Wiring Electric Brakes to Trailer Without Access to 7-Pin Wiring on Trailer
Question:
Just got a new axle for my single axle trailer. I understand it doesnt matter which wire is ground or coming from break controller. I have hot wire/ brake controller wire on both sides of the frame by the brakes, so I figure just run each wire to each brake and dont splice? The old axle had the ground wire from each brake mounted to the alum. frame with a screw. What they say is dont ground to the frame, can I run a ground wire directly from the trailer battery ground post to each side of the brake wire? The trailer battery is just grounded to the frame inside the battery box. I can not get to the axle trailer 7 pin wiring, the bottom of the trailer is sealed/closed.
asked by: Bradley B
Expert Reply:
Yes, it doesn't matter which wire is ground and which one is the power wire coming from the brake assemblies. If you have a brake wire on each side of the trailer, you do not have to splice. You can use a brake wire for each side.
Since the trailer is aluminum you cannot just ground to the frame because it does not conduct electricity well. The aluminum trailer probably has a hard metal core which is why the manufacturer was able to ground into the frame with screws. You won't be able to access that unless the original wires where the brakes were grounded are still there. If they are still there, you can connect the brake assemblies ground wires to them.
If the original wires are not still there you want to ground the brakes to the 7-way connector ground wire. Your best option is to find a place to splice into the 7-way trailer connector ground wire. Even if you have to cut all the wiring and install a junction box like part # 38656.
With that being said, if your trailer battery is grounded to the frame at the same location as the 7-way connector is then grounding the braking assemblies to the negative battery post works. You could also ground the brake assemblies to the negative post on the battery then connect a ground wire from the negative battery post to the ground wire on the 7-way. Although this doesn't sound like an easy option for you or you wouldn't have asked about grounding to the battery.
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