System Overview

WARNING: BEFORE SERVICING ANY AIR SUSPENSION COMPONENTS, TURN AIR SUSPENSION SWITCH OFF OR BY DISCONNECTING BATTERY GROUND CABLE TO PREVENT VEHICLE DAMAGE OR PERSONAL INJURY.

DESCRIPTION
The optional dual action rear air suspension:
^ is an air-operated, microprocessor-controlled, suspension system.
^ replaces the conventional rear coil spring suspension.
^ provides low spring rates for improved ride and automatic rear load leveling.

FEATURES
The optional rear air suspension system has the following features:
^ The system is operational with the ignition switch in the RUN position.
^ Automatic rear load leveling has limited operation for one hour after ignition switch is turned to OFF.
^ The air suspension switch, located on the RH side of the luggage compartment, must be turned OFF when the vehicle is on a hoist, being towed or jump started.
^ The CHECK AIR SUSPENSION warning indicator is located in the instrument cluster, to the left of the speedometer.
^ The warning indicator flashes five times and then stays on with ignition switch in the RUN position and the air suspension service switch turned off or when a system malfunction is detected.
^ The rear leveling system operates by adding or releasing air in the rear springs to maintain the level of the vehicle at a predetermined rear suspension ride height dimension, and is controlled by a control module. (Refer to Adjustments.)
^ The rear air suspension control module also controls the electronic variable orifice (EVO) power steering.
^ Air required for leveling the vehicle is distributed from the air compressor to the rear air springs by a nylon air line which runs from the compressor air drier through a Y-fitting to each individual rear spring.

SYSTEM INPUTS
Ignition Switch Input
System responds to ignition switch input as follows:
^ The control module stays powered for one hour after the ignition switch is turned to the OFF position in order to perform leveling corrections after occupants and luggage are removed from the vehicle.
^ When the ignition switch is turned to RUN, Circuit 293 (P/O) is supplied B+.
^ If there is an open in Circuit 1053 (LB/PK) or in its feed circuits, the control module will be inoperative and diagnostics cannot be entered.

Door Courtesy Lamp Switch Input
System responds to lamp switch as follows:
^ The control module uses the door courtesy lamp switch input for two different functions:
^ preventing vents when a door is open to avoid the possibility of the vehicle lowering and the door catching on an obstruction.
^ servicing a correction immediately, if needed.
^ The control module cannot sense which doors are open, only that one or more doors are open, or all doors are closed.
^ If a damaged door lamp switch (always open) or a short to battery in Circuit 344 (BK/Y) exists, the control module will interpret that a door is open and not vent unless vehicle speed is above 24 km/h (15 mph).
^ Above 24 km/h (15 mph) the control module disregards all door signals.