What shuts power window motors off?

[Stephen Tashiro]

I did my first ever replacement of a "window regulator" for a power window in a car yesterday. Two things confuse me. The first is that I don't understand what broke about the old window regulator. The cable was tangled up around the drive pulley, but I don't know how it got that way. The second thing is that I don't understand what shuts a power window motor off. I see no electrical connection between the window regulator and the motor. Does stopping the motor simply rely on the driver letting up on the window switch? Does the motor have a circuit to sense when it is encountering too much load?

[Mitchell Andrus]

Good questions. Have you called the manufacturer's customer service desk and asked them?

I'll assume you got the correct parts, if not, maybe there's a connection missing.
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[Stephen Tashiro]

The repair works fine. I'm merely curious why.

I haven't called the manufacturer's customer service - nor have I pulled out any of my fingernails, rubbed salt in my eyes or held my finger in a candle flame.

[Chris Harry]

Just a guess, but I think you are correct in the assumption that the motor stops when we let go of the switch. Especially noticeable in 2 door cars, if you make the window go up and hold the switch once its all the way up, you might be able to see the upper portion of the door skin bow out from the torque being put on the window frame/track/regulator.

There is probably some sort of circuit breaker or thermal overload that cuts off the motor after a while.

Newer cars probbaly have a more intelligent setup.......I know on most cars with windows that can go auto up (go all the way up at one press of the switch instead of holding the switch) have an interference-type sensor in case someone has their arm or hand in the way. Works similar to your garage door opener......once it senses something immovable in the way it either stops the window from going up, or stops it and reverses it all the way down. In that case the sensor would help in 2 ways......obviously saving hands/arms/fingers, and it can serve to cut off the window motor once it senses youve rolled the window all the way up.

[Mitchell Andrus]

- nor have I pulled out any of my fingernails, rubbed salt in my eyes or held my finger in a candle flame.

I don't get what you're saying here. When I need assistance, I usually get it. So do most people I know unless they're asking for something off the wall, like "read me the manual over the phone" or "can you come to my house and turn on my TV" or "read the backs of 20 or so DVD's to me".

I once had a problem with a 42" plasma set. One call got me to a person who spent 20 minutes helping me trouble-shoot and discover an intermittently faulty power supply. She authorized a refund.

One email to a lawn mower mfgr got me a return phone call the next day with a solution and a free part in the mail.

Perhaps rubbing salt in your eyes is the wrong approach.

Just a thought.
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[Stephen Tashiro]

I don't get what you're saying here. When I need assistance, I usually get it.
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You get what I'm saying; you just don't agree with my outlook. I'm getting assistance. I'm asking the knowledgeable and friendly people on SawmillCreek!

[Dan Friedrichs]

I'm also curious. I took one apart once, and didn't see anything that seemed to shut the motor off. I think that perhaps power is just applied to the motor until you release the button. The motor is not capable of generating much force (which is good - you wouldn't want it to sever someone's finger), so once the window is all the way up, the motor just stalls?

[Paul Ryan]

Stephen

You pretty much got it. It stops when you let go of the switch. Newer cars can sense the resistance in the BCM (body control module) when the window is up all of the way. Regulators are a funny deal, the cable will fray some times, come loose at one end, totally break, pulleys will get goofy up. If you can imagine it, it has happened. Sometimes just the motor fails and trying to rewind a cable is a pain in the arsh on most cars. The nice thing about power windows is as long as you have power and ground to the switch it is an easy diagnosis. If you loose one of those it can be a bear, because all of the manufacturers, supply power and ground to their switches and motors in different ways.

[Dan Hintz]

Stephen,

Window regulators sense the current draw of the motor... when it spikes up, the motor is no longer moving, so it shuts the motor off.

[Tom Godley]

Stephen - Is this a Mercedes E class. If so they have a small plastic part that rides on the guide -- it snaps and the cable gets all bunched up.

The automatic up/down windows are controlled by a module that can count the motor revolutions and also sense the current draw of the motor. You need to "teach" them when you remove the battery or do any work on the window. Don't ask me how I know all of this

Many of the older units simply stalled when the windows reached the endpoint - they were designed to handle this short overload

[Jay Allen]

It just depends upon the car in question. There are several different designs. Some work with a "scissor" lift that has built-in stops. They will only go so far. Some of the later models used a plastic/nylon "tape" that looks like the edges of old fashined "film". That tape runs in a track that pushes/pulls the glass. Again, the tape will only go "so-far" and it stops.
Almost all are powered by a circuit-breaker, so that they don't "blow" like a fuse. It will re-set and continue to work.

[Stephen Tashiro]

The car in question is 2000 Hyundai Tiburon and the part I installed is this:
http://www.amazon.com/gp/product/B0026MASOI/ref=cm_cr_mts_prod_img

The car belongs to a friend. I don't know much about the car except for its drivers door!

[Tom Godley]

That is very interesting -- same single rail design and white clips??

That part from Amazon is a Chinese aftermarket.


If the car has auto up -- it needs to have a much more sophisticated setup because it must be able to sense an obstruction -- like an arm and reverse.

If it does not have any auto - most I have seen just stall.

[Paul Ryan]

I didn't know you could buy car parts from amazon. As I stated earlier most just stall, it really depends on the car. But the fancier cars have more elaborate systems. A little old 00 hyundia it just stalls and is probably protected by a heat activated circuit breaker. It will open when it get so hot, and close when it cools off.

[Jim Koepke]

On both of our vehicles, it is easy to tell that the button has to be let go for the power to stop.

With one window up or down, start running the other window and press the button to make another window go to the position it is already in. Of course, this has to be done from the drivers seat with the engine off. You can often notice that when the non-moving window's button is pressed, the motor will slow down on the moving window due to the load of the non-moving window.

jim

[Rick Potter]

Maybe it's an epidemic.

A couple days ago the electric back window in my Ford Super Duty pickup just stopped working. I have gotten as far as checking the fuse, but still have to find time to take it apart. Hopefully the old dummy can fix it.

Rick Potter

[Stephen Tashiro]

That part from Amazon is a Chinese aftermarket.


No, the part is made in Korea - read my excellent review of it. It may be aftermarket, but I can't tell any difference between it and the OEM part that I replaced.

[Peter Stahl]

Maybe it's an epidemic.

A couple days ago the electric back window in my Ford Super Duty pickup just stopped working. I have gotten as far as checking the fuse, but still have to find time to take it apart. Hopefully the old dummy can fix it.

Rick Potter

Maybe you hit the window lock. Some keep ever the driver from operating them.

[Jerome Hanby]

I don't get what you're saying here. When I need assistance, I usually get it. So do most people I know unless they're asking for something off the wall, like "read me the manual over the phone" or "can you come to my house and turn on my TV" or "read the backs of 20 or so DVD's to me".

I once had a problem with a 42" plasma set. One call got me to a person who spent 20 minutes helping me trouble-shoot and discover an intermittently faulty power supply. She authorized a refund.

One email to a lawn mower mfgr got me a return phone call the next day with a solution and a free part in the mail.

Perhaps rubbing salt in your eyes is the wrong approach.

Just a thought.
.

Substitute Charter, Western Digital, or any of the satellite TV companies and those comments become germane (or maybe one of the other Jacksons :rolleyes:)