How to test a window power switch with a multimeter

How to Test a Window Power Switch with a Multimeter?

Some people love saving money when possible. My friend’s window broke down during last week when it was very rainy but my friend has fortunately closed the window so no rain got into the car.

He is one of those people that love DIY and saving money so this proved out to be quite an opportunity for him to have some fun and learn.

Although he managed to repair the window mechanism completely, he made a couple of mistakes and told me about them. This experience of his, coupled with two or three tiny anecdotal mistakes inspired me to write this guide for anyone who might need to do the same.

You’ll need:

  • a multimeter
  • pair of multimeter standard test leads
  • caps for probes
  • a set of screwdrivers.
multimeter for measuring
It depends from manufacturer to manufacturer what type of screw is the lid in the door of your car screwed in with.

Steps to take

Unscrew and remove the lid

Most screws are located in a lid that is positioned lower when compared to the power switch.

If you look inside you will see a screw or screws at the bottom of the lid.  In some cars, it is required to remove a part of the lid to uncover the screw.


Once you have located the screw, grab a screwdriver and unscrew it. Some screws can be cross-shaped and some can be star-shaped. That’s why it’s necessary to have a set of screwdrivers.

After you unscrew the lid off, remove it entirely.

Pry the power switch off

Take something that you will pry the switch off with and carefully do it. And remove sets of wires by pressing the lever next to them and take the power switch in order to test it.

Be careful when you are pulling the switch out because it has wiring attached at the bottom of it.

Set your multimeter on continuity mode and test the switch

Take your multimeter and insert the probes with the caps attached.

Then set the multimeter on continuity mode.

Reminder for inexperienced multimeter users:

  • In order for your multimeter to detect continuity, it will need to be in a closed circuit.  Once your multimeter detects continuity, it will produce a buzzing sound.
  • To close the circuit on window power switches, you will need to press and hold the switch, first in a ‘lower window’ position and then in a ‘raise window’ position.
  • If no buzzing sound is produced, your switch is probably broken. Don’t make the mistake of not moving the switch.
  • No continuity exists in a neutral setting.

Check for jams and broken mechanisms

If your switch is jammed, you will need to replace it immediately because there is no purpose in testing it. You shouldn’t try to repair it either, because chances are you will break it even more, besides, power switches are somewhat cheap and easily replaceable.

If possible, find a diagram of your switch online because it will make this process a lot easier.

Place a negative lead on the negative terminal and hold it there until the end of this test. You will now need to test each terminal in order to detect which one is broken and which one isn’t.

Test the switch

You will test it by placing the positive probe on the terminal and then pressing a switch in the ‘lower window’ position. Hold the switch in this position for one or two seconds, if no continuity signal is heard, release the switch and push it in the ‘raise window position’.

If no signal is heard release the switch in neutral position. Repeat this process for all terminals in the set until you hear a buzzing signal on the multimeter. If no signal is heard for all terminals on all settings, try the second set, since all power switches have two sets.

You should hear the signal once you put the positive probe on the correct terminal and press the switch into the correct position for that terminal. 

If no signal is still heard, check if you have placed the negative lead in the correct position and have in mind that it is possible that both functions of your switch are broken.

Put the switch back on or install a new one

In order to put the power switch back in or install a new power switch, you will need to take it and attach two sets of wires at the bottom of the switch.

Snap the switch into place and once it is in, put the lid back on. Screw it in, and that’s it. You have tested and replaced the window power switch!

Here are two mistakes my friend made:

Mistake number one

  • You need to use the caps for multimeter standard test leads because most power switches have parts on which you need to put the probes on in a tight little box.
  • Precision is a must, but even the steadiest hands will have some trouble with this.
  • There are two types of caps, ones that cover half of the lead’s head and ones that cover lead’s head entirely. You need the second type.

Mistake number two

Being careful with the power switch is a must. While testing for continuity, my friend thought that he isn’t pressing the power switch hard enough because no continuity signal came through. He almost broke the switch before realizing that the switch itself is broken. This is a common issue with some switches because you don’t have the feeling that you are pushing them in the position in which they need to be. So be very careful about this when testing.


  • It can pay off having a small alligator clip and attaching it instead of a negative probe on your multimeter because you won’t have to hold them in place all the time.
  • Be very gentle when prying the switch off. It can break easily.
  • Searching for a diagram of the switch online will make your job easier, faster and more accurate.
  • Most manufacturers have diagrams of power switches they made published online just for situations like this one.

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