1994 Audi Coupe 2.0e ABS issues

[m50yre]

Hi guys.
Wonder if you can help.
I have been fixing up an 80 Coupe for the past couple of years. Its now ready for MOT but i cannot get the ABS light out. Now all brakes have been removed, renewed, subframe off etc so everything is new. I cannot remember if the light was on when i got it, as it didnt run.

Ive had it on VCDS and the ABS controller cannot be communicated with.

Ive checked the ABS ECU and and got a spare to try that but makes no difference.

Only thing i can find is that the ABS ECU only gets a 6v feed - without a diagram im not sure if thats enough or if the only feed required?

Any thoughts?