Electronic Stability Control Indicator

The Electronic Stability Control (ESC) indicator gives an indication to the vehicle operator when the ESC has been activated. This indicator is controlled by a transistor on the IC circuit board based upon programming and electronic messages received by the IC from the CAB and the Final Drive Control Module (FDCM) over the CAN data bus. The IC will illuminate the ESC/BAS indicator for about four seconds as a bulb test each time the ignition switch status transitions to ON.

The ESC indicator LED is completely controlled by the IC logic circuit, and that logic will only allow this indicator to operate when the IC receives a battery current input on the fused ignition output (run-start) circuit. Therefore, the LED will always be OFF when the ignition switch status is anything except ON or START. The LED only illuminates when it is provided a path to ground by the IC transistor. The IC will turn ON the ESC/BAS indicator for the following reasons:

• ESC Indicator Lamp-On Message  - Each time the IC receives an electronic ESC/ indicator lamp-ON  message from the CAB indicating that the ESC system has been activated, the ESC indicator will be illuminated. The indicator remains illuminated until the IC receives a lamp-OFF message from the CAB, or until the ignition switch status transitions to OFF, whichever occurs first.
• ESC Off Textual Message  - Each time the IC receives an electronic ESC OFF indicator lamp-ON  message from the CAB indicating that the ESC system has been manually disabled, an ESC OFF  textual message will appear within the IC electronic display unit. The ESC OFF  textual message remains displayed until the IC receives a lamp-OFF message from the CAB, or until the ignition switch status transitions to OFF, whichever occurs first.
• ESC Textual Warning Message  - When the CAB or FDCM detects certain monitored fault conditions, it will send electronic messages requesting the IC display a textual warning message. Each time the IC receives an electronic ESC textual warning request  message from the CAB or FDCM, a WARNING! LIMIT SPEED  textual message will appear within the IC electronic display unit to accompany an ESC indicator that is illuminated solid. This message indicates that the CAB or FDCM has detected a problem in one of the ESC system circuits or components.

The CAB and FDCM continually monitor the ESC circuits and sensors to decide whether the system is in good operating condition. The CAB or FDCM then sends the proper lamp-ON or lamp-OFF message to the IC.

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