Only One Brake Light on Trailer??

[imaybail]

Hello, I have read abot 100 articles on trailer wiring, but haven't seen this particular problem yet.

On the trailer I have running lights, left and right turn signals, and the right brake light. Can't figure out why I can't get the left brake light to work. Trailer has LED taillight assemblies.

Connection is a standard 7-Pin RV type plug, and the pins tested at the bumper plug test out right.

By the way, this trailer works fine when hooked up to a Ford van.

Has me stumped.



ben

 

[cojhl2]

Verrrryyyy Interesting!



I'm gonna watch this thread for sure!!

 

[Rudity23]

Do you have an aftermarket stereo? My radio was killing lights and fuses because they hooked up the dimmer circuit to the new stereo. Cut that wire (blue?) and it "may" help your problem.

 

[imaybail]

No aftermarket stereo, the stock RBK radio installed.

I just figured out that the previous owner(or someone) had wired the 7-pin RV connnector in the bumper from the four pin setup that came with the truck from the factory, but the left side signal wire has no signal on it.

Also, tracing the wiring under the dash from the brake controller to the plug and then through the floorboard. When checking the wires under the body just behind the driver's side front tire, there are two wires cut and not in the plug. It does have the two wire harness going back to the bumper for the brake controller circuit.

I have tapped a wire further up the factory harness in the back for the left signal, but haven't found the brake signal for the left side.

I was under the impression that the brake signal would be in a single wire.

Is this the case, or is the brake signal sent on another wire with the directional signals or running lights?

 

[cojhl2]

No aftermarket stereo, the stock RBK radio installed.

I just figured out that the previous owner(or someone) had wired the 7-pin RV connnector in the bumper from the four pin setup that came with the truck from the factory, but the left side signal wire has no signal on it.

Also, tracing the wiring under the dash from the brake controller to the plug and then through the floorboard. When checking the wires under the body just behind the driver's side front tire, there are two wires cut and not in the plug. It does have the two wire harness going back to the bumper for the brake controller circuit.

I have tapped a wire further up the factory harness in the back for the left signal, but haven't found the brake signal for the left side.

I was under the impression that the brake signal would be in a single wire.

Is this the case, or is the brake signal sent on another wire with the directional signals or running lights?

The brake controller is completely seperate from the lights.



The brake circuit at the bumper is two wires, the same as RT and LT.



I don't know how you could have had both brake lights illuminate if the LT is dead. If it is dead at the bumper with the LT signal set, and it works with the brake pedal, then the problem must be in the steering column.



But on the other hand, do the lights on the pickup work correctly? If they do then is is not the column switches.



If it were me I would forget the trailer for a minute, concentrate on the towing vehicle. When that is straight then tap into the lights at the back of the towing vehicle.



Working with wiring done by others is always a real pain!!!!

 

[imaybail]

The brake controller is completely seperate from the lights.



The brake circuit at the bumper is two wires, the same as RT and LT.



I don't know how you could have had both brake lights illuminate if the LT is dead. If it is dead at the bumper with the LT signal set, and it works with the brake pedal, then the problem must be in the steering column.



But on the other hand, do the lights on the pickup work correctly? If they do then is is not the column switches.



If it were me I would forget the trailer for a minute, concentrate on the towing vehicle. When that is straight then tap into the lights at the back of the towing vehicle.



Working with wiring done by others is always a real pain!!!!

You got that right. Just to back up a bit, at first I didn't have left turn signal, but then tapped into that signal and got that working on the trailer. Now the left brake light on the trailer is not working. Trailer light fixtures are LED, so I'm leaning toward that having something to do with it.

I think I'll try it on another trailer to see if that is the case.

ben

 

[Prairie Dog]

It would be helpfull to know what your driving Ben.

If it's an 06 or newer you'll need to make a trip to the dealer as you've likely got a computer problem that calls for a reset.

 

[imaybail]

It would be helpfull to know what your driving Ben.

If it's an 06 or newer you'll need to make a trip to the dealer as you've likely got a computer problem that calls for a reset.

Thanks for the tip Prarie Dog. I filled out my sig line.

 

[DIverson]

I had this same problem with my 06 3500 ram and new 5er cameo by carrage. I found that the right side Turn and brake signals came through one wire light green in color and that the left side brake signal came through a white with tan stripe and the left turn signal came through a white with green stripe. I found it necessary to use a converter made by hoppy to bring these two wires back into one wire that connected to the 7 way connecter at the bumper. There is much more to this story than I can post here I was under my truck for most of four days befor I figured it all out. If you would like to call me I would be willing to give you my phone number.