Suspension Control System - Suspension Leveling Buick Rendezvous I

Fastener Tightening Specifications

Fastener Tightening Specifications

Scheme 1

Scheme 2

Scheme 3

Automatic Level Control Suspension Connector End Views

Auto Level Control (ALC) Air Compressor Connector End Connector Part Information 1205-9472 7-Way F Metri-Pack Mixed Series Sealed (BK) Pin Wire Color Circuit No. Function A OG 840 Battery Positive Voltage B OG 840 Battery Positive Voltage C WH 320 Auto Level Control Exhaust Solenoid Control D YE 321 Automatic Level Control Relay Coil Supply Voltage E OG 1240 Battery Positive Voltage F OG 840 Battery Positive Voltage G BK 450 Ground H WH 837 Automatic Level Control Inflator Relay Coil Control

Automatic Level Control (ALC) Compressor Relay Connector End Connector Part Information 12110787 4-Way F Metri Pack 150 Series (GY) Pin Wire Color Circuit No. Function 30 OG 840 Battery Positive Voltage 85 BK 450 Ground 86 YE 321 Automatic Level Control Relay Coil Supply Voltage 87 OG 1240 Battery Positive Voltage

Automatic Level Control (ALC) Inflator Air Switch Connector End Connector Part Information 12089248 4-Way F Metri Pack 150 Series (NAT) Pin Wire Color Circuit No. Function A OG 840 Battery Positive Voltage B - - Not Used C L- BU 1770 Ride Control Serial Data D WH 1245 Automatic Level Control Inflation Timer Relay Coil Control

Automatic Level Control (ALC) Inflator Solenoid Connector End Connector Part Information 12052643 2-Way F Metri Pack 150 Series, Sealed (RED) Pin Wire Color Circuit No. Function A - 840 Battery Positive Voltage B - 837 Automatic Level Control (ALC) Inflator Relay Coil Control

Auto Level Control (ALC) Sensor Connector End Connector Part Information 15326836 8-Way F GT 150 Series Sealed (BK) Pin Wire Color Circuit No. Function A WH 320 Automatic Level Control Exhaust Solenoid Control B YE 321 Automatic Level Control Relay Coil Supply Voltage C BK/WH 151 Ground D YE 843 Accessory Voltage E L- BU 1770 Ride Control Serial Data F WH 837 Automatic Level Control Inflator Relay Coil Control G WH 1245 Automatic Level Control Inflation Timer Relay Coil Control H OG 840 Battery Positive Voltage

Diagnostic Starting Point - Automatic Level Control

Begin the system diagnosis with the Diagnostic System Check - Automatic Level Control (With Inflator) . The Diagnostic System Check will provide the following information

1. The identification of the control module(s) which command the system.
2. The identification of any stored diagnostic trouble codes (DTCs) and their status.

The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 1: The presence of DTCs
2. 4: The symptom list in Symptoms will determine the correct diagnostic procedure to use.

Diagnostic System Check - Automatic Level Control (With Inflator)

Diagnostic Trouble Code (DTC) Displaying

All the Automatic Level Control diagnostic trouble codes are displayed with a blink code on the accessory inflator switch LED. The diagnostic codes will flash after the completion of the self test. The self test is achieved by pressing the accessory inflator switch for 3 seconds. The self test will take 200 seconds to complete.

The number of flashing pulses on the inflator switch LED shall represent the number of the diagnostic code. The flashing pulses shall have a repetition rate of 0.5 seconds and each code digit shall be separated by a 1.0 second delay. Each code cycle shall be separated by a 3.0 second delay. All current failure codes shall be flashed in numerical order. All current failure codes shall be flashed until they are acknowledged by depressing the accessory inflator switch, or until the module enters asleep mode. The module will flash these codes with every successive self test request until the failure is removed. The blink code shall take priority over other processes that have access to the accessory inflator switch LED.

Diagnostic Trouble Code (DTC) Clearing

The Automatic Level Control diagnostic trouble codes will clear when the ignition switch has been transitioned from off to on and the conditions that caused the code to set have been removed.

