If you have 12v with it in position 1, the motor is getting power. So, either the motor is no good or there is no ground.
Also, I have seen the voltage (12v) drop to nearly nothing when under a load due to a faulty connection. If you want to check for that as a possibility, with the wiper motor on, you would need to back probe the gray wire to see if the power drops.
As far as the tests you questioned above, if you have power to the gray wire, the only thing we need to confirm is power is consistent when requested and there is a good ground.
To check for continuity to ground, turn the multimeter to ohms. With the meter in this position, if you touch the two leads together, it should show 0.
With the vehicle power off, disconnect the connector at the motor. Probe the black wire in the connector with one lead of the meter and the other lead touching a known good ground. Does the meter change to 0 or near 0?
Here is a link you may find helpful:
Let me know.
Monday, October 30th, 2023 AT 6:59 PM