Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Traction Control Switch (TCS) Signal | 1 | 1 | -- | -- |
Traction Control Switch (TCS) Ground | -- | 1 | -- | -- |
1. Traction Control Switch Malfunction | ||||
Circuit Description
The TRAC OFF indicator is controlled by the instrument cluster via class 2 serial data messages from the electronic brake control module (EBCM). When the body control module (BCM) sees the traction control switch input grounded through the momentary traction control switch, it sends a class 2 message to the EBCM that tells the EBCM that the traction control switch has been pressed. The EBCM then disables traction control and sends a message to the instrument cluster to turn the TRAC OFF indicator ON. Each time the ignition is cycled from OFF to ON, the traction control system is enabled.
The following conditions will cause the TRAC OFF indicator to illuminate:
| • | The EBCM has disabled the traction control system (TCS) due to a DTC. |
| • | The driver manually disabling the TCS via the traction control switch |
| • | The instrument cluster bulb check--When the ignition switch is turned to ON, the TRAC OFF indicator will turn ON for approximately 3 seconds and then turn OFF. |
Reference Information
Schematic Reference
Antilock Brake System Schematics
Connector End View Reference
Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, observe the scan tool BCM data display parameter while pressing the TCS switch the reading should change between scan tool Released/Pressed and Pressed/Released switch value.
Circuit/System Testing
Important: Diagnose all vehicle DTCs before using this diagnostic.
The malfunction must be present during diagnosis in order to prevent unnecessary parts replacement.- Ignition OFF, disconnect the BCM harness at the traction control switch (TCS).
- Ignition ON, verify that a test lamp illuminates between the traction control switch signal circuit terminal C and ground.
- Verify the scan tool BCM TCS switch data display parameter is Released value.
- Install a 3A fused jumper wire between the TCS switch signal circuit terminal C and ground. Verify the scan tool BCM TCS switch data display is Pressed value.
- If all circuits test normal, test or replace the traction control TCS switch.
| ⇒ | If the test lamp does not illuminate, test the TCS control circuit for a short to ground or an open/high resistance. If the circuit tests normal and the control circuit fuse is open, test the signal circuit terminal C for a short to ground. |
| ⇒ | If not the specified value, test the signal circuit terminal C for a short to voltage. If the circuit tests normal, replace the body control module (BCM). |
| ⇒ | If not the specified value, test the signal circuit terminal C for an open/high resistance. If the circuit tests normal, replace the BCM. |
Component Testing
- Ignition OFF, disconnect the BCM harness connector at the TCS switch control circuit terminal C.
- Test for infinite resistance between the TCS switch signal circuit terminal C and ground with the TCS switch in the Released or open position.
- Test for less than 5 ohms between the TCS switch control circuit terminal C and ground with the TCS switch in the Pressed or closed position.
| ⇒ | If not the specified value, replace the TCS switch. |
| ⇒ | If greater than the specified range, replace the TCS switch. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM replacement, setup, and programming |
