Circuit Description
When the traction control system (TCS) is enabled, the body control module (BCM) illuminates the TRAC switch LED. The BCM will send a class 2 data message to the electronic brake control module (EBCM) indicated that traction control is requested. If the traction control is disabled, the BCM will send a class 2 data message to the EBCM indication that traction control is disabled. The TRAC switch is normally open switch. When the TRAC switch is pressed, the switch signal circuit is grounded to the BCM and the traction control LED indicator changes states.
The following conditions will cause the TRAC OFF to display in the IPC, and the LED indicator to turn off:
| • | The EBCM has disabled the TCS due to a DTC. |
| • | The EBCM has disabled the TCS due to a overheated ABS/TCS hydraulic unit. |
| • | The instrument cluster bulb check. When the ignition switch is turned to ON, the TRAC OFF indicator will turn on for approximately 5 seconds and then turn OFF. |
Diagnostic Aids
| • | It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction. |
| • | Thoroughly inspect any circuitry that may be causing the complaint for the following conditions: |
| - | Backed out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| - | Poor terminal-to-wiring connections |
| - | Physical damage to the wiring harness |
| • | The following conditions may cause an intermittent malfunction: |
| - | A poor connection |
| - | Rubbed-through wire insulation |
| - | A broken wire inside the insulation |
| • | If an intermittent malfunction exists refer to Inducing Intermittent Fault Conditions in Wiring Systems. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Computer/Integrating Systems Connector End Views in Computer/Integrating System | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
Press the TRAC switch. The LED should change states. Does the TRAC switch LED display on the scan tool change when pressed? | Go to Step 3 | Go to Step 4 | |
3 | Test the traction control indicator control circuit for a short to voltage. Did you find and correct the condition? | Go to Step 6 | Go to Step 5 |
Test the traction control switch signal circuit or traction control switch for an open. Did you find and correct the condition? | Go to Step 6 | Go to in Testing for Intermittent Conditions and Poor Connections Wiring Systems | |
5 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Is the replacement complete? | Go to Step 6 | -- |
6 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
