Here are the steps to find the diagnostic connector in a 1995 Mercedes SL 500:
1. Open the hood of the car.
2. Locate the air filter housing on the passenger side.
3. Remove the air filter housing cover.
4. Look behind the air filter housing and you will see the diagnostic connector.
The diagnostic connector is a 16-pin connector that is used to connect a diagnostic tool to the car. The diagnostic tool can be used to read and clear trouble codes, as well as to perform other diagnostic tests.