After some research I was able to pull the code on the 89 300SE, Code 3 indicated Slipring and Carbon contacts dirty. Code was not able to reset after cleaning contact ring and carbon connectors. What would be the proper way to proceed from here?

Code 3 means the return voltage thru the air bag & wiring was incorrect. Computer sends voltage signal to air bag & expects a return voltage back. Your car isn't sending the correct return voltage back. Too high(low) resistance in wiring, contacts, or air bag.

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