range mode sensor, sounds like the sensor on the outside of the transmission where the shift linkage mounts. If thats it, not much to it, and Id just replace the thing, why mess with attempting to clean it. What kind of symptons are you having, and what led you to this diagnosis? Trannys were never my thing, I do more electrican and drivability stuff, but there is a few of us on here that may be able to help out with more info.

Hey tmleadr03, fancy seeing you here!lol