I don't have a wiring diagram for 1968 handy. But for 1970, they show a Blu/Yel wire coming off of fuse #3 and running up to the switch. From the switch there are two Yel wires - one runs to the transmission (4th gear limiter) and the other Yel runs to the indicator light.
http://www.autozone.com/repairguides/Volvo-Coupes-Sedans-Wagons-1970-1989-Repair-Guide/WIRING-DIAGRAMS/WIRING-DIAGRAMS/_/P-0900c152800642d2
BTW, in that diagram they show two "Overdrive Switches". The second on is actually the 4th gear limiter on top of the transmission. From the limiter switch it's a red wire to the solenoid.
--
Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)
|