944 window winder electrics: Relay

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Dave Ryman - 20 Oct 2006 13:44 GMT

Hi,
Had the driver window "seize up" on me the other day. No noticeable
humming from the door (ie: I don't think it was the mechanism jamming,
but the motor not getting any juice).

     Checked the fuse - ok, and removed the relay, which I gave a cursory
look over (an almost pointless exercise - it's a sealed unit). Anyway,
the contacts on the relay are fine, and I failed to find any sensible way
of testing it with a simple multimeter.

     In the course of looking at it, I dropped it on the pavement (d'oh).
Plugged it back in, however, and the window-winder then worked.

     I'm figuring that either the relay has a loose component inside
(dropping it shook it up), or that the fuse box connections are getting
tired (pulling the relay out and pushing back in shook that up).

     I thought the simple approach was to buy a new relay and see if it
happens again (assuming it's the fusebox if it's not). Since the relays
retail for over £30 (about $50 US) here in the UK, it's not a very cheap
experiment (I was hoping for £10).

     The thing is, I've got a strong hunch it's not a 944-specific part,
and that I might be able to obtain a compatable relay for a lot less. The
relay is 12v (no surprise!), 40A. It has five pins: 30, 85, 85b, 86 and
87. pin 85b is the central one. I believe it's called a "change-over"
relay by some people, and it also looks as if there's a similar relay
used in some vauxhalls.

     Is there anyone who can shed some light on these relays? I've tried
searching the internet, and checked my local motor-factors (who don't
stock them), the only current option being the local AFN parts
department.

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Dave

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T o d d P a t t i s t - 20 Oct 2006 13:59 GMT

My passenger side was intermittent for a while. It worked
fine for a week, then would stop for a day, then work the
next day. I opened the door, pulled and cleaned all the
connections from the switch and motor with superfine wet/dry
sandpaper, lubed the tracks/roller wheels, hinge points and
the main window lift gear. That's fixed it for me.

>Hi,
> Had the driver window "seize up" on me the other day. No noticeable
[quoted text clipped - 29 lines]
>stock them), the only current option being the local AFN parts
>department.

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Dave Ryman - 20 Oct 2006 15:39 GMT

> My passenger side was intermittent for a while. It worked
> fine for a week, then would stop for a day, then work the
> next day. I opened the door, pulled and cleaned all the
> connections from the switch and motor with superfine wet/dry
> sandpaper, lubed the tracks/roller wheels, hinge points and
> the main window lift gear. That's fixed it for me.

(snipped)

Yep, I suppose it could be the contacts to the motor. Changing the relay
was the easiest option, since it avoids having to pull the door apart or
getting inside the fuse box.

It's an intermittant fault, so it's a little tricky to check the electrics
with a test meter (unless I'm lucky to catch it). Pulling the door apart is
not my favoured option because I park at the side of the road.

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Dave

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William Noble - 20 Oct 2006 16:33 GMT

you don't need to replace the relay. If you opened it up and cleaned the
contacts, it is fine. If you didn't do that, then dropping it may have
jarred the contacts free if they were stuck - I have never seen a "sealed"
relay on a car, only on some spacecraft and other aerospace applications -
all the relays on my 944, and on my 911 can be opened up easily. Some of
these relays (e.g. the DME relay) develop stress failures at solder joints
and so require repair, but I've never had a relay actually fail where
resoldering a connection didint fix it.

I have had the window lift motor fail (but not in a 944) - typically this is
on the driver's side and typically due to teh brushes wearing out. You can
change the brushes but changing the motor is a better bet since the
commutator is usually heavily worn by the time the brushes reach end of
life.

I have had the wires fail where they get flexed going into the door - again,
not on a 944, but on my 59 cad.

I have had the window switch fail - not on a 944, but on my 911, there is an
article on fixing it rather than replacing it on my web page,
www.wbnoble.com - look under hobbies/cars the 944 uses the same switch, I
believe - if not identical, it's very similar.

I have had the central electronics become intermittant, wiggling everything
and cleaning contacts fixes it.

hope this helps

>> My passenger side was intermittent for a while. It worked
>> fine for a week, then would stop for a day, then work the
[quoted text clipped - 13 lines]
> is
> not my favoured option because I park at the side of the road.

