Switch at the bottom left side of radiator puts fan to ground and it runs. I wired my to a toggle switch so I can kick it on ahead of time in heavy traffic. It still retains the auto mode too.
I basically did the same thing because Patriot Guard Mission escorts from the funeral home/church to the cemetery can be really slow and I didn't want Sandman overheating in our Southern heat and humidity. I'm using one of the switches in the Kury switchbox I mounted on the clutch master cylinder. Haven't done it to my I/S yet but I will.
Marty