ALC Sensor

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

• The Automatic Level Control Compressor
• The Exhaust Solenoid Valve
• 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.