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Dave Ryman - 20 Oct 2006 17:38 GMT

> you don't need to replace the relay. If you opened it up and cleaned
> the contacts, it is fine. If you didn't do that, then dropping it may
[quoted text clipped - 4 lines]
> failures at solder joints and so require repair, but I've never had a
> relay actually fail where resoldering a connection didint fix it.

(snipped)

Thanks for that - not sealed, but you're right - a tight fitting cover.
I'll have a look (carefully!).

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William Noble - 22 Oct 2006 08:09 GMT

oh, a follow up - I just realized I mis-spoke - I did have one relay fail
where cleaning contacts didn't fix it - I had the voltage sensing relay on
the voltage regulator on my 59 cadillac fail. The coil actually broke
internally - that's one where I finally bit the bullet and replaced the
whole regulator assembly - but your car is 30 years younger than that
cadillac, you souldn't see that kind of problem.

>> you don't need to replace the relay. If you opened it up and cleaned
>> the contacts, it is fine. If you didn't do that, then dropping it may
[quoted text clipped - 9 lines]
> Thanks for that - not sealed, but you're right - a tight fitting cover.
> I'll have a look (carefully!).

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Dave Ryman - 22 Oct 2006 11:40 GMT

> oh, a follow up - I just realized I mis-spoke - I did have one relay
> fail where cleaning contacts didn't fix it - I had the voltage sensing
[quoted text clipped - 7 lines]
>> Thanks for that - not sealed, but you're right - a tight fitting
>> cover. I'll have a look (carefully!).

Thanks - haven't opened it up yet, but I'll let you know.

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Dave Ryman - 01 Nov 2006 23:59 GMT

>> oh, a follow up - I just realized I mis-spoke - I did have one relay
>> fail where cleaning contacts didn't fix it - I had the voltage sensing
[quoted text clipped - 9 lines]
>
> Thanks - haven't opened it up yet, but I'll let you know.

Re-fitted the relay today (which seemed fine on close inspection), after
treating the socket in the fuse-box with some WD40.

The Windows seem to be working, but the fault was intermittent, so not
sure if that's the end of it.

However, now the interior heater is playing up - also intermittent. Makes
me wonder if the fuse box is actually the culprit. Possible that the
heater problems are coincidental with the window winder problem, I know,
but if I get another weird electrical gremlin, I'll really start to
wonder.

The heater problem, BTW, doesn't appear to be the heat control knob or
thermostat, because when I turn it up and down, the timbre of the sound
of the fan changes as if it's switching from cold air to "hot" air. The
hot air you get from the vents by pressing the windscreen demister button
(without the slider on the central vents slid up) is still there. Am I
right in thinking that the interior heater is seperate to the windscreen
demist heater?

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Dave

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William Noble - 02 Nov 2006 07:44 GMT

the thing youi call the "fuse box" is called by Porsche "centeral
electronics" - I've seen quite a few intermittants in my 85.5 that I
attribute to that assembly - disconnect battery, remove it (CAREFULLY!!!!)
clean it (don't use WD-40, use a real contact cleaner) and reassemble.

>>> oh, a follow up - I just realized I mis-spoke - I did have one relay
>>> fail where cleaning contacts didn't fix it - I had the voltage sensing
[quoted text clipped - 29 lines]
> right in thinking that the interior heater is seperate to the windscreen
> demist heater?

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Dave Ryman - 02 Nov 2006 22:21 GMT

> the thing youi call the "fuse box" is called by Porsche "centeral
> electronics" - I've seen quite a few intermittants in my 85.5 that I
[quoted text clipped - 35 lines]
>> still there. Am I right in thinking that the interior heater is
>> seperate to the windscreen demist heater?

That sounds like fun - I did notice that there's actually a piece of
plastic missing from the side - I think it's been that way for a long
while (seem to recall noticing it years ago), so maybe that's contributed
to things.

Time to find a proper contact cleaner and a workshop manual (I'm guessing
it just doesn't lift straight out as a unit).

Thanks for the advice.

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