William sorry I somehow missed your post--Yes JCNA has the wiring diagram for the 1977 XJ12. Write me off list at Publications@JCNA.com if you want a full wiring chart. As far as the fan relay etc. ---the fan has one wire (red) to an in-line fuse. From the fuse the hot wire for the fan (now Black and green) goes to the relay. The relay is wired one wire to ground (black)--one to the horn relay (Brown-green) --one to the horn relay (green) and one to the thermal switch (wire code not given) but the trigger wire to the thermal switch has two patterns-one for automatic and one for manual--assuming your car is manual the wire goes direct to the switch--if automatic it goes through the air conditioning relay. william I would give you the pin connections for the relays but they were not deemed necessary at the time--I have some more detailed charts I can check if this information is not sufficient.