Tilt/Trim Question

[rcnight]

I repowered my '83 with a '96 150 Evinrude. I updated with a new OMC trottle and a combo tach/check system. The engine came with a wiring harness, although I believe it was made by the boat mfg. All the connections/guages were accounted for, except for the trim guage. The engine has the sending unit, but I have no idea which are the leads nor does my book indicate such. Anyone have a suggestion on how to activate it or look for answers?