Sorry, I cannot answer your specific question. But here is the service manual.

eva2.homeip.net/W115/program/

Chassis and Body Manual Section 82 has some stuff on the wiper system. Also, you can find the wiring diagram in the Electrical Trouble Shooting Manual.

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1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).