GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 21867 Pressure Gage


Object Number: 155334  Size: SH

Line pressures are calibrated for two sets of gear ranges - DRIVE-PARK-NEUTRAL and REVERSE. This allows the transmission line pressure to be appropriate for different pressure needs in different gear ranges. The line pressure range for DRIVE, PARK and NEUTRAL should be 55-189 psi and the line pressure range for REVERSE should be 64-324 psi.

Before performing a line pressure check, verify that the pressure control solenoid for the transmission is receiving the correct electrical signal from the PCM:

  1. Install a Scan Tool .
  2. Caution: Keep the brakes applied at all times in order to prevent unexpected vehicle motion. Personal injury may result if the vehicle moves unexpectedly.

    Notice: The transmission may experience harsh, soft or mushy shifts for up to two days later.

  3. Start the engine and set the parking brake.
  4. Check for diagnostic trouble codes, including the diagnostic code for a stored pressure control solenoid.
  5. Repair the vehicle if necessary. Include the following areas:
  6. • Inspect the fluid level
    • Inspect the manual linkage at the transmission
    • Install or connect the Scan Tool .
    • Install or connect the J 21867 pressure gage at the line pressure tap.
  7. Put the gear selector in PARK and set the parking brake.
  8. Start the engine and allow the engine to warm up at idle.
  9. Access the PCS Control test on the Scan Tool .
  10. Increase DESIRED PCS in 0.1 amp increments. Read the corresponding line pressure on the pressure gage. Allow the pressure to stabilize for five seconds after each current charge.
  11. Compare your data to the DRIVE-PARK-NEUTRAL line pressure table. Refer to Line Pressure .

If your pressure readings differ greatly from the line pressure table, refer to the Diagnosis Tables.

The Scan Tool is only able to control the pressure control solenoid in PARK and NEUTRAL with the vehicle stopped. This protects the clutches from extremely high or low pressures in DRIVE or REVERSE ranges.

The pressures in the Line Pressure table assume an engine speed of 1500 RPM and a temperature of 66°C (150°F). The pressure will vary with a change in temperature. Refer to Line Pressure .