Should be a simple answer!

Hi there i have just got into the mk1 scene and do not have much knowledge of car electrics in general and was just looking for some help towards wiring in a head unit as there are only three wires where the head unit goes. One is blue, one is red and one is brown. HELP!!

My hunch is the red one is live, probably taken as a permanent live from the ciggy lighter or something.

Brown would be earth.

Blue is either an intercom to call your butler OR, it's live only when the ignition is on.

you REALLY need to check this with a multimeter before you wire up. Or you will toast your headunit.

Once tested, buy an ISO connector like this.

http://www.lowcostcara…Manufacturer&product=1002

for a couple of quid, they have tiny writing on each wire so you won't make a mistake,  a proper connector block and wire together using so you have iso connector fully wired up. Then you never have to think of these things again.

Unless you go old school, pre ISO connectors.

Peter.

Welcome to the forum briggsy! I'm no auto-electrician so can't help you much. However, I know you'll get an answer quick as there are a lot of ICE experts in here!

EDIT: oops - pete beat me to it!

When things are as VAG intended:

Red is permanent live (ie: not controlled by the ignition)
Brown is earth (negative)
Blue/white or blue/grey is dashboard lighting (used by modern stereos as a signal to dim the display to the same level as the rest of the dash lighting)

If the blue wire you mention is just blue (no gey or white stripe in it, then I'm not sure what it's for, but it may have been added to a chopped-off blue/white one - trace it back into the dash to see.

As per tallpete's recommendation, I would still use a multimeter (or even a 12v tail-light bulb) to check which wires are live and not live when the ignition is on or off, the lights are on or off, or everything is on or off. Your car may have had many owners, and the chances of the radio wiring being a bit strange, with colours not meaning what you'd expect, are relatively high…

Type17 said

Your car may have had many owners, and the chances of the radio wiring being a bit strange, with colours not meaning what you'd expect, are relatively high…

I'll second that!

The amount of redundant wiring (not connected at either end) that I tool out of my dash when I first bought my car was unbelieveable! there must have been about 15meters of the stuff! And the amount of those flippin' scotch locks that I had to replace…. :dontknow:

Blue is either an intercom to call your butler

             

tallpete

I know what u went through AL……i had about 10 metres & was able to reduce this to 4 wires in total plus AMP input cable!
Believe it or not it was all speaker cable & could've been wired thru the cable i have left in as it's 7 core cabling!

Why dont car owners leave wiring things to pople who know what they're doing????    it is something like the "Who wants to be a Millionaire" million pound question??
Is it the challenge of confusing the next owner of the car?? :dontknow:

Answers on a postcard to www.whatthehellhaveidone.com! :mrgreen: