[beef13]

Hopefully one of you clever people on here can help me. I've been banging my head against a brick wall for a solid month now and not really gotten anywhere
My car has decided to have constantly changing and very random fuel mixtures, so the rev range only consists of a flat spot and it's using uber fuel amounts. I've changed sensors and checked heaps of stuff and i thought i would try and get the codes from the ecu so i could see what it thought the issue would be. It's got a mk3 ecu and loom etc, and from what i can tell of the wiring diagram, the monitor coupler has 5 wires. The purple one in the diagram goes to the ecu and dash so that's the one for the engine light i think, that's where i've got my globe wired into anyway. The purple/yellow one goes to the ecu and fusebox, so i think this is the one that gets earthed to trigger the computer to release codes. No idea what the purple/green and purple/red ones are for because they only go straight to the ecu.
Anyway, i've been trying to pull codes by earthing the yellow wire, even connected the scan tool at work and tried to pull them using that. But so far i've only managed to blow the ecu fuse a couple of times.
Does anyone know if i am doing it right? Or how i am supposed to do it?

[masterA]

Try http://www.redlinegti.com

[matty_wall]

http://www.redlinegti.com/forum/vth.20895.error.htm

My gti loom is out of the car atm.. ill have a look and get back on here tonight with the diag light wiring.

[matty_wall]

It sounds like you have everything hooked up correctly. what light are you using as the check engine light? drawing to much maybe? I used a light thats used to illuminate the air vent controls works really well as it clicks into the dash nicely.

This is my set up:

The purple/yellow wire is the trigger to activate diagnostic mode for the check engine light: that goes to earth when you want it activated. (I used a switch)

The purple with silver spots goes to the check engine light.

The other wire that comes out of the check engine light goes to the alternator sense wire (ign) which is black/white.

[beef13]

Ok cool, that's the way I've set mine up too. The light is a little tiny t5 globe. Even tried without the globe there but as soon as the purple/yellow wire is earthed the fuse blows.