Diagnostic Trouble Code (DTC) List

Diagnostic Trouble Code (DTC) List

Circuit Description

The height sensor monitors the Accessory Inflator solenoid circuity for a short to battery, ground or an open circuit.

Conditions for Running the DTC

Ignition On.

Conditions for Setting the DTC

1. Open in control circuit of the accessory inflator solenoid.
2. Short to ground in the control circuit of the accessory inflator solenoid.
3. Short to battery in the control circuit of the accessory inflator solenoid.
4. A malfunctioning accessory inflator solenoid.

Action Taken When the DTC Sets

1. The height sensor disables inflator functions.
2. Leveling functions shall continue.
3. The height sensor will recheck the accessory inflator solenoid circuitry periodically.

Conditions for Clearing the DTC

The conditions that caused the DTC to set have been removed.

Diagnostic Aids

A sort to ground or an open circuit on the battery positive circuit of the accessory inflator solenoid will set this DTC.

The number(s) below refer to the step number(s) on the diagnostic table.

1. 2: Tests for voltage at the coil side of the accessory inflator solenoid. The ELC relay fuse supplies power to the coil side of the accessory inflator solenoid.
2. 3: Verifies that the height sensor is providing ground to the accessory inflator solenoid.
3. 4: Tests if ground is constantly being applied to the accessory inflator solenoid.
4. 9: Verifies that the sensor is self tested after replacement.

DTC 011

The System OK code is used to identify that the self test has found no faults with the automatic level control system.

Ignition On.

No DTCs are set after self test has been completed.

Automatic level control system functions normally.

The conditions that caused the DTC to set have been removed.

DTC 012

The height sensor internal circuitry monitors the body to suspension height and detects when this is out of range

Ignition On.

When the height sensor internal circuitry detects a body to suspension height that is out of range.

Leveling functions are disabled.

The Inflator function continues to operate

The conditions that caused the DTC to set have been removed.

This DTC is set when ride height is physically being held out of range.

This DTC can set when the sensor link is damaged or detached.

The number(s) below refer to the step number(s) on the diagnostic table.

1. 2: Tests for mechanical damage to height sensor link.
2. 3: Height sensor replacement.

DTC 013

The height sensor monitors the compressor relay coil control circuity for a short to ground.

Ignition On.

This DTC is set when the height sensor detects the compressor relay coil control circuit is shorted to ground.

1. The height sensor disables the compressor.
2. Lowering functions shall continue.
3. The height sensor disables inflator functions.

The conditions that caused the DTC to set have been removed.

The ignition has transitioned from off to on.

A short to ground in the compressor relay coil circuit will set this DTC.

The number(s) below refer to the step number(s) on the diagnostic table.

1. 2: Tests for voltage at the coil side of the accessory inflator solenoid. The ELC relay fuse supplies power to the coil side of the accessory inflator solenoid.
2. 3: Verifies that the height sensor is providing ground to the accessory inflator solenoid.
3. 4: Tests if ground is constantly being applied to the accessory inflator solenoid.
4. 9: Verifies that the sensor is self tested after replacement.

DTC 021

The height sensor monitors the compressor relay coil control circuity for a open circuit or short to battery.

Ignition On.

This DTC is set when the height sensor detects the compressor relay coil control circuit is open or shorted to battery.

1. The height sensor disables the compressor.
2. Lowering functions shall continue.
3. The height sensor disables inflator functions.

The conditions that caused the DTC to set have been removed.

A short to battery or an open circuit in the compressor relay coil control circuit will set this DTC.

The number(s) below refer to the step number(s) on the diagnostic table.

1. 2: Tests for battery positive voltage at the relay coil. The ELC fuse supplies power to the relay coil of the compressor relay.
2. 3: Verifies that the height sensor is providing ground to the compressor relay.
3. 4: Tests if battery positive voltage is constantly being applied to the compressor relay control circuit or the circuit is open.
4. 9: Verifies that the sensor is self tested after replacement.

