getting 12V to red power feed in trailer/camper wire harness

[akrockhound]

Brand new Duramax with HD trailer and camper/fifth wheel wiring harnesses.

There's no power in the red 12V "power feed" wire in either harness (I think there actually branches off the same harness). In older models this only required putting in a fuse in the appropriate vacant slot in the fuse box. However I can't find a vacant fuse slot and the diagrams in the owner's manual and on the fuse box covers don't help. Local RV equipment installer had a look and said "good question". Dealer isn't much help yet, but waiting to talk to another tech.

The other wires like turn signals and running lts have juice so it's not a matter of not having the harnesses connected somewhere.

It is a 2500HD ext cab.

[Idle_Chatter]

Rockhound, I can't be sure about your '03, but according to my '01 service manual, the trailer and camper 12v feed line (red line 742 - trailer connector pin E) comes off Stud 1 on the underhood box through a 40A Maxifuse. Hope this helps.

[zip]

Hi hound--
Man, I'm shootin from the hip on this, but the lack of 12 v dc could be because there is an isolator in the power line. With the key turned off, the 12v is not present. But with the key on it should be there. the problem I'm having with that statement is the power you're getting in the other wires. Someone will post an answer tho-- hang in there.
On my '02, the owner's manual showed the 7 pin towing wiring schematic. Seems like I had to open the power distribution box under the hood-drivers side- and install a 40 amp fuse to give me power for the towing wiring. I'm at work and don't have the manual in front of me. The info you need is in there tho. G'luck
zip

[zip]

Now that I think about it, it makes sense not to have ALL the wires being energized by the main hot lead. That way, in case the 40 amp blows out you still have power to the running lights, turn signals, etc. in your vehicle.
zip

[BigLakeDMAX]

I think I heard somewhere that GM saved a couple of bucks and shipped the '03's with a dummy 40 amp maxi-fuse in the #1 stud location in the driver side under hood fuse box. Replace that with the real thing and you should be good to go.

[railbuff]

Today, I installedthe brake controller (Jordan) in my new 2003 2500HD. The brake controller harness that came with the truck ($Can60) also had a 40A fuse which had to be installed in the underhood fuse box on post #1. This fuse box is located on the left hand side of the engine and has a removable cover about 10"square. (I am guessing the size, and since it is raining, I am not going outside to look).
To locate this post, stand by the left hand front fender and remove the cover. Since you are now looking across the engine bay, Post #1 is at your top left hand corner. The space in mine was occupied by a red blank which I removed and re located it in a spare hole.
Hope that helps.

[railbuff]

Today, I installedthe brake controller (Jordan) in my new 2003 2500HD. The brake controller harness that came with the truck ($Can60) also had a 40A fuse which had to be installed in the underhood fuse box on post #1. This fuse box is located on the left hand side of the engine and has a removable cover about 10"square. (I am guessing the size, and since it is raining, I am not going outside to look).
To locate this post, stand by the left hand front fender and remove the cover. Since you are now looking across the engine bay, Post #1 is at your top left hand corner. The space in mine was occupied by a red blank which I removed and re located it in a spare hole.
Hope that helps.