I have a VW Polo 2003 1.2 and would like to add a speaker to each rear door. I am a complete newbie when it comes to electrical work in cars (actually in most things about cars other than the important simple stuff I suppose). Currently the car has 2 front speakers. I have taken apart one of the rear door trim panels and noticed there is a space where a speaker could be added, however there was no wiring available other than the one that goes to the central locking (I think).

How would I go about passing the speaker wires to the Sony stereo? I was thinking of passing the speaker wires along with the wires that seem to be for the central locking. I assume that doing this would allow me to collect the speaker wire under the front passenger seats. However I am not sure where to go from here to reach the main head unit whilst keeping the wiring well hidden.

Where would the extra speaker wire then be connected to the stereo? I have noticed that there are various harnesses at the back of the stereo. also the head unit has several holes where RCA cables could be plugged into.

I haven't bought any speakers yet and I want to be sure what i need to do before buying them. How do speaker wires look out of the box generally speaking (description is enough)?

Thank you for your help

  • The datasheet(or the original manual if you still have it) of your radio may give some useful information, like a pinout from the rear side of the radio. But i guess that if you just connect the speakers to the RCA connectors that it'll be fine. You can try with the radio still out of its housing.
    – Bart
    Commented Feb 7, 2017 at 15:58
  • Thank you, I ll have a look ;) Just wondering do most car speakers come with RCA cables?
    – user25749
    Commented Feb 7, 2017 at 16:15
  • My radio did too along with another kind of connector, i believe it is fairly common for car radios. RCA is around since 1949 so it's a really well settled standard, guess that's why it's still so widely used in automotive. It's not really the best kind of connector though.
    – Bart
    Commented Feb 7, 2017 at 16:30
  • I've just looked at the handbook and it shows a diagram where the RCA cables plug into a power amplifier before connecting to the speakers. the problem with is that I don't want to install an amp. It also says that one of the connectors (the speaker connector has
    – user25749
    Commented Feb 7, 2017 at 16:38
  • I pressed enter accidentally; comment was going to be: I've just looked at the handbook and it shows a diagram where the RCA cables plug into a power amplifier before connecting to the speakers. the problem with is that I don't want to install an amp. Other than that, it also says that one of the two connectors (the speaker connector) has two cables (purple and purple stripped) for the rear right speakers and two for the rear left (green and green stripped). So I guess that the corresponding speaker wires need to fit into the car's own connectors opposite to the these terminals. Thank again!
    – user25749
    Commented Feb 7, 2017 at 16:50

2 Answers 2


Speaker cables are simple two-wire cables:

Speaker cables

There's a flexible rubber hose between the door and the door frame. You'll have to run a cable through this hose, then down the pillar to the sill, through the sill and the dashboard to get to the radio. This involves removing the trim panels from the sill and the pillar, the kick panel (that's the panel next to the pedals below the dashboard), and possibly some of the panels below the dashboard.


Car speakers typically come with speaker wire in the box. From memory, I believe that an '03 Polo will be 6.5" diameter round speakers so order a set in that size.

You can run the wiring through the little rubber bellows that the central locking loom goes into. From there, you'll be in the B-pillar. If you remove the plastic trim from the B-pillar you can feed the wiring down and if you remove the plastic inner sill covers too, route it along there towards the dashboard.

When it comes to connecting it to the stereo, you need to check the loom at the back of the stereo. Volkswagens on this period use ISO standard connectors which have one set of wires for power and the other for speakers. These are typically in the form of one black and one brown (although I have seen white) and the have a tab at one side to clip them together.

The pins for the rear speakers at the outside of the speaker connector. See the image below. More info about the ISO connector is available here.

ISO pinouts

This information applies to most cars built over the last 20+ years.

  • Thank you so much for your answer, it was very helpful!! Just to make sure, do I find the B connector and plug in the speaker wires both negative and positive into their corresponding places?
    – user25749
    Commented Feb 7, 2017 at 17:00
  • 1
    Generally, you don't plug the speaker wires into the connector. You buy an ISO connector with short wire stubs, and you solder the speaker wire to the stub.
    – Hobbes
    Commented Feb 8, 2017 at 10:30
  • The connectors labeled B is located behind the stereo in the dashboard. Commented Feb 8, 2017 at 10:30

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