* Brake Caliper Seizure: This is the most likely culprit. A seized caliper piston fails to retract, keeping the brake pads constantly pressed against the rotor. Rust and corrosion are major factors after two years of sitting, especially if the parking brake wasn't properly released.
* Parking Brake Cable: A frozen or stuck parking brake cable can also cause a wheel to lock. Again, rust and corrosion are the likely culprits after prolonged inactivity.
* Wheel Bearing Failure: A completely seized wheel bearing could theoretically lock a wheel, though this is less common than a brake issue. A seized bearing would likely also exhibit other symptoms like noise or excessive play before completely seizing.
* Damaged Brake Line: While less likely to cause a *complete* lockup, a severely corroded or damaged brake line could restrict fluid flow enough to create a dragging brake. This is more probable if other brakes are functioning abnormally.
* Differential Problem: An extremely rare possibility, a severely damaged differential could cause one wheel to lock. This would typically be accompanied by other noticeable problems with the drivetrain.
Troubleshooting Steps:
1. Try to rotate the wheel: If the wheel won't rotate at all, the problem is likely within the brake system or wheel bearing.
2. Inspect the Brake Caliper: This is the first place to look. Check for rust and corrosion around the caliper and piston. Attempt to manually move the caliper piston; it should move freely. If it's stuck, you'll likely need a caliper rebuild or replacement.
3. Check the Parking Brake Cable: Verify it's not seized or rusted in place. Try releasing the parking brake multiple times.
4. Examine Brake Lines and Hoses: Look for corrosion, damage, or leaks in the brake lines leading to that specific wheel.
5. Wheel Bearing Inspection: While less probable, if the brake system seems okay, a thorough inspection of the wheel bearing is warranted.
It's strongly recommended to have a qualified mechanic diagnose and repair the issue. Attempting to force a seized wheel can cause further damage. The priority is to get the wheel freely rotating before attempting to drive the vehicle.
