MK2 GTI ISO wiring help

[Bushboy]

Hullo,

First post here and im sure it wont be my last.

Just bought a nice 1990 MK2 Golf GTI 8v and having a little trouble getting my JVC aftermarket headunit to work from the Golf ISO.

Im basicly getting no power atall on the HU.  Ive run a few searches on here and come to the conclusion that the Golf ISO isnt a standard ISO layout and so isnt likely to work.

Can anyone please tell me the colours for the wires as bellow :

12v constant
12v Switched
GND
Ilumination (if there is a wire)

Im guessing red is 12v switched? or constant maybe.  and is brown, GND?  Either way, im getting no power with or without the ignition on 

Any help woul be greatly appreciated  Thanks!

[takethefifth]

Red should be constant 12v, brown should be earth.

There is no switched 12v or illumination wires. You would have to wire these in yourself. It can be done, have a search on here as i'm sure someone has done it in the past.

[garfayliu]

HTH, Garfay.

[Bushboy]

Thanks for that diagram! Will hopefully come in very useful!

Still confused as it seems the 12v and GND are correct.. may be that they are backwards though, will investigate after work.  There are a number of other wires on the block though so I need to check what they are aswell 

THanks!

[Gambit]

are u sure you just dont need a harness adapter? im not upto much on stereo wiring but im pretty sure mine has a harness adapter

[Mew]

Have you checked all fuses? Ie in the fuse box and also the inline fuse on the live feed.

[Brads MK2 GTI]

Trouble is that they aren't all going to be the same colours on different years etc. Why don't you cut the ISO off your Golf, get a voltmeter, find the constant, switched and earth, then just figure out the speakers and bullet crimp them in?

[Bushboy]

Speakers arent a problem.  Im planning on running them off amps in the future anyway so the standard speaker wiring is obsolete.

I looked at getting a wiring adapter as pictured but decided its nothing I cant just rewire anyway.  Im going to investigate later and see what happens  Cant be a dodgy fuse/wiring as the HU i took out was working perfectly

[rowlers]

You have your perm 12v???
I made my own ignition live, piggy backed off the fan switch - soldered and shrink wrapped - not those pesky blue clip on thingyies (word???)!
Then I bullet crimped this new ignition live into the head unit harness.

Would take photos, but I can't be @rsed pulling it all back out

Get your multimeter out

[Bushboy]

got it working 

The 12v plus on the golf ISO was connecting to the 12v switched on the standard ISO and so as far as the HU was concerned, it wasnt getting a 12v constant.  Ive just bridged the 12v switched and 12vconstant on the HU ISO an its all fine with a perminent memory and constant feed now.

My golf also has an illumination wire (blue.grey) and another wire which i cant work out.  its yellow with white stripe... any ideas?