Windshield Wiper Switch

[cuda426]

My windshield wipers on my 1973 Barracuda went on without rotating the round on/off knob. I was able to turn them off so they were resting at the bottom of the windshield. But when I commenced to drive the car I noticed some smoke coming from the switch. I disconnected the wiring harness plug to the switch and the problem went away. Do you think I have a short across the switch?

Thanks, Bill

 

[Katfish]

Is this a trick question?
From what you describe it appears so.
Swap in another switch and see what happens.

 

[cuda426]

is there a method to check the switch with a continuity tester to determine if its defective or not?
thanks

 

[Challenger RTA]

Power for the wiper sw comes off of splice 3 that feeds the acc side of the fuse box, via the ign sw.

 

[Katfish]

Possible to test 3 speed wiper switch?

I got a 3 speed switch, 378, and was wondering how to test it to make sure it works correctly. Anyone have know how to do so? Do you need a 3 speed wiper for testing the switch?

board.moparts.org

 

[devinism]

I would be taking a serious look at the firewall junction box and all of the wiring. They would have a difficult time turning themselves on by themselves via the switch. Sounds like something fed back through the switch wires (some of which go to ground via the switch case.

Please disconnect your battery!

 

[Challenger RTA]

I'm thinking it's the park switch malfunctioning. Drawing to much current when hanging up. 2 speed or 3?

 

[cuda426]

Thank you, the wipers were in the parked position when the switch stared to smoke. Where is the park switch located?

 

[Challenger RTA]

In the wiper motor itself. Look at #4 posting picture.

 

[Challenger RTA]

Do have a 3488764 three speed switch. In the off position on the switch, test the impedance between the B and P terminals. That should read 0 Ohms. The second test is between F1 and the metal frame of the switch. That too should read 0 Ohms. If both of those tests read correctly, then test the impedance between the switch socket and the bulkhead connector:

Bulkhead position 1 - Switch Socket A (Brown w/ White Tracer)
Bulkhead position 2 - Switch Socket F1 (Red)
Bulkhead position 5 - Switch Socket P (Blue)
Bulkhead position 6 - Switch Socket F2 (Green)

Each of these reading should show 0 Ohms.

Found from a post over on cuda-challenger.com

Testing a 3-speed wiper system

The 3 speed wiper system controls the speed by use of a resister in the switch, not in the motor. The switch also reverses the current to the motor in the "off" position, which causes the motor to seek the "home" position. There is also a circuit breaker built into the switch to protect the circuitry.

Testing the switch

There is a test for the switch that can be done with a continuity tester or an ohmeter. To do this test, on the back of the switch, the terminals are marked with an "A", "B", "B/U", "F1", "F2", "P" and "R1". In the tests, "Ground" is the switch casing.
While in the "Off" position there should be continuity between
B to B/U
B/U to P
A to F2
F1 to Ground

"LOW"
B to B/U
B/U to A
A to F1
F2 to ground
P - open

"Medium"
B to B/U
B/U to A
A to R1
F2 to ground
P - open

"HIGH"
B to B/U
B/U to A
F2 to ground
P - open

Testing the motor

The motor only has two speeds, high and low. The medium speed is a variable speed, which is configured by the switch varying the voltage to the motor.

"Low"
Connect the motor housing and the green wire to ground
Bridge the brown and red wires
Connect either the brown or red wires to 12v
Motor should turn slowly

"High"
Connect the motor housing and the green wire to ground
Connect the brown wire to 12v
Motor should turn fast

"Park"
Connect the motor housing and the red wire to ground
Bridge the brown and green wires
Connect the blue wire to 12v
Motor should turn backward, then stop in park position.

 

[MoparCarGuy]

Additional info for those troubleshooting their 3-speed (variable) wiper motor functionality.
The internal PARK switch is inside the wiper motor's gear drive section and is located under the cover with three (3) x flathead hold-down screws.
It is a normally-closed (NC) switch with contacts similar to a set of old-school distributor points and susceptible to carbon buildup.
The PARK switch remains closed while in the PARK position and must be closed for proper OFF-LOW-HIGH wiper function.
See the photo with RED arrow pointing to the switch contacts.

After using the wipers, and when the dash Wiper OFF-LOW-HIGH switch is turned to OFF, the wiper motor stops, reverses direction, and the internal mechanism opens (breaks) the contacts to stop the motor on the lower windshield moulding's wiper "shelves".
This is a brief opening of the contacts by the internal nylon gear and latch mechanism, it breaks the contacts open just long enough to stop the wipers, and then the contacts return to their normally-closed position.

With the ignition key removed or in the OFF position, you can measure the resistance across the two cover terminals (Blue wire terminal to the Green wire terminal). The measurement should be very close to 0 Ω if your PARK switch is closed which is the normal position of a correctly operating PARK switch.

If you have PARK function issues, the most likely culprits are either the lack of grounding at the dash wiper switch OR a problem with the PARK switch discussed above. Be very careful reinstalling the cover after removing it. The cover must index correctly with the PARK switch latch/lever AND the cover must fit into the proper E-Body notch in the housing body. See the first photo for that location.

I hope this removes some of the mystery from wiper motor function.