My sensor idiot light came on at 60K, like the manual said it would.  I found the reset switch under the dash, and flipped it to the down position.  The light comes on when starting, but goes out.  Do I leave the switch in the down position, or return it to up.  The manual is unclear if I should reset the switch.

Forgot to mention, bone stock '87 Samurai.  And it passed PA emissions with the light on, so everything seems to be working.

You are right the manual I also have is vague.......
I just left it in the opposite position as the light came back/ and stayed on when I flipped it back.
I think it comes on momentarily when you turn the key on as a system indicator check.
Hope someone that has more info responds and can give both of us a better clue!!
(P.S. I have just about all the ECU systems disconnected anyway as I have gone to a Weber Carb System)

CAPT

The sensor light lights up when the key is turned to run/start, to check the bulb, then it goes out once the engine is started, if there is no problem.  It is working as designed.