Trailer harness wiring question

I have a 2012 sr5 dcsb 4x4 with factory hitch and 7 pin connector. The trailer tail lights work, but no brake light or turn signals. At the 7 pin connector on the bumper I have voltage at the appropriate pin for the running lights, when parking lights are on, but have no voltage for brake lights when the truck brakes are on, or turn signals. There is, I believe 1 fuse under the dash for trailer lights, and 2 or 3 under the hood. I checked all of them visually( havent tested with a meter) and they looked good. Any suggestions?

 

Did you wire up the 7pin plug??

If not is it hard wired into the correct wires ??

is it using a converter box to a 4 pin plug to the 7 pin plug??

Does the trailer use the normal combo lights that share the brake and turn signal

Since our Trucks use a separate turn signal

Has it ever worked ??



Flashers and Brake lights work on the truck ??

My first step would be to double check all the wiring and connections.

Starting with the plug itself

 

I did not wire it. It is the factory connector that came on the truck. From the 7pin it goes to the factory plug/ connector under the bed. The most recent trailer I used had the shared lights, but still not the issue since I dont have the proper voltage on the 7 pin when the respective lights are on. Flashers and brakes do work on the truck.

 

Sounds to me like your towing converter relay is bad or possibly the 30 amp towing fuse

 

Weren't some trucks missing a relay even when equipped with the tow package? I seem to rememebrr reading this.

 

Thanks PSU, Ill use that to chase it all down. I think all of the fuses were good, but I didnt check the relay. Do you know if its possible for the tail lights to work, but not brake or turn signals with a bad relay?

 

Yes that would do it. The tail lights are on a seperate circuit. The relay controls the brake and turn signals.

 

Great. Thanks for the info. Ill let you know if that fixes it.

 

Im not sure an easy way to test relays. Kinda throwing spaghetti at a wall at this point. Gonna try to replace the towing tail relay. I picked up a relay from local auto parts store, was the same as every other relay in the fuse box, not the one that I actually needed.

 

relays are quite easy to test .

12vdc one positive and one ground to the coil check the contacts with your meter .

most relays have the pins labeled

Does not take much but a few pieces of wire some alligator clips inline fuse and spade connectors and a volt meter

A extra battery works great but the one in the vehicle works if it is all you have

 

Thanks caribe, Ill check those out.