GM Service Manual Online
For 1990-2009 cars only

Use the following procedure in order to manually adjust the automatic level control sensor in-trim zone:


    Object Number: 187241  Size: SH
  1. Load 250-300 lbs into the rear of the passenger compartment (enough load to activate the automatic level control air compressor), distributed evenly from left to right.
  2. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information. Ensure that the vehicle is roughly level and supported by the rear wheels or axle.
  3. Notice: When diagnosis or repair requires raising the vehicle on a hoist, it is important that the rear axle remains in the normal trim height position at all times. Therefore, the hoists should support the rear wheels or axle housing. Use two additional jack stands to support the rear axle when a frame contact hoist is used or damage to the auto level control air compressor could occur.

  4. Inspect the automatic level control sensor (5) for damage. Ensure that the automatic level control sensor link is properly connected to the rear differential bracket and automatic level control sensor arm (1).
  5. Turn the ignition switch to RUN and then to OFF. Wait for approximately 1 minute for the Air Replenishment Cycle to complete.
  6. Measure the D dimension at the rear axle (2) on both the right and the left hand side. Refer to Trim Height Inspection in Suspension General Diagnosis.
  7. The average D dimension should be 130.8-148.11 mm (5.1-5.8 in) (3). If the average D dimension is within this range, do not adjust the automatic level control sensor (5). If the D dimension is not within this range, adjust the automatic level control sensor (5) as follows:
  8. 6.1. Loosen the automatic level control sensor arm adjustment bolt (4).
    6.2. In order to raise the vehicle, move the plastic portion of the automatic level control sensor arm (1) upwards. In order to lower the vehicle, move the plastic portion of the automatic level control sensor arm (1) downwards. Rotating the plastic portion of the automatic level control sensor arm (1) one degree will change the D dimension by 4 mm (0.16 in).

    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.

    6.3. Tighten the automatic level control sensor arm adjustment bolt (4).

    Tighten
    Tighten the automatic level control sensor arm adjustment bolt (4) to 5 N·m (44 lb in).

    6.4. In order to verify that the automatic level control sensor (5) is adjusted properly, repeat steps 4 through 6.