Here's why:
* Parking Brake Cable/Caliper Sticking: The parking brake's cable might be slightly stuck or seized, applying a slight drag on the wheel. Reversing the car can momentarily release the tension on the stuck cable, allowing the wheel to turn freely.
* Parking Brake Caliper Piston Sticking: The piston in the brake caliper might not be fully retracting when the parking brake is released. The reverse movement might help dislodge the sticking piston.
* Worn/Damaged Parking Brake Components: Worn brake pads, a corroded caliper, or a damaged cable can contribute to this problem.
* Brake System Sensor Issue (Less Likely): While less probable, a faulty wheel speed sensor or a related ABS sensor could theoretically cause a strange interaction with the parking brake, leading to this behavior. This would usually be accompanied by other warning lights or symptoms.
Important Note: This is a safety issue. Driving with a potentially sticking parking brake is dangerous. Do not continue driving the vehicle until you have it checked by a mechanic. Ignoring the problem could lead to brake failure or damage to the braking system.
