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On my 2000 Toyota Sienna, the driver's side power window behaves strangely. The window rolls down just fine. However, when closing it, it begins rolling up in the normal rate, but half-way up gets slower until completely stops. I then wait some time and able to continue the roll-up some more - and repeat this sequence until it is completely closed.

Basically, you can think of it as if I "charge" the window motor's very "small" battery, which depletes on the way up. Then repeatedly allow it to "re-charge" and get depleted again while gradually rolling up.

What is the cause of this behaviour?

What part do I need to replace/service?

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2 Answers 2

Your window motor and/or regulator is going out. What happens is, the window motors have a thermal trip which tells them to stop when they get too hot. As a vehicle gets older, the window regulator and slides don't slide/move as well, so creates a lot more friction. The window motor starts wearing out because of this and more heat is produced, thus shutting down the motor. When it sits for a little while, the motor then cools down, thermal trips back to good, and you can then push the button and the window continues on its way.

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Thanks. That makes sense. I was not aware of a thermal protection. But, the interesting thing is that it is so now (freezing winter) but was the same last summer. I'd expect the winter temps to make it easier, but it is not so (of course, it is possible that the cold temps increase the friction itself, and that compensates for the heat dissipation). –  ysap Jan 13 at 19:23
    
So, I should fix the friction problem first, then replace the motor, right? –  ysap Jan 13 at 19:23
    
You can try cleaning the regulator/tracks, but more than likely motor replacement is your only choice. You can sometimes just replace the motor (much cheaper option, but a lot more work), or motor and regulator together (think of this as the dealership option ... what you'd get from the dealership if you go there to buy it). You should be able to purchase a motor online from rockauto.com or something similar. Just also check to ensure your source is reliable. There are a lot of crap motors on the market. Either way, you'll be doing both at the same time. –  Paulster2 Jan 13 at 19:27

What I've found in several of these is that the motor itself is fine, but it's internal thermal fuse goes bad (becomes higher resistance giving less voltage to the motor). I've even replaced the thermal fuse for a couple bucks and the motors then work like new. I wouldn't recommend doing this unless you are familiar with soldering and electronics.

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