Control Valve Lower Body and Upper Body Replacement .
    • Low and reverse/4-5-6 clutch assembly repair or replace. Refer to Low and Reverse Clutch Overhaul and 4-5-6 Clutch Overhaul in the Transmission Unit Repair Manual.
    • Control solenoid (w/body and TCM) valve assembly replacement. Refer to Control Module References for replacement, setup, and programming.