53b is certainly the high speed power supply to the motor, although your diagram is from a 1977 (no intermittent) rather than the 1978 which got intermittent via a complicated relay.
My post above Greg’s (hopefully) explains what we did to overcome the problematic behaviour of just applying power to 53b. What happened when doing that was that was that the wiper started very slowly, picked up speed about half way through the beginning of the wipe, returned and repeated the cycle. Not what we wanted, which was continuous high speed from the start. To achieve that we effectively cut 31b when using the remote switch. That isolated the park function.
I’m not sure if I can do this, but if so, the attached scan shows what we did.
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