Initial Inspection and Diagnostic Overview
1. Verify the customer concern.2. Visually inspect for the following obvious signs of mechanical and electrical damage.
Visual Inspection Chart
3. If the inspection reveals an obvious concern that is readily repaired, correct the concern before continuing with Inspection and Verification.
4. If the concern remains after the inspection, use scan tool connected to the Data Link Connector (DLC) (located below the steering column) to retrieve continuous Diagnostic Trouble Codes (DTCs) and to execute the air suspension control module diagnostics.
^ If the air suspension control module diagnostics passed and no DTCs are retrieved, go to Symptom Chart to continue diagnostics.
^ If DTCs are retrieved, go to Air Suspension Control Module Diagnostic Trouble Code (DTC) Index.
^ If the air suspension control module cannot be accessed by scan tool, go to Pinpoint Test A.
Rear Load Leveling System Does Not Seem To Be Working
This test is used to determine if all inputs to the air suspension control module are connected and functioning. If one or any combination of inputs is not connected correctly, the vehicle may feel excessively harsh or bouncy. Also, the system may not raise or lower the vehicle correctly.
To set up the vehicle for the test, carry out the following:
1. Connect scan tool to the Data Link Connector (DLC).
2. Monitor the following PIDS using the scan tool PID Monitor screen:
^ VSS_ARC.
^ IGN_RUN.
^ STEER_A.
^ STEER_B.
^ BOO_ARC.
^ DR_OPEN.
^ PCM_ACC.
3. Configure the air suspension control module:
^ Vehicle stopped.
^ Ignition switch in the ON position.
^ Regular brake not applied.
^ All doors closed, including rear tailgate and tailgate glass.
^ No throttle.
Air Suspension Control Module Diagnostics
1. Connect Battery Charger to the vehicle. Use of the air compressor will drain the battery if it runs for extended times.
2. Prepare the vehicle.
^ Open any door.
3. Connect scan tool to the DLC.
4. Run the On-Demand Self-Test.
5. Retrieve all DTCs.
6. Clear all DTCs.
7. CAUTION: If the air compressor runs in this test, do not allow the air compressor to run for more than three minutes. The air compressor could overheat and stop operating due to an internal temperature sensitive thermal breaker.
Use the following active commands to raise the vehicle. Run the compressor for 30 seconds.
^ REAR FILL
^ GATE VALVE
^ COMPRESSR
8. Use the following active commands to lower the vehicle. Lower the vehicle for 30 seconds.
^ REAR FILL
^ GATEVALVE
^ VENT
9. Retrieve all DTCs.
10. Clear all DTCs.
B1318-B1342:
B1485-B1565 / C1439-C1869:
Air Suspension Control Module Diagnostic Trouble Code (DTC) Index
Air Suspension Control Module Parameter Identification (PID) Index
Air Suspension Control Module Active Command Index
Intermittent Circuit Check
Note: The Intermittent Circuit Check cannot be started without erasing all stored DTCs. Record all DTCs or repair the fault(s) before starting the Intermittent Circuit Check.
1. Configure the vehicle:
^ Open any door.
^ Ignition switch is in the RUN position.
^ The vehicle is in PARK.
^ The brake pedal is fully depressed.
^ The accelerator pedal is fully depressed.
2. Connect scan tool.
3. Enter the PID monitor and select the following PIDs (make sure that the listed states are displayed before continuing):
4. Enter scan tool "I/O Circuit Check" in the air suspension control module menu. All inputs should indicate NO CHANGE. If not, then restart the I/O Circuit Check.
5. Wiggle the wire harness for the selected circuits, without disturbing the vehicle configuration.
6. If any PIDs indicate CHANGED, an intermittent fault exists near the location of the wiggling of the wire harness. REPAIR the circuits as necessary.