Fuse or relay being your two most likely culprits. I take it they've all worked before and this is a new thing?

 

Yes, this is a new thing. I've had my truck for 15 months and towed a lot of stuff and never had this problem until recently. Checked all the fuses with a test light and found they all work. The owner's manual is useless when it comes to fuse issues. I even brought it to a local garage and had a mechanic friend of mine look at it and he couldn't figure it out either. He didn't have a lot of time and said he would have to study the problem a little further. Any idea where the relay would be?

 

The relay is up under your hood in one of the boxes behind your battery. There are 3 of them, and I'm not sure which one it is that controls the tails/brakes. I'll check my service manual and see what it says. There are also fuses up there, not just in the fuse box in the cab.

 

The relays are next to the positive terminal of the battery. The trailer towing ones are the back two on the passenger side and the front one on the passenger side. The front one one is labeled as "Trailer tow relay 2" in my service manual. The back two are "trailer turn relay LH" and "trailer turn relay RH".

 

that was the issue with my 13 titan. (had those relays from my 07 frontier) and it that's what was needed to solve my problem. trailer lights work like they should !!! me so happy!!! thanks

 

Beat me to it. ^^^^

Can't find my disc to look. Honestly, I doubt it's a relay. They're pretty tough to damage. Might be connections up there though. :dunno:

 

check the two fuses under the steering wheel that what was wrong with mine. replaced with a higher amp fuse no problems since

 

my truck had the same problem , lts work before then all of a sudden my lt traler lt wasnt working. went to the dealer and they said it was the bcm. cost $300 for the bcm and $300 for install. now it works...got lucky it was still under warranty

 

Thanks for all the help. To the last post... what is a BCM?

 

Thanks for all the help. To the last post... what is a BCM?

body control module

Clint

 

I Recently Had This Problem. Checked Fuses Under Hood And Panel In Cab. But There Are Two Fuses Under The Dash Below The Steering Wheel. There Are Two White Fuse Holders. Unsnap The Covers And Check The Fuses. I Had One Bad, Replaced And Problem Solved. Might Be Your Problem Too.

 

There is 1 fuse in the engine compartment fuse block that controls the trailer tail lights that is probably blown. the 2 fuses under the dash by the stearing column is for the brake and turn signal lights. The problem i have is i pop by brake lights some times when i plug into shore power.