Ack! Resister is 10K (measured & replaced with another one, also measured). I've tried everything I can think of. If I pull the output wire, I get +5v on the input as I would expect. When I put the output wire back I get either 0.03V or 0.40V, neither of which is enough to pull the TTL high :(
Just as a sanity check, here's my setup:
+5 --+------------------+ sensor +5v/orange wire | 10K resistor | +--- output from sensor (brown wire) | | --+------+-----------+ input to PICGND ---------------------+ sensor gnd/blue wire
I've tried two different sensors & get the exact same results with both. The frustrating thing is everything else is working great.
Any additional thoughts much appreciated!