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Re: how does auto-down work? Posted by Ari [Email] (#2847) [Profile/Gallery] (more from Ari) on Fri, 12 May 2006 10:48:05 In Reply to: how does auto-down work?, bobc [Profile/Gallery] , Thu, 11 May 2006 11:50:07 Members do not see ads below this line. - Help Keep This Site Online - Signup |
There is an extra switch position for auto-down. When that contact is made, a small solid-state relay in the switchpack engages, and keeps the 'down' function engaged for about 5-6 seconds. Then it releases. That's true for the newer cars like your '95. For the older cars where the auto-down is only on the driver's side, the relay is under the seat. It's just a timing thing. So the function is implemented in the switch pack with time-delay relays.
The system doesn't know to stop when the window hits the bottom - it just counts to 5 and stops. It assumes the window has made it to the bottom by them.
You can obviously implement this in the rear windows, but those switches don't have the extra "auto-down" switch position. You'd have to add the time delay relays.
In terms of auto-up, manufacturers only implemented that with the inclusion of 'anti-pinch' circuitry. Basically, if the system senses that the window has hit an obstacle, it stops and reverses. I've got that in my VW. I don't know if they use a pressure switch, or just monitor motor current.
You could implement auto-up, all you'd need to do is add the relays and find an extra switch position.
The major issue is that the window switches don't have enough positions. You could have just auto up and auto down, but then you wouldn't have the option of stopping the window part-way. And it would require adding some time-delay relays, and figuring out the wiring.
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