Rear window wiper motor burned out -- again

[Yousuf Khan]

The rear wiper motor on my 2000 OBW just burned out -- again, for the
2nd time in 3 years. I replaced it myself about 3 years back, and now
even that one is now gone. What about this motor causes it to burn out
so quickly? There's plenty of harder working electrical motors and
generators on this car that have been running for a decade without
failure, including the front wiper motor, but not this motor. It gets
used fairly regularly whenever the front wipers are used too, but
obviously not for as long as the rear window doesn't get as wet.

It happened in exactly the same way as the previous motor. I started
noticing a few weeks prior to the failure that it wasn't moving as fast
as it used to. And then it got stuck completely. The motor is
self-enclosed, so I don't think water should be directly in contact with
its electricals. This is not so much a question as venting. Yeesh!

Yousuf Khan

 

[Hachiroku $B%O%A%m%/(B]

The rear wiper motor on my 2000 OBW just burned out -- again, for the 2nd
time in 3 years. I replaced it myself about 3 years back, and now even
that one is now gone. What about this motor causes it to burn out so
quickly? There's plenty of harder working electrical motors and generators
on this car that have been running for a decade without failure, including
the front wiper motor, but not this motor. It gets used fairly regularly
whenever the front wipers are used too, but obviously not for as long as
the rear window doesn't get as wet.

It happened in exactly the same way as the previous motor. I started
noticing a few weeks prior to the failure that it wasn't moving as fast as
it used to. And then it got stuck completely. The motor is self-enclosed,
so I don't think water should be directly in contact with its electricals.
This is not so much a question as venting. Yeesh!

Yousuf Khan

Did you download the wiper motor driver directly from Subaru?

 

[Nobody > (Revisited)]

The rear wiper motor on my 2000 OBW just burned out -- again, for the
2nd time in 3 years. I replaced it myself about 3 years back, and now
even that one is now gone. What about this motor causes it to burn out
so quickly? There's plenty of harder working electrical motors and
generators on this car that have been running for a decade without
failure, including the front wiper motor, but not this motor. It gets
used fairly regularly whenever the front wipers are used too, but
obviously not for as long as the rear window doesn't get as wet.

It happened in exactly the same way as the previous motor. I started
noticing a few weeks prior to the failure that it wasn't moving as fast
as it used to. And then it got stuck completely. The motor is
self-enclosed, so I don't think water should be directly in contact with
its electricals. This is not so much a question as venting. Yeesh!

Yousuf Khan

Automotive DC motors are usually pretty robust, but they are subject to
the usual "motor-killers", as in low/erratic voltage and/or bad grounding.

Did you do any autopsy on this last failed one? Worn brushes? Arc-burnt
armature commutator? Both of these usually mean insufficient voltage
under load.

My thoughts are either/both bad tailgate grounding or corroded
connectors (and possibly a corroded (inside the jacket) wire somewhere.

**first, if any of the connectors are corroded, that's *prime*! Fix them
first***

For that matter, it could be weak contacts in the control relay.

This one's fairly easy to troubleshoot with a voltmeter, just measure
the voltage at each connection point going upstream from the wiper
motor. It would be easier if you temporarily substituted a heavy
resistor for the wiper motor. I don't know the exact draw on the wiper
motor, but a good guess would be about 6 amps. (It's better to err
slightly on the high-side for this, but stay under the fuse rating)

For this, you need a 2 ohm 100 watt resistor. Also, consider temporarily
attaching a 10-15 foot test-ground wire to the mail body ground. Using
the (-) of the battery isn't really good for this, use a convenient
mount bolt in the engine compartment.

Cobble the resistor leads into the wiper motor connector, may need some
McGyvering. Stub wires, bare 'push-in terminals, clippie leads,
whatever. Often you can just bend a loop/hook in the resistor leads and
it works.

The readings you get are all going to be somewhat relative, so figure
+/- 1 volt (supply side) and +/- 0.1 volt (ground side);and also take
into consideration the actual battery voltage, and scale from that.

Most of the "general voltages" I quote are from personal experience.

The first reading I would take would be the -/ground side to the
tailgate frame. It should be less than 0.3 volts. But hold off on that
until you go wiper - to the main body ground. Same thing, 0.3 volts.

