Lots questions I have....
1. Does you pump work but is currently wired to another switch?
2. Does your switch look like this?
https://www.iconicparts.com/wiper-switch-knob
3. If so does the molex connector have 4 wires installed on the car side? (like the switch side does)?
Assuming the above are yes. You may have a failed pump since the BDR folks should have wired that from the factory.
Turn the key on. turn on the ign key. Using a meter set at VDC back pin the connector one at a time. One should show 12vdc which is the feed+.
(Ensure the black lead of the meter is connected to a chassis ground)
Turn the wipers to Low, now you should see 12vdc on two pins feed+ will have power and power line pin to the motor.
Turn the wipers to High the feed+ will have power along with a different pin to the motor.
Twist the knob and you should have 12vdc on the remaining pin. That is the pump feed power.
If all four molex connector wires are installed on the (car side see #3)
is the wire color on the pump feed power match the wire going into the pump?
If yes check for 12vdc on the that wire when you twist the knob. If its good check for a good ground.