AUDIO THROUGH FACTORY SPEAKERS

As everybody knows, this is the main issue for this project. Mbai2 was too heavy to me and using a FM modulator is not a good option so we decided to make a custom harness to make it possible. Thanks to my friend vwcooper, who made it happen.

The first thing is to get a high enough level of sound from the PC so we used a minijack to RCA cable and plugged it to an ALPINE 2 channels amp, small enough to be located behind the climate control. Two channels is enough because the factory non-Bose system only provides right/left output.

The whole system is powered from one of the empty fuses at the box under the backseat. The cable (+) goes to 3 different fuses we located under the foam at the gearknob room.

The Yellow one (20A) is to feed the new amp.

The Red one (10A) is switched to turn on/off the computer.

The Orange one (5A) is switched to commute from one audio source (factory radio) to the other (computer).

To commute the audio sources we used two parallel 8 pins relays, so when the switch is off the speakers receive the audio from the factory radio and when it is on the audio comes from the computer.

Summarizing, the circuit is closed as follows:

All the outputs from the factory radio (ISO) are positive and they get to the 8 pins relays (that receive the signal from the computer as well and are switched by the button at the central console) and then to the factory amplifier (ISO).

If you are using a bluetooth hands free device to answer your phone calls (I have the Parrot 3100), you must put its ISO between the relays and the factory amp, so it will mute the audio no matter what source is in use at that time.