Awhile back my US2 quit working... I swapped df's around, everything
works fine elsewhere, but neither my 787 or 797 will work off the US

Trying to troubleshoot thoroughly before tearing into the motor, I just
happened to check for continuity on my adapter cable - the 6 or so inch
long one that converts from round threaded coupler on one end to H'bird
plug on the other. My question is, I have 4 pins coming from the tm.
I have four sockets in the tm end of the adapter. The H'bird plug only has
three pins. I only have continuity from two of these pins through the
adapter cable. The third pin is "dead".

Is this my problem? Or are only two used?
I'd love to see sort of a pinout explanation of what each pin does,
200, 83 freq., water temp, etc.