DTC 022

The height sensor monitors the compressor run time and is limited to 255 seconds for a leveling function.

Ignition On.

This DTC is set when the height sensor detects the compressor has been running for 255 seconds during a leveling function.

1. The height sensor disables the leveling functions.
2. The height sensor disables inflator functions.

The conditions that caused the DTC to set have been removed.

An AIR LEAK in the system will cause this DTC to set.

The number(s) below refer to the step number(s) on the diagnostic table.

1. 3: Tests for battery positive voltage at the compressor relay. The ELC fuse supplies power to the compressor relay.
2. 4: Verifies that the compressor relay contacts are working.
3. 5: Tests the ground circuit for the compressor motor.
4. 10: Verifies that the compressor relay is replaced.

DTC 023

The height sensor monitors the exhaust solenoid control circuity for a short to ground.

Ignition On.

This DTC is set when the height sensor detects the exhaust solenoid control circuit is shorted to ground.

The height sensor disables leveling functions.

The conditions that caused the DTC to set have been removed.

A short to ground in the exhaust solenoid control circuit will set this DTC.

The number(s) below refer to the step number(s) on the diagnostic table.

1. 2: Tests for voltage at the coil side of the exhaust solenoid. The ELC fuse supplies power to the coil side of the exhaust solenoid.
2. 3: Verifies that the height sensor is providing ground to the exhaust solenoid.
3. 4: Tests if ground is constantly being applied to the exhaust solenoid.
4. 9: Verifies that the sensor is self tested after replacement.

DTC 031

The height sensor monitors the exhaust solenoid control circuity for a short to battery positive voltage or an open circuit.

Ignition On.

This DTC is set when the height sensor detects the exhaust solenoid control circuit is shorted to battery positive voltage or an open circuit.

The height sensor disables leveling functions.

The conditions that caused the DTC to set have been removed.

Ignition switch has cycled from off to on.

A short to battery positive voltage or an open circuit in the exhaust solenoid control circuit will set this DTC.

The number(s) below refer to the step number(s) on the diagnostic table.

1. 2: Tests for voltage at the coil side of the exhaust solenoid. The ELC fuse supplies power to the coil side of the exhaust solenoid.
2. 3: Verifies that the height sensor is providing ground to the exhaust solenoid.
3. 4: Tests if ground is constantly being applied to the exhaust solenoid.
4. 10: Verifies that the sensor is self tested after replacement.

DTC 032

The height sensor monitors the exhaust valve on time when the vehicle is lowering and is limited to 255 seconds.

Ignition On.

This DTC is set when the height sensor detects the exhaust valve has been on for 255 seconds and the height sensor did not detect the calibrated downward movement.

The height sensor disables the leveling functions.

The conditions that caused the DTC to set have been removed.

The ignition switch has been cycled from off to on.

A air line or exhaust valve blockage in the system will cause this DTC to set.

The number(s) below refer to the step number(s) on the diagnostic table.

1. 2: Tests for something mechanical that is not allowing the vehicle to lower.
2. 3: Verifies the height connector to have a good connection.

DTC 033

Symptoms - Automatic Level Control

Review the system operation in order to familiarize yourself with the system functions. Refer to Automatic Level Control Description and Operation .

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the ALC system. Refer to «Checking Aftermarket Accessories»(/buick/rendezvous/i-2001-2007/remont/body-electrical/#wiring-systems-diagnostic-information-and-procedures__checking-aftermarket-accessories) in Wiring Systems.
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

Automatic Level Control Inflator Fill Valve Inoperative

Automatic Level Control Inflator Fill Valve Inoperative

Automatic Level Control Inflator Fill Valve Inoperative

Removal Procedure

1. Raise and support vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/rendezvous/i-2001-2007/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Remove the electrical connector (1) from the relay (2).
3. Remove the relay bolt (1) from the bracket.
4. Remove the relay (1) from the compressor assembly.

