Trailer wiring questions

[2310 guy]

I have a wiring problem right now on my tandem axle car hauler. I'm doing the wiring job myself. My question is does the dual filament light share one filament for turn signal and brake while other filament is used for running light? Because thats the way I have it wired. I'm assuming the tow vehicle will control the brake light and turn signal.

The problem right now is both right and left running lights are working, so are the brake lights. But when I try the turn signals only the lift side works. The crazy part is when I disconnect the left side and power up the right side the left side still works???? Some how power is back feeding to the left side while disconnected and still getting power.

Does anybody know what is causing this. I thinking a turnsignal is shorting to ground.... maybe.... or the light assembly is junk on the right side.

Any help would be great, Thanks in advance.

 

[billyvan]

I have a wiring problem right now on my tandem axle car hauler. I'm doing the wiring job myself. My question is does the dual filament light share one filament for turn signal and brake while other filament is used for running light? Because thats the way I have it wired. I'm assuming the tow vehicle will control the brake light and turn signal.

The problem right now is both right and left running lights are working, so are the brake lights. But when I try the turn signals only the lift side works. The crazy part is when I disconnect the left side and power up the right side the left side still works???? Some how power is back feeding to the left side while disconnected and still getting power.

Does anybody know what is causing this. I thinking a turnsignal is shorting to ground.... maybe.... or the light assembly is junk on the right side.

Any help would be great, Thanks in advance.

You are right on the dual element bulb. The turn signal and brake signal share the same element. The other is for the tail lights. So I think your intended wiring is correct. As to what the problem is, well could be many things. Would have to be there with a multimeter to check out your wiring. Sorry, that's all I can tell ya from here!

 

[MikeD74T]

Look here for trouble shooting How to Wire your Car or Truck for Trailer Lights and on that site search for "converter". It sounds like your tow vehicle uses single purpose bulbs for turn & stop?

Otherwize look for bad grounds, they can create weird symtoms. I think every trailer light problem I've ever had was from bad grounds. MikeD74T

 

[aczlan]

The problem right now is both right and left running lights are working, so are the brake lights. But when I try the turn signals only the lift side works. The crazy part is when I disconnect the left side and power up the right side the left side still works???? Some how power is back feeding to the left side while disconnected and still getting power.

what is still working? brake/turn lights or running lights? if it is running lights that is normal, if it is brake/turn lights I would start by getting a 12v power supply and applying power to one pin on the connector at a time, that should let you see if there is a short between wires. the page at How to Wire your Car or Truck for Trailer Lights that MikeD74T linked to is good.
if the trailer checks out, you might need to check the car end... had one on my wife's truck that I thought I did right, until the brakes started kicking in whenever the left turn signal turned on... turns out that I mixed up pins 5 and 2 on the 7 pin receptacle on her truck... I felt really smart (s m a r t e, thats me) after that one.

the concept is simple, just the implementation is a pain at times.


Aaron Z

 

[2310 guy]

what is still working? brake/turn lights or running lights? if it is running lights that is normal, if it is brake/turn lights I would start by getting a 12v power supply and applying power to one pin on the connector at a time, that should let you see if there is a short between wires.

Right now everything works except the right turn signal. (thats with jumping 12v to each wire)
I jump 12v to the left side it works. I jump 12v to the right side, the left side comes on. I disconnect the left side and jump 12v to the right side the left side still comes on, even when the power wire is disconnected.

I'm going to replace all the bulbs after work today, i've seen bad bulbs do wierd things before. I'm also going to make a long jumper wire for my ground wire and go back to the battery. I'll see what happens when the lights have a known "good ground"

 

[Diamondpilot]

I think you need the converter on your tow vehicle also. It will take 5 wires and convert them to 4 wires for the trailer.

Car side 5 wires
gnd
r turn
l turn
running lts
stop

trailer side 4 wires
gnd
r turn/brake
l turn/brake
running lights

Chris

 

[Eagleview]

You guys have a weird wiring system if thats how it's done . Our twin filament bulbs are for the stop and tail lights and the blinkers use a single filament bulb . The way i remember how the wires go is a little silly but it works . I imagine a street traffic light . The "red" light means "stop" , the "red" wire means "stop" ......The "green" light is the "right" light to go through , the "green" wire is the "right" blinker . I hope this is how your wires are colour coded . Just thinking about it , you guys do'nt have a seperate amber lense for your blinkers do you ?

 

[ray66v]

Things I have learned the hard way wiring trailers:

Always run a ground wire from the vehicle to the trailer. Don't rely on the coupler to give you a ground.

Always run a ground wire to EACH light fixture. Don't rely on a mounting bolt to provide as ground.

Always solder all connections, and use shrink tube to protect wire from the elements.

All lights should be Trucklight brand SEALED lights or equivalent.


Now that I have learned to do it right, I NEVER have to unexpectedly fool around getting lights working on a trailer any more.

 

[Diamondpilot]

I hope this is how your wires are colour coded . Just thinking about it , you guys do'nt have a seperate amber lense for your blinkers do you ?

Here in North America some vehicles have separate turn and brake lights in completely separate housings. I guess its not that way where you are from. I just put a hitch on a Subaru Wagon for a lady to tow a small 1,200# utility trailer and had to use a converter. As I stated before the car may have 5 wires and the trailer with no brakes will only need 4 wires so a converter is necessary.

Here is the one I use.
TRAILER LIGHT CONVERTER

Here is how you wire it.
How To Install A Trailer Light Taillight Converter In Your Towing Vehicle

Chris

 

[montejw]

Right now everything works except the right turn signal. (thats with jumping 12v to each wire)
I jump 12v to the left side it works. I jump 12v to the right side, the left side comes on. I disconnect the left side and jump 12v to the right side the left side still comes on, even when the power wire is disconnected.

I'm going to replace all the bulbs after work today, i've seen bad bulbs do wierd things before. I'm also going to make a long jumper wire for my ground wire and go back to the battery. I'll see what happens when the lights have a known "good ground"

Left side what comes on? Brake/signal filament, or taillight filament?

You should have one wire going to both left and right taillight filaments. One to the right side brake/signal filament, and another wire going to the left side brake/signal filament. Ground each light fixture to the trailer frame, then run another wire from the frame into the trailer plug pin. Run another wire from the vehicle plug ground pin to the vehicle frame. No real need to run a ground wire all the way to the battery unless you're running trailer brakes.

Is this all new wiring to new fixtures? I've seen old fixtures grow short circuits between the brake/signal and taillight "wiring" in the fixture and you get the wrong lights coming on.

Are there are only 2 wires coming out of each fixture? Maybe 3 if there's a ground wire.