1972 Only Bus Turn Signal Switch
The 72 Bus T/S Switch was obsolete many years ago from VW’s supplier SWF, so the 68-71 Switch has been the recommended replacement. Actually, it's pretty simple IF you know the differences between 68-71 and 72-only wiring. So here you go:
Ignore the Black w/Red Stripe, Black w/Yellow Stripe and Grey w/Black Stripe
wires coming from the 68-71 replacement switch. These are what operate the Rear Turn and Stoplight circuits on the 68-71, which were Double Filament Single
Bulbs (type 1157) on each side. On the 72 Bus, the Stoplight circuits run direct from the Stoplight Switches (rather than thru the T/Switch on 68-71's) to Single
Filament Bulbs (type 1156) and the Turn Signal Bulbs (also a 1156), both running on their own separate circuits. Simply tape the ends to prevent any accidental shorting to ground.
On a 72 Bus, the Black w/White Stripe (Left) and Black w/Green Stripe (Right) wires to operate both the front and rear Turn Signal Bulbs. The existing connecting block(s) in the harness actually make this easy for you, PROVIDED someone hasn't "butchered" the harnesses underneath the dashboard. (In which case you will need to match up the wires - for wiring diagram link see below).
All other wires are the same: Black w/Green & White - to the Hazard Light Switch (Terminal 49a) and the Headlight Dimmer Relay Wires (Brown w/White Strip to the H/L Relay and Brown to Chassis Ground).
It also helps to have a Wiring Diagram (see http://www.vintagebus.com)
whether replacing with the original, replacement or the retro-fit I described