The switch is kinda funny because the motor if I remember correctly has one positive and 3 negatives. One negative is for high, one for low, and one for off/return. I figured out the switch by carefully pulling it open by peeling the 4 prongs straight, seeing what went where, cleaning up the contacts, and then re-assembling it. This was all way before mud so I had to do that. Now that we have mud do a search in this forum for wipers and maybe even check out the FAQ and I bet you find a wiring diagram.