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

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

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

DTC P0970: Shift Pressure Control (PC) Solenoid Control Circuit Low Voltage

DTC P0971: Shift Pressure Control (PC) Solenoid Control Circuit High Voltage

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Signal

P0962, P0966, or P0970

P0962, P0966, or P0970

P0963, P0967, or P0971

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Circuit/System Description

The three linear pressure control (PC) solenoids are installed directly in the transmission valve body (V/B) and 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 0.1 amps, for maximum pressure to 1.1 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.
    • The transmission is not in Emergency Mode.

Conditions for Setting the DTC

DTC P0962, P0966, and P0970

The TCM detects that a PC solenoid actual current is less than a specified value (92mA) for a specified length of time (0.5 second, 25 occurrences

DTC P0963, P0967, and P0971

The TCM detects that a PC solenoid actual current is greater than a specified value (1356mA) for a specified length of time (0.5 second, 4 occurrences

Action Taken When the DTC Sets

DTC P0962, P0966, and P0967

    • Type A DTC
    • The transmission will operate in 5th gear in D or M range, 2nd gear in L range.

DTC P0963

    • Type A DTC
    • The transmission will operate in 5th gear in D or M range, 2nd gear in L range.
    • The engine torque is limited to 150 N·m

DTC P0970 and P0971

    • Type A DTC
    • The transmission will operate in 4th gear in D or M range, no engine braking.

Conditions for Clearing the DTC

DTC P0962, P0963, P0966, P0967, P0970 and P0971 are Type A DTC’s

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

    •  Automatic Transmission Inline Harness Connector End View
    •  Automatic Transmission Internal Connector End Views
    •  Automatic Transmission Related Connector End Views

Electrical Information Reference

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

DTC Type Reference

    •  Diagnostic Trouble Code (DTC) Type Definitions
    •  Diagnostic Trouble Code (DTC) List/Type

Scan Tool Reference

    •  Scan Tool Output Controls
    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Verification

  1. Ignition ON, observe the DTC information with a scan tool.
  2. Record Freeze Frame and Failure Records.
  3. Clear DTC’s.
  4. Engine running, using PC Solenoid Output Controls, observe the PC Sol. Actual Current and PC Sol. Ref. Current while varying the current. The actual and commanded values should be within 0.05 amps.
  5. Operate the vehicle under the conditions observed in the Failure Records.
  6. Observe the DTC information with the scan tool. Verify that the DTC does not set.

Circuit/System Testing

  1. Ignition OFF, disconnect the 22-way automatic transmission (AT) wiring harness connector (C2) at the TCM.
  2. Test for 5-8 ohms of resistance between the PC solenoid high control circuit terminal and low control circuit terminal.
  3. If not within the specified range
    • Remove the appropriate solenoid and test for 4-8 ohms of resistance.
         ⇒If not within the specified range, replace the valve body assembly.
    • Replace the AT wiring harness, refer to Wiring Harness Removal procedure and Wiring Harness Installation procedure.
  4. Replace the TCM, refer to Transmission Control Module Removal procedure and Transmission Control Module Installation procedure.

Component Testing

Test the PC solenoid for 5.0-5.6 ohms of resistance, at 20°C, between the control circuit terminal and the ground circuit terminal.

If not within the specified range, perform the Control Valve Body Replacement procedure.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.