Wiring through your firewall (AMP wiring)

[Wiscon_Mark]

After I figured out how to get through the firewall of my 2nd gen Legacy, with much help from 2deadlegs, if figured I'd take some pics and show everyone how to do it. This'll work for anything you want to wire in between the cabin and the engine bay.
https://sl-i.net/FORUM/images/imported/2005/06/IMG_5020Text-1.jpg
Make sure when you take that rubber stopper out (or push it in with your screwdriver) that you don't lose it. I did, and I have to seal it up now, using alternative methods.
https://sl-i.net/FORUM/images/imported/2005/06/IMG_5536text-1.jpg
https://sl-i.net/FORUM/images/imported/2005/06/IMG_5547text-1.jpg
Seal this up using some duct tape (or if you save the stopper, cut a hole in it and wire through) and then use some silicone to seal it so water doesn't get into the insulation. MOLD!!!
https://sl-i.net/FORUM/images/imported/2005/06/IMG_5549text-1.jpg
https://sl-i.net/FORUM/images/imported/2005/06/IMG_5546text-1.jpg
https://sl-i.net/FORUM/images/imported/2005/06/IMG_5554text-2.jpg
If you have a fuse holder, do not put the fuse in until everything is wired up properly (including to the amp). You don't want to ground out or electrify yourself.
https://sl-i.net/FORUM/images/imported/2005/06/IMG_5550text-2.jpg
It should be made clear (because it isn't in the text on the picture) that you want to keep the audio signal wires (RCA) away from the power wires. Why? Because of noise interference caused by the electricity. I put them on either sides of the center console, which should be enough, but you may opt to wire them around along the doors (unclearly mentioned in the caption above) on the outside, which would keep them better out of sight, but is a harder job to do.
https://sl-i.net/FORUM/images/imported/2005/06/IMG_5557text-2.jpg
https://sl-i.net/FORUM/images/imported/2005/06/IMG_5558text-2.jpg
https://sl-i.net/FORUM/images/imported/2005/06/IMG_5551text-2.jpg
I found that the screw underneath the carpet was too strong, so I peeled back the plastic cover over the strut tower and used one of those and it worked fine.
Much credit goes to 2deadlegs for helping me out on this one! Hope this saves you some money if you need to wire a wiring kit and don't want 'professional install' Good luck!

[pdawg]

great write up

[2deadlegs]

It's shake and bake...and I helped.

[belladonna]

nice write up mark...very clear on steps taken and the pictures help... :-D

[Wiscon_Mark]

...and the pictures help... :-D
Unless you have a 56K connection. Sorry to the folks with dialup! :?

[SubaruGenki]

Why didnt you run along the sides so you dont have ugly wires kickin it in your backseat? The edges along the doors just pop right out so you can keep the wires out of site. When im not lazy i will take a pic to illustrate.

[Wiscon_Mark]

I did mention that...although peeling up the panels has never been easy for me. The center was easy to tuck it under and I fixed the "I see your wires!" problem with my current setup. the main point of the entire thing was to get the wiring through the firewall, after that, its really up to you.

[Disturbed_beast]

OOOOH so it wouldn't been easier to put it through the side panels that's where most of the wiring is becuase that's what i did so there was no wires showing, but all-n-all nice tip for the firewall

[galek_98gt]

there is a flaw though. for those like myself that have a hydraulic clutch it won't work. i put mine through the fender anyway.

[Wiscon_Mark]

What? I have a manual transmission...this is just an unused plug, doesn't matter what car.

[galek_98gt]

after closer inspection i'm gonna recant what i said before. i had to move some hoses to see it but there is that extra hole with the plug in the firewall.

[96subeast]

this is an awsome write up, if you take your time you can get the wires under the carpet in the back, other than that its all teh same on a sedan, except you remove the seat and thread the wire through the bar under the seat. but for the carpet you might have to pulls it up a bit ill take pics to help but how fo you convert them for this

[xcntrk75]

What? I have a manual transmission...this is just an unused plug, doesn't matter what car.
??? Where’s your clutch master cylinder which occupies that area? I don’t have that hole, the only one I had right there was for the clutch cylinder.

Note: there’s also a convenient one down below the brake-booster, which is accessible underneath the pedals.

