Common trailer problems and the repairs that fix them
A trailer breaks down about as often as the truck pulling it, and it usually fails an inspection first. Most common trailer problems start at the lights, the brakes, or the landing gear, and most of them are cheap to fix when you catch them early. Here is what we see and what the repair takes.
Lights and wiring
Trailer lights are the top reason a good trailer gets a violation. A bad ground, a cracked lamp, a chafed harness, or a corroded seven-pin plug can drop a marker or a brake light. Federal rules spell out which lamps and reflective devices a trailer has to carry and keep working, so we trace the circuit, fix the ground, and seal the connector instead of just swapping a bulb. A lot of this overlaps with the electrical and sensor faults we see on the tractor.
Trailer brakes and ABS
Air reaches the trailer through the gladhands, and the trailer carries its own brakes, slack adjusters, and ABS. A leaking gladhand seal, a brake out of adjustment, or an ABS light that stays on will all show up at a scale. Trailer antilock brake systems are required, and the warning lamp has to work. We test the trailer brakes the same way we test the tractor's, which we cover in common air brake problems.
Landing gear and the upper coupler
The landing gear holds the trailer's weight when it is dropped, and bent legs, a stripped crank, or a dry gearbox make it hard to hook and unhook. The upper coupler and kingpin are what the fifth wheel locks onto, and a worn kingpin or a cracked upper coupler is a serious out-of-service item. We grease, straighten, and measure these parts, and we check the kingpin for wear before it lets go.
Suspension, axles, and tires
Air bags, hangers, U-bolts, and bushings hold the axles in line. When one side sags or a bushing is shot, the trailer tracks crooked and scrubs the tires, which is one cause of uneven tire wear. Wheel bearings and seals leak and run hot. We check ride height, look for a lean, and set the axle alignment so the tires last.
Floor, doors, and the frame
A soft floor, a door that will not seal, a cracked crossmember, or a rusted-through rail is the slow kind of trailer problem that gets worse with every load. A reefer trailer adds a cooling unit and an insulated box on top of all this. We look at the frame and the floor while the trailer is in, because a small crack is a weld and a big one is a tow.
What we check at our Breinigsville shop
When a trailer comes in, we run the lights and the ABS, test the brakes, grease and straighten the landing gear, check the kingpin and upper coupler, and look over the suspension and floor. Most of it is on the same DOT inspection checklist an officer uses, so we catch it before the roadside does. We are at 9883 Old US Highway 22 in Breinigsville, near Allentown on the US-22 and I-78 corridor, open 24 hours Monday through Friday and Saturday until midnight. The full list is on our truck repair services page.
FAQ
What is the most common trailer repair?
Lights and wiring. A bad ground or a corroded seven-pin plug drops a lamp, and a dropped lamp is an easy violation to avoid.
Why is my trailer ABS light on?
A wheel-speed sensor, the wiring, or the module. The trailer ABS lamp has to work for inspection, so we read the codes and fix the cause instead of clearing the light.
Can you fix a worn kingpin?
Yes. A worn kingpin or a cracked upper coupler is an out-of-service item, so we measure it and replace what is worn before it fails.
Do you work on reefer trailers?
We service the trailer itself: the brakes, lights, landing gear, suspension, floor, and frame. Call about the cooling unit so we can confirm we can do your job.
If your trailer is due, or it just failed a light or a brake check, call Royal Truck Repair at (610) 841-2521 and we will get it back in service.