Battery-to-Hatch Installation of 4 Gauge Wire: GTI

4 Gauge Cable Kit After 6 months of listening to the crappy stock stereo in my GTI, I finally broke down, bought some new gear and have begun the fun process of upgrading. I’ve got a new head unit on the way, but before getting to that I wanted to post about how I installed the 4 gauge power wire from the battery to the hatch location for powering up my amps. This can be a pain to do in some cases and with some cars, but in the GTI is actually really easy. I tried to take as many pictures as possible to show how I did it. This is by no means the only way, or even the best way to do it, but this is how I did it, and it only took a couple of hours to complete.

I bought a Street Wires 4 gauge amp install kit from Parts Express (who else?) which comes with almost everything you need to hook up as much as 800 watts worth of amplifiers. Not that I need that much, or even have that much power, yet, but I do want the option to get some new amps in the future, and in reality it’s just running the wire that’s the hard part, it doesn’t make much difference how thick it is, so might as well go as heavy as reasonable. Once you start getting into 2 and 1 gauge wires it’s probably more difficult, but I’ve never installed anything heavier than 4 gauge, and for most people, this is sufficient.

There is an unused hole in the firewall of the GTI just above the gas pedal from the inside, and above the master brake cylinder from under the hood. It’s plugged with a rubber grommet which can easily be removed by poking a screwdriver up through it. I’m not sure how big the hole is, I should have measured the grommet while I had it out, but it’s not much bigger than the diameter of the 4 gauge cable. I drilled a hole in the grommet and ran the cable back through it and down the hole and into the car and then seated the grommet nice and snug back in the hole. I left about 2 feet at the battery to hook up the fuse and for routing.

Once inside I ran the cable as high up and over the gas, brake and clutch pedals so as to not interfere. There’s plenty of room for routing the cable down the left front kick panel area and then down to the floor/door runner panel (is that what those are called? I have no idea). Getting these panels off requires pulling off the hood popper and then popping off the panel. It’s held in by one panel fastener in the middle, and one on the runner panel. It’s also held in around the door stripping. The base panels also pop off, with a screwdriver underneath at about every 8″ it comes right up, but not completely off. I ran the cable between the frame and the thick carpet padding underneath the runners instead of trying to run it below where the rest of the electrical cables are. It seemed like more of a pain for little value added. With the runners snapped back in place, that huge cable is completely out of view.

I couldn’t figure out how to remove the rear side panel, so I just managed to fish the cable up though it enough to get it behind the seat and into the hatch area. I did have to remove the rear seat cushion, which just pops out by squeezing the retaining locks and pulling it out. I ended up running the cable up the high-side of the back seat and coming out up top right into the emergency/first aid kit/CD changer compartment. Although my amp won’t fit in there, I just brought it to that location for the time being. And that’s about it. Back up under the hood I finished off the installation with a 100A fuse holder and bolted the cable right to the positive battery clamp using the bolt that tightens it to the battery. The cable came installed with a large ring terminal which fit right over the bolt for the battery clamp and makes a nice connection to the hot side of the battery. I sanded down the portion of the clamp that the ring terminal makes contact with as well as the washer on the other side of the ring terminal, just to ensure good electrical contact. The cable then follows the starter cable out the side of the battery cover, to the fuse which is mounted on the side of the battery cover, and then over it goes through the firewall, and the rest I already covered.

So that’s it in a nutshell how to install a 4 gauge power cable from the battery to the hatch of a GTI. Next week I’ll be hooking up the amp, the sub, the new head unit, and the patch cables from the HU to the amp. Until the, here’s some pics of the install.

4 Gauge Cable and 100A Fuse Holder Connected to Battery

Location of Hole in the Firewall for Running the Cable

Cable Through the Firewall Just Above the Master Brake Cylinder

Cable in Car Through the Firewall Just Above the Gas Pedal

Cable Tucked Away Behind Left Panel

Cable Running Under Floor/Door Runner Panel Things

Final Desitation of Cable in Hatch Area

TC Sounds dB-500 in Sealed Box

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