No back up lights

It is located on the side of the transmission and has the shift linkage shaft running through it.
I would double check the power and grounds before and after the switch before replacing it. They don't fail often. The power comes from the same fuse as the turn signals.

Thanks for the response. I had someone check the electrical (but he doesn't touch transmissions)stated the electrical is ok. I was also told by an ASE mechanic (while getting a quote) that the switch itself does many functions, including knowing if the car is in PRND12 etc. Could this also be why my key wouldn't come out of the ignition last week? Because the switch has failed & wasn't letting the vehicle know it was in park?

Could very well cause that. The switch tells the computer what gear your in. It in turn displays the gear on the dash, stops the vehicle from starting in gear, and activates the ignition interlock solenoid when in park as well as the back-up lamps. It does a couple other things as well.