Circuit Description
For vehicles equipped with a U23 or a UH8 instrument cluster, the TRACTION OFF indicator is controlled by the EBCM/EBTCM via serial data UART.
For vehicles equipped with a UB3, a U2F, or a U50 instrument cluster, the TRACTION OFF indicator is controlled by the EBCM/EBTCM via the brake lamp driver module. The instrument cluster or remote indicator bank supplies voltage to the indicator. The brake lamp driver module acts as an inverter. When the EBCM/EBTCM supplies ground to the brake lamp driver module, the indicator remains OFF. When the EBCM/EBTCM removes ground from the brake lamp driver module, the brake lamp driver module supplies ground to the TRACTION OFF indicator.
Diagnostic Aids
| • | Buick uses the U23 and the UB3 instrument clusters. |
| • | Oldsmobile uses the UH8 instrument cluster. |
| • | Pontiac uses the UB3, the U2F, and the U50 instrument clusters. |
| • | 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. |
| • | An intermittent malfunction can be caused by poor connections, broken insulation, or a wire that is broken inside the insulation. |
| • | If an intermittent malfunction exists, refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. |
Test Description
The number below refer to the step number on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the ABS Diagnostic System Check? | -- | Go to Step 2 | |
Is this vehicle equipped with a U23 or a UH8 instrument cluster? | -- | Go to Step 3 | Go to Step 8 | |
3 |
Does the switch status change as the TCS switch is pressed and released? | -- | Go to Step 6 | Go to Step 4 |
4 |
Does the resistance equal the specified value? | OL (infinite) | Go to Step 10 | Go to Step 5 |
5 | Repair a short to ground in CKT 1571 (BRN/WHT). Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |
6 |
Does the indicator turn off? | -- | Go to Step 10 | Go to Step 7 |
7 | Inspect the instrument cluster. Refer to Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges and Console. Is the diagnosis complete? | -- | -- | |
8 |
Does the switch status change as the TCS switch is pressed and released? | -- | Go to Step 9 | Go to Step 4 |
9 |
Does the TRACTION OFF indicator turn off? | -- | Go to Step 10 | Go to Step 11 |
10 | Replace the EBCM/EBTCM. Refer to Electronic Brake Control Module Replacement . Did you complete the repair? | -- | -- | |
11 |
Is the resistance less than the specified value? | 2 ohms | Go to Step 12 | Go to Step 15 |
12 | Turn ON the ignition leaving the engine OFF. Is the TRACTION OFF indicator on? | -- | Go to Step 13 | Go to Step 14 |
13 | Repair a short to ground in CKT 1660 (DK BLU). Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |
14 | Replace the brake lamp driver module. Refer to Lamp Driver Module Replacement . Did you complete the repair? | -- | -- | |
15 | Repair an open in CKT 1572 (PPL/WHT). Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- |
