i can't find any decent information anywhere.
There is info out there, Autodata, Bosch ESi & Tis. Pin 2 comes from a fuse, 3 goes to earth. 1 & 4 go to the controller.
You don't say what Fault (code) you have, but I would have thought (for EGR) that Live Data & Component Actuations would initially be your best friends here.
A good scanner will have EGR Command, Pulse Duty, Reply & Air Mass and an actuator function.
You could (with powers & grounds confirmed) have the scope on pins 1, 4 & MAF signal, Amp Clamp on 2 or 3 as you actuate it for the pretty picture.