Re: [Chrysler300] Chrysler 300C windshield wiper motor

["John Grady jkg@xxxxxxxxxxxxxxxxx [Chrysler300]" <Chrysler300-noreply@xxxxxxxxxxxxxxx>]

Hi,
Carlton ,
Whoever hooked it up to try it did not ground the wiper switch housing
which caused no field magnetism and  burned out the armature  ..you are
right , now toast. But that caused it.

But if someone tries that "lets test it "  again with a brand new rewound
one or whatever it too will burn right up. There really was nothing wrong
with the armatures initially  ----they were burned out by someone not
hooking it up right to 'try it" is my  point. ....with no field magnetism
the motor may not spin just sits there across full 12v on armature, no
spin,  with only the DC resistance of the windings to limit current. that
might be 30 or 40Amps. This will not happen in the car, (possibly even with
wiper switch off ----if not parked when taken apart. it is alive to park
itself ,with dash  switch off) Why didn't it happen in car? First because
the field is correctly grounded through the switch housing mounted to the
dash, it spins, so no issues. ,and two, if no field,  the circuit breaker
will click open or fuse blows if it does not spin. . So armature left
undamaged. Somewhere along the line someone trying to test it, not knowing
to ground switch housing  ---- they burned it out. And will burn out the
next one if the point is not understood? if tested on bench you must run -
side to switch housing and to motor.

I only know about this as I was running it on bench and saw ammeter on my
power supply go through the roof, I shut it right off at power supply in
seconds, led me to trace how it works.  .which is not obvious .The switch
reverses the two field wires so it runs forward and backward (to park)--
after reversing or forward connection is made in the switch, by you
shutting it off, it grounds the low side of field 12v, , one (-) wire
..right at switch, not motor .

Bob might save this explanation under wiper motors, very easy to fry it--
if tried the way it looks like it should work. Even with the switch off!
realistically only way to melt solder is to hook it up to 12 v battery and
put - on motor ..even if dash switch hanging on wires to try it, is off.

I was into mine over nylon park cam would take three pages. Works perfectly
now, as did another one used I got off internet. Kind of cool thing,way it
works, intrigued me. When it does go backwards it picks up cam which stops
it in park position. Running forward cam does not get picked up, switch
says closed ...That is mechanical.



On Mon, Aug 19, 2019 at 10:17 AM Carlton Schroeder <schroe99@xxxxxxxxxxxx>
wrote:

> Thanks John,
>
> I always appreciate your well-informed comments and input.
>
> A long time Chrysler mechanic helps me with work I am not able to handle,
> so Craig has been helping me with this wiper motor problem.  There was a
> short in my first motor that caused non repairable damage   On the second
> unit this is what Craig said:  “Unfortunately we now have two wiper
> motors that need armatures to make them run again. The armature was hot
> enough in the ebay motor that it de-soldered  the armature windings from
> the commutator bars. It flung the solder off and deposited on the inside of
> the motor housing”.
>
> I’ll send Craig your input, but I think I will need another motor..
>
> Thanks,
>
> Carlton
>
>
>
>
>
> *From:* John Grady [mailto:jkg@xxxxxxxxxxxxxxxxx]
> *Sent:* Monday, August 19, 2019 8:58 AM
> *To:* Carlton Schroeder
> *Cc:* Chrysler300@xxxxxxxxxxxxxxx
> *Subject:* Re: [Chrysler300] Chrysler 300C windshield wiper motor
>
>
>
> What is “armature shot “ really mean? Physically burned or shorted ?
>
> Usual problem is park switch or jamming of that ,the nylon pieces stick in
> plate  or stuck  brushes ; I did two — really got into them at the time .
>  57 variable speed .
>
>
>
> You do know you cannot test it unless switch housing is grounded too ? You
> can damage it by trying to run on bench with 12v to hot and a ground on
> motor .switch too must be grounded, return current to - of field is through
> switch ground and dash metal  . Not motor . How it reverses to park . But
> motor ground needed too . I doubt armature is bad . Without field it will
> burn up and try to run weakly very fast . Test setup probably not right .(
> unless you do know about this)  Was going to write this up for bob — but no
> time recently .
>
> Very rugged thing in fact , impressed me as EE . While in the wipers or
> restoring,  if open, pivot at wiper hood mount press fit gets loose why
> they flop . Clamp ground of welder to arm there and weld it . And little
> brass washers at pivot there often gone and wrong clip .
>
> I hated that flop , mine do not do it in now and park in right place . So
> they did work new without a big play or flop!
> Also only comes apart right and back together right if in parked position
> by dash switch  .
>
> Sent from my iPhone not by choice
>
>
> On 19 Aug 2019, at 9:36 am, 'Carlton Schroeder' schroe99@xxxxxxxxxxxx
> [Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:
>
>
>
>
> Hello,
>
> If anyone has a working windshield wiper motor/transmission or a lead to
> one, I would appreciate hearing from you.
>
> The armature is now shot in my existing motor, and another one I bought
> through ebay in ‘as is’ condition also has a bad armature..
>
> Thanks,
>
> Carlton
>
>
>
>
> 
>
>


[Non-text portions of this message have been removed]



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Posted by: John Grady <jkg@xxxxxxxxxxxxxxxxx>
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