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**VetteVet** · 03-25-2018, 06:57 PM

Possibly because multiple functions of a device are easier to control using a common ground rather than running several live wires and switches. The same holds true with the dome light and the ground switches that turn it on. I think mainly it was cheaper for the factory to do it that way.

The blower motor is an example of using positive switching for different speeds but the speeds are designed by using resistors instead of separate windings in the blower motor.
Just my theory but a very interesting question.

03-25-2018, 06:57 PM	#2
VetteVet Msgt USAF Ret Join Date: Jan 2005 Location: Kalamazoo, Michigan Posts: 8,723	Re: Why are wiper motors switched ground? Possibly because multiple functions of a device are easier to control using a common ground rather than running several live wires and switches. The same holds true with the dome light and the ground switches that turn it on. I think mainly it was cheaper for the factory to do it that way. The blower motor is an example of using positive switching for different speeds but the speeds are designed by using resistors instead of separate windings in the blower motor. Just my theory but a very interesting question. __________________ VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative.