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Old 07-02-2013, 05:08 PM   #1
Drives: Yaris 2008 RS
Join Date: Apr 2013
Location: Montreal, Canada
Posts: 17
Steps to install a subwoofer in Yaris 2008 HB

Hi everyone.

I know there are lots of posts about subwoofers on Yaris World already and I'm sure you can find all the information there but I thought some might be interested in having this complete guide for the 2008 hatchback Yaris. This might also work with other HB Yaris models.

This actually summarizes what I did a few days ago to install a subwoofer. I might add some pictures later if I get the time to take them. In the meantime, I hope the text description is enough.

The sub is a Polk Audio db1222 (two 12'' woofers) that is driven by a Kenwood KAC-8105D amplifier, delivering 500 W "RMS" for a single 2-ohm channel. The db1222 box has an angle at the back so this fits well behind the rear seat with a 2-3'' gap between the woofer ABS grilles and the hatchback door.


Get an appropriate gauge for the power cable. I personally used 4 AWG, which I think is way too much for my application.

Remove the passenger side glovebox: open it and press on both sides inwards while pulling the whole box. It should come off easily. You will have access to a carpet covering the metal body on which the firewall is installed on the other side. Unlock both pink clips. One of them is easy to see; the other one is at the top right corner (your head will need to be down there). To unlock, use long nose pliers and pull the center part. The clip will open but won't come off: that's okay. The new shape of the opened clip will allow the carpet hole to go through it.

Open the hood. Disconnect the ground cable from the battery.

At the left side, you see the engine control unit that's screwed on the body/firewall. Just above this unit, you should see a ½-inch rubber grommet. If you push that, you're pushing on the freed carpet on the other side. Working with someone else will help here. One pushes the grommet, the other one tries to catch it under the carpet. You just found your way through the firewall for the power cable.

Pass almost all the power cable by this hole, leaving just enough to hook it on the battery. Make sure the power cable doesn't touch the engine; use cable ties to tie it to other wires against the firewall.

If you have an inline cable fuse, install it there (near the battery).

Hook the power cable to the battery (the ground cable is still disconnected right?).

You may add silicone around the power cable in the hole to protect against water and noise but that's really not necessary.

At this point, the power cable is all on the floor of the passenger side.


Remove the receiver like this:

The passenger glovebox is still removed. Pass the remote cable (usually blue, around 18-20 AWG) and audio RCA cable behind where the glovebox is supposed to be so they are available for the receiver. Connect somehow (electrical tape, soldering, etc.) the remote cable to the receiver remote output (also called "power antenna") and the RCA cable to the receiver's "sub out" or "line out" (prefer the former).

Place the receiver back. Behind the glovebox, secure the two new cables with cable ties (so that you don't break connections if you pull them gently).

To the back

Bring the remote cable next to the power cable and tie them together (under the dash, behind the passenger glovebox). Then, tie them together every 4-5''. Remove the plastic covers over the doorsills and you will find very useful cable trays there, only occupied by a washer fluid tube for the hatchback door window. Make your way to the back of the car.

For the RCA cable, hide it under the center cover (where the handbrake is) so that the audio is not close to the power line. Hide it under a carpet behind the passenger seat and make your way to the back of the car (I brought it at the opposite side of the power line to avoid any interference).

Find ground

There are a few places where you will find a good ground connection. Remove the spare tire and you will find a piece of metal with two holes above where it was. I used sandpaper to remove the paint and then used a screw and a matching bolt to secure the ground cable there.

Connect the amplifier

Connect everything to the amp.: power, ground, remote and of course the subwoofer. Make sure the ground and power are not touching eachother (you can use a multimeter for this).


Connect the battery ground cable back. You might see some sparks; this is normal, the battery is being used as soon as it's connected by some electronic systems (clock) and maybe indoor lights.

If you smell smoke, see big light flashes or if the power line becomes very hot here, remove the battery ground cable ASAP and verify connections again.

Start the engine (you don't want to empty the battery since the amplifier might use lots of power) and test the subwoofer. Of course, begin with a minimum volume and increase it if you see everything is working as supposed to.

Stop the engine. If you're doing this when it's cold outside, make sure the engine is hot enough before stopping it.


Replace the plastic covers around the receiver, the passenger glovebox and the plastic covers over the doorsills once you know everything works. Close the hood.


I use the above setup without a power capacitor and with an old battery. I didn't experience any current drop (no lights dimming, etc.) and the sound is just great and powerful.

Last edited by eepp; 07-02-2013 at 05:24 PM.
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Old 11-20-2013, 04:58 PM   #2
What is a clutch?
Drives: 2007 Yaris HB
Join Date: Dec 2012
Location: United States
Posts: 21
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Photos of the completed job would be appreciated. :)
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Old 11-20-2013, 07:30 PM   #3
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Drives: 08Yaris2D, 88LandCruiser.
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No pics = never happened.
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