Where is the Automatic Transmission Output Speed Sensor

[ka1qyx]

had the same issue, drove me nuts
first the trand fl looked OK-

OUTPUT SPEED sensor is on the top of trans towards back under brake master cyl- 3 pin connector, one bolt holding it in
its a pain to twist/ get it out

pull out, put 3pin connector in, turn key to IGN ON (where everything lights up), spin the gear. does ODO work?
if yes then you know thats OK

youll feel the mating gear in the trans where you just pulled the output speed sens

can you spin it? is it loose?

if yes chances are that gear is loose and its not able to spin the output speed sens.

can it be fixed without pulling trans apart?
probably not easily. GM dealer isnt of much help. since i cant even really see it dont know if its a plastic or metal gear

from what can gather from their lousy diagrams its mounted on a shaft
mine was working just great then it stopped working after i parked it 3 hours

GM has a service bulletin on it, saying trans fl & coolant mixing so that causes this issue.....