How do you check the voltage of the dimmer switch in a 1992 Chevy Lumina and is it hard to replace?

I believe it is within the turn signal wand. I have replaced a few of these on other GM cars. Not that hard to do. If pulling the switch towards you does not activate the dimmer, then the switch is most likely shot.You will need: steering wheel puller, basic metric/sae socket set, torx screw drivers tx15, tx20. Now disconnect neg on battery, disable yellow connection for AIRBAG, remove trim around horn,loosen nut on center of steering wheel,pull wheel with puller. Now you should be able to see switch assembly, remove the torx fasteners and unplug the harness and then feed the wire harness thru the column, tilt wheel as necessary. I get parts like this at a salvage yard cause you can get the entire column with parts for about 75.00 plus you can practice on the workbench vs on your car.Reverse the procedure. Be sure you disable the air bag yellow harness near column under dash. Good luck, I hope this helps you.