VZ Commodore - Subwoofer Install

Hello again. This time we'll be installing a subwoofer into my VZ Commodore. Specifically a Blaupunkt subwoofer (the same brand as the stock radio head unit). If you've seen a previous post, you may remember that I did a different subwoofer install... but it was shite so we're running it back.

To start, I managed to grab hold of a copy of the Commodore VZ service manual online, for which Apple's Preview refused to interact with, but a questionable copy of Adobe Acrobat worked happily enough. I printed out whatever relevant page I found through the entire process, and I'll provide the entire manual at the bottom.

The goal is to wire up a subwoofer in the boot. That requires us to wire, a) thick gauge power wires to always-on power sources, and b) high level audio signal tapped from the current speaker wires. My subwoofer has a civilised 75W RMS and 200W burst, which works out to be around 15-17A at most. To grab this power source for this, I ended up using a fuse socket wire tap (yes the one online says it has a 10A max, but for some reason mine came saying 20A). This was to be ran out the cabin fuse box, rightwards and down into the drivers side floor trim, down the car, behind the rear seats, and into the boot. The speaker wires would come from both sides of the car, tapped from the stock rear speaker wires that run under the carpet.

The loom that runs wires from the front to the back of the car is under the "side sill trims". First step to accessing the loom is to remove the "front seat outer front cover". This is merely the trim covering the drivers side seat track. To do this, first slide out the rear component accessible from behind the drivers seat. Try pressing down in the middle of the rear component nearest to the seam. If this proves very difficult, you may take a risk and skip this entire step, as the next steps aren't exactly dependent on this cover being off, but they will struggle and creak upon being pulled out.

If you miraculously got past the previous step and have gotten the rear trim bit off, next take a screwdriver and undo this screw below the fuel filler lever. Store it somewhere safe and labelled. Next, just ease the entire trim out, you may find it easier to pull the lever upwards and slide the trim out through the lever.

If you've completed that without breaking anything, you should have something like this. Note the seatbelt/safety system wiring, be careful and don't prod it.

Next, pull hard from the top of the lower B pillar trim. It should unclip, and you should be able to unhook it from the side sill.

Next, very slowly and carefuly pry off both of front and rear side sill plates using a our trim safe chisel.

After that, there are seven torx screws (size T25) to undo. Four are beneath the front plate, two beneath the rear. The last one is horizontal, bolting the entire piece to the B pillar. After those are undone and safely stored, slide the entire piece towards the steering wheel, and lift it free. It helps to lift up the rear seat cushions to free the back of the trim. Trim off, you should be able to see the wiring loom.

Before we do anything though, we need to figure out how to run our power wires from the fusebox down into the loom. If you haven't already, you can reveal the cabin fusebox by pulling down hard on the trim beneath/behind the steering wheel. It is hinged at the back, and has 3 clips that clip it upwards into the dash. To run the wires, we're also going to remove the piece of trim directly rightwards of the fuse box.

Remove a screw that the side sill revealed, and another screw hidden behind the bonnet release. Pull towards the center dash, and the whole trim should come off to reveal the wiring looms behind. This is where we're going to run the power cables.

Now we can have a rest from manual labour by figuring out which wires in the conglomerate belongs to the pair of speaker wires. To find this, we refer to the colours outlined in the wiring diagram of the enterainment system.

Page 12D-55. Now, we know we're looking for the pair of wires running to the rear speakers, since the pair for the front speaker tees off into the front door early. By the diagram, the differential pair BU/BK (primary blue, striped black) and BU/OG (blue, striped with orange) is what we're looking for. Now in the car, particularly looking at the bunch that runs into the B piller and supposedly into the rear door, we can find our pair.

Bit hard to see here, but we've got our pair. Now, very very unfortunately, you get to enjoy the process of doing the entire trim removal again for the passenger side, looking for a pair of Brown/Black and Yellow/Blue wires.

Now, we switch to a different, more headache inducing activity, which is to solder our power cables to the fuse tap. I used a pair of 2mm² wires for a total of 4mm² of copper. These i wound together, and shoved inside the bullet connector of the fuse tap.

Bloody shite soldering job I'll save you from viewing it here. Do the speaker wire taps as well, by trimming a bit of the insulation and just soldering your new cable on.

Now we're on the final stretch. Chuck a couple fuses on the tap and wire it into an unused slot. You may have to cut away a bit of the padding on the fold down panel like I did here.

I routed all my wires to the boot by first taking the rear seat cushion out, and then pulling up to dislodge the rear right hand seatback (taking care to undo the bolt first). Side note, an easy ground connection can be achieved by sanding and crimping a wire underneath that bolt.

Now you shall have easy access to the boot.

We wire everything in, and then we're done. Make sure that you have (1) 12-14.4V 20A power, (2) 20A GND, (3) speaker L + R, (4) remote wire (if used). If you have all those, lovely!