Car window won’t go down: How to fix it

Why Your Car Window Won’t Go Down: Common Causes and Solutions

When a car window won’t go down, it can be more than just an inconvenience, especially in hot weather or when you need to interact with drive-thru services. Diagnosing and fixing the issue can often be done with some basic tools and a little patience. Here’s a step-by-step guide to help you identify and fix the problem.

It’s Usually Caused by a Corroded Driver’s Door Master Switch

Why that switch? Because it the one that’s used most often. Because the driver’s window is opened more often, it wears out faster. Plus, the driver’s master switch is exposed to the elements; snow, rain, coffee, etc.

If your windows won’t go down, start by checking the master switch and window motor wiring. However, it can sometimes be caused by a broken sash clip or binding in the window track that’s causing a mechanical issue rather than an electrical problem.

How to diagnosing why the car window won’t go down

If your car window won’t go down, it’s either a mechanical or electrical problem. If it’s a mechanical problem on a modern cable-operated window regulator, it usually makes a noise first, and the glass usually falls down into the door. If your window is stuck up, 99% of the time, it’s due to an electrical problem.

If you can’t move the window with the master switch or window switch and don’t hear any noise when you activate the switch, don’t assume it’s a bad window motor. The switches fail more often than window motors. And, if the motor operates the window in one direction but not the other, that’s usually a switch issue, not the motor itself.

If none of the car windows operate, start your diagnostics by checking the power window fuse or circuit breaker. Power window motors usually have a built-in circuit breaker to prevent the motor from starting on fire, so if the fuse is blown, chances are you’ve got a wire short and not a bad motor. If the fuse is good, remove the door panel so you can check for power at the window motor connector.

How to test a power window switch

Here’s the deal with testing a power window switch: it’s impossible

Driver’s door master switch wiring connectors

to do without a wiring diagram, especially on the master switch. In older vehicles, ALL the power and grounds for each window go through the master switch.

On newer cars, where the windows are controlled by the body control module (BCM), the master and door switches send DIGITAL commands to the BCM, which switches power to the motors. On still other late-model vehicles, the switches send a digital command directly to the door switch module for the passenger windows, which sends power to the motor. In other words, it’s complicated. So, unless you have a wiring diagram, start by testing right at the window motor.

How to test a power window motor

Power window motors are pretty simple—they only have two wires. The window switch supplies battery voltage on one wire and ground on the other. When you reverse the window direction, the polarity on the wires switches.

To test the switch operation, set your digital voltmeter to 20 volts or less DC. Place the positive test lead in one connector cavity and the negative lead in the other cavity, and the switch will be operated up and down. If you get a reading in one direction but not the other, chances are you’ve got a master switch problem. Why? Because in most cars where the windows aren’t controlled by a computer, the power and ground for each window flows through the master switch. Don’t get fooled here; the master switch can provide power and ground for three windows but not the fourth. So, your next step is to remove the master switch from the driver’s door and test the wires going to the problem window.

If you get a toggled voltage reading, then check for signs of a broken sash clip or binding window tracks. Sash clips connect the glass to the window regulator. When a sash clip breaks, the glass can jamb and bind. In the worst cases, binding can bend the window tracks and even break a regulator cable. You can’t repair a cable-style window regulator, so don’t even try. A new regulator with motor costs less than $100 from any auto parts store.

See this post for more information on how to diagnose and fix a car window won’t go down issue.

©, 2016 Rick Muscoplat