Newbie here. I have an 88 S10 and the wiper switch packed it in. I know the grey wire is low speed and the purple wire is high speed on the motor. What are the other two wires for? I can get the motor to go by directly applying power to the grey or purple wire but I don't want to wire in a dashmounted toggle until I know what the other two wires are for, anybody help me out with this? I would they are grounds but even with the harness unplugged and power directly to ONE of the pins I get wipers.