2 or 3 Position Swithch on '81 300TD Rear Light?
 

My rear light on my '81 300TD only comes on when I use the button on the dash. According to the wiring diagram, it should come on when the rear doors or the hatch is open. The wiring diagram also shows that the switch in the light housing should have 3 positions. Mine has only 2. Given my POs' penchant for messing (horribly) with things electrical, I'm wondering if they swapped in the wrong light housing sometime.

Should my light fixture have 3 positions?

yup, up - on, down - on, and middle off.
John