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-   -   Diagnosing Power Windows (http://www.supraclub.ca/forums/showthread.php?t=6034)

Dan_Gyoba 07-13-2018 09:15 AM

Diagnosing Power Windows
 
This came up on the Facebook group a couple of times recently, so I figured that I'd re-post where it might be findable for a while.

Reference diagram:

TSRM Wire diagram 4-1

For the passenger side window, the power has to go through both switches in order to activate the motor. Each switch has 2 sets of contacts. Those contacts have 2 positions each, normally closed, or normally open. When you push the switch, one goes from normally closed to the normally open position, and depends on the other switch being in the normally closed position. the driver's side switch normally closed position is ground, the passenger side normally closed position is the common terminal of the driver's side switch.

The normally open contacts rarely are the problem, it's almost always the normally closed contacts in the other switch.

If you unplug and check the pins on the passenger side switch, there should be 5. 1 and 4 should go to the motor, so they ought to float. 2 and 3 should go tot he up and down pins on the driver's side switch respectively. If that switch is present and plugged in, they should both show ground. Pin 5 should show battery voltage (If the ignition is on.) Switch side, Pin 1 should connect to 2, and 4 should connect to 3. In the "up" position, pin 1 should connect to 5. In the down position, pin 4 should connect to 5.

Pins 2 or 3 floating shows a problem with the normally closed contacts in the driver's side switch. Pin 5 floating is a wiring issue, assuming that the driver's side window works. Pin 2 floating, but pin 3 ground means that the window can go down, but not up. My '89 did this way too often. It sometimes worked if I put both switches to "up"

For the driver's side switch not working, check for continuity between pins 3 and 4. These should be connected through the normally closed contacts in the passenger side switch to the motor. If this is an open circuit, the passenger side switch is at fault.

On the switch side, in the neutral position, pins 3 and 4 should both connect to 5. Up, pin 3 should connect to 1, down, pin 4 should connect to 1.

Corrective procedure:

Each switch contains a pair of shaped copper bars, which the switch mechanism presses against copper contact pads in the switch. These get corroded or dirty, and the contact is lost. This is seldom the normally open position that stops working, it is usually the normally closed position that gets something worked in underneath the contact and it becomes poor.

This is from memory. Please forgive anything I might miss. I have a switch or two in the garage, maybe I'll take one apart to refresh my memory.

Each switch cap is clipped in place. Carefully pry up the switch cap from the side. Be careful not to let the copper bars fall out. The bars are bent with a flat side and a pointed side, and will point in opposite directions. Use a soft brush to clean the copper and contacts inside. Apply a light coat of dielectric grease, and reassemble. Test that switch operation is as above. The driver's switch is a bit more complicated, and it is nearly impossible to fix the driver's side, however the driver's side seems not to have the same degree of problems.

I've repaired the window switches on several cars, and it has always been the passenger side switch at fault.


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