I found and fixed my D2's ABS modulator fault this afternoon. The post for the pins for the shuttle valve switch wire sockets would loose contact on 1 wire with the main harness socket if the post moved a little, suggesting faulty contact at the circuit board. I dug out the sealant directly behind the base of the post and resoldered the pins. After reassembly and checking that it was now fixed, I refilled the hole with new sealant and refitted the modulator, bled the brakes then gave the modulator a rigourous ABS and TC workout.
Resoldering can be done without disconnecting any pipes or removing the shuttle valve switches, but by only removing the modulator from its mounts enough to get access to the sealant below the front mounting stud, although disconnecting the brake lines to the wheels may give better access. It would be very worthwhile for anyone who has intermittent (or permanent) open circuit on the shuttle valve switch circuit to resolder these joints and see if that fixes their problem.
Pics of the resoldered joints:
https://www.aulro.com/afvb/images/im...009/07/157.jpg
https://www.aulro.com/afvb/images/im...009/07/158.jpg