* Parking Brake: The most common cause. Make absolutely sure the parking brake is completely released. Sometimes a cable can stick or a mechanism can bind.
* Brake Caliper(s): A seized caliper piston is a very common culprit. This means the piston is stuck in the "on" position, constantly applying pressure to the brake pads. This can be due to corrosion, a damaged seal, or low brake fluid.
* Brake Hose(s): A restricted or damaged brake hose can prevent the proper release of brake pressure. A collapsed or internally blocked hose will act like a valve always on.
* Master Cylinder: While less likely than a caliper issue, a faulty master cylinder could be causing uneven brake pressure or preventing proper release.
* Brake Lines: Similar to hoses, corroded or blocked brake lines can restrict fluid flow and prevent proper brake release. This is less likely but possible, particularly on an older vehicle.
* Vacuum Booster: A failing vacuum booster can result in increased brake effort and potentially contribute to a locked-up brake, though it's less likely to cause a complete lockup on just the front.
* Proportioning Valve: An issue with the proportioning valve (which regulates front/rear brake pressure) is possible, but less common as the main cause of a front-only lockup.
What to do:
1. Safety First: Do NOT drive the truck until this is fixed. Locked brakes are extremely dangerous.
2. Check the Obvious: Start by making absolutely certain the parking brake is off.
3. Inspect the Front Brakes: Visually inspect the front calipers and brake pads. Look for signs of seizing or binding. If you're comfortable doing so, try to manually move the caliper piston. It should move freely. (Caution: Be careful not to damage anything. If you aren't comfortable doing this, skip it and go to a mechanic).
4. Check Brake Fluid Level: Check your brake fluid reservoir. Low fluid can indicate a leak somewhere in the system.
5. Professional Help: If you've checked the obvious and can't identify the problem, take your truck to a qualified mechanic. They have the tools and expertise to diagnose and repair the issue safely.
Ignoring this problem is dangerous. Locked brakes can lead to accidents. Get it fixed promptly.
