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 Descriptors

DTC P0961: Line Pressure Control (PC) Solenoid System Performance

DTC P0962: Line Pressure Control (PC) Solenoid Control Circuit Low Voltage

DTC P0963: Line Pressure Control (PC) Solenoid Control Circuit High Voltage

DTC P0965: Torque Converter Clutch (TCC) Pressure Control (PC) Solenoid System Performance

DTC P0966: Torque Converter Clutch (TCC) Pressure Control (PC) Solenoid Control Circuit Low Voltage

DTC P0967: Torque Converter Clutch (TCC) Pressure Control (PC) Solenoid Control Circuit High Voltage

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Line PC Signal

P0962

P0962

P0963

P0961

TCC PC Signal

P0966

P0966

P0967

P0965

Circuit/System Description

The linear pressure control (PC) solenoids use pulse width modulated signals from the transmission control module (TCM) to control transmission pressures. The TCM varies the current to the PC solenoids from 1.1 amps, for maximum pressure to 0.1 amps, for minimum pressure. Internal current monitors within the TCM provide feedback in order to determine actual PC solenoids current draw.

Conditions for Running the DTC

    • The engine is running for greater than 2 seconds.
    • The transmission is not in Emergency Mode.

Conditions for Setting the DTC

P0961 and P0965

The TCM detects that the PC solenoid actual current differs from the commanded current by greater than 80 mA for 2.75 seconds.

P0962 and P0966

The TCM detects that a PC solenoid actual current is less than a specified value for 12.5 seconds.

P0963 and P0967

The TCM detects that a PC solenoid actual current is greater than a specified value for 0.5 second.

Action Taken When the DTC Sets

P0961

    • DTC P0961 is a Type A DTC.
    • No neutral control until vehicle speed is greater than 50 km/h (31 mph).
    • No N-D control.

P0962 and P0963

    • DTC P0962 and P0963 are Type A DTCs.
    • The transmission will operate in 4th gear in D range, Reverse in R range.

P0965 and P0966

    • DTC P0965 and P0966 are Type A DTCs.
    • No L-up control.
    • 3-4 shift inhibited when transmission fluid temperature (TFT) is greater than 150°C (302°F).

P0967

    • DTC P0967 is a Type A DTC.
    • No L-up control.
    • No squat control.
    • The transmission will operate in 1st gear when the vehicle speed is less than 10 km/h (6 mph).
    • 3-4 shift inhibited when TFT is greater than 150°C (302°F).

Conditions for Clearing the DTC

DTC P0961-P0963 and P0965-P0967 are Type A DTCs.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Transmission General Information

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

Circuit/System Verification

  1. Engine running, observe the PC Sol. Actual Current and PC Sol. Ref. Current while varying the current using the scan tool. The actual and commanded values should be within 0.05 amps.
  2. 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. Ignition ON, observe the DTC information with a scan tool.

Circuit/System Testing

  1. Ignition OFF, disconnect the automatic transmission (AT) wiring harness at the transmission.
  2. Test for 2-7 ohms between the appropriate PC solenoid high control circuit terminal and low control circuit terminal.
  3. If not within the specified range.
  4. Remove the appropriate solenoid and test for 2-7 ohms.
  5. If not within the specified range, replace the valve body assembly.
    If within the specified range, replace the AT wiring harness.
  6. If all circuits test normal, replace the TCM.

Component Testing

Test the PC solenoid for 2-7 ohms, at 20°C (68°F), across the solenoid.

If not within the specified range, replace the valve body assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Control Module References for TCM replacement, setup, and programming.
    •  Wiring Harness Removal
    •  Wiring Harness Installation