As I continue add accessories to my truck, I am running out of options for passing wires thru the firewall.
Has anyone ever drilled thru the firewall for access? Did you use a grommet to seal it?

You definately can do that. Make sure there is nothing on the other side and try to keep the drill but from going through to far. A step drill works good for that. You can also use one of the existing gromets and poke through them. The only thing wrong with that is if that wire harness ever has to be changed your wires will be cut. That is a very rare occurance though.

MaineMax,

DmaxalliTech (Eric) showed me a spot to the left of the bottom bolts of the master cyl, just under the edge of that "felt" cover on the firewall, and in between the master cyl and the main wire harness going into the cab. It's a simple dimple in the sheetmetal. In the first two pics, its at the end of the orange "pointer". It's not easy to get a drill in there, but it is possible. It may be easier if the inner wheel well were removed, but I didn't explore it that far.
This spot exits out a pre-cut hole in the rubber firewall insulation inside the cab. How convienient!!! ):h On my '02, there are two of these holes, both to the left of the steering column and "hidden" behind that "electrical box" mounted to the lower firewall, next to the brake pedal. You can see the upper one in the pic with the box there, the lower one is the one you'll be using, but it is directly behind that elec box. You can see the green wire for my high idle above the box, follow that back, and there is the door! I used a 1/2" drill and a gromment from Eric, but I'm sure you could use a bigger size if you wanted to. I made sure to move that elec box before I stated drilling, IIRC it was one bolt. Simple.

My pic quality isn't real good, but I hope this helps.

Tom http://dieselplace.com/forum/attachment.php?attachmentid=107&stc=1

I drilled here:

http://image05.webshots.com/5/9/91/29/62999129kALUYB_ph.jpg


T:cool: NY

I started with a high idle wire, then the brakesmart sensor cable, next ? Next will be attitude, or Boost/EGT, driving lights, etc. If I had to do it all over again I would drill at least a one inch whole through the standard area (obvious area on the firewall with a cutout in the felt mesh) and install a quality pass through instead of just a grommet. not sure what they are called, but a pass through with a short threaded tube and a nut on both sides. You can "fill" the area around the wires with foam ( pipe insultation or whatever) to cut down on air and noise in the cabin and keep filling with wires until full.

Tony, I'll bet thats where the "upper" precut hole comes in from the engine compartment....I couldn't find where that one went...Thanks.


Tom http://dieselplace.com/forum/attachment.php?attachmentid=107&stc=1