newbie, how do i know which wire is which

i have a homelink module from a 2011 Audi A4, it has three wires one brown one WHITE/ black one purple / YELLOW one must be ground one must power (+) the other illumination. How do i figure out which one is which? Can i do it with a multimeter? thanks I'm really new at this. thanks again

is there no way to test the unit without being plugged in? I need to find out which wire is which so i can hook it up properly. thanks

Typically you will need to find a wiring diagram from the 'donor' vehicle to know for sure what wires are what. Going from my knowledge of typical VW/Audi wiring, I would GUESS the following: Brown - Ground WHITE/ black - 12v constant Purple / YELLOW - Illumination Note that these are merely a GUESS at the wiring and connecting them like so could damage the module. Your best bet to be sure is to find a wiring diagram via google. Kenny

Owner / Technician

KKD Garage LLC

Albany, NY 12205

If i can't get wiring diagram. (i've looked for one). Is there away to test the wires with a multimeter with a power source? Could i use a 12V battery? thanks

Brown will definitely be the ground, the other two don't correspond to VAG colour codes, unless by illumination you mean headlights which are WHITE/ black for low beams. Constant would be red or RED / XXX. Ignition black or BLACK/ XXX. Illumination would be grey or grey/XXX.

WHITE/ black is 12v, brown is ground and the purple / YELLOW wire is data.

How can i test if the unit actually works? Can i hook up the brown wire (-) to a negative post of a 12V battery and the WHITE/ brown (+) to the positive post on the same battery? thanks

a ten dollar electrical tester would be a good investment right about now.... tester tester link this type pierces the wire. making sure you know what the wire is doing before you connect to it would be a good idea imho.:->