Symptoms
- Trailer doesn't seem to brake or slow down when towing
- Trailer brake controller shows an error or no output
- Possible burning smell from the trailer wheels if brakes drag instead of failing to engage
Likely causes
- CommonPoor connection at the trailer hitch wiring plugCorrosion or a loose pin in the connector is one of the most common trailer brake issues.
- CommonFaulty or miscalibrated brake controller in the tow vehicleThe controller needs to be set correctly for the trailer's brake type and weight.
- PossibleBlown fuse for the trailer brake circuitAn easy and cheap thing to check before assuming bigger problems.
- PossibleWorn trailer brake magnets or shoes (electric brakes)Like vehicle brakes, trailer brake components wear out over time.
- Less commonTrailer brake actuator issue (surge brakes)Relevant only on trailers using surge (hydraulic) brakes rather than electric.
What to do
- Check the hitch wiring connector for corrosion, looseness, or bent pins.
- Check the tow vehicle's fuse box for a blown trailer brake fuse.
- Test the brake controller's manual override to see if it triggers any braking response.
- Check the controller's settings to confirm gain and brake type match your trailer.
- Have a mechanic or trailer shop inspect trailer brake magnets, shoes, or the surge actuator if wiring and the controller check out.
- Have any worn trailer brake components replaced before towing again.
Tools and parts
- Multimeter (helpful for testing connections)
Trailer brake controllerSearch: “trailer brake controller for your tow vehicle”
Trailer brake magnets or shoesSearch: “trailer brake kit for your trailer's axle size”
When to call a pro
See a trailer specialist or mechanic before towing again if trailer brakes aren't responding.
Safety
Use caution
Towing without working trailer brakes significantly increases stopping distance and risk, especially with a heavy load; don't tow until this is fixed.