Don’t loose sleep over it! The wiring harness is a common issue.
Step one: Interview dealer and independent service managers in your area. Choose the one you think you would feel most comfortable working with.
Step two: Book an appointment to have the whole car evaluated. Ask them to make a list of what needs to be done.
Step three: Be prepared to invest in fixing any issues that come up. Do any critical things first… evaluate if you can handle any of the work yourself.
Best of luck and enjoy.
1988 300 SL (5 Speed)
1994 E320 Wagon