Had to get the reading glasses out scrutinise the wiring diagram for the later and alternator equipped models with two-speed wipers. For these the live side is switched, but the motor also has a constant live from the ign position (rather than acc) of the ignition switch which then goes through fuse 2, before splitting to go to both the motor directly and also to the three terminal switch. The live feed to the motor is green, the live feed to the switch is also green. The two-speed motor then has:
Two constantly earthed earths, one from the loom and one local to the motor, which is nuts! - Black.
A live as mentioned above having come through the ignition switch then through fuse 2 - Green
A switched live for slow speed - Yellow
A switched live for high speed - Red
Not sure if the yellow remains live when the red is made live when switched to high-speed. It probably does as that way the switch internally could be the very same switch as used for the sidelamps/headlamps, just with different markings.
Is this any help, are you hoping to fit a two-speed motor where you once had single-speed one? So do I, someday.