GM Caprice 1990-1993 Repair Guide

Automatic Level Control (ALC) System

Print

See Figures 1, 2 and 3



Click image to see an enlarged view

Fig. Fig. 1: Automatic Level Control (ALC) components



Click image to see an enlarged view

Fig. Fig. 2: ALC height sensor assembly location



Click image to see an enlarged view

Fig. Fig. 3: ALC height sensor assembly adjustment

The ALC, formerly referred to as the Electronic Level Control (ELI) system, was used on 1988 and later vehicles and, keeps the rear of the vehicle level by automatically adjusting the rear trim height with varying vehicle loads. The system is activated when the ignition is on and excess weight is added to the vehicle. When the excess weight is removed from the vehicle, an exhaust solenoid connected to the battery positive, allows air to be released from the system even with the ignition off. This system is used in place of the standard rear shock absorbers.

Air Lines and Fittings

The air lines include spring clip connections with molded sealing shoulders in the retainer and on the end of the air line with double O-ring seals. Before making any air line disconnection, clean the connector and surrounding area. Turn the spring clip to release the connector. To reassemble, lubricate the O-rings with petroleum jelly and push the air line fully into the fitting.

Height Sensor Assembly
REMOVAL & INSTALLATION
  1. Disconnect the battery ground cable.
  2.  
  3. Raise and safely support vehicle on jack stands.
  4.  
  5. Disconnect the electrical connector.
  6.  
  7. Remove the nut attaching link to upper control arm.
  8.  
  9. Remove the two bolts attaching height sensor assembly to rear crossmember.
  10.  
  11. Remove the height sensor from the vehicle.
  12.  
  13. Installation is the reverse of removal procedure.
  14.  

ADJUSTMENT

The attaching link should be securely connected to the height sensor arm when any adjustments are made. For every 1 degree change in arm angle the trim height will change approximately1/4inch. The arm angle may be changed a total of 5 degrees, resulting in a trim height change of approximately 11/4inches.

  1. Loosen the locknut securing the metal arm to the plastic arm.
  2.  
  3. To decrease the amount of suspension travel required to turn on compressor (To raise vehicle height), move the plastic arm to the top of the slot and tighten locknut.
  4.  
  5. To increase the amount of suspension travel required to turn on compressor (To lower vehicle height), move the plastic arm to the bottom of the slot and tighten locknut.
  6.  

Compressor Assembly and Bracket
REMOVAL & INSTALLATION
  1. Disconnect the battery ground cable.
  2.  
  3. Raise and safely support vehicle on jack stands.
  4.  
  5. Disconnect the air hoses and tubing assembly at the compressor assembly.
  6.  
  7. Remove the bolts retaining the mounting bracket with compressor assembly to rear crossmembers.
  8.  
  9. Remove the bolt attaching the ABS wheel speed sensor wire clip from the compressor mounting bracket, and remove the ABS wire clip from the mounting bracket.
  10.  
  11. Disconnect the compressor electrical connector.
  12.  
  13. Remove the mounting bracket with compressor assembly from the rear crossmember.
  14.  
  15. Remove the screws attaching the compressor assembly to mounting bracket, and remove the compressor assembly.
  16.  
  17. Installation is the reverse of removal procedure.
  18.  

 
label.common.footer.alt.autozoneLogo