Trailer Dome Lights - GMC Denali
 

Hi All,

Since purchasing our '98 Wells Cargo Autowagon, we have not had trailer interior dome lights. All exterior lights work just fine. We always thought it was something trailer related until a friend hooked up his truck to the trailer and sure enough the inside lights work.

Now we're thinking it's two vehicle related (we have a 2012 GMC Denali). All fuses look good. Even replaced a few just to be safe.

What else could it be? Anyone have similar problems?

Thanks,
Dave

Sounds like your friend's truck enables something that yours doesn't, currently. I may be able to assist with the GMC. What kind of truck does your friend have, that allows the lights to work?

John

He has a mid 1970's Ford stake-bed truck. Nothing modern...

Thanks,
Dave

I think there is a fuse that you have to add to the underhood "BEC" ("bussed electrical center").

It is a "J Case" fuse that will get you B+ to your trailer connector at the rear of the vehicle.

See if there is a red "dummy fuse" in the Stud 1 location (location 68). Replace that with an actual fuse.

http://www.autogenius.info/gmc-yukon...e-box-diagram/

I'm going from memory here so I do not recall what size fuse.

K

When your 7 wire plug setup was wired in to the Denali they may not have used the auxiliary wire. my 95 Silverado won't power up the interior lights of my hallmark trailer but my 2000 K3500 (OBS) will. Same plugs on both. You may find only 6 of the 7 wires are actually being used.


Tommy

On a gm 7 way connector the center round pin is the auxiliary circuit, Check it for + DC voltage

...

Thanks Guys.

Will check.

Best,
Dave

That's what I did on my 2005 Suburban. That took care of it.