How to mount an aftermarket subwoofer in your Volvo

If you want to mount a subwoofer in your Volvo, you can try to get hold of an OEM subwoofer that fits perfectly. But it may be very expensive to aquire, and if you do so, you still may have to pay a Volvo technician to activate it in CarConfig. This is how you can mount an aftermarket subwoofer in a 2005:

The spare wheel compartment in the trunk is the ideal place for the subwoofer. Enough space and short distance to the battery. And there is probably already a plug for the OEM subwoofer in the trunk. Locate this plug in the far rear side.

The left and right rear speakers are directly connected to this plug. Use these wires to connect the audio signal to your subwoofer. These wires are high output wires, so you have to use the high input channel on your subwoofer. If you only have low signal input you have to use an adapter.

The +12V and GND you can connect directly to the battery. The subwoofer probably needs a 12V signal wire which is activated when the ignition is on. You can use the signal from fuse number 25. That one is activated only when the ignition is in position II.

You have to build some kind of bracket to hold the subwoofer in place.