Installation Procedure

1. Install the relay (1) to the compressor assembly.
2. Install the relay nut (1) to the bracket. Tighten: Tighten nut to 6 N.m (53 lb in)
3. Install the electrical connector (1) to the relay (2).
4. Lower the vehicle.

1. Remove the accessory fill valve access cover.
2. Remove the lower rear quarter trim panel. Refer to «Trim Panel Replacement - Rear Quarter Lower (Aztek)»(/buick/rendezvous/i-2001-2007/remont/exteriorinterior-trim/#interior-trim) or «Trim Panel Replacement - Rear Quarter Lower (Rendezvous)»(/buick/rendezvous/i-2001-2007/remont/exteriorinterior-trim/#interior-trim) in Interior Trim.
3. Disconnect the air hose (1) from the accessory fill valve (5).
4. Remove the cap (2), nut (3), and washer (4) from the accessory fill valve (5)
5. Remove the accessory fill valve from the trim panel.

1. Install the accessory fill valve into the trim panel.
2. Install the washer (4) and the nut (3) to the accessory fill valve. Tighten: Tighten the accessory fill valve nut to 6 N.m (53 lb in).
3. Install the cap to the accessory fill valve.
4. Install the hose (1) onto the accessory fill valve (5).
5. Install the lower rear quarter trim panel. Refer to «Trim Panel Replacement - Rear Quarter Lower (Aztek)»(/buick/rendezvous/i-2001-2007/remont/exteriorinterior-trim/#interior-trim) or «Trim Panel Replacement - Rear Quarter Lower (Rendezvous)»(/buick/rendezvous/i-2001-2007/remont/exteriorinterior-trim/#interior-trim) in Interior Trim.
6. Install the accessory fill valve access cover.

1. Remove the inflator fill valve access cover.
2. Remove the lower rear quarter trim panel. Refer to «Trim Panel Replacement - Rear Quarter Lower (Aztek)»(/buick/rendezvous/i-2001-2007/remont/exteriorinterior-trim/#interior-trim) or «Trim Panel Replacement - Rear Quarter Lower (Rendezvous)»(/buick/rendezvous/i-2001-2007/remont/exteriorinterior-trim/#interior-trim) in Interior Trim.
3. Remove the switch from the inflator control panel.
4. Disconnect the electrical connector (1) from the accessory inflator switch (2).

1. Connect the electrical connector (1) to the accessory inflator switch (2).
2. Install the inflator switch in the inflator control panel.
3. Install the lower rear quarter trim panel. Refer to «Trim Panel Replacement - Rear Quarter Lower (Aztek)»(/buick/rendezvous/i-2001-2007/remont/exteriorinterior-trim/#interior-trim) or «Trim Panel Replacement - Rear Quarter Lower (Rendezvous)»(/buick/rendezvous/i-2001-2007/remont/exteriorinterior-trim/#interior-trim) in Interior Trim.
4. Install the inflator fill valve access cover.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/rendezvous/i-2001-2007/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Remove the hose (1) from the air dryer (2).
3. Remove the mounting screw (1).
4. Rotate the air dryer (1) to remove from compressor.

1. Install the air dryer (1) to the compressor.
2. Install the air dryer mounting screw (1). Tighten: Tighten the screw to 6 N.m (53 lb in).
3. Install the hose (1) onto the air dryer (2).
4. Lower the vehicle.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/rendezvous/i-2001-2007/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Squeeze the clips on side of the filter.
3. Pull the filter out of the hole in the rail.
4. Remove the automatic level control air compressor filter from the hose.

1. Install the automatic level control air compressor filter to the hose.
2. Install the automatic level control air compressor filter to the underbody rail.
3. Lower the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/rendezvous/i-2001-2007/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.

Note. When you are servicing the automatic level control sensor link, ensure that the sensor link and the sensor arm are not damaged. Ensure the sensor arm and the sensor link are properly oriented. Improper orientation of the sensor arm and the sensor link may cause damage to the automatic level control system or the vehicle.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/rendezvous/i-2001-2007/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Remove the ALC sensor link from the lower control arm ball stud.
3. Remove the ALC sensor link from the sensor arm ball stud.

