Brake wiring harness?

[kburati]

Where does it plug in under the dash, the diagram that came with the harness is so tiny that even with a magnifying glass I can't tell which location. There's 3 that it'll fit in, top left, one over and 3 over I believe.

Also, it says that for truck with the alt HD battery the fuse does not need to be put in under the hood? Is this true? On my 2001 D-Max I had to put the fuse in.

Truck is a new 2007 classic

[JohnC]

Does your '07 look like my '06?

http://www.thedieselpageforums.com/photopost/data/500/P3120001.jpg

I think it really only fits in one of the positions, even though it looks like it might fit elsewhere.

The fuse makes the accessory circuit in the trailer plug hot. The brake controller circuit is already hot (much to my surprise...)

[kburati]

Not sure it looks exactly like that, good ole GM has to change it slightly every year for some reason. Anyways, you're correct that it only really fits in one spot, for me it ended up going in on the top row 3 spots over (I think) and that did illuminate the brake controller. Next step is to put the fuse in and connect to my trailer to make sure I get a connection. I thought the fuse had to go in but the tag on the OEM wiring harness says it's not needed for vehicles with the Alt HD battery. Maybe that means when the Alt HD Battery is an option only, as it is with gas trucks.

[JohnC]

On mine the brakes and lights worked fine without the fuse, but the aux power to the trialer, for internal lighting, didn't work without the fuse. The way the tag was worded made no sense to me...

[DmaxMaverick]

The turn/markers have individual fuses (10 amp each, IIRC), as does the brake circuit in the underhood fuse panel. The 40 amp fuse install is required to power the charge/power circuit to the trailer connector(s). This applies to Diesels. Gasser fuse panels should have the fuse already installed, regardless of how many OEM batteries. (maybe the source of confusion??)

[JohnC]

First, there was no indication of what the 40 amp fuse is for. Silly me figured it was for the brakes. I found out the hard way that was not the case. Foolish of me to think that since the cable and the fuse came attached together, they had something to do with each other...

Here's the "confusing" text:

4) Do only one of the following: (duh...)
1) For vehicles without the TP2 option (auxiliary battery) plug in the 40A B+ trailoring J-Case fuse in the stud #1 location of the UH electrical center.
2) For vehicles with the TP2 option (auxiliary battery): Discard the 40A B+ trailoring J-Case fuse - it is not needed.

When I found out the brake circuit was already hot, I wrongly assumed that second battery under the hood was TP2. Fortunately I was too cheap to discard the fuse...

[kburati]

So now that we have that all straightened out, where exactly does the fuse that's taped to the OEM harness go under the hood? I knew where it went on my 2001 but the instructions that came with that truck were much better.

[Chris Rosenberger]

The 40 amp fuse goes in stud #1. The space a filler plug that you have to remove.