Trailer and tow vehicle wiring

[Duke Hardester]

Hello folks,<br />I recently rewired a boating trailer that I am re-doing and found out that the four wire plug on my 95 S-10 was a U-Haul type and wouldn't work with the new plug on the trailer. I purchase a new T-connector that was listed for my truck and installed it and that's where the trouble started. The turn signals on the trailer are real dim and blink real fast and when I disconnect the trailer from my truck, the truck turn signals blink real fast until I put my foot on the brake pedal and then they slow down, but never go out completely. This is not a constant situation. Sometimes they work fine on my truck and sometimes they blink fast. I also purchased a heavy duty flasher because I was told I would need one. It didn't change a thing. All I did was unplug the U haul T-connector and plug in the new one. I am really confused with what looks like it should have been so simple. Any feedback will be appreciated.<br />Thanks

 

[jimr]

Re: Trailer and tow vehicle wiring

sounds like you need to replace your flasher with a heavy duty one and also check your grounds

 

[Duke Hardester]

Re: Trailer and tow vehicle wiring

Thanks jimr for the reply. That's one of the things that I did do and it didn't make any difference. It really comfuses me how my truck will be okay one time and then it messes up again. Why wouldn't be bad all the time?

 

[DJ]

Re: Trailer and tow vehicle wiring

You have a short.<br /><br />Check where and how U Haul tapped into your wiring harness. Sometimes U Haul installs special light bulbs in th rear tail lights.

 

[Duke Hardester]

Re: Trailer and tow vehicle wiring

Thanks DJ,<br />I was a bit leary about jumping into the wiring on my truck not knowing if the plugs for the T-connector were factory installed or if U haul had installed the plugs for the connector. I hate to have to take it somewhere and have someone else find the problem. Something about ego, I think. If that's what I have to do, it may end up at that point. Maybe I will work up enough courage to check it out myself.<br />Thanks again.

 

[cr2k]

Re: Trailer and tow vehicle wiring

As I remember, and it's been awhile, U-Haul uses two separate light wires each with a hot and a ground. This avoids using a trailer ground wire.

This type of wiring is NOT compatible with a standard flat 4 plug which most all boat trailers use.

My guess is you need to ground your trailer (the WHITE wire on a flat 4 plug) because grounding through the trailer ball is not good enough and intermittent.
Use a test light and see which wires are your turn signals L & R they go to the Green and yellow wires on the flat 4 the brown is the tail/side lights.

If your trailer has disk brakes you need a flat 5 and the blue wire goes to the back up lights.

Hope this gives you some direction.

 

[Silvertip]

Re: Trailer and tow vehicle wiring

You cannot get by without a trailer ground. The lights demand one or they won't work. You also don't have a short or you would be replacing fuses. What you do need is use a test light and verify that the truck is working properly. There is nothing special about S-10 trailer light wiring so either you have the wrong "T" adapter or you have some other wiring issues on the truck. You are dealing with only four wires on the truck and trailer so this is not difficult to figure out. The white wire on the trailer is ground and must be attached securely to the trailer frame. Brown is tail and running lights. That wire splits and runs to the dimmer tail light filament and the side marker lights. The green and yellow wires feed the brighter filament on each light for the brake and turn signals.

 

[caperman]

Re: Trailer and tow vehicle wiring

most of the time you will find a bad ground under your truck on the frame,thats where the trucks rear lights grounds to,found lots with that prob..
hope that helps

 

[redone4x4]

Re: Trailer and tow vehicle wiring

Haha, this was from 2004!!! still good info though...

 

[escapade]

Re: Trailer and tow vehicle wiring

back from the dead