Mk3 TDI Brake upgrade / ABS conversion

My Golf TDI has puny brakes - the fronts are smallish dual rotor vented discs and the rears are drums. The wheel fittings are 4×100 PCD.

The idea behind this project is to upgrade in stages, so initially I will replace the rear drums with discs, and eventually I will have a complete ABS system with bigger front brakes from a GTI also.

Obviously, this project is safety critical, so I have to take care that at no point I end up with a dangerous vehicle.

My Donor vehicle has an earlier ABS system with seperate pump and ABS ECM. So far, I've stripped the entire rear axle and both hubs, and am stripping the front next.

In the mean time, here is a photo (with labels) of the ABS wiring harness I've extracted. If I'd known the inside was socketed I wouldnt have cut the wires, but I can always get another harness from a scrapper…

Click to enlarge…