View Full Version : Basic Head Unit Install Wire Guide

10-18-2004, 02:56 PM
I just installed a new head unit in my 99 A4 1.8TQ Tip. It was just a head unit and retained the factory speakers. I spent a lot of time on the phone with the good people at Crutchfield and kept pretty decent notes. THIS IS NOT A BOSE SYSTEM!!! Here's the basic wire guide:

There are 6 plugs in the back of the OEM: Red, Brown, Black, Yellow, Green, and Blue. You will not be using the wires for the red or blue, so do not cut the wires (the blue is for the cd changer).

When you cut the wires off the rest of the plugs, you will be left with:

Red - Accessory Power (switched)
Red/Blue - Constant Power
Brown - Ground
White - Remote T/O lead
Grey/Blue - Illumination
Blue/Brn - Left Front (LF) Positive
Blue/Grey - LF Negative
Brown/Green - RF Positive (mine was Brown/Grey)
Red/Gray - RF Negative

To keep your OEM speakers the following wires must be run through an adaptor (PAC-OEM-2 $29.99):

Blue/Green - LR Positive
Blue/Red - RR Positive
There are 2 Brown/Red wires that are the common ground (negative) for the rear speakers.

Do Not Use:
Brown/Grey (see note above)

Once you have the harness for the new head unit, it's pretty simple to just match up the wires and crimp.

Note: On the antenna adaptor, the blue wire that runs from this should be attached to the (Power Cont Ant) wire on the wire harness.

In all cases the first color indicates the wire color and the second indicates the chaser line.

Tip: If unsure on speaker wires, find the desired ground, press it to the negative side of a "D" battery, and then press positive speaker wires to the battery until the correct speaker "pops" (it sounds like low static).

Hope this helps anyone who's switching out the head unit. Even with just a half decent stereo (I got a kenwood for $199), the improvement in sound is very noticeable and I finally have cd's so I don't have to listen to Hoobapark, Linkin Smack, Nickelstank, or any other "nu-metal" crap band that clogs up the radio.

white fish
10-18-2004, 08:00 PM
do you know if this is true for other years?

10-19-2004, 05:23 AM
the crutchfield guy said it was for 96 thru 01...

the oem headunit was a concert. i don't know if it changed with the concert 2 or the symphonies.

10-19-2004, 06:19 AM

you cut the wires?!?!?!

Why didnt you just purchase an adapter kit it would have made life sooooooooooooooooooooo much simpler.
The adapter kit would have cost you $10.00 and you didnt have to hack up your wiring.

That is so bad... Hope he told you about the K-wire otherwise you will be unable to read error codes in your ECU via OBDII port.

Stupid morons at crutchfield.

10-19-2004, 06:22 AM
I used the adaptor, but there is no wiring harness for an audi because of the amped rear speakers (they have to be run through an adaptor).

were you able to use the VW wiring harness? did you keep the OEM speakers?

10-19-2004, 06:27 AM
because of the amped speakers....?
If you have a concert radio with bose... then all of the speakers are amplified.
I only used the wiring harness to run power initially... I ripped out all of the speakers and installed a full stereo system in my A4.