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

Tools Required

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

    Important: Perform this test only 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 line pressure tap bolt from the transmission case.
  3. Install J 35752 into the line pressure tap.
  4. Install a 90 degree male elbow inverted flare brass fitting with a 3/16 inch tube OD and a 1/8 inch male pipe thread into J 35752 .
  5. Install J 21867 into the brass fitting.
  6. Lower the vehicle.
  7. Route the J 21867 hose over the front fender and through the driver's window so that you can read the hose from the passenger compartment.
  8. Apply the parking brake and block the vehicle wheels.
  9. Press the brake pedal fully and start the engine.
  10. 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.

  11. Place the manual selector to Reverse (R) and record the line pressure at idle speed (750-850 RPM).
  12. 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.

  13. With the manual selector still in Reverse (R), press the accelerator pedal fully (wide open throttle) and record the line pressure.
  14. Release the accelerator pedal and let the engine return to idle speed.
  15. Move the manual selector to Drive (D) and record the line pressure at idle speed (750-850 RPM).
  16. With the manual selector still in Drive (D), press the accelerator pedal fully (wide open throttle) and record the line pressure.
  17. Place the selector lever in the Park (P) position and turn the ignition switch to LOCK.
  18. Remove J 21867 from the passenger compartment.
  19. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  20. Remove J 21867 from the brass fitting.
  21. Remove the brass fitting from J 35752 .
  22. Remove J 35752 from the line pressure tap.
  23. 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.

  24. Install the line pressure tap bolt into the line pressure tap at the rear of the transaxle.
  25. Tighten
    Tighten the line pressure tap bolt to 17 N·m (12 lb ft).

  26. 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.

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D Range Line Pressure

R Range Line Pressure

Line Pressure Results 1.6L Engine

  • Idle Speed

382-598 kPa (55-63 psi)

362-402 kPa (73-81 psi

  • Stall Speed

1294-1539 kPa (166-188 psi)

931-1079 kPa (202-237 psi)

Line Pressure Results 2.0L Engine

  • Idle Speed

372-422 kPa (54-61 psi)

520-578 kPa (75-84 psi

  • Stall Speed

951-1098 kPa (138-159 psi)

1265-1520 kPa (183-220 psi)

Line Pressure Results 2.5L Engine

  • Idle Speed

382-431 kPa (55-63 psi)

647-706 kPa (94-102 psi

  • Stall Speed

1108-1245 kPa (161-181 psi)

1442-2226 kPa (209-323 psi)

Line Pressure Test Diagnosis

Results

Possible Cause

Correction

Line Pressure Higher than Specifications in Each Range

  1. Malfunctioning regulator valve
  2. Malfunctioning throttle valve
  3. Throttle cable out of adjustment
  1. Inspect the valve body.
  2. Inspect the valve body.
  3. Adjust the throttle cable.

Line Pressure Lower than Specifications Level in Each Range

  1. Defective overdrive clutch
  2. Defective oil pump
  3. Malfunctioning throttle valve
  4. Malfunctioning regulator valve
  5. Throttle cable out of adjustment
  1. Inspect the overdrive clutch.
  2. Inspect the oil pump.
  3. Inspect the valve body.
  4. Inspect the valve body.
  5. Adjust the throttle cable.

Line Pressure Lower than Specifications Level in Drive (D) Range Only

  1. Fluid leakage from forward clutch
  2. Defective overdrive clutch
  3. Leakage within Drive (D) range fluid pressure circuit
  1. Inspect the forward clutch.
  2. Inspect the overdrive clutch.
  3. Inspect the transmission case.

Line Pressure Lower than Specifications Level in Reverse (R) Range Only

  1. Fluid leakage from direct clutch
  2. Defective overdrive clutch
  3. Fluid leakage from reverse brake
  4. Fluid leakage within Reverse (R) range fluid circuit
  1. Inspect the transmission case.
  2. Inspect the overdrive clutch.
  3. Inspect the transmission case.
  4. Inspect the transmission case.