Code C1205 on the 2022 Cadillac CT5 indicates a malfunction in the right side electric parking brake actuator. The CT5 features an Electronic Parking Brake (EPB) system with motor-driven actuators built into the rear brake calipers, eliminating the traditional parking brake lever.
EPB Actuator Technology
Each rear caliper contains an integrated electric motor that drives a spindle mechanism to press the brake pads against the rotor. The EPB control module coordinates both actuators for simultaneous application when you press the parking brake switch. The system also integrates with the automatic vehicle hold feature that keeps the brakes applied at stops.
Problem Indicators
With C1205 active, the parking brake warning light illuminates and a message may display in the Driver Information Center. The parking brake may not apply fully, or may apply unevenly. Auto-hold functionality will likely be disabled. During operation, you might hear grinding or clicking from the right rear brake.
Diagnostic Process
Compare left and right actuator behavior by commanding EPB apply and release while listening at each rear wheel. A healthy actuator produces a smooth motor sound. Inspect the right rear caliper connector for corrosion - water exposure from road spray can damage these connections. Check whether the caliper slides properly, as binding can overload the actuator motor.
Repair Considerations
GM's EPB actuators are integrated into the caliper assembly. Depending on the specific failure, you may need to replace the entire caliper rather than just the motor. After replacement, a calibration procedure using GM diagnostic software is required to program the proper apply force and ensure both sides operate symmetrically.