Trailer Battery (Pin7) not working

[Rukus]

2017 Silverado Crew LT Z71

When I bought the truck the fuse was blown (portion #2/30A fuse) for the trailer battery.   This also powered the interior lights in the trailer.   I replaced the fuse (trailer not connected) and the fuse blew instantly.  Tried another with same result (of course).  Took to dealer and they "no trouble found".   I pulled the fuse and they had a new one put in.  I took truck home and tested the fuse and it is good.   However, lights still do not work on the trailer.  (tried 2 trailers and get same results.) I have little trust for this dealer (for various reasons but it is where I bought the truck from 2 weeks ago.  I fear they just disconnected the trailer wiring for pin 7.  Any way I can check this?  Ultimate goal is to fix the issue.   Could care less about the dealer being shady.   Not a fan of the service Dept. at this point but just need the damn things work.  I know the trailers work as I tested them with my Jeep and they (1 of the trailers to be honest) worked 3 weeks ago with the 2015 I traded in.   Other trailer was about 2.5 -3 months ago.   Again, any ideas on how I can resolve this issue?   I am mechanically (and electronically) proficient.  

[silveradosid]

here is the wiring

 

trailer wiring.pdf

[vinemann12]

Its time to get out the DVM / Digital Volt Meter or basic VOM to trouble shoot your power / ground issue..

Problem "could" be deffective relay,  wire crimp in harness or bad connector.

When fuse keeps blowing, grounded-power is usually the case..

Its unfortunate that some dealer techs have no clue on basic wiring..

 

Cheers----K

[aseibel]

To solve your fuses blowing, you need to inspect that wire to see if there is any damaged insulation on it, or its pinched, or pulled out of the trailer harness. If it shorts out instantly, its touching bare metal somewhere.

[Rukus]

Thanks for the info.... I fixed the issue myself... in the cold... on my 2 week old truck... that the dealer couldn't.  traced the lead back until I found a pinched group of wires.  (3 wires locked damaged/fixed all).   Good to go now.  If only the "mechanic" knew his ass for a hole in the ground.  The strike here cleaned out ll the good ones.   I, of course, will no longer go to that dealer.