Double check your wire, it should be Blue/White. If you never have voltage here, in all likelihood you have either damaged wiring or a failed 4WD ecu. While it is possible the fused power to the 4WD ecu could be blown, it is highly unlikely that you would still have fault indication.
It should be known that this wire will NOT have voltage at all times.
There are no relays in the system, as there is no need for them (entire system is low voltage).
4WD ecu is fused by #7 and #11 fuses in the in-dash fuse box, both are 10A.
Worth noting is a failure of fuse #7 will result in an air conditioning malfunction and an inoperable rear defogger.... so if those work, the fuse is good.
A failure of fuse #11 will result in malfunction of the ABS, dome light, and power locks systems... so if those work, the fuse is good.
I would still strongly advise that you recover the codes from the system just to be sure you know what it "thinks" is wrong, just as an aid.
Here is the diagram you requested for the entire system: