[DNickel]

Long road to a simple solution, thanks Autoban.

I have the elctrical drawings and my '88 cab and went in circles yesterday. No grey wire anywhere. Had the meter out and found no connection to the relay or the fog switch.
Diagrams are missing important bits like the fog switch and the high beam cutoff.
Thought I had it with the simple solution of activating pin 86 blu/wht with 12V key switch power. Fogs were on and everything seemed well, then I noticed my car had permanent high beams! There is a feedback loop somewhere but the diagrams are redacted for simplicity.

I now have fuse 8 box 2 to fuse fuse 8 box 1 as fuse 7 box 1 was too full.
My whole car is LED except the fogs which are next from spoke and then the fuse rating will be fine.