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Running Amplifier Power Wire Through Integra Firewall

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  • Running Amplifier Power Wire Through Integra Firewall

    Some people have covered this topic in various levels of detail, but I thought I'd record it for other people while it's still fresh in my mind from doing this for my 93 Integra. Read all of this before starting.

    In order to run power from your battery to your amplifier you'll need to route the power cable through the firewall and into the cabin. Here are some notes to help you out:

    1) This isn't intended as a full instruction guide on installing your stereo. Get that and your install kit from your vendor, Crutchfield etc.
    2) Disconnect your battery before you do any of this work. Don't even think about doing any stereo install without disconnecting.
    3) The DA9 Integra, like all cars, has holes in the firewall for routing electrical, steering, control, AC and other components.
    4) You shouldn't need to re-use holes for other components. There's at least one unused hole on the Integra covered by a rubber grommet you'll need to remove.
    5) The best grommet to use is the one closest to where your amp is going to be. For a reference on grommet holes search for "93 integra grommet kit". That should give you a picture of where all the grommets in the Integra are. The following is what I did on my 93. The unused grommet you're looking for is on the drivers's side of the car on the firewall just behind the fuel injectors / header. There are two grommet holes there. One is large and lower down. Leave that alone. There's a smaller one, higher up. That's the one you want to remove. It's 20mm.
    6) Opening the grommet hole is a pain since it's hard to reach from either side.. I recommend you have a long screwdriver and a long-ish pair of needle nose pliers. A small flashlight will be extremely useful to see when you're crammed into tight spaces.
    7) Make sure you've decided on the location of your amplifier.

    Step 1: Remove the inner grommet seal inside the cabin. It's about 1.5 ft above the accelerator pedal and a bitch to reach. It's about an inch in diameter. Use a long screwdriver with a thin, flat head to pry it out along its edge. Keep this seal. You'll may need it later.

    Warning: Once the inner seal is out you will be tempted to punch the exposed grommet out from the inside. Resist this temptation. If you do that it will drop into the engine compartment and you will spend hours trying to find it. You absolutely need it because the grommet protects the 12v power cable from abrading and shorting against the sheet metal on the firewall. You really don't want to find out what happens when 400 cranking amps shorts through an 8 gauge power cable against your grounded firewall in rush hour traffic.

    Step 2: Use a longish flathead screwdriver with a semi-fine tip to pry the grommet out *slowly* from the outside. Once you can grab it with a pliers get it out of there before it falls into the engine compartment.

    Step 3: Drill a hole through the grommet and seal to fit the 8 gauge power wire through. It should only be large enough to barely thread the wire through. There shouldn't be a gap between the wire and the grommet.

    Step 4: Thread the power line through the wiring loom that came with your wire kit. Then thread it through the external grommet far enough to reach your amp.

    Step 5: Follow the instructions for your install kit to install the fuse block and then test wire it to the positive power lead of your battery. Run the loomed power wire, following the old power wiring loom as long as possible and then along the firewall keeping it as far from the engine as possible. As you run the new power loom through the engine compartment, secure it with cable ties.

    Step 7: When you reach the firewall hole carefully thread the wire through. Don't insert the grommet yet.

    Step 8: Inside the cabin you can now optionally thread the cable through the grommet seal. The grommet seals are very fragile and may fracture from drilling. They're really optional as long as you properly seal the external grommet.

    Step 9: Inside the cabin, secure / test fit the power cable through the cabin area / through carpeting etc. Do not run it alongside audio or speaker cables. Keep it from bending around or catching on sharp metal surfaces. Pull any excess power cable through the grommet and into the cabin and after test fitting the power cable, secure it in critical places using cable ties. You can now attach it to the amplifier after cutting excess cable etc. When you can't use cable ties, use duct tape to secure it down. Wait until you have your amp secured to the car before trimming any cable.

    Step 10: Make sure the engine compartment cable run is secure and the loom covers the power cable throughout the compartment.

    Step 11: Secure the grommet and grommet seal against the firewall. Apply silicone glue to seal the grommet against movement and weather. Reconnect your battery and test your amp. (This assumes that you've already run a proper ground to your amp and hooked up your speaker and patch cables).

    You're done.

    Good luck.

    Last edited by eris; 03 Jul 2019, 05:49:37.

  • #2
    Excellent write up.!


    • #3
      Originally posted by RoyalsJunkie View Post
      Excellent write up.!
      Thanks. I've been sweating it out running all the cabling. I'm also connecting a backup camera and a dash cam. I'll document the techniques I used to route the camera video and hookup the power wiring through my 93's hatchback. That's a serious pain in the butt since the only wiring loom that goes from the license plate area is the two power wires going to the license plate lights. The real trick is taking advantage of the backup light tap on the trailer lighting socket and the undocumented trailer harness grommet. You need a fish tape and some loom tubing to run the camera wires from the license plate through the bumper area and into the trailer harness grommet. (I assume it's for trailer harnesses since it's right underneath the trailer lighting socket). More later.


      • #4
        Originally posted by RoyalsJunkie View Post
        Excellent write up.!
        BTW: I'm just now finishing up this install. We're talking a month and a half of my spare time. Good god. I could have done a B20V conversion in half that. I'm definitely going to do a write up on the entire rabbit hole I've gone down just to avoid buying a bling $200 radio from Worst Buy. Stay tuned.