TR2/3/3A wiper motor parking

[TFB]

Got my wipers installed todaqy but wipers park in random spots.I have 12v to motor and 12v from switch.Motor runs regardless of switch if I switch leads.I know I should be able to adjust park position by rotating dome on motor top but think they should still stop in the same place even if out of adjustment.Any thought s appreciated before I attempt to adjust or open up the motor.
Thanks
tom

 

[ShawnC_at_Moss]

Tom,
Our tech guys "Hans" did a video on wiper motors recently. It might answer some of your questions.

Happy Motoring,

Shawn

 

[Geo Hahn]

You might mention what year (or commission number) you have as TR2/3/3A wiper wiring changed significantly at one point in the run.

It is a common problem as one widely circulated wiring diagram is incorrect for many (if not most) cars.

Since you say "I have 12v to motor and 12v from switch" it sounds like you have the early version of the wiring scheme.

 

[TFB]

SorryGeo ,I misspoke.Its a DR2 1959 with 12v, constant earth,and earth thru the switch.3 terminals.I forgot the switch is another ground circuit.
Thanks Shawn,I will watch the video.
Tom

 

[Geo Hahn]

In that case, it's like mine.

You might closely examine that red wire that goes from the wheel box to the motor. As I recall (and it has been awhile):

... If that wire has a break in it the wipers will not park - they will just stop wherever they are when you switch the wipers off.

... If that wire shorts out (most likely to happen where insulation abrades against the motor case where it goes in) the wipers will not stop when switched off.

As I said -- it has been awhile -- but I definitely recall that failure of that red wire can cause some strange motor behavior.

 

[alanjohnturner]

There are two kinds of cap in use on DR2's

https://flickr.com/gp/90670218@N04/0205z7
https://flickr.com/gp/90670218@N04/34jB1c

One uses a reliable springy finger like a DR3A, the other a rather tricky bent contact thing that is prone to poor contact and is hard to adjust.

Take the plate off and clean with Scotch-brite and set the contact so they touch nice.

All these motors need a permanent 12V supply on the correct contact, usually maked 2 and the on/off is done by making the ground side, usually marked 1.

Mess with this and the self-park contact will short the battery and overheat.

Here I am spiffing up some DR2s
https://flickr.com/gp/90670218@N04/pC19gj

 

[TFB]

There are two kinds of cap in use on DR2's

https://flickr.com/gp/90670218@N04/0205z7
https://flickr.com/gp/90670218@N04/34jB1c

One uses a reliable springy finger like a DR3A, the other a rather tricky bent contact thing that is prone to poor contact and is hard to adjust.

Take the plate off and clean with Scotch-brite and set the contact so they touch nice.

All these motors need a permanent 12V supply on the correct contact, usually maked 2 and the on/off is done by making the ground side, usually marked 1.

Mess with this and the self-park contact will short the battery and overheat.

Here I am spiffing up some DR2s
https://flickr.com/gp/90670218@N04/pC19gj

Thanks again Geo,and Alan or the pics.I have the cap on the left in first pic.I did resolder the connection on top so some troubleshooting to follow.
Thanks again
Tom

 

[alanjohnturner]

You got the common, easy, type of cap.

But these have an "interesting" failure mode. You see how the brass-disc and outer contact are held with two rivets. Insulation is sandwiched in so they dont touch the main cap.

Well the rivets can stop making a good "through" contact. They tend to touch when you check them with a test-meter and then go off-duty when you are not looking.

A tap with a hammer or maybe a dab of solder.

I drill these out and re-rivet them when I re-build these. Here is a set of photos of a DR3A rebuild showing me doing this.
https://www.flickr.com/photos/90670218@N04/sets/72157641071372515/

I also always replace the wire. This can fail internally but still look OK outside. The original is rubber coated but PVC will do.

When this stops in the "wrong" place short the contact on the top of the cap to the body. If it moves the fault is inside the cap or the body of the motor does not have a good contact to the car body.


Al.