Troubleshooting Brake Magnets On Boat Trailer Losing Voltage When All 4 Brakes Are Connected
Question:
My 2008 F350 brake controller works fine on several other tandem axle trailers but not my boat trailer, it tells me the trailer is not connected. When I pull the breakaway pin the brakes are weak. I have tested each brake independently by connecting each to a battery and they all work perfectly. I have also tested the braking system by connecting each brake in series and pulling the breakaway pin, brake 1, then brakes 1and 2, then brakes 1,2, and 3 then with all four the brakes become weak. I have repeated this process in reverse and again brakes 4,3, and 2 work great until I attach brake 1 then all four are weak. In all cases the TV tells me the trailer in not connected. Each brake in the series has 12V, and the resistance across each is 3.5 Ohms 10inch drums. My conclusion is that for some reason my system, though no wiring connection issue can be found, cannot carry the load of a fourth brake. This is not the case with my other tandem axle, 4 brake trailers with identical wiring, other than initially having a smaller gauge wire, which I replaced with larger 10 gauge wire with no positive results.
asked by: Brad S
Expert Reply:
It sounds like you have already done quite a bit of troubleshooting on why your electric trailer brakes are losing voltage when all 4 brakes are getting power.
I recommend checking that the grounds on each brake magnet are securely connected to the frame in a location that is corrosion free. A loose ground could cause the voltage ground you are experiencing.
If the grounds are securely connected but your boat trailer has an aluminum frame you may need to jump the grounds to the main ground on the trailer tongue, as aluminum is pretty hard to get a good ground on.
Besides this the only other option would be going ahead and replacing all of the wiring going from the 7-way connector to each brake magnet using # 10-1-1.
Please let me know what you find.
