GM Service Manual Online
For 1990-2009 cars only
Table 1: Line Pressure Results
Table 2: Line Pressure Test Diagnosis

Tools Required

    • J 35752 Oil Pressure Gage Adapter
    • J 21867 Pressure Gauge

    Important: This test should only be performed at a normal operating fluid temperature of 70-80°C (158-176°F).

  1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Remove the left splash shield.

  3. Object Number: 209433  Size: SH
  4. Remove the pressure tap bolt from the front of the transaxle.

  5. Object Number: 209438  Size: SH
  6. Install J 35752 into the line pressure tap at the rear of the transaxle.
  7. Install J 21867 into J 35752 .
  8. Lower the vehicle.
  9. Route the J 21867 hose over the front fender and through the driver's window so that it can be read from the passenger compartment.
  10. Connect the scan tool to the Data Link Connector (DLC) and display the engine RPM.
  11. Apply the parking brake and block the vehicle wheels.
  12. Press the brake pedal fully and start the engine.
  13. Caution: For the following four steps, procedures for testing line pressure at idle and stall speeds, the brake pedal must be fully pressed throughout the measurement procedure. Failure to do so could result in personal injury and/or property damage.

  14. Place the manual selector in the drive (D) range and record the line pressure at idle speed (800-900 RPM).
  15. Notice: DO NOT run engine at stall speed for more than five seconds continuously or engine oil and transaxle fluid temperatures may become excessively high.

  16. Press the accelerator pedal fully (wide open throttle) and record the line pressure in the drive (D) range at stall speed (2,000-2,500 RPM). Release the accelerator pedal.
  17. Keeping the brake pedal fully pressed, place the selector lever in the reverse (R) range and record the line pressure at idle speed (800-900 RPM).
  18. Press the accelerator pedal fully (wide open throttle) and record the line pressure in the reverse (R) range at stall speed (2,000-2,500 RPM). Release the accelerator pedal.
  19. Place the selector lever in the park (P) range and turn the ignition switch to LOCK.
  20. Remove the scan tool from the vehicle.
  21. Remove J 21867 from the passenger compartment.
  22. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  23. Remove J 21867 from J 35752 .
  24. Remove J 35752 from the line pressure tap at the rear of the transaxle.
  25. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  26. Install the line pressure tap bolt into the line pressure tap at the rear of the transaxle.
  27. Tighten
    Tighten the line pressure tap bolt to 9 N·m (80 lb in).

  28. Install the left splash shield.
  29. Lower the vehicle.

Evaluation

Compare the line pressure test results with the Line Pressure Results in the following table. If the line pressure is not as specified, refer to the Line Pressure Test Diagnosis for further evaluation.

Line Pressure Results

Engine Running at

R Range Line Pressure

D Range Line Pressure

Idle Speed

5.5-8.0 kPa (78.2-113.7 psi)

2.0-4.0 kPa (28.5-56.8 psi

Torque Converter Stall Speed

10.5-14 kPa (149.4-199.1 psi)

5.0-7.0 kPa (71.1-99.5 psi)

Line Pressure Test Diagnosis

Line Pressure Measurement

Probable Cause

Higher than specification in Drive (D) and Reverse (R) ranges

    • Fluid pump malfunction
    • Pressure regulator valve malfunction
    • Throttle valve malfunction
    • Out of adjustment accelerator and/or throttle valve cable

Lower than specification in Drive (D) and Reverse (R) ranges

    • Fluid pump malfunction
    • Pressure regulator valve malfunction
    • Throttle valve malfunction
    • Out of adjustment accelerator and/or throttle valve cable

Lower than specification in Drive (D) range only

    • Forward clutch fluid circuit leak
    • Drive (D) range fluid circuit leak

Lower than specification in Reverse (R) range only

    • Direct clutch fluid circuit leak
    • 1st-reverse brake fluid circuit leak
    • Reverse (R) range fluid circuit leak