How to identify which Wiper Motor (2 speed or 3 speed) Should be on 75 Duster

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shanker

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I'm working on my wife's 75 Duster 360. I've always noticed that the wiper switch is a 3 speed switch, and the windshield wiper motor (has a 2 speed motor mounted to car) only has on/off, irregardless of what speed the switch is in.

How can I go about identifying if the car has the wrong motor, or the wrong switch? Fender Tag is long gone. Build sheet was in too many pieces to re-assemble when we did re-did the seats. The car does have the rear window defogger (and all the associated wiring and switch is still bundled into the dash harness) which leads me to believe that the dash harness is original to the car.

This was my wife's first car and her daily driver for YEARS (she's 40 now) and I've been with her for 20 of those years and know the history of the car and the previous owner was, uh, well, a unique character who's nickname was "opossum".

The dash harness has never been swapped, but under the hood it was painted black (I know, worst thing that can be done to any mopar) with the wiring harness still in place, so all the wires are black.

I've got the cluster out of it at the moment while I'm replacing two wiper pivot bushings and taking care of a few other things that I've been putting off.

10-23-20 Progress.jpg
 
Get the part #'s off switch and motor, go from there.


The Switch is 3488764 (Most Definitely a 3 Speed Wiper Switch, google results indicate 1972-74 E-Body & 72-76 A-Body 3 Speed Wiper/Washer Switch)

Wiper Motor is 3799083 ( google results indicate its a 72-76 A-Body part number)

and the Linkage's are 3431688 & 3431684, which I don't think are specific between 2 & 3 speed units.


are there any tale-tale signs that would be unique to the wiring I can look at to see if the motor has been swapped? Specifically on the dash harness side since the firewall side of the wiring would have been easily changed with the motor swap if that's what was done.

Wiper Motor Switch Part Number 3488764.jpg
 
The 2 speed motor has wires that attach with plug-ins at the motor, whereas the 3/variable speed motor is wired directly into the motor inside the case, so there may be telltale evidence there. Swapping from 2-3 speed and visa versa is not uncomplicated - a lot of work to have a less desirable system, so why would someone do that?
 
The linkage is somewhat different in that the arm that attaches to the motor is different and they don't interchange.
 
The 2 speed motor has wires that attach with plug-ins at the motor, whereas the 3/variable speed motor is wired directly into the motor inside the case, so there may be telltale evidence there. Swapping from 2-3 speed and visa versa is not uncomplicated - a lot of work to have a less desirable system, so why would someone do that?

knowing the previous owner, and that he was a mopar hoarder. If something broke, he would've just grabbed something off a car in the field that would at minimum *kinda* bolt up and *sort of* work as long as it didn't cost any money.

I get what you said about the harness on the firewall side. I think I've got a few 3 speed motors in my parts stash in the barn. I guess I should grab one and see if It functions with the existing switch & wiring.

Either way, I don't really care if it's got a working 2 speed or 3 speed setup, as long as it works as intended is all I'm after. Currently I've got one speed and have to turn the wiper motor switch off at just the right time as it doesn't park itself.

If I have to put a 2 speed switch in it, it'd be A LOT easier to do it now than after I put the dash back together.
 
I bet a 2 speed switch would fix the park issue...
 
I bet a 2 speed switch would fix the park issue...

Do the 2 speed switches have the same function that you push them for the windshield washer pump to spray? (I don't know as my B-Body has an independent button to spray the washer pump)
 
I've been trying to figure this out. When you push in on the button it feels sprung, but I've been told that the answer is no. The car I'm working now had a 2 speed and a manual foot pump for the washer. I've been working with another member to convert the foot pump to an electric momentary switch which I will wire to an electric washer set up. Seems like the best of all worlds to me.
 
I've been trying to figure this out. When you push in on the button it feels sprung, but I've been told that the answer is no. The car I'm working now had a 2 speed and a manual foot pump for the washer. I've been working with another member to convert the foot pump to an electric momentary switch which I will wire to an electric washer set up. Seems like the best of all worlds to me.

I can tell you with absolute certainty that the 2 speed wiper switch in my 74 Ramcharger is depressed to pump windshield washer fluid.
 
When was the last time wipers AND washer worked properly?
Is there a motor on bottom of reservoir?
Pics of motor?
 
Sure that's a 3 speed switch? I'm seeing the little sidecar resistor that they usually have. 4 switch positions.....right? Off, 1,2,3?
 
When was the last time wipers AND washer worked properly?
Is there a motor on bottom of reservoir?
Pics of motor?

That's a great question that made me look up the windshield washer stuff in the FSM. There is washer fluid tank in the engine bay. And if I'm looking at it correctly, being that the car has Cruise Control, I don't see how the tank would mount over the passenger side inner fender w/o interfering with the cruise control servo.