[xcntrk75]

EDIT: okay I lied.. I do have it there too.. The reason I choose not to mess with it is because your chassis harness is directly behind that hole on the inside. You better be VERY careful running things through that hole as to not interfere with the chassis harness. Like a stabbing screw-driver for example... :shock:

SEE... (http://66.49.172.173/subaru/swap/swapSPF/Image021.jpg)

[Wiscon_Mark]

??? Where’s your clutch master cylinder which occupies that area? I don’t have that hole, the only one I had right there was for the clutch cylinder.

Note: there’s also a convenient one down below the brake-booster, which is accessible underneath the pedals.

Cable Clutch here :|

But there's still some empty holes, as you mentioned.

[subba]

running the power, remote and rca wires together might cause engine noise in the system.

--------------------------------------------------------------------------------
Sorry I Edited the post after i relooked at the pics.
Great Write up, but i had to seach like hell for mine at first :P

my wagon is a JDM so it was more visible.

[Wiscon_Mark]

running the power, remote and rca wires together might cause engine noise in the system.

yes, I mentioned that, and have since changed it.

[subba]

i left my rubber thing on cuz the heat from the engine and dust was tormenting me when i was driving.
https://sl-i.net/FORUM/images/imported/2006/11/IMG_0557-1.jpg

[Reason]

Mark are you really running your wires over the tranny hump like that?

[Wiscon_Mark]

Mark are you really running your wires over the tranny hump like that?

I was, when there as a garbage can setup on that hump (so the wires were covered). Now I'm running them under the rear floormats.

[subba]

good thing you decided to do the steps at that stage, prob if u did it neat the first time it would have been harder to understand

[Reason]

Maybe next time you do (if you do, or anyone else setting up a amp) run them through the floor panels. You can't see wires and dont have to worry about someone screwing up the wires with their feet.

[Wiscon_Mark]

That's been mentioned before in this thread as well, Shane...

[Reason]

That's been mentioned before in this thread as well, Shane...

lol I was too lazt to read all the posts :grin:

[95legacyl]

just out of curiousity what subs/amp are you running

[Wiscon_Mark]

Just a simple self-powered Bazooka Bass Tube. Nothing fancy.

[Aken]

That's a tiny power wire :D

Just wanted to quote on a couple things for future reference to people who aren't very experienced with stereos.


Seal this up using some duct tape (or if you save the stopper, cut a hole in it and wire through) and then use some silicone to seal it so water doesn't get into the insulation. MOLD!!!
Definitely seal up holes as best as you can. After driving through an entire Wisconsin winter with a very open grommet, you'll definitely want to keep your warmth :D You can also get some really funky wind patterns, even with just a tiny grommet opening.



If you have a fuse holder, do not put the fuse in until everything is wired up properly (including to the amp). You don't want to ground out or electrify yourself.
There should never be an IF regarding a fuse on a stereo or any other aftermarket wire coming off the battery. ALWAYS fuse wires coming off the battery. And yes, please put the fuse in LAST to avoid live power wires romping around free.

Just a couple of tidbits :) Carry on.

[Wiscon_Mark]

I said duct tape? Wow, I don't remember that.

I used silicone caulking instead. 100% sealed.

[cyberbackpacker]

Check these out:

http://www.cardomain.com/item/STIPG12

Description:

This professional style grommet allows you to pass power wire through the firewall or any other flat surface while maintaining a water and wind tight seal. The ultimate way to seal wires through surfaces up to 1/2" thick. Accepts 4 gauge wire, and requires a 7/8" diameter hole.

They also come in 0awg and 8awg sizes. This is THE way to run your amp wires through your firewall. Pull the plug- insert this grommet through engine bay, tighten nut on inside of car, put cap over wire, run wire through grommet, and once the wire is positioned where you want it, hand tighten down the cap on the grommet.

Perfect seal.

[kyle86na]

Since It was nice last night, I ran power for my amp... I found a nice hole to use...

I will take pictures tonight after work..

Directly above the clutch pedal, there was a "punch out" in the carpet, I said Hmmm, I wonder if this goes through; I stuck my flashlight in there.. Low and behold, I could see the light. I was a tight fit to get my hand in there but I fed the cable down and pulled it through.

I fed the wire up and over the steering column, running behind the mounting bracket for the accel. pedal, and through the center console and back to the rear... I will probably fill the hole with insulation foam, or I may leave it as is. it was just a piece of felt blocking the hole before so I am sure its fine...