If you see more than 0.5 volts at a main-body ground and less than 0.3
volts to the tailgate, you have tailgate grounding problems.

If nothing shows bad on the grounding, now you have to work the supply
side. I'd expect to see at least 10 volts at the + wiper side. If not,
then I'd move to the control relay output. That should show at least 10
volts. If it's below 10 volts replace the relay. Then recheck
(This is called half-split troubleshooting)

If the voltage drop discrepancy is between the relay and the tailgate
connector for the wiper motor, it's time to dig out the wiring diagram
for your S00b. If there are any intermediate connectors, check both the
ins and outs volts of each. Those are often fail-points.

Sometimes, it's just easier to say "crap to all" this and run a fresh
wire from the relay all the way back to the wiper motor. It may be
overkill, but I wouldn't use anything less than 16 ga wire.

PS, I also own a oughty-ought OBW (Limited). I've had similar problems,
but most were just bad grounding (easily fixed). The car was originally
sold in New Jersey USA, and it does have corrosion issues. (Body/paint
seems OK, but the engine is *ugly*)

PS, this is also a good way to troubleshoot most problems


--
"Shit this is it, all the pieces do fit.
We're like that crazy old man jumping
out of the alleyway with a baseball bat,
saying, "Remember me motherfucker?"
Jim “Dandy” Mangrum

 

[TheSeeker]

Automotive DC motors are usually pretty robust, but they are subject to
the usual "motor-killers", as in low/erratic voltage and/or bad grounding..

Did you do any autopsy on this last failed one? Worn brushes? Arc-burnt
armature commutator? Both of these usually mean insufficient voltage
under load.

My thoughts are either/both bad tailgate grounding or corroded
connectors (and possibly a corroded (inside the jacket) wire somewhere.

**first, if any of the connectors are corroded, that's *prime*! Fix them
first***

For that matter, it could be weak contacts in the control relay.

This one's fairly easy to troubleshoot with a voltmeter, just measure
the voltage at each connection point going upstream from the wiper
motor. It would be easier if you temporarily substituted a heavy
resistor for the wiper motor.  I don't know the exact draw on the wiper
motor, but a good guess would be about 6 amps. (It's better to err
slightly on the high-side for this, but stay under the fuse rating)

For this, you need a 2 ohm 100 watt resistor. Also, consider temporarily
attaching a 10-15 foot test-ground wire to the mail body ground. Using
the (-) of the battery isn't really good for this, use a convenient
mount bolt in the engine compartment.

Cobble the resistor leads into the wiper motor connector, may need some
McGyvering. Stub wires, bare 'push-in terminals, clippie leads,
whatever. Often you can just bend a loop/hook in the resistor leads and
it works.

The readings you get are all going to be somewhat relative, so figure
+/- 1 volt (supply side) and +/- 0.1 volt (ground side);and also take
into consideration the actual battery voltage, and scale from that.

Most of the "general voltages" I quote are from personal experience.

The first reading I would take would be the -/ground side to the
tailgate frame. It should be less than 0.3 volts. But hold off on that
until you go wiper - to the main body ground. Same thing, 0.3 volts.

If you see more than 0.5 volts at a main-body ground and less than 0.3
volts to the tailgate, you have tailgate grounding problems.

If nothing shows bad on the grounding, now you have to work the supply
side. I'd expect to see at least 10 volts at the + wiper side. If not,
then I'd move to the control relay output. That should show at least 10
volts. If it's below 10 volts replace the relay. Then recheck
(This is called half-split troubleshooting)

If the voltage drop discrepancy is between the relay and the tailgate
connector for the wiper motor, it's time to dig out the wiring diagram
for your S00b. If there are any intermediate connectors, check both the
ins and outs volts of each. Those are often fail-points.

Sometimes, it's just easier to say "crap to all" this and run a fresh
wire from the relay all the way back to the wiper motor. It may be
overkill, but I wouldn't use anything less than 16 ga wire.

