Bench Testing 3 Speed Wipers

[RabidScott]

Hi guys!!

The rainy season is approaching here in my area of California, and I haven't gotten the wipers on my Challenger working yet.  I had to convert to the 3 speed wiper because I added the Shaker, the 2 speed wiper worked fine but didn't fit with the bubble.

I have a couple of 3 speed wiper motors, and a couple of 3 speed switches, but before I install them I'd like to ensure everything works correctly.

What do the terminals on the wiper correspond to?

Can I apply a direct 12 volts to each of them without burning anything up?

Does it ground through the body of the unit?

How should I test the switches?

Is the wiper linkage the same between the 2 speed and 3 speed wipers?

Many thanks!!   

[72hemi]

I don't have my books with me so I can't give you the testing procedures for the motors or switches, but I can tell you that the entire wiper arm assembly is different between the 2 and 3 speed systems and if you haven't already you will have to swap it out.

[Kapteenikosmos]

Do a google search about mopar 3 speed wiper testing. There is an article on some web page (should be easy to find with good enough search words) with detailed instructions for testing out an old mopar 3 speed wiper. I've read it couple of times, but cannot remember where it was, and right now I'm so sleepy that I'll have to do the googling tomorrow if you haven't received an answer before that.

[RabidScott]

the entire wiper arm assembly is different between the 2 and 3 speed systems

Does any other body styles interchange with the E-body linkage?  '71-'74 B-bodies?

Do a google search about mopar 3 speed wiper testing. There is an article on some web page (should be easy to find with good enough search words) with detailed instructions for testing out an old mopar 3 speed wiper. I've read it couple of times, but cannot remember where it was, and right now I'm so sleepy that I'll have to do the googling tomorrow if you haven't received an answer before that.

Thanks, I'll go look for it.

[Chryco Psycho]

I do not believe so , the B body linkage is different + the linkage is different between 70 & other year E bodys as well

[JayBee]

I printed out a testing article by "restorick", try him.

www.restorick.com

Unfortunately I have a '70 and need to test my variable switches instead.

[72bluNblu]

And to make it complete, how do you test a 2 speed wiper motor? need to get my wipers working soon, rain is right around the corner...

[Bullitt-]

Scanned from the '73 service manual may be different on a 70

[RabidScott]

Thanks for the link Jay Bee!

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"
Conect 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.

Rick Kreuziger

[Chryco Psycho]

so I assume the motor should reverse in any position , & if it won`t where is th eproblem ?

[Chryco Psycho]

NO one has ever tested this or knows ?

[gkring]

I think the problem with most is they do not reverse. I had read on one of the wiper rebuilder webpages (I thought it was Jules's, but I guess not) what normally goes wrong. There is some kind of reverser relay inside the motor that goes bad. When it comes time to reverse the polarity and reverse the motor it doesn't work. Supposedly an easy fix once you get the motor apart. Kind of like cleaning and setting points. I looked for the page when you originally asked, but could not find it. There are probably pics in a service manual. For the price of a local auto store rebuild I just replaced mine and enlarged the wiper arm lever a little where it attaches to the motor. The arm on the early cars are smaller than the post 72 wipers. You can only buy auto store rebuilt motors for the post 72 models. I wasn't worried about matching casting numbers, plus for the $10 core I just kept my original.

[Chryco Psycho]

I would like to keep the original motor case as it is # matching original , I can swap the guts to match the wiper lever as the gears are good still but it will look different with the non flat top plate

[73EStroker]

On the posted schematic you will see a park switch. That switch makes contact once the wipers leave the parked position. If this switch is not made the wipers will run but they will not reverse back to the park position. To reverse the motor the polarity of the field is reversed inside the switch when you turn it off. Thats the way I see it based on my 1970-73 training at technical college for electrical.  A little more Elect 101 - To slow the wipers down a full 12V is applied to the shunt field. To speed them up you weaken the power to the shunt field. Hence the resistors either external or internal to the switch. Whenever the wipers run you must have power going through the series field/armature.