1. Locate the fuse box on the lower dash, on the left hand side of the steering wheel and open the cover. Examine the fuse diagram on the inside of the fuse cover lid to pinpoint the exact location of the sunroof fuse. It varies with different year 190Es. Pull the corresponding 15 amp fuse with needle-nose pliers and replace it with a new one. Test the sun roof.
2. Open the hood and remove the negative battery cable with an adjustable wrench.
3. Pry the trim piece from around the sunroof button off with a flat-head screwdriver.
4. Unplug the old sunroof switch from the plastic wiring harness. Remove the old switch from the small clip holding it in place. Hold the new switch in place and clip it into position.
5. Plug the new sunroof switch into the plastic wiring harness and re-install the plastic trim piece around the switch by snapping it back into place by hand.
6. Use a screwdriver and an old toothbrush to clear any debris from the sunroof track. Examine the track carefully to make sure its not dented. If it is, pry it back into place with the needle-nose pliers. Lubricate the track with a spray lubricant such as WD-40.