GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 22124-B Pressure Gage (0 - 300)

The air dryer is equipped with valving that maintains a residual pressure of 48 to 97 kPa (7 to 14 psi) in the struts to improve ride characteristics during light load conditions. Additionally, strut air sleeve life is improved when the ELC system maintains residual air pressure. The following steps must be followed to perform the "Residual Air Pressure Check" properly.

  1. Turn ON the ignition switch.
  2. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information. NOTE: The vehicle must be raised on a drive-on lift or be supported at the rear under the rear axle. Full vehicle weight must be on the rear suspension.
  3. Disconnect the air tube from the air dryer.
  4. Connect the J 22124-B adapter tube to the air dryer.
  5. Connect the J 22124-B gage to the J 22124-B adapter tube. Open the J 22124-B toggle valve.
  6. Disconnect the vehicle air tube from the pressure limiter valve.
  7. Connect the vehicle air tube to the J 22124-B gage.
  8. Disconnect the link from the height sensor and move the arm up. The air compressor should operate, inflating the struts.
  9. Move the arm down. The air compressor should stop and air should be escaping. Allow the rear of the vehicle to go down as far as possible.
  10. Connect the link to the height sensor.
  11. Read the pressure gage.
  12. If the pressure gage reads less than 48 kPa (7 psi), replace the air dryer. Refer to Automatic Level Control Air Dryer Replacement in Automatic Level Control.

  13. Disconnect the J 22124-B adapter tube and gage from the air dryer and vehicle air tube.
  14. Connect the air tube to the air dryer.
  15. Connect the air tube to the pressure limiter valve.
  16. Lower the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  17. Turn the ignition OFF.