weird windshield washer problem (c900)

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John B - 13 Sep 2004 17:07 GMT

Hi,

I'm experiencing a very weird problem with my 1992 900s. I drove a few hundred
miles this weekend, and the car functioned perfectly in every respect. I
especially enjoyed using my newly repaired cruise control. I parked the car as
usual last night, and went to bed a happy Saab owner.

This morning, when I started the car, the windshield washer started spraying
immediately, wipers going, and headlamp wipers/washers going. Very strange. I
fixed the problem temporarily by pulling fuse #8, which is labeled "headlamp
wipers," and appears to also govern cruise control and the power side mirrors.

So, my question: what could cause the wipers/washers to behave this way? I
might blame the switch, although it was replaced only a year or two ago. I'm a
little worried that my cruise control repair is somehow involved, since the two
things are on the same fuse.

Any ideas?

Thanks,

John

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Mats - 16 Sep 2004 21:17 GMT

You could try to disconnect the headlamp wipers, just to be sure you
don't have a problem in one of the headlamp wipermotors. There are a 3
terminal connector about 20 cm from each motor that you could pull to
test.

/Mats

>Hi,
>
[quoted text clipped - 18 lines]
>
>John

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John B - 17 Sep 2004 17:42 GMT

> You could try to disconnect the headlamp wipers, just to be sure you
> don't have a problem in one of the headlamp wipermotors. There are a 3
> terminal connector about 20 cm from each motor that you could pull to
> test.

Thanks, I will try that. I have a hard time imagining, though, how a problem
with the headlight wipers could somehow feed back to the intermittent relay,
thus activating the windshield wipers and washer pump. And yet it seems like
that's what is happening.

John

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R. Frist - 18 Sep 2004 14:16 GMT

> You could try to disconnect the headlamp wipers, just to be sure you
> don't have a problem in one of the headlamp wipermotors. There are a 3
[quoted text clipped - 14 lines]
> >fixed the problem temporarily by pulling fuse #8, which is labeled "headlamp
> >wipers," and appears to also govern cruise control and the power side mirrors.

Hi John,

The same thing happen to me about two years ago except I was in the
middle of traffic. I pulled the fuse then found that when I
disconnected one of the headlight wipers things were OK. When I
looked up the circuit diagram for the car (a 94 9000CSE) I figured
that it had to be a shorted diode but when I took the wiper motor
apart there was no visable diode. As it turns out, the diode is
embedded in a rubber like plug of stuff on the edge of the motor
housing and one does not have to disassemble the wiper motor. There
are probably diodes for the main motors as well so it could be one of
them. The purpose of the diodes is to allow the wipers to return to
their resting position after the power to them is shut off. There are
internal switches in the motors that get there power through the
diodes. If anu diode shorts out it sends power to the all the motors
and the washer pump.

The alternative is to simply replace the whole motor assembly. They
come up on Ebay all the time.

Good luck, R. Frist

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Malcolm William Mason - 19 Sep 2004 07:59 GMT

>Hi John,
>
[quoted text clipped - 15 lines]
>
>Good luck, R. Frist

This solution is the only one that makes sense, although there are
some weird arrangements. Is it possible that the manually operated
switch is so constructed that it can fail to a condition that it can
"Transfer" power from one circuit to another (continuous or
intermittent) but not "Interrupt" the power to both?

I still like the diodes, however.

Malcolm Mason

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John B - 25 Sep 2004 23:02 GMT

>>diodes. If a diode shorts out it sends power to the all the motors
>>and the washer pump.
[quoted text clipped - 3 lines]
>>
>>Good luck, R. Frist

<snip>

> I still like the diodes, however.

Thanks for the replies. I finally had a chance to check things out today.
First, I tried unplugging both wiper motors. This resulted in the problem going
away. So then I tried having each plugged in, one at a time. Still no problem.
So finally I plugged them both back in, and the problem still failed to
manifest itself.

So it seems as though unplugging and re-plugging the motors has solved the
problem. However: the left side motor doesn't seem to be working. The plastic
panel on the back of the motor isn't totally attached, and the wiper moves
freely when the motor is off.

So I'm thinking I might want to replace that motor. It looks like I'll have to
pop the headlight assembly out to do it. Will it be necessaary to re-aim the
headlight after this? This is a 1992 900 (slant-front headlights).

John

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