Troubleshooting Electric Trailer Brake Wiring Voltage Issues

Question:

i have 3 car trailer 10 15 k electrical brakes not work i chek all and change all not work like bed power only 5 volt in one tires

asked by: Valentyn

Expert Reply:

It sounds like you have replaced your brake assemblies and still are experiencing issues due to wiring. I recommend first using your meter like # PT89ZR or circuit tester like # PTW2993 on your 7-way on the 5 o'clock pin. That is the pin from your brake controller. Using the manual override on your brake controller you should be getting 12V power on that brake controller output pin. If you are not seeing the gradual increase when hitting your manual override on your controller, there is an issue on the vehicle side and you will want to test your brake controller itself for function. I've attached an article to assist.

If you are getting the correct power at the back of your vehicle with the trailer disconnected, then I recommend checking your trailer wiring. You will want to make sure the ground wire of your trailer is attached to the frame where there is no rust, corrosion, or debris and the connection is bare metal to metal. You will also want each ground on your electric brake magnets to have the same connection of bare metal to metal at each of their ground locations. Next, check the wire leading from your 7-way to your brakes. I recommend using # 10-1-1 or # 12-1-1 for your wiring. If you have any issues with your trailer wiring, I recommend using the 7-Way Molded Trailer Plug with Junction Box # HS381-9000 and ring terminals # 44-5310A. This will allow you to test each function as needed and give you a clean connection for each.