1. Install the ALC sensor link to the lower control arm ball stud.
2. Install the ALC sensor link to the sensor arm ball stud.
3. Lower the vehicle.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/rendezvous/i-2001-2007/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Remove the automatic level control sensor electrical connector (1).
3. Remove the automatic level control sensor link from the lower control arm ball stud.
4. Remove the automatic level control height sensor bracket bolts (1).
5. Remove the automatic level control height sensor with the bracket from the vehicle.
6. Remove the automatic level control height sensor link from the height sensor arm.

1. Install the automatic level control height sensor link onto the height sensor arm.
2. Install the automatic level control height sensor with the bracket onto the vehicle. NOTE: Refer to «Fastener Notice»(/buick/rendezvous/i-2001-2007/remont/oem-general-information/#cautions-and-notices__fastener-notice) in Cautions and Notices.
3. Install the automatic level control height sensor bracket bolts (1). Tighten: Tighten the height sensor bracket bolts to 85 N.m (63 lb ft).
4. Install the automatic level control sensor link to the lower control arm ball stud.
5. Install the automatic level control sensor electrical connector (1).
6. Lower the vehicle.
7. Perform a diagnostic system check. Refer to «Diagnostic System Check - Automatic Level Control (With Inflator)»(/buick/rendezvous/i-2001-2007/remont/electronic-suspension/#suspension-control-system-suspension-leveling) .

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/rendezvous/i-2001-2007/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Remove the automatic level control sensor link from the lower control arm ball stud.
3. Remove the ball stud from the rear lower control arm.

1. Install the ball stud to the rear lower control arm. Tighten: Tighten the height sensor ball stud to 4 N.m (35 lb in).
2. Install the automatic level control sensor link to the lower control arm ball stud.
3. Lower the vehicle.

Scheme 4

At the rear shock absorbers, the air tube connectors are held on with spring clips which snap into the grooves of the shock absorber air fittings. Air tube connectors are sealed using two O-rings.

To disconnect an air tube from a shock absorber, rotate the spring clip 90 degrees out of the slots, and pull the connector from the shock absorber.

To connect an air tube to a shock absorber, lubricate the two O-rings using silicone lubricant, rotate the spring clip 90 degrees into the slots, and push the air tube connector on the shock absorber fitting until spring clip snaps into fitting groove.

Scheme 5

1. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/rendezvous/i-2001-2007/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Disconnect the air tube from the left rear shock absorber.
3. Disconnect the left rear air tube from the tee connector and remove from the vehicle.
4. Disconnect the air tube from the right rear shock absorber.
5. Disconnect the right rear air tube from the tee connector.
6. Remove the air tube from the routing clips and from the vehicle.

1. Install the right rear air tube on the vehicle in the routing clips.
2. Connect the right rear air tube to the tee connector.
3. Connect the right rear air tube to the right rear shock absorber.
4. Connect the left rear air tube to the tee connector.
5. Connect the left rear air tube to the right rear shock absorber.
6. Lower the vehicle.

Air Line Tubing Repair

1. Locate the leaking area with soap and water or a stethoscope.
2. Cut and remove the leaking line (2) section.
3. Remove the plastic retainer pin from one of the nuts.
4. Slide the air line tube onto the nut until the line bottoms in the rubber seal (5).
5. Hold the air line tube in position. Tighten: Tighten the air line tube repair nut to 8 N.m (70 lb in).
6. Install the air line tube to the other end of the coupling.
7. Repeat Steps 3 through 5.
8. Install the air line tube to the vehicle.
9. Inflate the automatic level control system and inspect for leaks.
10. Lower the vehicle.

