VZN130 surf speedo & 4wd issues

[MRV8]

Hi all, I have a 1992 v6 surf, and the speedo has stopped working and the 4wd has engaged itself and wont disengage. They both occurred at the same time. The sender unit and speedo head test ok on the test bench, and all 4wd sensors and motor all test ok. Any help, or even a wiring diagram would be appreciated.
Cheers, Anthony.