Since it is turning over I would start at the coil and work my way back testing at each junction while turning it over to see where to juice stops. (make sure you let it run until it cuts off first)

As for the difference between the 9 and 10 pin. I have no idea bud. I know they both show up on Fastlane as parts for the 89 so I am assuming that either one will work.

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89 190E
2.6L
Arctic white
Grey leather
Sunroof
Pirelli P400 rubber
Smoked corners