After looking this over, and I hope I have it right because these older type wiring diagrams give me a headache reading them...
Looking at what 410 posted pics of...
When the 4WABS Main Relay is energized, on 42-1, it goes out on orange/yellow "A" to 42-2, then splits at S150, then "B" takes you to diagram 42-3 where you see the diode.
If the diagram is correct, that diode is oriented with the cathode side connected to "B", so it should be blocking 12V from getting further in the circuit, not passing 12V. It looks like the primary purpose of the diode is to prevent back EMF coming from the ABS solenoids, not provide needed power to the ABS module, though I admit that I may not have kept up with exactly what the correct circuit diagram is for your vehicle. What I see on the diagram that 410 posted is the diode only goes to the instrument cluster warning lamp and ABS module pin 18 used to trigger that warning lamp.
That plus the readings you got from the diode when testing it, which look correct with 0.61 (Vf) being about what you'd expect for a silicone diode, and not passing voltage the other way on the test (open circuit), the diode seems fine. I don't think there is anything to gain by jumpering where the diode was.
However you wrote #17 (pin 17?) so I am not understanding something. I mean that power doesn't have to pass through that diode according to the diagram, that power to pin 17 comes instead from the 4WABS Main Relay as seen as "A" on diagram 42-2, so with the ignition on, you should measure for 12V on the 4WABS Pump Relay contact for relay pin #85, and if voltage is present there, then you have a break in the wiring between that point and the ABS module connector, or if voltage isn't getting to that point, then measure (again with ignition on) at 4WABS main relay WIRE corresponding to socket contact #30, and if voltage is present there, then you have a break in the wire between these two relays, or socket contacts fouled.
If power is not making it that far, them measure for 12V on 4WABS Main Relay socket contact corresponding to relay contact #87, and if power isn't getting to it then there is a break in the wiring between the power distribution box feed and that point. If power is getting to it, then either the 4WABS Main Relay is bad, or it is not being triggered, so check with ignition on for 12V at that relay socket contact #85, and at ABS module pin 20.
I'd also check resistance between 4WABS Main Relay contact 86 and ABS module pin 19. If resistance there is not low, then you have a wiring or connector fault between these two points. The diagram does not make clear whether there is a physical relay inside the 4WABS Control Module to pull that down to ground, or if it might be a transistor doing so, but you could try temporarily jumpering 4WABS Control Module pin 19 to ground to rule out that internal relay or transistor being bad. This is the internal relay or transistor I'm talking about if I didn't make it clear:
Also you need to have 12V on 4WABS Control Module pin 20 with ignition in run position. Did I mention (or did you?) swapping in a different ABS Main Relay? If it is the same relay part # as the ABS pump relay then you could just swap those two, assuming the pump relay is still good.
I hope I didn't mix up what I wrote above. I really really hate these old diagrams.
