Rick's Free Auto Repair Advice

Silverado C0161 brake lights stay on

Diagnose Silverado C0161 brake lights stay on

The brake pedal switch doesn’t actually switch power to the brake lights; it only acts as a signal input to the body control module (BCM).  If the switch isn’t working properly, you can wind up with a Silverado C0161 brake lights stays on condition.

During a stop application, the Electronic Brake Control Module (EBCM) sees the brake pedal application via digital data from the BCM. The EBCM then monitors brake pressure, vehicle speed. It’s looking for increased brake pedal pressure and vehicle slowdown, or the opposite condition where the brake pedal isn’t applied and the vehicle is accelerating. If the EBCM see either of the conditions listed below that don’t make sense, it sets a C0161 00  Antilock Brake System (ABS)/Traction Control System (TCS) Brake Sensor Circuit.

Conditions for setting a Silverado C0161 brake lights stay on

• The EBCM detects vehicle speed is greater than 13 mph and the brake pedal is applied for 1 minute, with brake pressure is not increasing.

• The EBCM detects the brake pedal is released and the vehicle speed is decreasing while the brake pressure is increasing.

The most common cause of a C0161 brake lights stay on condition

Shops are finding that a faulty brake pedal switch is the most common cause. Here’s how to test it. Refer to the brake pedal wiring diagram below.

The BCM sends a 12-volt reference signal to the brake pedal switch on the orange/white wire and sees a return on the purple wire. This tells the BCM, the pedal is not applied. When the pedal is applied, the contacts open and the BCM sees a 12-voltage drop, meaning the driver has applied the brakes. The BCM digitally communicates a brake apply condition to the BCM and turn on the brake lights. NOTE. The center-mounted brake lights are not controlled by the BCM.

Test the brake pedal switch and wiring

Using a multimeter. Backprobe the purple wire at the brake pedal switch with the brake pedal released. You should see close to 12-volts. If you don’t see that, check for 12-volts on the orange/white wire.

Silverado C0161 brake lights stay on

If you see 12-volts on the Orange/white wire but no voltage on the purple wire with the brake pedal released, replace the brake pedal switch with a dealer part.

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Posted on by Rick Muscoplat

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