The pictures in the manual are black and white and not close up so I cannot see where they come from or their color and this manual does not have the wiring diagram.However I have an aftermarket PDF of the wiring diagram for 1986 760 and if I understand it correctly the "Heater Fan Temp Sensor" has a white wire coming through the firwall and the other connector was grounded. And my old memory says that these wires came through the firewall in the same grommet that the two vacumm tubes do which should be lower on the firewall but same area side to side as the valve. So the switch is missing and the "T" fitting is plugged? I would have hoped when it was remove they connected the two wires together so as to 'cheat' the system into thinking there was warm water. Scot