The Automatic Level Control (ALC) Scan Tool Data Definitions contains a brief description of all scan tool parameters.

Battery Voltage: The scan tool displays 0-26.0 volts. The battery voltage represents the system voltage measured at the controller battery input.

Compressor Relay Cmd.: The scan tool displays On/Off. The scan tool will display On when the vehicle trim height is below a preset value. The ALC compressor inflates the rear airlift shocks until the vehicle reaches the desired trim height. When the vehicle is at the desired trim height, the scan tool will display Off.

Exhaust Valve Command: The scan tool displays On/Off. The scan tool will display On when the vehicle trim height is above a preset value. The ALC exhaust solenoid deflates the rear airlift shocks until the vehicle reaches the desired trim height. When the vehicle is at the desired trim height, the scan tool will display Off.

Suspension Position Sensor: The scan tool displays the voltage signal input from the suspension position sensor.

Vehicle Speed: The scan tool displays 0-255 km/h (0-159 mph). The ESC system obtains vehicle speed data from the powertrain control module (PCM) on a dedicated input. The PCM is responsible for calculating correct vehicle speed data.