DIY: Polo 6R subwoofer install and routing wires through firewall (easy)

[sparrow77]

I ran the wires for my newly installed subwoofer a few weeks ago, but it wasn't easy - I wasn't able to find any guides or DIYs (until after I had already finished...). This post is to help other people who might be searching for an answer. My car is a LHD 1.2 TSI, for what it's worth. Link to a photo guide is at the end of the post.

In searching for help online, I came across this very short but surprisingly helpful video from someone on YouTube. He routes the power cable from his battery through the bonnet release passthrough at the top of the firewall, right by the windshield.


On LHD vehicles, you would ideally have to remove the plastic cowling and wiper mechanisms to get to the grommet at all, as it's buried quite deep. However, there is also a bonnet release passthrough on the other side for RHD vehicles! It's blocked off with a rubber grommet, but is far, far easier to get to as you can just pull the rubber seal of the firewall back and bend the plastic cowling up.

I cut a hole into the grommet and carefully fed my power cable through it. You might have to push quite hard as there is a large piece of insulation immediately past the firewall. I pushed about a metre of cable into the car and then went fishing for it behind the removable panel on the passenger side of the dashboard. Luckily, the wire had fallen through into the dashboard so I was able to pull it through and down into the passenger footwell, where I then tucked it underneath the plastic sills and into the boot.

Funnily enough, after I had done lots of research and finally managed to run my wires properly, I found a German DIY guide for this exact proceidure. The photos are pretty useful, and coincidentally are more or less exactly what I did.
http://www.polo9n.info/Wissen/anleitung ... r-verlegen

[ciclo]

Thank you for sharing.

[sparrow77]

Update:
Basser seem to be the only company that offer bespoke sub boxes for the Polo. As a result, I ordered one to see how it would fit and unsurprisingly, it was perfect. I recommend ordering directly from them (basser.pl) as it seemed to be a bit cheaper than going through ebay.
Easily recommended for a small 10" sub, as its only a 17 litre box. It even comes with a new false floor with a cutout for the element, which also helps hold the box in place. I also used it to mount my amplifier to free up the now half-sized negative space beneath the false floor. The cutout is not the most elegant solution, but I think it's a small price to pay to retain a completely usable boot (and the spare wheel and tools).

I think it would be pretty easy to make your own box to fit in the same space beneath the false floor, but I have neither the tools nor the space for a project like that. This is a great solution for a reasonable price.

[17pologt]

Hi chaps.

Where are you getting the feed for the cables. Have you got standard head units? As there is no where to put the RCA cables from the head unit to there sub?
Really appreciate that in put on the power cable. Going to target that shortly.

Thanks

[sparrow77]

Have you got standard head units?

Yup, I have an RCD-310. I used an amplifier with a built-in line out converter, so I just tapped into the front speaker wires at the quadlock connector and ran the wires all the way back to the boot. A separate line out converter would work great as well.

[17pologt]

Thank you so much.

So there is nothing to say these cars have a seperate amplier unit that supplies the source for the speakers?

[sparrow77]

Some models have a different radio that (I think) has the unit itself inside the glovebox, with just the screen being in the dash. So in that sense, yes, but I doubt it would have RCA outs - most factory radios don't, probably for cost reasons.

[17pologt]

Baffled as anything. Think im going to have to tap into the speaker wires then.

[sparrow77]

Baffled as anything. Think im going to have to tap into the speaker wires then.

I had a choice, I would do it again with a quadlock extender like this: https://www.amazon.co.uk/52-Pin-Quadloc ... B00MCM2G0Q and splice into that. That way the install is entirely reversible without fiddling about/ruining the factory wiring. You could even install some kind of connectors on the extender before you plug into the wiring loom - that way when you go to run your speaker wires, it's more or less plug and play.

You'll need to splice four wires (ideally): the right front door speaker positive and negative, and the left front door speaker P+N. You'll need to look up the wiring loom for your model year just to be safe, but my radio happened to have the diagram right on the side:


Otherwise its just a matter of running the power wires on one side of the car along the plastic sills, and the speaker wires on the other side. All the panels are fairly easy to pull up enough to tuck the wires underneath.

If you need RCA outs, by far the cheapest option is a line out converter. https://www.amazon.co.uk/s?k=line+out+converter Aftermarket radios will have RCA outs, but they also will cost a lot more than a converter.