Traction Control Indicator

A traction control (ASR) indicator is standard equipment on all instrument clusters. The traction control indicator is located near the center of the speedometer in the instrument cluster. The traction control indicator consists of an "!" (exclamation point) imprinted within a triangular cutout in the opaque layer of the instrument cluster overlay. The dark outer layer of the overlay prevents the indicator from being clearly visible when it is not illuminated. An amber Light Emitting Diode (LED) behind the cutout in the opaque layer of the overlay causes the exclamation point to appear silhouetted against an amber field through the translucent outer layer of the overlay when the indicator is illuminated from behind by the LED, which is soldered onto the instrument cluster electronic circuit board. The traction control indicator is serviced as a unit with the instrument cluster.

The traction control (ASR) indicator gives several indications to the vehicle operator concerning the operating status of the traction control (ASR) system. The traction control indicator is controlled by a transistor on the instrument cluster circuit board based upon cluster programming and electronic messages received by the cluster from the Controller Anti-lock Brake (CAB) over the Controller Area Network (CAN) data bus. The traction control indicator Light Emitting Diode (LED) is completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator to operate when the instrument cluster detects that the ignition switch is in the On position. Therefore, the LED will always be off when the ignition switch is in any position except On. The LED only illuminates when it is provided a path to ground by the instrument cluster transistor. The instrument cluster will turn on the traction control indicator for the following reasons:
- Bulb Test - Each time the ignition switch is turned to the On position the traction control indicator is illuminated for about two seconds as a bulb test.
- Traction Control (ASR) Indicator Lamp-On Message - Each time the cluster receives a traction control indicator lamp-on message from the CAB, the indicator will be illuminated. This indicator can be flashed on and off, or illuminated solid, as dictated by the CAB message. The indicator is illuminated solid when the traction control system has been deactivated; and is flashed when the traction control is activated or when the driven wheels lose traction with the traction control deactivated. The indicator remains flashing or illuminated solid 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 traction control (ASR) switch and the four wheel speed sensors to determine the correct operating mode for the traction control system. The CAB then sends the proper lamp-on or lamp-off messages to the instrument cluster. See the owner's manual in the vehicle glove box for more information on the features, use, activation and deactivation of the traction control (ASR) system. For proper diagnosis of the traction control system, the CAB, the CAN data bus, or the electronic message inputs to the instrument cluster that control the traction control indicator, a DRBIII(R) scan tool is required. Refer to the appropriate diagnostic information.