trailer wiring "short or ?" new wiring harness?

[hoosiermark]

Bought a 10 yr old car trailer. Noticed when I put the turn signals on the side marker lights flashed also (during the day). At night now I notice I lose all lights when I hit the brakes. I also noticed that the side markers have both wires hooked up to wiring. I always thought one was the ground and one the hot wire from truck. It only has one bulb and one filament.
I need to rewire the trailer and would like to find a ready made trailer harness. I know they make them for small trailers, do they make them for larger ones?

[Turtle_n_Peeps]

K Charles wrote:
fix the ground wire, it's loose somewhere.

This ^^^^^^^^^^^^. Fix that and your issues will go away.

[ScottG]

Somewhere you are lacking a ground and the circuit effected is grounding through the filament of a light bulb.

[RoyB]

I picked up one of these 7-way trailer connector adapter and this helps me eliminate the trouble source.

If this works normal when plugged into the truck side then the trouble is on the trailer side...



GOTO ETRAILER.COM and read up on how the trailers are wired up. might give you some ideas on where to check for problems..

A BAD FRAME ground or burned out/shorted 12VDC bulbs does strange things to trailer safety lights.

I also spray some WD40 into my trailer plug before hooking up and wiggle things around alot to clean up the connectors. This solves problems for me sometimes...

Roy Ken

[Heavy_Metal_Doc]

I see a fellow GJ'r is also an RV'r 🙂

Both wires of any light can be hooked into the harness if the trailer has been wired with a dedicated ground circuit all the way through to the connector plug. Many better quality lights are made with a ground wire, they don't all just rely on a mounting screw to ground through. This is better, IMO, than relying on a ground jumper from the plug and then bonded to the trailer frame and then all lights also bonded to the frame -- this has more weather-affected connections and more potential for a corrosion to interrupt the grounding....of course, a dedicated ground wire run throughout needs to have good connections to be any better....



There are modular harness systems designed for big truck type trailers (tractor trailers). They are very nice and weatherproof, but are very expensive. Too expensive for the private user to spend that kinda money on one little landscape / utility trailer / camper. Most people just get a roll of the 4-wire trailer cable and go to work hooking it up. I have used some SO cord (rubbery type extension cord wiring) as it is a little better protected - no wrap / loom needed in a harsher environment, just string it from connection to connection and secure it with wire ties.

[rhagfo]

Start with the basics,
Make sure the connector on the TV is wired correctly and the ground pin is grounded to the frame.

Make sure the trailer connector is wired correctly, that the ground pin is also tied to the frame of the trailer. You will likely find your issue.

[K_Charles]

fix the ground wire, it's loose somewhere.