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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.

  • Ryan from Lanse

    Posted on 8/1/2023

    Is there a way to run a wire through the firewall. I have a 2005 Mercury Montego and I don't see any grommets.

  • John Lazar from Bellport, NY

    Posted on 4/26/2023

    What is the best place to run a power wire through the firewall on a Volvo 2013 S60?

  • Tips From A Tucson from SomewhereUSA

    Posted on 3/5/2023

    Just an FYI, a 2007 Hyundai Tucson (and probably other Hyundais) have a rubber grommet behind the glove box, towards the wheel well. If you have the glove box taken out, it is up and towards the wall (goes into the wheel well). It is easier to find from the wheel well side (after removing the plastic). This routed the power cables nicely, into the front of the engine bay.

  • David Olszewski from Windsor Locks

    Posted on 2/18/2023

    Help! I installed many stereos. But struggling to find a good safe spot for a 2021 Honda Ridgeline.

  • Damien from Florida

    Posted on 1/26/2023

    Any ideas for running a 2 awg through the firewall of a 2014 Hyundai Tucson? The stock harness grommet is has a plastic shield on it that makes it hard to accept another wire. On the other side of the harness is a bunch or air condition items like the blower etc. Thanks

  • Franklin Pearson from Des Moines

    Posted on 6/19/2022

    1998 Honda Passport.. Best place to run power cable and a few small volt gauge wires.. 1-1/0 power cable 1-6g power cable

    Commenter image

    Buck Pomerantz from Crutchfield

    on 6/21/2022

    Franklin, It's difficult to describe in words, not pictures. There are two large grommets in your vehicle, left and right sides, not very low on the engine bay firewall, that will accommodate your wiring.
  • Joseph Burroughs from Newark

    Posted on 3/31/2022

    Do you have the grommet firewall locations on the 2015 escalade platinum

  • Shane

    Posted on 2/9/2021

    Does anyone know where to pass through the firewall on a 2012 Honda Pilot LX?

  • Randy from New Kensington

    Posted on 12/25/2020

    I'm trying to run a 4 gauge power wire through the firewall on a 2007 Honda Civic EX sedan. Where is the best location to do so? All the videos I watch show to go through the drivers side front fender to the foot well area but the wire is too big for that. Thank you in advance.

  • Gerard Durocher from Tucson

    Posted on 11/15/2020

    I would like to know the best way to get through the firewall on a 2012 Chevrolet Colorado. I got a JBL Bass Pro SL2 I plan on laying on the floor between to two back seats of an extended. Besides a fuse I would like to install a 40amp relay to switch off power when the stereo is not on. Suggestions welcome.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 11/17/2020

    Gerard, According to our research files, while facing the rear of your vehicle from in front of the engine, there's a large grommet at the top right of the firewall.

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