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 instrument panel cluster (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 . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Confirm if the scan tool can turn on and off all the indicator lamps in the instrument cluster.
-
Verify if the circuits going to the instrument Cluster or the cluster is at fault.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Data Communication Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
All indicators will turn ON when commanded ON. Does the TRAC OFF Switch LED Indicator turn ON? | Go to Step 4 | Go to Step 3 | |
3 |
Press the TRAC switch. The LED should change states. Does the scan tool display ON with TRAC switch pressed? | Go to Step 8 | Go to Step 7 |
Measure the voltage at the TRAC switch between terminal D and ground. Is voltage present? | Go to Step 6 | Go to Step 5 | |
5 | Test the traction control switch signal circuit for an open. Did you find and correct the condition? | Go to Step 12 | -- |
6 | Activate the TRAC OFF switch, switch activated. Measure the voltage at the TRAC switch between terminal A and ground. Is voltage present? | Go to Diagnostic Aids | Go to Step 10 |
7 | Test the traction control switch ground circuit for an open. Did you find and correct the condition? | Go to Step 12 | Go to Step 11 |
8 | Measure the voltage at the TRAC switch between terminal C and ground. Is voltage present? | Go to Step 10 | Go to Step 9 |
9 | Test the traction control indicator control circuit for an open or short to ground. Did you find and correct the condition? | Go to Step 12 | -- |
10 | Replace the traction control switch. Refer to Electronic Traction Control Switch Replacement . Did you find and correct the condition? | Go to Step 12 | -- |
11 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Is the replacement complete? | Go to Step 12 | -- |
12 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
