GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The consecutive intake register will keep track of the number of times a compress sequence is initiated, without an exhaust sequence, while the vehicle is moving. This allows detection of air leaks when the vehicle is moving.

Conditions for Setting the DTC

When the number of compress sequences is more than 10, without an exhaust sequence.

Action Taken When the DTC Sets

    • All compressor activity is disabled.
    • The LEVELING indicator lamp flashes.
    • DTC 12 is stored as a history code at the end of the ignition cycle.

Conditions for Clearing the DTC

    • Initiation of an exhaust sequence.
    • Cycling the ignition.
    • Using a scan tool.

Diagnostic Aids

Perform the system leak test. Refer to Automatic Level Control.