Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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:
- Two air assisted shock absorbers.
- A level sensor with an integrated control module.
- A compressor with an integral exhaust solenoid valve.
- A compressor relay.
- A inflator solenoid valve.
- 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.
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.