I have a 99.5 Mk IV Golf with 2.0, auto. Of late the ABS light has come on as soon as the car goes faster than 13mph (or so). The dealer pulled the vag code 01276, which refers to an intermittant problem with the ABS pump or ABS controller. From the dealer the parts cost >$600 each.
(1) I'm new to the DIY VW world. Where can I buy these parts online for less?
(2) If I have the pump/controller unit out of the car on my workbench, how can I tell which of the two units has failed?