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2008 SRX-V8, 1991 Eldorado
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Discussion Starter #1
According to my FSM for the 1992 Eldorado, there is a current draw limiter for the power window motor, which in effect stops the motor when the current draw is limited (end of travel typically). The FSM drawing seems to show it in the power window motor, but I don't think it is there. I suspect it is built into the window switch circuit board. Anybody have any experience with this?
 

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White Diamond '03 DHS (with DTS floor shift)
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I would not swaer to it but I believe it is in the motor.
 

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It is part of the motor itself.
Usually GM uses what is called a "PTC" or a positive temperature coefficient device.
It's a small wafer of silicon based material and as heat and current increase, the resistance of this device increases. This effectively blocks the flow of current in a shorted motor condition.
It's not something you'd recognize if you took the motor apart.
Usually power window systems use a traditional circuit breaker to feed the circuit, but the individual motors have a "draw limiter" built right into the motor. The window motor armature is likely going bad and causing your windows to stop.

Oh by the way, when the voltage is removed from the device, it cools and it's resistance returns to normal and allows the flow of current, that's why after a minute or so your window will move again.

From the service manual
Each window motor is protected by an electronic circuit breaker. If a window switch is held too long with the window obstructed or after the window is fully up or down, the circuit breaker opens the circuit. The circuit breakers have positive temperature coefficients (PTC) and reset automatically when voltage is removed from the motors.
 

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2008 SRX-V8, 1991 Eldorado
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Discussion Starter #4
ewill3rd said:
It is part of the motor itself.
Usually GM uses what is called a "PTC" or a positive temperature coefficient device.
It's a small wafer of silicon based material and as heat and current increase, the resistance of this device increases. This effectively blocks the flow of current in a shorted motor condition.
It's not something you'd recognize if you took the motor apart.
Usually power window systems use a traditional circuit breaker to feed the circuit, but the individual motors have a "draw limiter" built right into the motor. The window motor armature is likely going bad and causing your windows to stop.

Oh by the way, when the voltage is removed from the device, it cools and it's resistance returns to normal and allows the flow of current, that's why after a minute or so your window will move again.

From the service manual
Thanks for your answer!

After performing a diagnostic, I found the motor to be thermally tripping. The motor still works, but as you say is going bad by stopping. Thanks again for your very informative answer. Yes, I did see that quote in the FSM regarding the "PTC" I was not sure "where" it was.

Locked rotor due to slipped (worn) regulator would seemingly do the same. I wanted to be sure before I removed the door panel and dug any deeper. I've ordered a new motor today.

One more thing I learned today. If you remove (unplug) the master switch, the passenger side switch will not work.
 

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On older cars, the master switch supplies the ground for all the other doors.
Newer cars like yours have computers in the doors and will work independently of one another.

Glad to have been able to help.
 
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