Thread: Sony headunit into a4, b6

Some advice please

I want to change my single din standard audi head unit with a sony sony bt37000 head unit
MEX-BT3700U | XplMd® Bluetooth® CD Receiver | Sony | Sony Store USA .

The car has a half amped system. what harness do i need and what is the best dash surround to get.

Cheers

You'll need to pair the perm live & ignition on feeds as there is no switched live on the Audi loom. You will need the PC9-404 adapter to feed the rear RCA's to the Audi rear/sub amp (and connect the blue flying lead on this adapter to the power antenna feed from the Sony). Also the wraparound fascia adapter and antenna amp adapter:
CT24AU03 Facia Plate for Audi A4 2000>
CT27AA05 Aerial/Antenna VAG Active ISO Adaptor

You will need to fade to rear quite a bit to get the puny 2 x 20w rear amp to match the 2 x 50w Sony output to the fronts

would i be better disconecting the amp and sub all together?

Technically yes, but the sub does help. Rewiring the rears to the HU and adding a proper sub is the best way forward.

Originally Posted by AndyMac

You'll need to pair the perm live & ignition on feeds as there is no switched live on the Audi loom.

Does this mean just short the two across? I'm a bit new to fitting car stereos and would hate to fry something!

Yes you need to cut the unused yellow wire from the HU and splice it to the red wire (after the inline fuses if they have any) preferably by cutting the red wire and using a solid terminal block to join all 3 together or using a high gauge bullet connector with the yellow and red in one side and the original red wire on the other. The adapter cable should come with the male/female ISO power adapter so you can perform this surgery on the adapter rather than cutting the Audi loom or indeed the wiring from the HU (if it has any). The HU just needs two 12v sources in order to work. All you are doing is getting both of them from the single permanent live source on the Audi loom. You can't fry anything as long as the connections are insulated and solid. Don't use a crappy piggyback connector as this will be unreliable.