Originally Posted by
moesin2005
some bits on the light plugs clocks where quite easy but the stalks where a bit more involved had to put in new relays sure i seen some one on here who had done the conversion and also got the warning lights on the dash to work
You would need to completely rewire the headlamp circuits, the horn and the wipers. The MK3 uses direct links to each operation from the stalks (+12V), the MK4 runs everything through earth connections from the stalks via relays in the fusebox.
There is actually a lot of stuff that is different between the 2 looms. Central locking is polarised differently, rear wiper, etc...
It is possible, but is more work than it is worth.