Back up lights wouldn’t come on, checked to see if I had power at the switch, yup, jumping the wires lit up the back up lights, so switch must be broken. The switch on the syncro is on the left hand side of the transmission, right beside a protrusion. Its an easy repair, 19 mm wrench, less than 5 min.
The old switch, the round end moves in and out:
shooftie 
#1 by Matthew on September 8, 2012 - 4:55 pm
Our 83 (water cooled 1.9) camper developed the same no reverse light issue as you noted above with the shorted wire producing light, so the switch is bad. For whatever reason, I am having the toughest time finding this part. Bus Depot has it with the shorter leads, but then you have to cut the boot to make it fit, and you don’t get the moisture protection seal. Same deal with Van-Cafe. It appears that Van-Cafe used to have them, but got their latest shipment with the shorter leads. Found a guy on Samba who had them, but he is now out. At this rate I am going to buy two when I find them…sheeeesh! Some days are better than others. Thanks for your site, I enjoy the shared info.
Peace,
Matthew