PS, I also own a oughty-ought OBW (Limited). I've had similar problems,
but most were just bad grounding (easily fixed). The car was originally
sold in New Jersey USA, and it does have corrosion issues. (Body/paint
seems OK, but the engine is *ugly*)

PS, this is also a good way to troubleshoot most problems

--
"Shit this is it, all the pieces do fit.
  We're like that crazy old man jumping
out of the alleyway with a baseball bat,
saying, "Remember me motherfucker?"
Jim “Dandy” Mangrum

Hi,

I don't know if the wiper motors are the same, but in my 2002
Forester, the rear wiper acted in a similar fashion to what the OP
describes (wiper slows down and stops).

In my case, after investigation, I found the motor actually was OK,
but the two bushings the wiper shaft pass through were both quite
stiff. After lubricating, and helping the shaft move, I was able to
work in some lubrication, and it has worked fine since.

In the Forester at least, the wiper shaft is angled as it exits the
body of the door, and thus water that comes onto the shaft runs down
it and into these two bushings.

Duane

 

[clare]

Automotive DC motors are usually pretty robust, but they are subject to
the usual "motor-killers", as in low/erratic voltage and/or bad grounding.

Did you do any autopsy on this last failed one? Worn brushes? Arc-burnt
armature commutator? Both of these usually mean insufficient voltage
under load.

My thoughts are either/both bad tailgate grounding or corroded
connectors (and possibly a corroded (inside the jacket) wire somewhere.

**first, if any of the connectors are corroded, that's *prime*! Fix them
first***

For that matter, it could be weak contacts in the control relay.

This one's fairly easy to troubleshoot with a voltmeter, just measure
the voltage at each connection point going upstream from the wiper
motor. It would be easier if you temporarily substituted a heavy
resistor for the wiper motor. I don't know the exact draw on the wiper
motor, but a good guess would be about 6 amps. (It's better to err
slightly on the high-side for this, but stay under the fuse rating)

For this, you need a 2 ohm 100 watt resistor. Also, consider temporarily
attaching a 10-15 foot test-ground wire to the mail body ground. Using
the (-) of the battery isn't really good for this, use a convenient
mount bolt in the engine compartment.

Cobble the resistor leads into the wiper motor connector, may need some
McGyvering. Stub wires, bare 'push-in terminals, clippie leads,
whatever. Often you can just bend a loop/hook in the resistor leads and
it works.

The readings you get are all going to be somewhat relative, so figure
+/- 1 volt (supply side) and +/- 0.1 volt (ground side);and also take
into consideration the actual battery voltage, and scale from that.

Most of the "general voltages" I quote are from personal experience.

The first reading I would take would be the -/ground side to the
tailgate frame. It should be less than 0.3 volts. But hold off on that
until you go wiper - to the main body ground. Same thing, 0.3 volts.

If you see more than 0.5 volts at a main-body ground and less than 0.3
volts to the tailgate, you have tailgate grounding problems.

If nothing shows bad on the grounding, now you have to work the supply
side. I'd expect to see at least 10 volts at the + wiper side. If not,
then I'd move to the control relay output. That should show at least 10
volts. If it's below 10 volts replace the relay. Then recheck
(This is called half-split troubleshooting)

If the voltage drop discrepancy is between the relay and the tailgate
connector for the wiper motor, it's time to dig out the wiring diagram
for your S00b. If there are any intermediate connectors, check both the
ins and outs volts of each. Those are often fail-points.

Sometimes, it's just easier to say "crap to all" this and run a fresh
wire from the relay all the way back to the wiper motor. It may be
overkill, but I wouldn't use anything less than 16 ga wire.

PS, I also own a oughty-ought OBW (Limited). I've had similar problems,
but most were just bad grounding (easily fixed). The car was originally
sold in New Jersey USA, and it does have corrosion issues. (Body/paint
seems OK, but the engine is *ugly*)

PS, this is also a good way to troubleshoot most problems

better than 90% of rear wiper motor problems are NOT related to
electrical issues - the wiper pivot seizes.
If the "gaitor" or "boot" that covers the pivot, under the arm, is bad
or missing, water gets into the bushing and it is "done" in short
order. If there is no boot,a good covering with silicone grease can
help keep the water out.

Just an observation from many years experience with the darn things.

