Cruise Control doesn’t work
Some of the following vehicles may encounter a situation where the cruise control doesn’t work and may set a B3894 (Stop Lamp Switch Circuit Plausibility Failure) code. If you’ve checked the cruise control switches and brake pedal switch and still have the same problem, check the Master Cylinder Pressure Sensor parameter listed in the Trailer Brake Control Module data list. If it is displaying pressure with no brake pedal input, there may be a concern with the master cylinder pressure sensor, wiring/terminals, or Electronic Brake Control Module (EBCM). On models with Stabilitrak (RPO JL4), the master cylinder pressure sensor is internal to the Brake Pressure Modulator Valve (BPMV)/EBCM.
The models affected are Yukon Denali, Yukon XL, Yukon Denali XL models equipped with a Trailer Brake Controller Trailer Brake Control Module