Second Gen - Wires Through Firewall

I could've sworn I saw another thread, but I cant seem to find it. I'm aware of slipping a few wires through the main boot in the firewall, but what if I have more? I'm rerunning all of my wiring from a new aux fuse block. I have a wire loom about 1/2" in diameter that has the wiring for my aux. lights, seat warmers, cb radio, and aux. power port. I admit I haven't checked, but I don't think there will be room in the main boot to slip this by. Where is a safe place to run something this size through the firewall?

 

You should be OK going through the standard grommet. I'd double check your specific Truck, but I recently ran a fuse tap through it, and the fuse tap was at least 1/2'' tall, and the X cut I made would definitely fit a 1/2'' bundle. I went through Bottom-Left (below the stock main bundle). However, this has some tips going through the firewall itself (warranted it's 3rd Gen, same applies). https://www.tacomaworld.com/threads/wiring-through-firewall.566766/

Cheers.

 

Thanks for the info! I'm planning on doing this work on Thursday, so I'll find out for sure then. I like to do as much research as I can beforehand so I don't end up getting stuck somewhere.

 

Should fit through the main boot with no issues. I ran some 1/0 gauge plus a few smaller wires through with no issues and 1/0 is pretty close to 1/2" diameter.

 

There is also an unused hole on the passenger side firewall. It has a plug. Remove the plug and you can run your wires. I ran an oversized 4 gauge wire through it for my amp.

 

Another option to the suggestions listed above would be to get a custom firewall grommet.

-J

 

I used the passenger side grommet with a 6x 16awg wire. Worked out great.

 

Thanks for all the replies, its good to know i have a couple of options!

 

Did you just poke multiple holes in the boot? I need to run 3-4 runs of 1/0 and I’m still undecided on drilling out holes for aftermarket grommets or poking up the stock boot. A quick picture would do wonders if you don’t mind.

 

3 to 4 runs of 1/0? Are you powering up multiple amplifiers? I'm just concerned because you could be looking at an electrical fire if your wires aren't protected well enough to pass through the firewall.

-J

 

So I have already found some adapters from home depot that I would be use if I go the firewall hole drilling route. They are plastic pieces that screw together with an internal plastic seal to keep any water out. I they they’re originally for routing copper pipe through sheet metal or something but they fit 1/0 wire perfectly. The issue is that there isn’t many spots on the drivers side fire wall that are flat and void of internals within the wall. Plus drilling permanent holes makes me worried I’ll mess up or whatever.

But yes, the runs (probably just 3 for now) are for my big audio system build that I’m doing. 1 run for my sub amp, 1 run for my speaker amp, and 1 run that will split off to several 4ga strands to power my tweets amp, a fuse panel that will power my dsp and any other miscellaneous electronics in the rear. I have an XS power D3100 and will be getting a 240 alt soon.

this firewall issue is the only thing holding me back right now and I haven’t found a great solution anywhere besides drilling :/

 

You're probably going to have to look at getting a step-drill and enlarging one of the preexisting grommet spots on the firewall. If you cant get it to lay flat against the body of the truck, you can fill small voids with some FIPG. I believe the red stuff is the high temp RTV. I would seal the engine side but you may get adequate results sealing in the cab. Is the plastic PVC? Id be concerned with it melting from the heat but your mileage may vary, rubber bushings/grommets would be best choice.

There are a few choices for larger grommets if you look under the cab beneath the seats. There's also an opening on the back of the cab that's used as a vent, however you'll need a lot of wire to route all the way back there and you will experience voltage drops over that length of wire but if you do a battery relocate to the bed of the truck, this might be a better choice.

-J

 

That’s a very good point regarding the PVC plastic. Pretty sure that’s what it is. I guess I’ll try and find a 3 pack of grommets online and go with those instead. Thanks for that advice.

I experimented a while back on using the holes near the seats and that would work, but the issue is that I would have to route the wires close to the exhaust manifold in order to get them to run along the frame to where the hole is. Unless I’m missing another path?

 

Maybe something like some heat sleeving over the wire that is near the exhaust?

-J

 

An easy one is the AC condensate drain hose. Pull the hose, run the wire(s) replace the hose. There is no bare metal (at least on my truck) were the hose goe through the fire wall.

I drilled an access point just above and to the right of the main harness. The red arrow is the added access point while the green arrow is the main harness.

BTW, the picture was taken after a 4,000 plus mile road trip over 3 months through quite a few dust storms, smoke from wildfires and some snow.

 

When I ran power to the bed from the engine I used alum foil tape as a wrap over the plastic accordion sheathing the wires run in.

 

Here is a tip you probably know.
If you don’t have soapy water you can use KY for as lube for easier insertion.

 

Its a possibility, but I am skeptical about the one you linked being able to reflect 90% of radiant heat. I don’t have the truck near by at the moment, but if I recall, there is about 5-6 inches from the manifold to the side of the bay.

I was planning on working on the truck this weekend anyways so I’ll do some experimenting with runs to see what will be the best. I’ve had this project on the back burner for way too long.

 

Are you running it down back behind the battery? Like right next to the exhaust?

 

Yes but on the RH side positioned as far from the manifold as possible, from what I could tell there's not much difference in that regard on ether side.

The wiring follows the RH frame rail from the bed all the way to the firewall staying on the same side. Where it curves up toward the UCA along the exh is where the foil tape is used. I saw no reason to cross over to the drivers side before that, I cross over on the firewall towards the top. From there it goes to a circuit breaker behind the battery mounted on the inner fender wall. I worked in the electrical industry and we used high strength nylon tiewraps in critical locations, that's what I use to attach the wiring to the frame rails.