How to Test Rear Window Defroster With Multimeter

To test a rear window defroster with a multimeter, first set the multimeter to measure resistance. Then remove any connectors attached to the defroster and locate the two terminals on either side of it. Connect one probe from the meter to each terminal and note the reading that appears on the display screen; this is your resistance measurement.

If it’s within specifications for your vehicle, then you can be sure that your defroster is working correctly. However, if there’s no reading or an abnormally high reading displayed, then there may be an issue with either wiring or components in your rear window defroster system and further investigation will likely be needed.

  • Start by ensuring that the rear window defroster is off and disconnect it from the power supply
  • Set your multimeter to measure ohms (Ω)
  • This will allow you to measure resistance in the circuit of the rear window defroster
  • Connect your multimeter’s leads to either side of the terminals on the rear window defroster, then take a reading from the meter display screen
  • If you get a reading between 0-10 ohms, this indicates that there is no defect in connection or wiring and that it should work properly when connected back to power supply again
  • However, if you get a reading higher than 10 ohms or an “OL” indication on your meter display screen, this may indicate an open circuit or loose wire which needs fixing before connecting back up with power supply again for proper functioning of rear window defroster system

Checking Rear Window Defogger

How Do You Test a Rear Defroster With a Multimeter?

Testing a rear defroster with a multimeter can be done in three steps. First, you will need to ensure that the power is disconnected from the rear window before beginning your tests. Once this has been confirmed, use your multimeter to test for continuity between the two terminals on the defroster grid.

If there is continuity present, then the circuit can be assumed to be working properly and no further testing needs to be done. However, if there is no continuity present then further investigation should take place as this could indicate a fault within either one of the elements or within its connection wiring. Finally, check all connections are secure and free of corrosion before attempting any repairs to prevent short circuits occurring due to loose wires or other faulty components being used in lieu of good ones.

How Do I Know If My Rear Window Defroster is Working?

If you own a vehicle, then it is important to know how to tell if your rear window defroster is working. The rear window defroster helps keep your windows clear and free of frost, fog, and ice buildup. It also helps prevent snow from accumulating on the back windshield during winter months.

To check if your rear window defroster is operational, first make sure that the switch in the cabin of your car or truck has been turned on. Once this has been done, look for a small red light near the upper corner of the glass. If this light comes on when you turn the switch on and stays lit while running, then it’s functioning properly.

You should also be able to feel heat coming through when lightly touching a finger to lower portion of glass where defrost lines are located. If these two tests come out positive then you can rest assured knowing that your rear window defroster is fully functional!

What is the Voltage of the Rear Defroster?

The rear defroster is a device that helps to clear frost, fog and mist from the windows of a vehicle. It works by heating up the glass in order to melt any ice or snow on it. The voltage needed for this system varies depending on the size of the window and type of car, but typically ranges between 12V-24V DC.

In most cases, you’ll need approximately 12 volts for an average car rear window defroster; however, some cars may require more power if they have large windows or aftermarket tinting films applied. If your vehicle’s manufacturer recommends using 24 volts for its rear defroster system then it is important that you follow those instructions exactly in order to ensure safety and proper functioning.

What Causes Rear Defrost Not to Work?

Rear defrost not working is a common issue in vehicles, and it can be caused by many different factors. One of the most common causes is a blown fuse or faulty wiring. If your car has been involved in an accident, this could also cause rear defrost to malfunction due to damage sustained from the impact.

Additionally, if you have recently replaced any components related to your rear window that may also contribute to the problem. In some cases, even excessive dirt or debris buildup on the inside of your rear window can interfere with its ability to heat up properly and allow condensation build-up which leads to fogging. Finally, another possible reason for rear defrost not working could be a worn-out heating element located behind the glass which needs replacing as soon as possible before further damage occurs!

How to Test Rear Window Defroster With Multimeter


How to Tell If Rear Defroster is Working

If your rear window has a defroster, it is important to make sure that it is working correctly. One way to tell if the rear defroster is functioning properly is by using a voltage meter. If you have access to one, set the multimeter to measure DC volts and then place one probe on each of the two metal contacts inside the defrost grid on your back windshield.

When you turn on your vehicle’s ignition switch, power should be sent through these wires and will register as an electrical current when measured with a multimeter. If there is no current detected, then this means that something in the system may not be working correctly and needs further investigation.

If a Small Portion of Rear Window Defroster Grid is Scratched off What Should You Do

If a portion of your rear window defroster grid is scratched off, you should immediately replace it to ensure that the car’s heating and cooling system remains functional. Not only will a damaged grid reduce the efficiency of your car’s climate control system, but it can also lead to costly repairs down the road if left unchecked. To fix this issue, locate an appropriate replacement part online or at an auto parts store and install it according to manufacturer instructions.

Where is the Rear Defroster Fuse Located

The rear defroster fuse is typically located in the vehicle’s main fuse box, which can usually be found under the dashboard or beneath the hood of your car. The exact location of the fuse will vary depending on your make and model, so it’s best to consult your owner’s manual for more information.


Overall, testing a rear window defroster with a multimeter is an easy process if you follow the right steps. By checking for power at the fuse box and then measuring the resistance of each grid line in both directions, you can quickly determine whether or not your defroster is working as intended. With these simple instructions, you should be able to properly identify any potential problems with your rear window defrosting system and take appropriate action to fix them.

David Jon

David Jon

I'm a long-time Ford and automotive enthusiast, and I've been writing about cars for over 10 years. I started Fordmasterx as an effort to combine my two passions – writing and car ownership – into one website. I hope that you find everything you need on our website and that we can help guide you through all your automotive needs.

We will be happy to hear your thoughts

Leave a reply