I have a eurpoean import 1986-87 300D wiper that was starting to get slow and beginning to shutter when moving. It seems to not have the same speed between normal and fast when switched to that mode. I got a used 1991 replacement (entire assembly) and installed it just fine. But when turning it on it does not stop or obey the switch signals. I have to turn off the key. I noted that the motor number is slightly different but other than that everything seems identical. I thought the 124 series wipers were interchangable if it would install correctly and everything else. Does anyone have any experience with this? Have I installed the wiper properly?

thanks

 

I don't have a wiring schematic but it could be that the signal to the "motor park" is not the same between the two model years.
I think I'd try a wiper assembly with the correct part number.
Did you try plugging the old one back in to see if it still operates correctly?
If so, it seems it would point to the motor assembly.

 

I wonder why the part number would be different if they were the same unit??