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How to get through your car's firewall

Deciphering the tricky part of amplifier installation

When installing a new amplifier in your car, one of the most difficult steps is figuring out how to get the power wire from the engine compartment into the interior of the vehicle. You need to find a way to get that big wire through the firewall.

The secret is to use an existing pass-through, which will have a thick rubber plug or "grommet" sealing the passage. Sometimes you'll have to use a grommet that already has wires running through it and sometimes you'll be lucky enough to find an unused grommet. It all depends on the vehicle. Either way, the process is the same.

Amplifier installation help

In this video, we'll show you how to manage this task, and share some expert tips and tricks to make it easier. And if you purchased your amp from Crutchfield, you'll have the benefit of our outstanding tech support team standing by if you have any questions. If you're having trouble finding the best place to get through the firewall, just give them a call. 

If you're still trying to figure out what you need to purchase for your amplifier installation, talk to our advisors. They answer questions about this stuff every day, and they'll be happy to help you, too. 

Read video transcript

We're going to run this power wire up through here. We're going to put it in some flex loom to keep it protected from the heat of the engine. We're going to install a fuse somewhere in this neighborhood right here that will keep our entire vehicle safe in case there's any kind of short in the power wire, all the way from the front of the car to the back of the car.

We're going to run it over there, to a nice big huge grommet in the firewall where a lot of the factory wires go from the engine compartment through the firewall and into the passenger compartment. We're going to use this knife to poke a small hole in the rubber next to the wires, making sure not to cut any of the wires of course, and then we're going to poke this coat hanger through so that we can fish our wire through the grommet.

So let's see here, all right, that should do. I'm going to take this coat hanger, and I've already put a little hook on it. The idea here is that once we get the coat hanger through and we find it on the other side behind the glove compartment, we're going to take this power ring, just hook it on and pull it right back through. That's the idea, hopefully it works out just that easily.

All right, got the coat hanger through the hole and I'm pushing it through pretty much almost all the way, so just there's still enough for me to grab on this side and pull it back once I've got it connected to the power ring on the other side. So now we're going to go around to behind the glove compartment see if we can find our coat hanger and that hook to hook the wire on to. All right, let's pull our wire through. Oh yeah, just like it's supposed to work.

And if you need any help picking out an amp and a sub, or any combination thereof, check out Crutchfield. Give us a call we can certainly help you get the right stuff. And of course, we can help you get it installed as well.

Please share your thoughts below.

  • David P Beardslee from Martinsburg

    Posted on 9/2/2020

    does anyone know the best place to run the power wire through the firewall in a 2011 Honda civic

    Buck Pomerantz from Crutchfield

    on 9/3/2020

    David, Crutchfield's Vehicle Guide database doesn't picture the firewall grommet/pass-through for this vehicle. I suggest you consult a Honda Civic forum for that information.
  • Rob Joslin from North Tonawanda

    Posted on 4/28/2020

    Does anyone know where the location to pass the power wire through would be in a 2007 Honda CR-V? Looking under the hood I can't see any time of hole going through to the cabin of the vehicle

  • Henry Wells from Mableton

    Posted on 4/7/2020

    How to locate firewall on a 2011 Chevy Malibu ltz

  • Ben from Saint Charles

    Posted on 4/5/2020

    Any tips or tricks on running a power wire for a 2004 toyota matrix xr? Found a grommet but hard to run it through.

  • Chris Destry from Zionsville, IN

    Posted on 1/26/2020

    Looking for place to run large power wire through firewall on 2020 Outback. Has anyone attempted this ?

  • Ben Sharp from Hobart

    Posted on 12/17/2019

    2001 Chev Silverado 1500 has a flat THICKER grommet on the inside. I had no problem getting through the softer one on the engine compartment but cannot get to the inside one WAY up under the dash above a secondary Fuse box. How?

  • Zachary Tretter from Brainerd

    Posted on 11/26/2019

    Where in a 2003 Volkswagen Passat do I go through the firewall?

  • Jordan from Corvallis

    Posted on 11/24/2019

    I cannot for the life of me find a way through 2005 ford fivehundred firewall

  • Ror from Regina

    Posted on 11/20/2019

    I am installing an amp in a 2005 Buick Lacrosse , do you know where I can get through the firewall ? Please and thanks.

  • Mike Trosan from Pittsburgh

    Posted on 10/21/2019

    Yeah but what about a 2015 c300 w205? It's killin me! No accessible grommets. Help!

  • Kane

    Posted on 9/2/2019

    I can't find anything in my 2006 Kia Optima, any ideas or tips?

    Buck Pomerantz from Crutchfield

    on 9/4/2019

    Kane, Crutchfield's Research File shows a useable grommet high on the driver's side of the firewall.
  • Steve Burleson from Enoch

    Posted on 7/19/2019

    I have a 2001 Ford Saturn LX and I believe it's a double firewall I have I've never taken so long to do something in my life and I still can't locate or visualize a good safe place to do it

  • Gage

    Posted on 7/7/2019

    2014 Ford Fusion and currently installing sub and can't find a way to get the power wire through fire wall.

    Buck Pomerantz from Crutchfield

    on 7/9/2019

    Gage, There seems to be a rubber-type wiring boot high on the passenger side of the fire wall. It looks like it has enough room to punch a hole for your power wire to go through without disturbing the other wires there.
  • Edrick J Mendez from Florida

    Posted on 12/17/2018

    Have a 2007-12 Nissan Versa HB 1st. Gen and I cannot find the Firewall Grommet, any details where can it be?

  • JJ from Cape Town

    Posted on 11/11/2018

    Coat hanger. Genius!

  • Gary Schmidt from Plano

    Posted on 1/15/2018

    Works great on most cars . But on Saabs not so well double firewall

  • Mark Baxter from Summerton

    Posted on 5/18/2017

    Long time customer. I can honestly Crutchfield has the best support & advice team.