Circuit Description
The TRAC OFF indicator is controlled by the instrument cluster via GMLAN 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 GMLAN 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 (TCS) is enabled.
The following conditions will cause the TRAC OFF indicator to illuminate:
| • | The EBCM has disabled the 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. |
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 for further diagnosis. |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Does the scan tool display Released? | Go to Step 3 | Go to Step 4 |
3 |
Does the Traction Switch parameter change state? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 4 |
4 |
Does the scan tool display Inactive? | Go to Step 7 | Go to Step 5 |
5 | Test the signal circuit of the traction control switch for a short to ground. Refer to Testing for Short to Ground . Did you find and correct the condition? | Go to Step 10 | Go to Step 6 |
6 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs . Did you find and correct the condition? | Go to Step 10 | Go to Step 8 |
7 | Inspect for poor connections at the harness connector of the traction control switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 10 | Go to Step 9 |
8 | Replace the BCM. Refer to Control Module References . Did you complete the replacement? | Go to Step 10 | -- |
9 | Replace the traction control switch. Refer to Electronic Traction Control Switch Replacement . Did you complete the replacement? | Go to Step 10 | -- |
10 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
