Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Good evening. It is possible that you have a problem with the BCM. The only way to know for sure is to be able to check the BCM data when the brake lights are staying on. The brake switch sends a signal to the BCM and then the BCM controls the brake lights. If the switch is operating correctly then the BCM is the only other part that could keep the brake lights on.
Hi Tim, I'm Clayso a certified master automobile technician with 30 years of automotive repair and diagnostic experience.
From your description most likely you're dealing with aftermarket stop lamp switches. I have dealt with and have read many issues with switches from the aftermarket world. If you have an original equipment switch installed. Verify at the switch with a voltmeter there is battery voltage on the purple wire with the brake released. When the brakes are applied, the switch contacts open and battery positive voltage is interrupted to the BCM. The BCM then supplies voltage to both the turn/stop lamp supply voltage circuit and trailer rear turn/stop lamp supply voltage circuits. The BCM also supplies a control voltage to the Center High Mounted Stop Lamp (CHMSL) relay energizing the relay and illuminating the CHMSL. If no voltage is present when the lamps stay on, on the purple wire at the brake switch let me know and I'll get you a pin out for the BCM connector to verify the circuit between the BCM and the stop lamp switch before replacing a BCM.
I hope this information is helpful. If you have any questions let me know. You can reply back to me through this thread at any time.
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