ASCM Pre-Diagnostic Troubleshooting Procedure

For a complete wiring diagram, refer to appropriate SYSTEM WIRING DIAGRAMS article  .

PRE-DIAGNOSTIC TEST PROCEDURE 

1. Perform the following steps prior to any diagnostic procedure(s):
   • Check for any Service Bulletins/Recalls that may apply.
   • With the scan tool, read and record the Environmental Data to help identify the conditions in which the DTC was set.
   • With the scan tool, read the Powertrain Control Module (PCM) Diagnostic Trouble Codes (DTC)s. If any PCM DTCs are present, and perform the appropriate diagnostic procedure(s) before proceeding. Refer to DTC INDEX - 2500 HD & 3500 HD .
   • With the scan tool, read the Body Control Module (BCM) DTCs. If any BCM DTCs are present, and perform the appropriate diagnostic procedure(s) before proceeding. Refer to DIAGNOSIS AND TESTING .
   • With the scan tool, record and erase ASCM DTCs.
   • Check the fuses for the Air Suspension Control Module (ASCM) and the Air Suspension Compressor Assembly.
   • Using the wiring diagram as a guide, inspect the wiring and connectors related to this circuit and clean/repair as necessary.
   • Inspect the Air Suspension intake air lines for kinks, restrictions, debris or leaks and clean/repair as necessary.
   • Inspect the Air Suspension exhaust air lines for kinks, restrictions, debris or leaks and clean/repair as necessary.
   • Inspect the Air Suspension compressor fittings for damage or leaks repair as necessary.
   • Inspect the Air Suspension reservoir fittings for damage or leaks repair as necessary.
   • Inspect the Air Suspension springs for damage or leaks repair as necessary.
   • Inspect the Air Suspension height sensors and linkage for damage or incorrect mounting replace/repair as necessary.

   Did any of the above procedures repair the vehicle?

   Yes 

   • Testing Complete.
   • Perform the ASCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .

   No 

   • Refer to DIAGNOSIS AND TESTING  and perform the appropriate diagnostic procedure.