Seized brake calipers are caused when the inboard pad on a brake pad has more wear than the outboard pad. This make the brake pads push on the rotor as the pistons are seized into the caliper bores, resulting in seized brake calipers.
Whether the vehicle has a floating or fixed caliper, if the pistons get seized into the bores on the calipers, the brake pads drag on the rotor. Some caliper boots develop signs of leakage, while others take on a cracked, more hardened appearance. The piston corrodes over time, seizing in place if a caliper boot develops a defect.
When pistons end up stuck in damp situations for long periods of time, they seize if the caliper boot permits moisture to gather. If calipers have integrated hardware for the parking brake, it is important to check that for leaking fluid and correct any issues in the parking brake operation. In some situations, the driver has to use the parking brake on a regular basis to make up for the poor operation of the conventional brake system. The parking brake caliper or cable hardware ends up seizing if the driver does not use the parking brake often, or if the caliper hardware or cable on the parking brake has seized.