GM Service Manual Online
For 1990-2009 cars only

Conditions for Setting the DTC

This DTC is set when the automatic level control sensor detects an internal hardware or software error. Examples of these errors are listed below.

    • Position data out of range
    • History code block error
    • Trim-set block error
    • Calibration block error
    • A/D conversion error
    • Ram integrity error
    • Read/Write to EEPROM error

Action Taken When the DTC Sets

The LEVELING indicator lamp will flash while this DTC is present. The function of the ALC system may be degraded or disabled, depending upon which error has been detected.

Conditions for Clearing the DTC

The position data out of range and the A/D conversion error are checked continuously and can be recovered from during the same ignition cycle. All other errors are checked during the start up self test at each ignition cycle. The DTC will clear when no error is detected and the cause for the error has been repaired.

Diagnostic Aids

    • Cycle the ignition.
    • Use the scan tool to re-check for DTC 01.
    • If DTC 01 is still present, replace the automatic level control sensor. Refer to Automatic Level Control in Suspension.