1. Remove the ELC/TRAILER fuse.
2. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/rendezvous/i-2001-2007/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
3. Remove the air line (1) from the left rear shock absorber.
4. Remove the air line (1) from the right rear shock absorber.
5. Remove the air line from the retaining clips.
6. Remove the clips from the vehicle, if necessary.

1. Install the clips to the vehicle.
2. Install the air line (1) to the right shock absorber.
3. Install the air line (1) to the left shock absorber.
4. Lower the vehicle.
5. Remove the ELC/TRAILER fuse.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/rendezvous/i-2001-2007/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) .
2. Lower the automatic level control (ALC). air compressor assembly. Refer to «Air Compressor Replacement»(/buick/rendezvous/i-2001-2007/remont/electronic-suspension/#suspension-control-system-suspension-leveling) .
3. Remove the ALC shield bolt (1) and retainers.
4. Remove the ALC shield (2) from the vehicle.

1. Install the ALC shield (2) onto the vehicle.
2. Install the ALC shield bolt (1) and retainers to the vehicle. Tighten: Tighten the bolts to 6 N.m (53 in lb).
3. Install the ALC compressor assembly onto the vehicle. Refer to «Air Compressor Replacement»(/buick/rendezvous/i-2001-2007/remont/electronic-suspension/#suspension-control-system-suspension-leveling) .
4. Lower the vehicle.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/rendezvous/i-2001-2007/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Remove the air compressor filter from the underbody rail. Refer to «Automatic Level Control Air Compressor Air Filter Replacement»(/buick/rendezvous/i-2001-2007/remont/electronic-suspension/#suspension-control-system-suspension-leveling) .
3. Remove the air tubes (1) from the inflator solenoid. Refer to «Inflator Solenoid Replacement»(/buick/rendezvous/i-2001-2007/remont/electronic-suspension/#suspension-control-system-suspension-leveling) .
4. Remove the compressor bracket bolts.
5. Remove the compressor bracket nuts.
6. Disconnect the air compressor electrical connector.
7. Remove the air compressor assembly from the vehicle.
8. Remove the compressor wires from the connector.
9. Remove the air dryer. Refer to «Automatic Level Control Air Dryer Replacement»(/buick/rendezvous/i-2001-2007/remont/electronic-suspension/#suspension-control-system-suspension-leveling) .
10. Remove the air compressor bolts (1).
11. Remove the air compressor from the air compressor assembly bracket.
12. Remove the bolts (1) and bracket from the compressor motor.

1. Install the bolts (1) and bracket to the compressor. Tighten: Tighten the air compressor bolts to 6 N.m (53 lb in).
2. Install the air compressor to the air compressor bracket.
3. Install the air compressor bolts (1). Tighten: Tighten the air compressor bolts to 6 N.m (53 lb in).
4. Install the air dryer. Refer to «Automatic Level Control Air Dryer Replacement»(/buick/rendezvous/i-2001-2007/remont/electronic-suspension/#suspension-control-system-suspension-leveling) .
5. Install the air tubes (1) onto the inflator solenoid. Refer to «Inflator Solenoid Replacement»(/buick/rendezvous/i-2001-2007/remont/electronic-suspension/#suspension-control-system-suspension-leveling) .
6. Install the compressor wires into the electrical connector.
7. Install the air compressor filter to the underbody rail.
8. Install the air compressor bracket nuts. Tighten: Tighten the air compressor bracket nuts to 10 N.m (89 lb in).
9. Install the air compressor bracket bolts. Tighten: Tighten the air compressor bracket bolts to 10 N.m (89 lb in).
10. Connect the air compressor electrical connector.
11. Install the air compressor and bracket to the underbody rail.
12. Lower the vehicle.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/rendezvous/i-2001-2007/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Remove the hoses (1) from the inflator solenoid.
3. Remove the electrical connector (2) from the inflator solenoid.
4. Remove the screws (3) from the inflator solenoid to the air compressor assembly bracket.
5. Remove the inflator solenoid from the air compressor bracket.

