Traction Off Indicator Inoperative With No DTC Set

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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 U21F, 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 U133 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.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
2. This step checks if the instrument cluster is controlled by serial data or hard wired through the brake lamp to the EBCM/EBTCM.
4. This step checks if the instrument cluster can turn the TRACTION OFF indicator on.