solved, wierd trailer light issue
This was a weird one; had a trailer lights problem, truck lights always worked OK.
I had my right side trailer light hot/on all the time, even with key out.
When the right turn signal was turned on it worked properly, blinked.
Brake lights were good and hazards where good.
Weird/dangerous part, when left turn signal was turned on the right side blinked as well, looking like hazards were on.
Found the same issues in the 7 pin and chased it up to the fuse box. When fuses where pulled(prevent any feedback from back of truck), still had same issues. So problem is in front of fuse box. Now I was stumped so I went GOOGLE hunting and weeded through all the “it’s a ground problem” and found it.
Behind the fuse panel is the Blinker/Brake/Hazard Trailer control module. I had replaced these in other trucks but the symptoms were blinkers not working at all. I guess this one shorted out inside the module somehow.
$90 at the local auto parts, this module runs both truck lights and trailer lights even though they have separate fuses for each corner(4 fuses).
More wierd, I pulled the module out before going to the parts store, hate getting the wrong parts. At the time I didn’t know it controlled truck lights, as well, luckily I still remembered my hand signals. So after trying to use my non working turn signals my truck starts surging like it’s out of gas or starving for air. Non working lights I could handle, for a couple blocks, but I dying truck was too much. I pulled over put the module back in and truck ran fine. I don’t know what all systems that module interacts with but it does “stuff”.
Lastly, I should mention this was all found while trailering the boat. I believe the problem could have developed after backing into the water where the electrical connector might have been submerged. Ya I don’t really know I can only guess and try not to do it again.
Might help someone, some day
2011 Wildwood T26BHXL
2004 Yukon XL Denali
43yrs of camping; one lucky guy