1. Install the inflator solenoid to the air compressor assembly bracket.
2. Install the screws (3) into the inflator solenoid and the air compressor bracket. Tighten: Tighten the screws to 6 N.m (53 lb in).
3. Install the electrical connector (2) onto the inflator solenoid.
4. Install the hoses (1) onto the inflator solenoid.
5. Lower the vehicle.

Automatic Level Control (ALC) System

The ALC system controls the ride height of the rear of the vehicle. The system consists of the following components

1. Two air assisted shock absorbers.
2. A level sensor with an integrated control module.
3. A compressor with an integral exhaust solenoid valve.
4. A compressor relay.
5. A inflator solenoid valve.
6. A accessory inflator switch with an LED for diagnostics.

The level sensor senses the height of the rear of the vehicle. The exhaust valve energizes if the vehicle is higher than desired. The compressor relay energizes in order to activate the compressor assembly if the vehicle is lower than desired.

Voltage is applied at all times to the rear suspension leveling air compressor and the ALC sensor. This allows the ALC system to vent after the load is removed from the vehicle, even if the ignition is in the OFF position. Approximately 30 seconds after the ignition is turned to the ON position, the compressor will run for 4 seconds to ensure that the shock absorbers will be filled with adequate residual pressure.

The ALC sensor must detect an out of trim state for 20 seconds before activating the intake or exhaust output. This action prevents operation during normal riding motions. In addition, the sensor limits the compressor run time or the exhaust solenoid valve energized time to a maximum of 255 seconds. This time limit is necessary to prevent continuous compressor operation in case of a severe system leak or continuous vent. Cycling the ignition resets the 255 second run timer.

Rear Suspension Leveling Air Compressor

The compressor is a positive displacement rocking piston air pump powered by a 12-volt direct current permanent magnet motor. The compressor head casting contains the piston intake valves and contains the piston exhaust valves. The compressor is mounted to the underbody by a bracket.

ALC Sensor

The ALC sensor is an electronic device. The following is controlled by the ALC sensor

1. The Automatic Level Control Compressor
2. The Exhaust Solenoid Valve
3. The Inflator Solenoid Valve

The sensor circuitry provides a 20 second delay before either circuit can be completed to prevent falsely actuating the compressor or to prevent falsely actuating the solenoid valve circuits during normal ride motions.

The sensor also limits the compressor run time or the solenoid valve energized time to a maximum of 255 seconds. This time limit function is necessary to prevent continuous compressor operation in the case of a severe system leak or in the case of a continuous exhaust valve operation. Turning the ignition off and on resets the electronic timer to renew the 255 second maximum run time. The sensor is located in the rear of the vehicle mounted to the underbody. The actuator arm of the sensor attaches to the rear suspension by a link.

The ALC system is capable of performing diagnostics on all components of the system. This self diagnostic feature will aid in the repair of the system. The diagnostic codes will be used to provide more detailed information regarding the system fault found during self test. The self test will be entered by pressing the accessory inflator switch continuously for 3 seconds. The self test will begin by raising the rear of the vehicle. Then hold the rear of the vehicle up for a calibrated amount of time to check for leaks, then lower the rear of the vehicle to trim height. The self test will take roughly 200 seconds to complete. The flashing pulses on the accessory inflator switch LED shall represent the number of the diagnostic code.

When the sensor has been replaced a" System Untested" code will be represented by a continuous flashing pulse with a repetition rate of 0.25 seconds. The self test will have to be performed and a code 12 system OK will have to be displayed on the accessory inflator switch LED before the system can function normally.

Rear Leveling Shock Absorbers

The shock absorber is essentially a conventional shock absorber enclosed in an air chamber. The shock absorbers are constructed with a rubber-like sleeve attached to the dust tube and attached to the shock reservoir. This makes a flexible chamber which extends the shock when the air pressure in the chamber is increased. The weight of the vehicle collapses the shock absorber when the air pressure is reduced. To maintain proper operation and to maintain reliability of the shock absorber a minimum residual air pressure of 55 kPa (8 psi) is maintained at all times by the air dryer.

