I'm working on my 1970 coronet. I have a six amp 12 V charger connected to the black and red battery terminals (No battery connected). When I connect my three speed wiper switch and turn it on, the wipers function in all speed positions and parks when in the off position. The 12 V lead gets hot and the heat breaker inside the switch pops. I am expecting that this means I have a ground issue. I grounded the switch body to the dash. No good. With the switch disconnected, I tested all the wiper motor leads at the switch connector. I found that the brown and blue leads have continuity with chassis ground. I disconnected the bulkhead connector and tested the leads on the motor's bulkhead plug. The brown and blue still had chassis ground. The bulkhead terminals, showed no ground. I rebuilt my wiper motor myself. It tested fine. All wiring is new and correct gauge. Any ideas if those two wires are supposed to be grounded or why my switch is roasting?🔥🔥🔥

If the motor is not parked the brown an blue wires will go to ground. If its parked the blue wire should be open in relation to ground. Did you install the 3 metal bushings on the mounting studs before you installed the motor?
Bruce
Ns1aar.com

There were what looked like top hats that were on the mounting bolts. They were painted over and kind of stuck in place. Might that be what you are referring to? I can't remember if I got it parked before the breaker popped and I checked continuity. I can do that tomorrow afternoon.

Hey Bruce, I parked the wiper motor and tested continuity. Blue is open and brown goes to ground. Do those bars I described sound like the bushings you mentioned? It's such a simple circuit I don't know why that switch would heat up. I've tested that motor so many times. The jumpers never feel warm.

I did an extended test with jumpers letting the wipers run for 3 minutes or more. All is good. No hot wires. Replacing the jumpers with the switch, the positive gets too hot to touch in 30 seconds. The positive terminal gets hot regardless of on or off position.

Remove the paint from them and reinstall them that's the main ground path for the motor.

If the switch is not mounted in the car there will not be a ground path. If it is mounted in the car I'd do the continuity check or send it out to get rebuilt.

On the 1970 Coronet, the switches are not bolted to ground. They're bolted to plastic. I ran a ground wire to the dash. What continuity check are you speaking of.

Also, to reply to your previous comment, can I achieve ground to the wiper motor by running a ground wire from the motor case to the firewall? Removingthat motor at this stage will be a beotch.

If you have a FSM there is a continuity check for the switch If you don't have that contact me and I'll email it to you.

yes you could run a wire but if its in the car working without the switch involved I'd look real close at the switch.

A member on the board J&S restorations rebuilds the switches