Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2004 GMC Yukon XL, 2004 GMC Yukon, 2004 Chevrolet Tahoe, 2004 Chevrolet Suburban, and 2004 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

DTC C0455 may be falsely set if you did not turn OFF the ignition for 5 seconds after clearing DTCs from the EBCM. This is why all diagnostic tables which apply to this system always instruct you to turn OFF the ignition for 5 seconds after clearing DTCs. If this DTC has set after you cleared DTCs from the EBCM or used the scan tool to clear all DTCs from all modules and you did not cycle the ignition afterward, it is likely that no actual malfunction exists.
Whenever any one of the steering signals to the EBCM is lost, the scan tool displays a fixed steering wheel position, which indicates the last known steering wheel position. This can aid you in diagnosing an intermittent malfunction.
If the DTC does not reset during step 2 or 3 of the diagnostic procedure, the stability system disabled message may be displayed due to an unsuccessful initialization. This occurs if the EBCM does not receive any signal from one or both of the digital inputs during the entire ignition cycle. If this occurs, refer to Stability System Disabled Indicator Always On for further diagnosis.
Inspect the vehicle for proper wheel alignment. Ensure the vehicle does not pull toward the left or right while driving straight forward on a level surface.
Communicate with the customer to determine the conditions under which the message center displays the service stability system message. Learning the conditions under which the DTC sets may help you duplicate the failure.
Use the Snapshot function on the scan tool in order to assist you in locating an intermittent malfunction.