Brake Lock Up

There are several reasons trailer brakes may lock up, but one of the most common is a condition known as “Lot Lock.”

What is “Lot Lock”?

“Lot Lock” occurs when a trailer has been sitting unused for an extended period, especially in humid or wet environments. Corrosion can build up between the brake pads and the rotor, causing the pads to stick or “freeze” to the rotors. This condition is similar to what happens with vehicles left parked for long durations.

• It’s more common with metallic brake pads, but it can happen with ceramic or organic pads as well.

• Typically, this affects trailers stored without a boat or load, as there’s not enough weight to help break the pads free during movement.

• “Lot Lock” is not considered a warranty issue, as it results from environmental exposure over time.

What You Can Do:

1. Manually Test the Wheels:
   Try pushing the trailer backward and forward to see if the wheels will roll freely.

2. Rock the Trailer:
   Rocking it gently back and forth can sometimes break the bond between the pad and rotor.

3. Inspect and Free the Pads:
   If the brakes are still locked, carefully use a wide blade putty knife or similar tool to gently pry between the rotor and brake pad to release them.

4. Clean or Service the Brakes:
   If the trailer has been sitting for a long time, it may be necessary to remove the wheels and brake components for cleaning. Inspect the pads and rotors, and remove any corrosion or buildup.

Tip: To help prevent “Lot Lock,” consider moving the trailer periodically or storing it in a covered or low-humidity environment.

If your trailer brakes lock when you reverse, here are the most common causes—and how to fix them:

1. Ensure the Reverse Lockout Solenoid Is Powered

Many trailers with surge (inertia) braking systems include a reverse lockout solenoid. When your tow vehicle is put in reverse, it sends power (usually via the blue wire in the trailer harness) to this solenoid, which then blocks brake fluid pressure to the calipers—allowing you to back up freely

• If the reverse lights on the trailer don’t illuminate, it’s often a sign that this wire isn’t receiving power or the circuit is broken

• Secure a solid ground on the solenoid—many common issues stem from a poor ground connection

2. Check the Wiring

• Inspect the blue wire along the tongue, especially if it’s part of a swing-away. It can get pinched or fatigued from constant movement

• Confirm continuity between the trailer connector and the solenoid using a multimeter; test both power and ground paths

• Also, verify the fuse for the reverse lights/trailer circuit; a blown fuse may be why the solenoid isn’t activating

3. Maintain or Replace the Solenoid

• A failing solenoid won’t click or block fluid as designed. If power and ground are good, but the solenoid doesn’t click: it’s likely defective

• Ensure the solenoid can vent the brake pressure properly when activated

4. Use the Manual Lockout Pin

As a backup, most trailers include a manual “lockout pin”. This physically prevents the actuator from engaging the brakes when reversing, even if the solenoid fails

To prevent your trailer’s disc brakes from “freezing” or locking to the rotors during storage, follow these key tips:

1. Store the Trailer in a Dry, Protected Area

• Ideally, keep your trailer under a roof or inside a garage.

• If using a tarp, ensure adequate air circulation around the brake area. A tightly sealed tarp can trap moisture and create a greenhouse effect, accelerating corrosion.

2. Avoid Storing With Brake Pressure Applied

• If your trailer has a “stop flow” solenoid, make sure it’s not holding hydraulic pressure when disconnecting.

• This often happens when parking on an incline or backing into a tight space—if the actuator compresses and locks in fluid pressure, the pads may bind to the rotor.

• Always set the actuator to a neutral position after parking. Gently pull the coupler out or forward to relieve any pressure.

3. Prevent Corrosion on the Rotor Surface

• For long-term storage, consider applying a very light coat of high-temp spray paint (like zinc or rotor-specific paint) to the exposed rotor face.

• Be careful to avoid spraying the brake pads, calipers, or trailer parts.

• Once the paint dries, rotate the wheels to align the pads on the painted area. The coating will wear off cleanly during first use.

4. Avoid Using Oils or Lubricants

• Never apply WD-40, penetrating oils, or greases to the rotors or pads. These substances can soak into the brake material, reducing stopping power and compromising safety.

5. Perform Basic Brake Maintenance Before Storage

• Inspect the brake fluid in the actuator reservoir and top it off with DOT 3 brake fluid if needed. Disc Maintenance

• Look for signs of moisture or rust around the calipers and rotor area.

• Test-rotate the wheels after parking to ensure they’re not already binding.

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Pro Tip: Before putting the trailer back on the road after storage, conduct a quick brake check by gently pulling forward and applying the brakes. If there’s any hesitation, noise, or pulling, inspect the calipers and pads before use.