The Instrument Bezel is also labeled Wipe - Wash above the wiper switch. I wonder if the cars with a foot pump also said that.

Sure that's a 3 speed switch? I'm seeing the little sidecar resistor that they usually have. 4 switch positions.....right? Off, 1,2,3?

yes, off, 1, 2, 3 and I can push it to engage the washer pump and it'll automatically roll into position #1.
 
I've been trying to figure this out. When you push in on the button it feels sprung, but I've been told that the answer is no. The car I'm working now had a 2 speed and a manual foot pump for the washer. I've been working with another member to convert the foot pump to an electric momentary switch which I will wire to an electric washer set up. Seems like the best of all worlds to me.

Just to maybe help you. This is the 2 speed wiper motor switch out of my 74 Ramcharger. Part Number 2864152 When You push it (about a 1/4 Movement at most) It triggers the electric washer. Then of course there are 2 clockwise positions for Low/Hi on the wiper speed.

WiperSwitch2Speed01.jpg


WiperSwitch2Speed02.jpg
 
Little bit more investigation with this car.

I noticed (while replacing the upper speedometer cable) what appears to be a grommet where a tube would pass thru the firewall.

Is this where the foot pump tube passes thru the firewall? If so, it'd answer my question.

I'm just not seeing any physical space for the washer bottle even though I know it'd be right there.

WindsheildWiperFootPumpFirewallPossible01.jpg


WindsheildWiperFootPumpFirewallPossible02.jpg
 
Little bit more investigation with this car.

I noticed (while replacing the upper speedometer cable) what appears to be a grommet where a tube would pass thru the firewall.

Is this where the foot pump tube passes thru the firewall? If so, it'd answer my question.

I'm just not seeing any physical space for the washer bottle even though I know it'd be right there.

View attachment 1715700162

View attachment 1715700163

Not certain, but I think that might be for the interior hood release? I am sure it isn't for the foot pump though as that would have a hose going and going out and would require a bigger hole than I am seeing there.
 
Did they even have a foot pump option that late? I thought they did away with it by then.
 
Look for witness holes, for place where the tank may have been mounted. The cruise control kinda throws everthings mounting place off. My '72 Dart ( I know that 3 yrs changed a lot under the hood) has the tank on the drivers side in the normal place just above the shock stud. My ign module is mounted just in front of it and the starter relay is in the normal place . Your relay is up on the firewall, ign module is in an odd place ( to me). Wondering if everrhing has been moved around for some reason. Also, has the wiring been tampered with. I am thinking the car should have had electric washers, but they are correct I think that under the dash, that arm that attaches to the motor is different between the 2 and 3 speed. Is the wiring and ballast resister for the 2 speed motor look orginal? Are there any holes in the floor above the dimmer switch for where the foot pump would have been?
 
Look for witness holes, for place where the tank may have been mounted. The cruise control kinda throws everthings mounting place off. My '72 Dart ( I know that 3 yrs changed a lot under the hood) has the tank on the drivers side in the normal place just above the shock stud. My ign module is mounted just in front of it and the starter relay is in the normal place . Your relay is up on the firewall, ign module is in an odd place ( to me). Wondering if everrhing has been moved around for some reason. Also, has the wiring been tampered with. I am thinking the car should have had electric washers, but they are correct I think that under the dash, that arm that attaches to the motor is different between the 2 and 3 speed. Is the wiring and ballast resister for the 2 speed motor look orginal? Are there any holes in the floor above the dimmer switch for where the foot pump would have been?

This car was rode hard and put away wet in the 80's and early 90's. When my wife was a teenager and the engine/transmission was pulled for a rebuild. The firewall was blasted black. (I know most of us think of this as a deadly sin, but my Father-in-law who built this car for his then teenage daughter is a paint/body man by trade, and one of his Cuda's was even featured in and on the cover of Mopar Muscle *11/1998 iirc*. He said that before he put the engine back in, due to not wanting to get into an engine bay restoration it looked better flat black than F8 green as the exterior was painted purple, and he's probably right). All of the electronics in the car we left in the same locations as when he got the car for her, but the way the wiring is ran, it seems right. I've patched in lots of repair splices though, and I *used* to grab whatever color wire I had a spool of (I don't do that anymore though).
 
a 3 speed wiper motor is wired directly to the motor (no connectors visible on the outside of the motor, just wires from the bulkhead connector into the motor) and a 2 speed has wires from the bulkhead connector to a plug (4 wires) that plugs into the outside of the motor. If you find the plug it's a 2 speed.
 
1974 was the last year washer manual foot pump was offered. 2 speed wiper switch for 1975 is part #3746851. Go to Ebay .then enter 1975 dodge dart and click on search. Now look on left side of screen under category scroll down to sold items and click there. Then look at original listing and you will see location of washer tank from under hood photo.
 
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