How can I play mp3s from my smartphone in a Volvo s40 2005? There's no cassette deck and no auxiliary plug. Thanks.

 

The fast way is a FM transmitter. It hooks to the phone's audio jack and transmits on a very low FM channel like 88.1 or 88.3. You tune your FM radio to that channel listen.

 

I agree, FM transmitter is the easiest, cheapest way.

Or for a little $ you could get a USB kit like this one:

Volvo 01-06 USB Android iPod iPhone Bluetooth AUX adapter

They have kits that fit Volvo's. Then you can just use a USB thumb drive loaded with mp3's, or connect a iPod/Phone, Android phone... bluetooth too

 

I tried the FM transmitter. Easy install, but as I drove, stations would fade in and out, messing with music signal.

3rd choice is an FM Modulator. This is connected into the antenna terminals & is more resistant to strong FM stations. I did this, paired to a Crutchfield's bluetooth dongle. Happy camper.

 

Thanks! Is this hard to install on an S40? I'm pretty handy with basic tools, but I don't know much about cars.

 

There's a PDF out on the internet by Gregg Rocheford. The file I've got is English_install_ver_6_5.pdf

The plan is to inject the FM signal into the antenna amplifier. The connectors are two 9V snap pigtails.