In a message dated 97-06-09 22:41:25 EDT, larryhoy@juno.com (Larry A Hoy)
writes:
> Here's one for the list. What makes the windshield wipers park? Or more
> to the point what makes them not park?
>
> It seems as though when I turn of the wipers they stop where they are. I
> have become proficient at turning them off at the precise moment so they
> will coast to the park position. Of course I would prefer that they
> operate correctly.
Larry:
It's a little hard to explain without diagrams, but basically, there is a two
way switch (park switch) at the wiper motor, where the cable from the dash
connects. This switch is driven by a cam in the wiper motor. When the wiper
is NOT in the park position, this switch applies power to the wiper motor
regardless of the position of the wiper switch on the dash. Thus, when you
turn off the dash switch, the motor keeps running till it reaches the park
position. At this time, the switch disconnects power, and at the same time,
shorts the motor winding. When this happens, the motor stops instantly (and I
mean instantly. If you are holding it in your hand when it parks, it'll jump
right out of your hand!).
In your case, either the park switch is bad, or the green wire to the wiper
motor has an open. With the key on, check for voltage at the green wire where
it connects to the wiper motor. If you have voltage, most likely the park
switch is bad. If not, the green wire needs fixing.
Another possiblility is the dash switch is bad. Power is fed from the green
wire through the park switch, then back through the dash switch, and then
back to the motor. I know this sounds like a round-about way of doing things,
but it is the only way to make it all work.
The good thing about it is, the park switch is readily available, and is not
TOO expensive, and is very easy to replace. The dash switch is also
available, and is even easier to replace.
Another possibility just occured to me. Right off hand, I can't remember if
the switch is driven UP by the cam, or allowed to fall DOWN by the cam when
the motor is in the park position. It may be that the grease inside has
hardened, preventing the pin that operates the switch from moving. Tomorrow,
I will go to the shop and check on the spare I have, and get back to you.
Dan Masters,
Alcoa, TN
'71 TR6---------3000mile/year driver, fully restored
'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
www.sky.net/~boballen/mg/Masters/
'74 MGBGT---3000mile/year driver, original condition
'68 MGBGT---organ donor for the '74
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