ESP Indicator

ESP INDICATOR

DESCRIPTION
An Electronic Stability Program (ESP) indicator is standard equipment on all instrument clusters, but is only functional on vehicles equipped with the optional ESP system. The ESP indicator is located near the lower edge of the instrument cluster, to the right of the multi-function indicator display. The ESP indicator consists of a stencil-like cutout of the text "ESP" 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 text to appear in amber 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 ESP indicator is serviced as a unit with the instrument cluster.

OPERATION
The ESP indicator gives an indication to the vehicle operator when the ESP system is faulty or inoperative. This 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 Antilock Brake (CAB) over the Controller Area Network (CAN) data bus. The ESP 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 ESP indicator for the following reasons:
- Bulb Test - Each time the ignition switch is turned to the On position the ESP indicator is illuminated by the cluster for about two seconds as a bulb test.
- ESP Lamp-On Message - Each time the cluster receives a lamp-on message from the CAB, the ESP 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.

The CAB continually monitors the ESP 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 instrument cluster. If the CAB sends a lamp-on message after the bulb test, it indicates that the CAB has detected a system malfunction and/or that the ESP system has become inoperative. The CAB will store a Diagnostic Trouble Code (DTC) for any malfunction it detects. For proper diagnosis of the ESP system, the CAB, the CAN data bus, the electronic message inputs to the instrument cluster, or the instrument cluster circuitry that controls the ESP indicator, a diagnostic scan tool is required. Refer to the appropriate diagnostic information.