transmission overload (protection) switch
 

When I put my car in reverse, it takes a few seconds to think about going in and then it always does. When hooked up to the scanner it says "transmission overload switch not closed".
What does this do? I have found it on the transmission, but how can I check it and what is its purpose?
1992 500SEL

Posting the year, make, and model of your car will help others better answer this for you.b Otherwise, my guess would be worn reverse clutch.

Thanks Ismalley. I totally forgot that important part.