Tubing and Fittings

The snap-on connectors attach the tubing to the rear shock absorbers. The connector housings contain retainer clips. When a tubing is attached to a shock fitting, the retainer clip snaps into a groove in the shock fitting, locking the tubing in position. All tubing fittings are sealed with 2 O-rings.

Air Compressor Filter

The air enters the ALC system through the filter mounted to the air compressor bracket. The filter housing contains a foam filter which prevents contaminants from entering the ALC system.

Raising Vehicle

The vehicle body is forced downward when a load is added to the vehicle. This load causes the sensor actuating arm to rotate upward. The upward movement of the sensor actuating arm activates the internal timing circuit. The sensor completes the compressor circuit to ground after an initial delay of 20 seconds. With the compressor circuit complete, the compressor runs, taking in air through the air compressor filter and sending the air though the tubing to the shock absorbers. As the shock absorbers inflate, the rear of the vehicle moves upward, rotating the sensor actuating arm back toward its original position prior to the load addition. The sensor opens the compressor circuit and shuts off the compressor once the body reaches its original height +/- 4 mm (+/- 0.16 in).

Lowering Vehicle

The body is forced upward when an excess load is removed from the rear of the vehicle. This causes the sensor actuating arm to rotate downward. The downward rotation of the actuating arm activates the internal timing circuit. The sensor completes the solenoid valve circuit to ground after an initial delay of 20 seconds. With the solenoid valve energized, the air begins to exhaust out of the shock absorbers back through the air dryer, the solenoid valve, the air compressor filter and into the atmosphere. The sensor actuating arm rotates upward toward its original position as the rear of the vehicle lowers. When the vehicle body reaches its original height +/- 4 mm (+/- 0.16 in), the sensor opens the solenoid circuit, de-energizing the solenoid valve, which prevents any further air from escaping.

Air Replenishment Cycle

The air replenishment cycle serves to ensure that the shock absorbers are filled with at least minimum residual pressure. The sensor commands an air replenishment cycle each time the ignition switch is turned on. Sensor position is checked when the ignition switch is turned on. If the sensor indicates that it is not necessary to raise or lower the vehicle, an internal timer circuit is activated. After a 30 second delay, the compressor is turned on for approximately 4 seconds. This ensures that the shock absorbers are filled with adequate residual pressure.

If the weight is added to, or removed from, the vehicle during the initial 30 second delay, the air replenishment cycle will be overridden and the vehicle will raise or lower after the normal delay.

Compressor Head Relief

A 1.5 second actuation of the exhaust solenoid valve occurs each time the compressor is to start to ensure the low compressor motor starting current. The 1.5 second actuation of the exhaust solenoid valve reduces the air pressure in the compressor head cavity.

Inflator Solenoid

The inflator solenoid has battery voltage to it at all times and is controlled buy the height sensor with providing a ground to the solenoid. The solenoid valve is mounted to the compressor bracket under the vehicle.

Inflator Switch

The inflator switch is in the rear cargo area on the drivers side on the vehicle. When the switch is depressed, the compressor is activated along with the inflator solenoid and air pressure is directed to the schrader valve that is located next to the Inflator switch. The LED on the switch is also on during the inflator function. Depress the switch again and the compressor and the LED are deactivated. The switch and LED are also used for diagnostics. Depress and hold the switch for 3 seconds and the system enters self test. After roughly 200 seconds the LED will blink out the diagnostic codes.

See also:
• Circuit Testing
• Wiring Repairs
• Testing for Intermittent Conditions and Poor Connections
• Testing for Continuity
• Checking Aftermarket Accessories
• Lifting and Jacking the Vehicle
• Fastener Notice
• Trim Panel Replacement - Rear Quarter Lower (Aztek)
• Diagnostic System Check - Automatic Level Control (With Inflator)
• Diagnostic Trouble Code (DTC) List
• Symptoms - Automatic Level Control
• Automatic Level Control Inflator Fill Valve Inoperative