OEM MK4 management wiring => Mk1/2/3 harness install FAQ (Now with added dieselness!)

Gonna put my real inside near fuse box.

 

cheers bud

 

Quick question, I'm currently doing a conversion for a golf from a 1.6 to 1.8t.
The 1.8t lump wiring loom and ECU is from an Audi a3. The problem I'm having is that the engine wiring loom won't fit my golf. Does anybody have suggestions? I've been told I need a hybrid loom. My golf is a 2001 se model. Cheers

 

The loom (AGU) is from an audi a3. Golf loom had 5 plugs .. A3 loom has 3 plugs of which only two plug in to the golf fuse box. And it won't run at all.. Not to mention the engine is cable thottle and car was electric. i have been told a 1.8t engine loom from an AGU will work. Others have also suggested the loom needs to be modified to fit my 1.6. it is a 16v

 

Engine code is AZD.

 

Hi
Quick question
i am using an ARY loom from a 4wd TT
is this essentially the same as a mk4 loom ?
its got a wideband lambda sensor on the down pipe and is dbw
ta

 

I have a few differences in my plug colours and wires to your list
as follows

Brown 6 pin

t1 double blacks
t2 purple/white (late i guess)
t3 thick red
t4 same
t5 same
t6 empty

orange 10 pin

t1 same
t2 green/red
t3 red/green
t4 empty
t5 empty
t6 same
t7 green/gray
t8 blue/purple
t9 same
t10 brown/black

10 pin white

t1 empty
t2 orange/black spiral
t3 orange/faint grey spiral
t4 same
t5 same
t6 empty
t7 same
t8 same
t9 same
t10 same

black 10 pin

t1 empty
t2 empty
t3 empty
t4 same
t5 same
t6 empty
t7 empty
t8 empty
t9 empty
t10 empty

I also have the following BLUE 10 terminal plug

t1 grey/white
t2 green/white
t3 yellow/green
t4 grey/red
t5 blue/white
t6 grey/blue
t7 empty
t8 empty
t9 empty
t10 empty

Can you shed some light on the differences ?
Thanks
Steve

 

To wire up the mk2 cruise control stalk to the mk4 AUM ecu I'm pretty sure this is all that's required (customary paint wiring diagram):


(12v rated LED or LED and resistor) (Brown being Earth)

That's based on mk2 switch which is as follows:


And the mk4 golf cruise wiring which is as follows:


I came across some info that stated the first mk4s with cruise only had a light that came on when the cruise switch was in the ON position (regardless of being set or not). Based on this if you run the white wire to an LED then earth (as per above) you should get a light on whenever cruise is on.

I've fitted this as per above now. Will be able to tell you pretty soon if it works for sure.

 

Thanks, I'm interested to know too. Just need to find one of the stalks with cruise - easier said than done!

 

So let me get this straight in my head as after reading this through 3 times i still cant grasp what i must be doing

This mk2 wiring loom will be plugged back into my fusebox eventually


i will not use any of this digifant wiring


This is the TT engine Loom, i will leave this intact and connect it back to the engine, cutting off what plugs i no longer need like A/C, VVT and maybe more


This is the main loom from the audi TT engine bay, i will remove the plugs that used to connect to the original fusebox, delete some of the wiring like the sai relay and other stuff that i no longer need as your guide says


I will then join some of the Audi loom to the MK2 loom at the positions indicated by you IE: T10a - 10-pin connector: 1 blk D/1 or D/21
Does this sound correct ?

Your post says get a t10a/t14a plug from a mk4 loom , its the headlight plug, can you supply a pic of the actual plug please
Why do you use this plug ? and where do you plug it into after the wires are connected as per your guide ?

I know i probably sound like a fool and people have grasped your post better than me but i cant for the life of me figure out where to start

I have the soldering skills, bundles of heat shrink and lots of new loom tape, i even have buckets of enthusiasm and loads of spare VW loom parts, i even own a comprehensive terminal removal toolkit with a few of my own design in there too, i am the goto guy at work for electrical issues on cars and fix all types of electric and electronic stuff around the house

Please Jonny tell me where i am going wrong and help this old codger get it right .... First time

Thanks
Steve

 

the t14 plug is not the headlight plug but is found by the n/s headlight one half of it is the 3rd plug down on the right hand side in the top pic of the tt loom. you will need to cut the other side of the body loom from the car

dont remove the vvt wiring you will still need this

 

I could not get the plugs for the lambda off without cutting them, I hope I still have them, if not I'll go to the scrapyard and chop another off
I have downloaded the wiring diagrams from your sig and will delete the post cat wiring, leaving the pre cat for my downpipe

 

When I get home from work today I'll lay it all onto the car to give myself some idea where it all goes.
I seem to have forgotten that the 2 audi looms join together and not just plug into the ecu separately.
I had visions of each loom plugging into the ecu and not joining anywhere else, this I think is the main reason I can't get it straight in my head
I'll keep you posted
Steve