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Q: all four windows will not operate on 1999 Pontiac Grand Am

circuits are working and motors are powered
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All windows ground through the drivers power window switch. Try the following tests at one of the door window motors. With all switches connected, unplug one window motor. Using a test light to ground test the connector for power in both up and down directions. One wire should have power in the down direction and the other should have power in the up direction. If that test is ok the place the test light across the connector for the motor (one end of the test light on one wire and the other end on the other wire). The light should light in both the up and down switch positions, if it does not then There is a problem with one of the switches or the main ground. If the test light lights during all of the previous tests then the motor is the most likely fault. Start this test with the drivers door as there is only one switch involved with that window.
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