Troubleshooting Blown Vehicle Fuses Every Time Trailer is Connected
Question:
I keep blowing fuses on my truck when I plug my trailer in. The turn signals and brake lights will still work but no running lights
asked by: Joseph S
Expert Reply:
It sounds like there is a short somewhere along the wiring of your vehicle or trailer that is causing a fuse to blow every time you connect.
The first thing I recommend doing is disconnecting the trailer and using a circuit tester like # PTW2993 to test the vehicle side connector. You can have a buddy run through the functions from inside the vehicle while you test each pin on the connector. If you detect any power to a circuit when there should not be any, then you know there is a short somewhere on the vehicle side. Simply trace along the wiring and look for any exposed areas that might be touching bare metal.
Also check that both the vehicle side and trailer side connectors are free of dirt and corrosion. If the connector is corroded or dirty, it can cause excess power draw and blow a fuse. Simply clean out as needed.
If everything checks out fine on the vehicle side, then you will want to check along the wiring for the trailer, again looking for any damaged or exposed wiring. You can also test the trailer wiring for function by connecting each wire to a 12V battery. Lastly, make sure that the main trailer connector ground and all the light grounds are securely attached to clean bare metal surfaces.
If you are unable to find the issue, please let me know and I will be happy to look into this further.
Ge
3/25/2020
Good morning my trailer battery fuse keeps blowing any suggestions where I can look?
Chris R.
3/25/2020
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on Wiring
Andrew F.
5/12/2020
Good afternoon, I recently replaced my 4-pin on my boat trailer. The original 4-pin on it had 7 wires going to it. 1-yellow, 1-green, 2-brown, 3-whites. The new 4-pin only has 4 wires, yellow, green, brown, white. When I spliced them together, I put each color together (therefore there were 3 white wires I spliced to the 1 white wire on the connector and 2 browns to the 1 brown on the connector). When I plugged it in, it all worked but by the time I got my boat to storage and unplugged then replugged it in, I noticed the lights didn't work anymore. Turns out I blew 2-20amp fuses. I wanted to inquire if this could have been caused by my splicings of the different colored wires touching (at the time, they weren't heat shrinked and could have touched the other exposed wires I spliced together in transit to storage), or if it could be overloading the ground wires having 4 wires all connected? Thank you for your assistance.