transmission overload (protection) switch

[Tidyman]

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

[lsmalley]

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.

[Tidyman]

Thanks Ismalley. I totally forgot that important part.