September 25, 2018

Window regulators are usually located inside doors of cars and control the motion of electric windows. Going up and down seems simple enough but electric windows require a complex electrical system in order to function effectively with a long lifespan.

How do they work?

A window regulator has an electric motor that is made up of several spur gears and a worm gear.  When combined and synchronized, this gear system makes the right level of torque to lower and raise the window. The gears are powered electrically from the car battery. When a driver or passenger presses the button, a signal is relayed to the motor in the door. The motor’s operation then works with a vertical motion to make the window go up or down. 

Why do window regulators fail?

One of the most common reasons for window regulators to fail is due to unnecessary over-use. Often children, or indeed childish adults, may push the up and down buttons in quick succession. This creates confusion with the breaker signals reaching the engine often blowing a fuse in the motor or jamming the relay switch.

Window regulators in newer cars are generally a lot more reliable. This is because the newest designs of electronic motors can be made smaller and more powerful. This means that they are more durable, quieter, smoother and faster than older ‘power windows’.

Where does the power come from in window regulators?

Electric windows derive their power directly from the car battery. The voltage is routed by a fuse panel and transferred to the motor of the window regulator. There are often buttons to control the windows on every door. However, it is common, for there to be a master control on the driver side door. A master switch is able to override commands sent from any other button by have a direct circuit to the motor. When a master switch is initiated, all passenger buttons are disabled.

In the very newest car models, electrical systems are a lot more holistic. Rather than just having window regulators operating motion there will be general electrical modules (GEM) or body control modules (BCM). These circuits will control other electrical systems including A/C, radio and GPS navigation.

If you are planning on testing your power windows with a voltmeter then make sure that all electronic controllers are disconnected first. Otherwise, you may get a nasty electrocution!

How is the glass of windows protected?

At the bottom of car doors there are stops, cradles and rests. These are made of soft material that will cushion the bottom of the glass when windows are retracted. In turn, this creates a slight overload in the window regulator motor and makes it stop spinning.

The window glass is also kept in place by a pair of tracks with window guides that keeps the glass in place. In this way, the glass of the window does not rattle or crack while the car is in motion.

How is the window regulator connected to the window?

Window regulators are usually bolted and riveted inside the door. They are made up of tracks, sprockets, rollers and cables in order to support the weight of the glass window. The glass is either bolted or glued to the regulator. On some occasions the regulator will be attached to the glass by a roller device.

2 Types of Window Regulators

There are two main types of window regulators and all use electric motors with a sprocket to provide the up and down motion.

Direct Drive Regulator

These regulators have toothed gears with a single arm to directly drive the movement of the glass. They are often equipped with steel springs able to withstand high tension. If you’re planning on fixing a direct drive window regulator manually then be careful when removing it because the spring may ping out and high speed.

High Tension Cable Regulator

This is the most common regulator in modern cars. They are fast and reliable but if they do break, they are expensive to replace. It is made of a thin steel cable wound around a reel, a mounting bracket and a roller that is attached to the glass. The reel is driven by the electric motor which affects the tension of the steel cable. When the window button is pressed the reel tightens or loosens the steel cable in order to move the window up or down.