How to Test a Power Window Motor with a Multimeter

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If your car’s power windows don’t work, the problem may be with the window’s motor, which needs repair. To test if your power window motor is working, you need to use a multimeter.

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A multimeter is a device that can check circuit voltage and determine if the power window motor is working. 

Testing your Window’s Motor.  

For those of us who have to work with old vehicles or old electronics, the humble multimeter is an essential testing tool. It can help you diagnose everything from a loose battery cable to a faulty electric brake switch. Since it is not a complicated device, it is also perfect for beginners who have never used a multimeter before. Here’s a quick look at testing a power window motor with a multimeter. 

  1. The first step in testing the power window motor is to open the door. This step is necessary to reveal the window engine. Then you need to have a multimeter and a pair of jumpers. 
  2. You also need to find the wiring diagram for your vehicle. You can find the wiring diagram for your vehicle in several places. If you have an older vehicle, you may need to look through the glove box. If you have a newer vehicle, you should be able to find it in the fuse box or look it up online. 
  3. The multimeter should be set to test for continuity – it should also be set to read in ohms. Also make sure the multimeter is not sending the wrong signal to the window motor. 
  4. Test the window motor by connecting a multimeter to the motor terminals. Some window motors have thermal protection. When the fuse heats up, it blows, stopping the window motor and preventing it from damaging other parts. Test the fuse by connecting the multimeter’s red probe to the motor’s red wire and the black probe to the black wire. 
  5. Start the engine with the positive probe of the multimeter and place the negative probe on the window frame. Hold the sensors in place and wait for the fuse to blow. If the window motor fuse is not blown, there is a serious problem with the motor. 

Sometimes one of the power window motors in your vehicle may fail. If one motor is not working, your vehicle’s power window will not work properly and driving in this condition can be quite a hassle. However, you can test the power window motor with a multimeter before deciding to replace it. 

What is a power window motor? 

A power window motor is usually the cheapest and easiest way to operate a window. The electric window motor consists of a rotor, a fixed stator and a set of windings. It is an electric motor that moves the glass, allowing the window to open and close. These motors use direct current (DC) in the form of a series of pulses. 

The electric window motor is a fairly simple device that does exactly what it sounds like: it moves the electric window. When the power is on, it activates, pulls the power window panel up or down, and turns off. It restarts automatically when the driver activates the power window switch. The difficult part about this device is that it is usually very difficult to test. 

If the motor does not work properly, it must be disassembled and inspected. A multimeter is used to test the motor before disassembly to determine if time and effort is required to repair. In general, there are three ways to test a power window motor with a multimeter: you can test resistance, continuity, and voltage. 

Voltage drops

If the power window motor is faulty, one of the first tests is a voltage drop test between the black and red wires that should be connected to the motor. A multimeter can be used to test for voltage drop, but there are a few things to consider before you start testing. 

  • Be sure to check both the red and black wires first. 
  • Second, be sure to check each wire for working voltage. (A bad power window motor usually has low voltage.) 
  • Third, make sure you test the wiring, not the window itself. 
  • Finally, never be afraid to test the wires connected to the window motor to make sure there is no problem with the window itself. 

You have to be very careful too. Although you might think it’s just a motor with some wires, there’s a lot more. You have to make sure you don’t damage anything while testing because it can cause a lot more damage than you think. 

Important Reminders for Power Testing  Windows 

Let’s assume you are a professional repairman reading this. In that case, you should skip it because it is more for novice electricians, DIY enthusiasts, or people that are into automotive electronics. Most home window repairs can be done by instructing the customer to try the repair.

You don’t necessarily have to pay for a service call. For example, if the window won’t go down, a technician can give the customer a multimeter and tell them to check the continuity of the window motor. If the windows motor passes this test, the technician will ask him to try this. 

When testing the power window motor with a multimeter, it is important to remember that the multimeter sensor must be connected to two different wires. Normally, on an AC shorted motor, the black probe of the multimeter should be in contact with the red wire and the red probe should be in contact with the black wire. (On a DC motor, the red probe should always touch the red wire.) If the probes are on the wrong wires, the multimeter will read a different voltage than expected. 

To sum up…

Testing a power window motor is a relatively easy thing to do. But, sometimes, it can be tricky to determine if your power window motor is bad – or the window regulator is bad. The important thing to remember is to test the motor (and the regulator) before you buy a new one. If you don’t, you may find yourself replacing something that works fine.