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 P0961:  Line Pressure Control (PC) Solenoid System Performance

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

PC Solenoid High Control

P0961

P0961

P0961

P0961

PC Solenoid Low Control

P0961

P0961

P0961

P0961

Typical Scan Tool Data

Scan Tool Parameter Data

Circuit

Normal

Short to Ground

Open/High Resistance

Short to Voltage

Operating Conditions: Engine running in Park, normal operating temperature

Parameter Normal Range: 0.02-1.10 amps

PC Sol. Actual Current

0.02-1.10 amps

Less than 0.02 amps

Less than 0.02 amps

Less than 0.02 amps

PC Sol. Ref. Current

0.02-1.10 amps

Less than 0.02 amps

Less than 0.02 amps

Less than 0.02 amps

Circuit/System Description

The pressure control (PC) solenoid valve is located in the valve body. The PC solenoid valve controls transmission line pressure based on current flow through the windings. The transmission control module (TCM) determines desired line pressure based on throttle position and other inputs. The TCM then varies the duty cycle on the high side of the PC solenoid valve to control current flow to the solenoid. Current is controlled from about 0.02 amps for maximum line pressure to 1.1 amps for minimum line pressure. The TCM monitors the actual current to the solenoid.

Conditions for Running the DTC

The PC solenoid valve is enabled.

Conditions for Setting the DTC

The PC solenoid duty cycle is outside the range of 0.5-95 percent for 4 seconds.

Action Taken When the DTC Sets

DTC P0961 is a Type C DTC.

Conditions for Clearing the DTC

DTC P0961 is a Type C DTC.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

    •  Automatic Transmission Inline 20-Way 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

Scan Tool Reference

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

Special Tools

    • J 35616 GM Terminal Test Kit
    • J 44152 Jumper Harness (20 pins)

Circuit/System Verification

Start and idle the engine. Using the scan tool, select PC Solenoid under the Transmission Output Controls. With the scan tool, command several values of solenoid reference current from 0.1 amp through 1.1 amps and observe the PC Sol. Actual Current and the PC Sol. Ref. Current. The PC Sol. Actual Current should not vary from the PC Sol. Ref. Current by more than 0.16 amps.

Circuit/System Testing

  1. Disconnect the AT inline 20-way connector. Install the J 44152 on the transmission side on the connector. Using the J 35616 , measure the resistance between the PC solenoid high control circuit and the PC solenoid low control circuit. The resistance should be between 3-7 ohms.
  2. If the resistance is greater than 7 ohms, test the PC solenoid high control circuit or the PC solenoid low control circuit for an open or a faulty PC solenoid valve.
    If the resistance is less than 3 ohms, test for the PC solenoid high control circuit and the PC solenoid low control circuit shorted together of a faulty PC solenoid valve.
  3. Measure the resistance between the PC solenoid high control circuit and the transmission case. Measure the resistance between the PC solenoid low control circuit and the transmission case. The resistance should be greater than 10K ohms.
  4. If the resistance is less than 10K ohms, replace the automatic transmission wiring harness assembly.
  5. Measure the resistance between the PC solenoid high control circuit and all other circuits of the J 44152 except the PC solenoid low control circuit. Measure the resistance between the PC solenoid low control circuit and all other circuits of the J 44152 except the PC solenoid high control circuit. The resistance should be greater than 10K ohms.
  6. If the resistance is less than 10K ohms, replace the automatic transmission wiring harness assembly.
  7. Remove the J 44152 from the transmission side and install on the engine side of the harness. Disconnect the TCM connector. Using the J 35616 , measure the resistance of the PC solenoid high control circuit between the TCM connector and the AT inline 20-way connector. Measure the resistance of the PC solenoid low control circuit between the TCM connector and the AT inline 20-way connector. The resistance should be less than 10 ohms for each circuit.
  8. If the value is greater than 10 ohms, repair the open in the affected circuit.
  9. Measure the resistance between the PC solenoid high control circuit and ground. Measure the resistance between the PC solenoid low control circuit and ground. The resistance for each circuit should be greater than 10K ohms.
  10. If the value is less than 10K ohms, repair the short to ground in the affected circuit.
  11. Reconnect the TCM connector. Turn ON the ignition with the engine OFF. Test the PC solenoid high control circuit and the PC solenoid low control circuit for a short to voltage.
  12. If a short to voltage condition is found, repair as necessary.
    If all circuits/connections test normal, test or replace the PC solenoid valve.

Component Testing

Verify the PC solenoid valve resistance is between 3-7 ohms.

If the resistance is not within the specified range, replace the PC solenoid valve.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

    •  Pressure Control Solenoid Valve Replacement
    •  Wiring Harness Replacement
    •  Control Module References for TCM replacement, setup, and programming.