Automatic Level Control Description and Operation: Notes

The Automatic Level Control (ALC) system controls the ride height of the vehicle to a desired level using air springs at each of the 4 corners of the vehicle suspension. The ALC provides a consistent ride height by compensating for variations in loading, excluding overload conditions, and enables the vehicle to be operated at ride heights above and below the nominal design condition for the purpose of enhancing vehicle performance and usability. Some of the automatic ride heights the system can adjust to are outside of the measurements of customer selectable ride heights. The ALC system is capable of limiting vehicle speed with or without DTC if it is determined to be in an unsafe condition. After the vehicle is turned Off, the ALC system may adjust for up to 60 seconds.

The air suspension will not allow height changes with any of the driver or passenger doors open (exception is the rear hatch), or the hood open.

The air suspension considers multiple vehicle parameters when deciding how to change height. If it has determined no driver is in the vehicle, it will lower using a lower-then-pause method.

If the vehicle is shutdown at Normal Ride Height, the front of the vehicle may slightly lower for aesthetic purposes.

When lowering to Entry/Exit Height and the front of the vehicle hits a solid object (such as a curb), it will detect this and return to Normal Ride Height.

If the Air Suspension detects heavy vehicle loading, it will reduce Normal Height by 20 mm and prevent the vehicle from going to any height above Normal Height.

If the vehicle has a fault causing a loss of Electronic Stability Control (ESC), the air suspension will take action at certain vehicle speeds to lower the vehicle.

If the vehicle has a fault causing a loss of variable shock absorber damping, the air suspension will limit air suspension functionality.

Controlling Ride Height 

The system will use the average of the left and right vehicle heights on an axle basis to use as the criteria for position when adjusting the vehicle up or down.

Maintaining Vehicle Trim 

The Air Suspension System will maintain vehicle height within a designated range, which changes based on vehicle speed, to ensure optimal appearance and performance. When the vehicle is turned off, the K5 Automatic Level Control Module will continue to monitor trim and lower the vehicle if required for up to 60 seconds. If the vehicle is parked on an uneven surface, the system will delay correcting trim height until the vehicle is driven.

In a constant temperature environment, the expected air leakage within the complete load leveling system should not result in more than 2 mm (0.08 in) drop of the suspension height in a 24-hour period. However, as the system (air springs) cool from extended use or if there is a significant change in outdoor temperature, it is normal for the vehicle height to change significantly more. The suspension will return to the target height when the vehicle is started or ignition is cycled on.

Changing Vehicle Ride Height 

The Air Suspension System determines which ride height to target by considering the following:

• Manual selection from the driver via the ride height buttons
• The active Driver Mode (Tour, Sport, Off-Road, etc.)
• Driver enabled Automatic Entry/Egress Mode status
• Vehicle parameters such as speed and transfer case mode
• Vehicle loading
• Dynamic driving
• Status of other vehicle features such as Electronic Stability Control & the Semi Active Damping System

Manually Commanded Ride Heights 

Depending on vehicle optional content, up to four ride heights may be available for customer selection via the ride height buttons. The ride height selected by the driver may be automatically overridden as necessary to ensure that the vehicle will always be in a safe state. Each ride height is only available for selection under certain circumstance (except Normal), see owner's manual for details. These are as follows

• Entry/Exit Height: Lowers the vehicle 50 mm from Normal
• Normal Height
• Increased Height: Raises the vehicle 25 mm from Normal
• Maximum Height: Raised the vehicle 50 mm from Normal

Automatic Entry/Egress Mode 

Automatic Entry/Egress Mode can be enabled/disabled in the settings menu in of the infotainment system. When enabled, the vehicle will automatically lower to Entry/Exit Height when the vehicle is placed it in PARK. It will take about 10 seconds for the vehicle to fully lower to Entry/Exit height from Normal Height. Automatic Entry/Exit Mode is disabled when the vehicle is raised above Normal Height, when Tow/Haul or Off-Road Mode is active, or if the vehicle detects a trailer is connected.

Special Air Suspension Mode 

The air suspension has two special modes available for selection in the settings menu of the infotainment system. Both these modes can either be manually disabled or they will automatically disable when the vehicle is driven above 16 kph. They are:

• Service Mode: When active, completely disabled the air suspension. Useful for when working on the suspension, under the vehicle, towing the vehicle, and more. Service Mode will be automatically enabled when the air suspension detects the vehicle is being lifted by either a hoist or jack.
• Alignment Mode: Optimizes air suspension for a vehicle alignment. To enable Alignment Mode, the vehicle must be at Normal Height and in Neutral.

The electronic suspension control system consists of the following major components:

• The K5 Automatic Level Control Module
• Air Suspension Controller
• Reservoir
• Compressor and air dryer (includes intake, exhaust filters, and muffler)
• Four Air Springs
• Four Position Sensors
• Airlines and fittings
• Door Latch Switches
• Hood Latch Switch