[chipLRX-SLI]

i ran my amp wire through the hole in the firewall . worked great. i have a wrx carpet swap so my amp and crossover and all wires are hidden under the carpet . great write up very usefull

[WinterKnoll]

Is this relatively similar for a 2001 Outback? With regards to location of this hole?

[Wiscon_Mark]

Is this relatively similar for a 2001 Outback? With regards to location of this hole?

should be, but the sheetmetal changed in that model, so I'm not sure how different the firewall will be. Poke around a bit, you should be able to find an easy way in.

[WinterKnoll]

Alright cool, thanks.

[jonklein611]

I just tried this on my 96 legacy, it didn't go down to the pedals, it just kinda didn't go anywhere. Help????


oh duh, wrong one...... :shock:

[patrack92314]

i did an amp in my 99 leagcy and i ran my amp power wire under my brake vacuum booster then took out the center console and the back seat and ran in under the center console and the carpet so it just pops out in the trunk

[Brockley]

There is also a grommet right above the frame rail under the brake master.

One more thing about running wires.

While it is true that a power wire CAN cause interference with RCA's, its so super unlikely that you shouldn't worry about it unless you are running some heavy wire and a bigger system. anyone running 8Ga wire is wasting their time if you run them separately. I run Comp woven 4GA Fosgate wires, and although I personally ran mine separate (I installed professionally for a while, and I had no interior in my car at the time)

Basically, everyone that tells you about how the cables are going to interfere ar talking about big boy systems, not an 8 or 4 ga kit and a 500watt amp...

[LegacyGT97]

before I got my subaru I had a 1994 Chevy S10 and I ran my subwire through the same hole that my antenna cable came through,
and then I ran my power line, rca cable and remote cable side by side. (I actually used zip ties to hold them together) I had the sub and amp in my truck for 5 months and never had any weird noices or any problems occur with my sub or amp.

[tylerkroh]

any advice for a BE? i cant find anywhere

[amgarrety]

any advice for a BE? i cant find anywhere

I did some wiring on the passenger side. Look under your car for the hose that the AC drips from. That hose goes through your firewall to the passenger side floor, and it is held in place by a rubber gasket that can be removed and replaced easily. From inside, just pull some carpet back and reach down behind the carpeting. It is much easier if you stick something like a screwdriver up from under the car so you can see inside where it comes up through.

[02_Legacy]

I ran my amp wiring through the drivers side fender and through a grommet that was not used. It is to the far left side under the dash, kinda where parking brake pedals are if we had one on our car. The grommet goes through to the space above the fender liner.

[tylerkroh]

I ran my amp wiring through the drivers side fender and through a grommet that was not used. It is to the far left side under the dash, kinda where parking brake pedals are if we had one on our car. The grommet goes through to the space above the fender liner.

do you have any pics please?

[Flyboy888]

Im bout to run an amp on my BE and could use some advise and pics too :P

[02_Legacy]

OK here are some pics:
here you can see the wires, red is the amp wire, this is to show the general location of where it is ran. Notice the clutch pedal in the foreground. This is in the drivers side foot well facing the left side of the car.
https://sl-i.net/FORUM/images/imported/2012/01/ampwire001-1.jpg

As the wire goes up, notice that there is a piece of carpet/foam that normally covers the grommet.
https://sl-i.net/FORUM/images/imported/2012/01/ampwire004-1.jpg

A closer pic of the wire with the foam still in place. Notice the huge wire loom that is coming through just to the right, it can be used a reference to find the grommet.
https://sl-i.net/FORUM/images/imported/2012/01/ampwire003-1.jpg

With the foam pulled back. Notice again the wire loom to the right.
https://sl-i.net/FORUM/images/imported/2012/01/ampwire007-1.jpg


To get the wire that far you can pass it though a cut out in the engine bay under the fuse box under the hood right by the battery. Remove the fender liner and you should be able to push it through the grommet. From there behind the kick pannel as my picture shows. Then tuck it under the door sills and from there behind the rear seats.

Hope this helps.

[Flyboy888]

Perfect! Thanks a lot man, the clears that right up :) next quick question, how do you take rear seats off? Lol I didn't find much, however I hadn't looked that hard. Lol

[Wiscon_Mark]

next quick question, how do you take rear seats off? Lol I didn't find much, however I hadn't looked that hard. Lol

Please direct this question to the appropriate forum. (Interior & Accessories)