I have never seen the value in an "alarm" for the oil pump. The only way one would work is with a 1 or 2 psi hobbs switch on the outlet, but a scavenge pump does not pump a continuous stream of oil but rather slugs of oil as the pump moves more oil than what is coming from the turbo. They are prone to a lot of false annoying alarms. Besides, if it stops working for some reason, you will know simply from all the white smoke from the exhaust.

The WORST thing one can do to a 12vdc motor is to try and use resistors to run it on reduced voltage at low vehicle speed to reduce pump noise at idle or low speed. This is a sure fire way to burn up a pump.