Troubleshooting 4-Way Trailer Wiring Causing Blown Fuse Each Time Connected

Question:

My trailer lights wiring blows my 7.5 amp small lights fuse every time. Another trailer works fine. Am I correct that you just plug in the flat 4 -wire plug to my SUV trailer wiring connection and thats it, or is there a ground wire to attach somewhere.

asked by: David C

Expert Reply:

Different trailers can have slight differences in materials, and wiring function. Since this trailer blows the fuse in your vehicle every time it is connected, it sounds like there is a short to ground somewhere on your trailer. This bad connection can be anywhere from the trailer connector back, since other trailers work fine with your SUV.

I recommend using a battery to test the wiring functions of your trailer when not connected to your vehicle. You can then use a tester like # PTW2993 to find the short and replace the wire using # 16-1-1. Make sure you have a clean ground connection free of rust, corrosion, or debris that is metal on metal. If you determine you want to add a different harness instead of splicing, I recommend # A10-4225VP. I've attached a trailer wiring article to assist.

expert reply by: Jason S