 

[Asbjørn]

better than 90% of rear wiper motor problems are NOT related to
electrical issues - the wiper pivot seizes.
If the "gaitor" or "boot" that covers the pivot, under the arm, is bad
or missing, water gets into the bushing and it is "done" in short
order. If there is no boot,a good covering with silicone grease can
help keep the water out.

Just an observation from many years experience with the darn things.

Thats probably right.
The abrupt rear end of such cars sucks up a lot of dirt when driving. And
here we even have salt spray in the winter.
On my Corolla Wagon the o-ring on the wiper arm bearing was bad, an the dirt
got into it and the arm got stuck.
The motor was fine.
I disassembled the mechanism, cleaned the wiper arm bearing thorougly,
greased it up, got a new o-ring, and it has been fine for many years after.
Asbjørn

 

[Yousuf Khan]

Did you download the wiper motor driver directly from Subaru?

Yeah, but next time I'll go with the Dell website.

Yousuf Khan

 

[Yousuf Khan]

Hi,

I don't know if the wiper motors are the same, but in my 2002
Forester, the rear wiper acted in a similar fashion to what the OP
describes (wiper slows down and stops).

In my case, after investigation, I found the motor actually was OK,
but the two bushings the wiper shaft pass through were both quite
stiff. After lubricating, and helping the shaft move, I was able to
work in some lubrication, and it has worked fine since.

In the Forester at least, the wiper shaft is angled as it exits the
body of the door, and thus water that comes onto the shaft runs down
it and into these two bushings.

Duane

On my original motor, I didn't do more than a cursory examination of the
lubrication on the motor. It looked like a sealed unit, so it didn't
seem as if water getting in would be a major issue. I think I tried a
little WD-40, and when that didn't help, I just replaced the motor. What
sort of lubricant should I use?

Yousuf Khan

 

[Hachiroku $B%O%A%m%/(B]

Yeah, but next time I'll go with the Dell website.

Yousuf Khan

You should have gone directly to Denso....git!

 

[Hachiroku $B%O%A%m%/(B]

On my original motor, I didn't do more than a cursory examination of the
lubrication on the motor. It looked like a sealed unit, so it didn't seem
as if water getting in would be a major issue. I think I tried a little
WD-40, and when that didn't help, I just replaced the motor. What sort of
lubricant should I use?

Yousuf Khan

Yousuf, WD-40 isn't a lubricant, it's a Water Dispersant (WD....)

I have seen it actually REMOVE grease!

You want a good grease, one person said waterproof Lithium. I personally
like GM Rust Preventative/Heat Riser Lubricant. They sell it for $9-12 a
can (depending if you buy it at a Chevy dealer or a Cadillac dealer
...no, really, different dealers have different prices). It removes
rust, lubricates bicycle chains, frees stuck nuts and bolts, etc. Great
stuff...

and about the ONLY thing I would buy at a GM dealer...

 

[TheSeeker]

On my original motor, I didn't do more than a cursory examination of the
lubrication on the motor. It looked like a sealed unit, so it didn't
seem as if water getting in would be a major issue. I think I tried a
little WD-40, and when that didn't help, I just replaced the motor. What
sort of lubricant should I use?

        Yousuf Khan

Hi,

In my case, I started with something light (like engine oil) to get
lubricant in and loosen things up. I had to help my wiper move in the
beginning.

After that I started using heavier oils, like 80-90 gear oil. The
suggestion of a glob of grease on the outer boot section for sealing
out water and debris is a good one, once things are moving freely. It
helped to have my door open, so what I put on the shaft could run
_down_ by gravity and into the motor bushings

Duane

 

[Yousuf Khan]

better than 90% of rear wiper motor problems are NOT related to
electrical issues - the wiper pivot seizes.
If the "gaitor" or "boot" that covers the pivot, under the arm, is bad
or missing, water gets into the bushing and it is "done" in short
order. If there is no boot,a good covering with silicone grease can
help keep the water out.

Just an observation from many years experience with the darn things.

My first thought was that it has got to be water-related too. But I
would've also thought that all of the washers and stuff would've
protected it.

