ASR/BAS Indicator - Operation

OPERATION

The Acceleration Slip Regulation (ASR) (also known as traction control)/Brake Assist System (BAS) indicator gives an indication to the vehicle operator when the ASR or BAS systems, or a circuit or component of these systems are ineffective. This indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster over the Controller Area Network (CAN) data bus from the Controller Antilock Brake (CAB) (also known as the Antilock Brake System/ABS or Electronic Stability Program/ESP controller).

The ASR/BAS indicator Light Emitting Diode (LED) or icon and textual message display is completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator or icon and textual message display to operate when the instrument cluster detects that the ignition switch is in the ON position. Therefore, the LED or the icon and textual message display will always be OFF when the ignition switch is in any position except ON. The LED only illuminates or the icon and textual message is only displayed when it is activated by the instrument cluster logic. The instrument cluster will turn ON the ASR/BAS indicator or icon and textual message display for the following reasons:

- Bulb Test - On vehicles not equipped with the optional steering wheel buttons, each time the ignition switch is turned to the ON position the ASR/BAS indicator is illuminated by the cluster briefly as a bulb test.
- ASR/BAS Indicator Lamp-On Message - Each time the cluster receives an electronic ASR/BAS indicator lamp-ON message from the CAB indicating that the ASR/BAS systems have been deactivated, the ASR/BAS indicator will be illuminated. The indicator remains illuminated until the cluster receives a lamp-OFF message from the CAB, or until the ignition switch is turned to the OFF position, whichever occurs first. On vehicles equipped with the optional steering wheel buttons, each time the cluster receives an electronic ASR/BAS indicator lamp-ON message from the CAB, the ASR/BAS icon and a Visit workshop or unavailable textual message will appear within the cluster multi-function display. The icon and textual message remain displayed until the message is acknowledged by momentarily depressing one of the steering wheel or cluster buttons, until the cluster receives a lamp-OFF message from the CAB, or until the ignition switch is turned to the OFF position, whichever occurs first.

The CAB continually monitors the ASR and BAS system circuits and sensors to decide whether the system is in good operating condition. The CAB then sends the proper lamp-ON or lamp-OFF messages to the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN or KOMBI). If the CAB sends a lamp-ON message after the bulb test, it indicates that the CAB has detected a system malfunction or that the ASR system or the BAS system has become ineffective. The CAB will store a Diagnostic Trouble Code (DTC) for any malfunction it detects.

For proper diagnosis of the ASR or BAS system, the CAB, the EMIC, the CAN data bus or the electronic communication related to ASR/BAS indicator operation, a diagnostic scan tool is required. Refer to the appropriate diagnostic information.