I have the single CD, 6 speaker system and want to install an amp and sub. I was thinking that I would tie in to the speaker wires since I'm assuming there are no RCA outs on the stock head unit. Does anyone know where the easiest place is to do this on the S40s. Also, any tips on where to connect the remote turn on lead? Thanks for you help, this is a great forum.

 

You will see a serious improvement in your overall sound if you buy a "clearance priced" aftermarket head-unit for 40 bucks at walmart. It eliminates a lot of those problems, and most of them also have an amplified signal for your mid-range speakers too. There are ways to tap into factory systems, but your stock setup isn't factory amplified, it can be a little tough. So far as the remote wire, just tap into any fuse that is only on when the key is turned, like the radio, etc. Preferably the radio fuse, that way if a short occurs, you won't kill your engine.

 

Just be careful checking the wires on the newer cars they are starting to use Fiberoptics in the systems.

I agree about the tapping onto the fuse for the turn on lead.

 

This is all great information, thanks. It sounds like getting an aftermarket head unit is the way to go. The reason I didn't consider replacing the head unit is that it appears that the stereo operator interface is shared with the general computer/climate system. Is this not the case?

 

What year is your car?

If it is a 2004.5 or 2005 the radio is also a control module.

Most likely you will have to have the dealer perform a software download to remove the radio function and it will not see if as a control module anymore.