Troubleshooting Brakes not Functioning after Adding Brakes on Tandem Axle Trailer

Question:

I recently replaced/added brakes to both axles 3500lb on my car trailer. It had a single axle brake setup so I added another set of brakes during this project. They are 10inch self adjusting units. Now when I apply the brakes at full power the trailer does not stop well and it pulls to one side. It feels like the trailer is not getting enough power to one side. I have used the trailer for a 500 mile tow so I would think that the brakes are broken in and adjusted by now. The wiring runs down the left frame rail, feeds the left side brakes and then crosses through the stock wiring in one of the axles where it feeds the right side. When I installed the second set of brakes I only added jumper wires to the new set. Do I need to upgrade the wiring and possibly run it down both sides of the trailer? My theory is that the additional draw from a second set of brakes is causing voltage on the far from a wiring perspective brakes. If I need to add wiring should I run cables down both sides and what gauge should I run?

asked by: Sean M

Expert Reply:

The first thing I would check would be the grounds of the brake assemblies on the side of the trailer that does not seem to be working properly. If the grounds are not making solid connections the brakes would not activate.

You should also check for voltage at every brake assembly. You would do this by having a buddy activate the override function of your brake controller while you use a circuit tester like # PTW2993 to see if there is voltage on the circuit.

As long as you used adequate gauge wire when you wired up your brake assemblies the way you wired up your brake assemblies should be fine.

I attached an FAQ on trailer wiring for you to check out also.

expert reply by: Jameson C