Here's a tip for you GM owners with power windows. I have seen a lot of problems with power windows in the 86 Buick. I have had windows that didn't work at all from either the drivers station or the window station, others which work in the down mode but not in the up mode. The circuit which controls the window motors is complex, permitting operation from two locations, sort of like the "three way" switches used to control the lights at the top and bottom of the stairs in some homes.
I have never had a motor fail in any of the windows, however I have had a lot of trouble with the switches. There is a major reason for the problems with the switches and it starts with dirty contacts. The problems aren't always very obvious, for example the right rear window failed last year. I measured the voltages at the motor and the switches and found nothing. After reading the schematic in the service manual I determined that the main power for all the windows goes through the master switch at the drivers console - make sense. So, I took the driver's console switch apart and found that the problem was that the switch was dirty and while in the "normally closed" position, failed to complete the circuit to the right rear switch.
Now you shouldn't be fooled by what appear to be "unserviceable" parts. The power window switches fall into that category, however upon close inspection you will see that they do come apart. So I bent a few tabs, and took the switch apart to find plain old dirt had gotten between the "normally closed" contacts. A bit of "tuner cleaner" and some compressed air was all it took to clean out the dirt. I put it back together and it has worked ever since.
Another problem I have encountered in the switch assembly is the plastic rocker part of the switch - you know, the part of the switch that you press when you operate the window. It seems that GM has made the little legs on the switch that press the contacts together out of a thermoplastic. What happens is this; the switch contacts get contaminated with dirt. not contaminated enough to prevent operation, but contaminated enough to cause the resistance of the contacts to increase. Now if you know anything about electrical circuits you know that power is dissipated in a circuit where the resistance is increased. What this means is that the contacts get hot! Hot and thermoplastic switch parts don't go very well together. What happens is that the plastic legs on the switch get soft when they get hot, the nature of any thermoplastic. Of course since the switch is dirty and its resistance is high you have to press rather hard to make the window operate properly. Pressing hard on the soft plastic legs deforms them, sort of mushrooms them over and reduces their length. Finally, they are no longer sufficiently long to engage the contacts and the window no longer functions.
So hurry on down to your local GM dealer and try to buy new plastic buttons - they don't sell them separately! You have to purchase the whole switch for a hundred dollars! However being the frugal mechanic that I am I figured out a solution. The simplest solution is to swap the plastic button from the driver's control panel with one in the rear. That will make the one in the rear inoperable, but it's better to have the driver be able to operate the windows than the kid in the back seat, right? The other fix is a bit more time consuming but when you are finished you will have a switch that is better than new. Here's what I did.
I took the plastic button into my shop and used a very small drill in my Dremel Tool. The drill is a few thousands of an inch smaller that the diameter of a standard straight pin. I took a pin and cut it to be the length of the hole I drilled plus enough length to make up the missing material that had mushroomed over due to the heat and pressure, leaving the head of the pin intact. I then heated the pin with a soldering iron and pressed it into place. After it cooled I stole some plastic from the inside of the body of the button and built up the area around the pin using the tip of the soldering iron. The resulting button is far stronger than the original one, the steel pin dissipates the heat from the contact and the switch will function far longer than it would if you had been able to get a new button from GM - and you have a hundred dollars in your pocket that GM didn't get!!
Tools required: A straight blade screwdriver to press the release clip for the switch assembly. A voltmeter or continuity tester (12 volt light) for circuit testing.
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