Troubleshooting Trailer Brakes that Dont Operate With Manual Brake Switch on Brake Controller

Question:

When stopping the trailer brakes lockup, all lights and signals work, controller gives n.c only if I move manual lever and by doing this it does not engage the brakes.brakes lockup when stopping, it feels like full amps ,could this be magnets, trailer is 7500lb 18ft dual axle car trailer it has sat for 2yrs but gets moved around .

asked by: Ty

Expert Reply:

There are a few things that might be causing the issue you describe. You might have an open ground in the brake system, the connector on the trailer or the vehicle might be damaged, corroded or incorrectly wired. Your brake controller might also be faulty.

Perhaps the easiest place to start would be to try the tow vehicle with another trailer that's equipped with electric brakes. If everything works fine with another trailer, then it's a sure bet that the problem is in your trailer wiring.

If you confirm that the problem is in the trailer wiring, first check the connector on the trailer. If it's dirty, damaged or corroded - clean, repair or replace as needed. Check the grounds at the brake magnets and on the trailer tongue. Make sure the ground connections are secure and aren't corroded. Make sure the magnets aren't overly worn. Pull the hubs off and examine the face of the magnets. If they're worn to the point where you can see the copper windings exposed, the magnets should be replaced.

If the brakes still don't work when you try using another trailer, then the problem is likely with the controller itself. I've linked you to a brake controller troubleshooting FAQ and video that you should find helpful.

expert reply by: Mike L