Wiper motor wires? Black single wire. Help

[steveo3318]

Ok so my wipers were not working when I got the truck. After doing some research and some understanding of the wiring i tore into it. My switch is a three position switch which can be depressed for the squirter, I can hear the relay close but no squirt. Thats not the question though.

My question is do I have a single speed motor? It has a yellow wire which is constant hot that jumps from the relay to the motor terminal. And a blue wire beside it which is the ground from the switch. my other question is whats the black wires purpose coming from the motor? I understand it is the ground feed for the switch but it was not grounded internally. so nothing would work but the squirt relay.

In other words I removed that ground wire from the motor and made a good positive under dash ground and the wipers now work. But they only have one speed in either position. Hows the wipers suppose to work on these trucks!