Cars - LS200 Windshield Wiper Problem

"GRISWOLD3" > wrote in message
...
On May 19, 2:57 pm, "Oppie" > wrote:
> "GRISWOLD3" > wrote in message
>
> ...
>
> > Hi all - The Wipers on my 2001 LS200 will not return to the home
> > position when turned off. Instead they stop about half way across the
> > windshield. They work fine when running & do make a complete cycle.
> > This is pretty annoying. Any ideas?
> > Thanks,
> > Griswold
>
> Sounds like the cam that drives the shut-off switch slipped position. Not
> sure if this is a brute force switch that shuts off the wipers in the
> 'home'
> position or a low power switch that signals the BCM (body control module)
> when to cut the motor power. If I get a chance tonight I'll check my '01 L
> series service manual. I have the lw300.
> Oppie

Thanks so much for investigating this. I tried pushing the wipers with
the motor on to try & re-position them. This did change the exact spot
they parked in slightly but now they're more on the top of the
windshield. Anyway maybe this bit of info is of use to you.
Thanks again & I look forward to your help!
Griswold

======================

My post with attachment seems to have been lost.
Scan of the manual is on news:alt.binaries.automotive.manuals-tech
Wiring diagram from the L series 2001 service manual
(body/electical volume II). (If the scan gets lost, I can re-post to a
binaries group)

I concentrated on the electrical (since I'm an electrical engineer) but your
problem may actually be a mechanical one.
The motor connector is a black 5 cavity connector with:
pin 1= low speed power through wiper relay and wiper switch.
pin 5= high speed power (ditto)
pin 2= chassis ground
pin3= park brake
pin 4= 12V

The Wiper relay for our purposes, will be de-energized. It is only used for
intermittent wiper (mist) operation.
Wiper power comes from wiper switch terminal F through to wiper motor pins 1
(low speed) or 5 (high speed).
The Wiper relay is shown in the de-energized position.
The wiper motor park switch is shown int eh park position ( my notation on
the scan is backwards).
Assumming the wiper is running and is switched to the off position, 12V fed
to the wiper motor (connector pin 4) flows through the run/park switch and
to the wiper relay (circuit 196) where it continues to power the motor
through the low speed (pin 1) terminal until the motor comes to the park
position and the run/park switch pulls the motor to ground. This
essentially short-circuits the motor and causes it to abruptly stop.

The fact that your wipers stop mid-way and consistently, I would rather
think that a mechanical linkage has broken.
I will have to look elsewhere in the manual to find the mechanical R&R for
the wipers. My guess is that has shifted in the motor affecting relation
between output crank and the run/park cam. Possibly the output crank has a
shear pin that protects the motor from burn-out if the wipers are locked in
place (as with ice). You will most likely have to remove the motor and check
the linkages and inspect for a bad shear pin. Let me know how you make out.

Oppie

===========
I had a chance to look at the mechanical portion of the wipers. Looks like
the caps over the end of the wipers flip up and there is simply a
compression nut to tighten the arms against the tapered drive spindle. From
what the manual said, there is no shear pin that is customary on most cars.
Manual recommends using new nuts as "the old ones may not have enough
torque". Information was a bit sketchy but I would remove both arms and
clean both mating surfaces. Inspect for galling or grooves which would
indicate slippage. If the surfaces are not smooth enough to properly grab
against one another, you may have to use some rubbing compound to lap them.
If you have to do this, apply some to the surfaces, press the parts together
and rotate them against each other for a few passes. Clean, inspect and
re-assemble. You may have to use a shim washer between the nut and arm to
get correct tension.

Hope this was useful.