Yousuf Khan

 

[Yousuf Khan]

Thats probably right.
The abrupt rear end of such cars sucks up a lot of dirt when driving. And
here we even have salt spray in the winter.
On my Corolla Wagon the o-ring on the wiper arm bearing was bad, an the dirt
got into it and the arm got stuck.
The motor was fine.
I disassembled the mechanism, cleaned the wiper arm bearing thorougly,
greased it up, got a new o-ring, and it has been fine for many years after.
Asbjørn

Yup, salt spray is a huge issue here too.

Yousuf Khan

 

[clare]

On my original motor, I didn't do more than a cursory examination of the
lubrication on the motor. It looked like a sealed unit, so it didn't
seem as if water getting in would be a major issue. I think I tried a
little WD-40, and when that didn't help, I just replaced the motor. What
sort of lubricant should I use?

Yousuf Khan

Waterproof silicone or synthetic grease. Or the stuff used in the
bottom units of outboards, perhaps?

Shooting a bit of turbine oil on the pivot can't hurt either.

 

[Yousuf Khan]

Automotive DC motors are usually pretty robust, but they are subject to
the usual "motor-killers", as in low/erratic voltage and/or bad grounding.

Did you do any autopsy on this last failed one? Worn brushes? Arc-burnt
armature commutator? Both of these usually mean insufficient voltage
under load.

My thoughts are either/both bad tailgate grounding or corroded
connectors (and possibly a corroded (inside the jacket) wire somewhere.

Okay, I finally got around to doing the repair today. I did end up
buying a new motor to replace the old one. Here's the autopsy on the old
one.

When the old motor was taken out, it was quickly inspected on the
outside for any signs of corrosion. It didn't look corroded at all, in
fact it looked pretty pristine, almost in identical condition to the new
one. I then stripped it down to the gears and coils. I inspected the
gears, and there were no stripped gears, even amongst the plastic ones.
No scorch marks on the internal body anywhere, just some black grease
marks.

I then took the rotor body apart. It seemed in outwardly good condition,
and even inside it looked okay. Took the rotor out to inspect it, looked
okay, but there did seem to be some light carbon deposits on the coils,
evenly distributed around it. So I would assume that this is the
aforementioned arc-burnt armature?

So it looks like it was a slow electrical problem, rather than a
mechanical or rusting problem, probably a grounding problem. I don't
want the new motor to fail on me in another couple of years, so I'd like
to know where (what location) to start in inspecting for possible
grounding fail points? All of the obvious grounding points seemed to be
in good shape, corrosion free.

Yousuf Khan

 

[Asbjørn]

Okay, I finally got around to doing the repair today. I did end up buying
a new motor to replace the old one. Here's the autopsy on the old one.

When the old motor was taken out, it was quickly inspected on the outside
for any signs of corrosion. It didn't look corroded at all, in fact it
looked pretty pristine, almost in identical condition to the new one. I
then stripped it down to the gears and coils. I inspected the gears, and
there were no stripped gears, even amongst the plastic ones. No scorch
marks on the internal body anywhere, just some black grease marks.

I then took the rotor body apart. It seemed in outwardly good condition,
and even inside it looked okay. Took the rotor out to inspect it, looked
okay, but there did seem to be some light carbon deposits on the coils,
evenly distributed around it. So I would assume that this is the
aforementioned arc-burnt armature?

So it looks like it was a slow electrical problem, rather than a
mechanical or rusting problem, probably a grounding problem. I don't want
the new motor to fail on me in another couple of years, so I'd like to
know where (what location) to start in inspecting for possible grounding
fail points? All of the obvious grounding points seemed to be in good
shape, corrosion free.

Yousuf Khan

Hopefully all is well, but I find that some questions remain unanswered:
In a used wiper motor there will allways be some black carbon dust from the
brushes.
How did the brushes look? Did you ever try to power up the demounted motor ?
A permanently bad ground should be easy to find for someone clever with a
multimeter.
Test the voltage between the motor ground and the car chassis with the wiper
running (That should be close to zero).
Intermittently bad connections are worse, but you could test when moving the
rear door.
Especially Volvos are known for breaking the cables at the rear door
hinge....

And did the wiper arm move freely all the way in the pivot ? Have you
cleaned and greased the pivot?
As you see, I am reluctant to completely rule out the stuck wiper arm....

Asbjørn