Diagnostic Strategies - Automatic Level Control (ALC)

1. Perform the Diagnostic System Check - Automatic Level Control (w/o F45) or Diagnostic System Check - Automatic Level Control (w/F45) before using the Symptom Tables in order to verify that all of the following are true: Diagnostic System Check - Automatic Level Control (ALC)
^ There are no DTCs set.
^ The control module(s) can communicate via the serial data link.
2. Review the General Description and System Operation in order to familiarize yourself with the system functions. Refer to Automatic Level Control Description and Operation.

Visual/Physical Inspection
^ Inspect for aftermarket devices which could affect the operation of the Automatic Level Control System. Refer to Checking Aftermarket Accessories in Diagrams/Diagnostic Aids.
^ Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent and Poor Connections in Diagrams/Diagnostic Aids.

Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:
^ Air Compressor Leak Test Component Tests and General Diagnostics
^ Rear of Vehicle High (w/o F45) or Rear of Vehicle High (w/F45) Rear of Vehicle High - ALC
^ Rear of Vehicle Low (w/o F45) or Rear of Vehicle Low (w/F45) Rear of Vehicle Low - ALC