How to Test Led Backlight with Multimeter

Nowadays, most people are using LED backlights on their screens. These lights have many benefits, including energy efficiency and a longer life span. However, they can also be pretty expensive to replace if they go out. 


If you want to save money in the long run, it is important to know how to test led backlight with multimeter before you make any purchase from an electronics store or online retailer. This blog post will show you how to do that in simple steps! 

Summary: Testing a LED backlight with a multimeter requires a few simple steps. Start by setting the multimeter to its diode test function, then make sure the LED is disconnected from any power supply. Next, connect the probes of the multimeter to both terminals of the LED and check how much voltage is being applied. If it reads zero, then there’s an issue; if it reads between 1-2V, then the LED backlight is functioning correctly.

What Is a Multimeter?

If you are not familiar with a multimeter, it is a device that measures voltage, current, and resistance.

When testing led backlights, a multimeter is an essential tool because we need to know how much voltage the light module produces and the capacity (in amps) of the battery or power supply to calculate the time between each charge.

It is recommended that you use a multimeter for testing the backlights if you are not good with a soldering iron.

A multimeter is easy to operate and does not require any additional skills or knowledge of electronics tools. You can attach it to the front of the backlight and then test whether it is working.

If you are interested in selling, buying, or repairing any electronic devices, a multimeter is an essential tool to have on your workstation.

Procedures: How to Test Led Backlight With Multimeter

Follow the steps mentioned below to make sure that you purchase only quality products: 

Step 1:

Read out all the specifications listed on the packaging. Then, use your multimeter to measure the voltage, current, and resistance of the light module.

The voltage should be between 4.0 and 5.5 volts when running at 6V from a 3S Li-Po battery. Check that if there is no corrosion or any other signs of damage, such as cracks or pinholes.

Step 2:

To test the led backlight with a multimeter, you want to connect your multimeter in parallel to the backlight that you wish to purchase.

Then, see the display reading and observe if it produces any current. A typically led backlight should have between 25 and 50 milliamperes (mA). 

Step 3:

Check the value of resistance in your multimeter dial. It should be less than 1 ohm because these are low-voltage devices, so their resistance is also low.


If the resistance is more than 1 ohm, there could be a problem with your backlight. In this case, check all its components like wires and connectors for any signs of damage or oxidation.

Step 4:

Check that there are no short circuits inside the modules using your multimeter. To do this, plug your multimeter in parallel with the backlight.

The value of resistance should be between 1 and 2 ohms. If it is higher than that, then there could be a short circuit inside.

Step 5:

When you test the led backlight with a multimeter, unplug the light module or battery from all power sources.

Check your multimeter for any damage and check that it is not producing any shorts. Make sure that the chip controlling the backlight has no scratches or cracks on it.

If there are any signs of damage, you should not test the led backlight with a multimeter further and send it back to the seller. 

Step 6:

Check if you have direct access to the battery or power supply that powers the led backlight. Then check whether the module can run for at least 10 minutes.

If it cannot, then the battery or power supply is not strong enough. Make sure that you use alkaline batteries to test whether the backlight has an open circuit.


If there is no voltage across the battery’s terminals when you attach them to the light module, then the problem is with the power supply. You will need to adjust it or find a new one.

Step 7:

If you suspect that the led backlight does not have a short circuit, try testing its other functions, such as high and low beam lights. If they are working correctly, then check whether the resistors are burnt up.

If there is no visible damage, the soldering points are more likely corroded, or the backlight does not work due to internal issues.

Step 8:

However, if the backlight does not work after you checked all the above problems, there may be some internal issues that professional tinkers and hackers can only fix. You will need to disassemble the light module to identify these issues.

Step 9:

If you are satisfied with all the above steps, try to plug your battery or power supply into the module.

If it works and there is no damage to the chip, then you can check whether the led backlight fits into your model or not.


You might also want to test the led backlight with a multimeter by measuring its load capacity. To do this, connect your power supply to the module and measure the current between 6 and 8 amps.

Step 10:

If you are not satisfied with your led backlight’s capacity, consider buying a new one. But if you are happy with this backlight, test it thoroughly before installing it in your model. 

If you are not sure about removing the backlight, then take it to a professional repair technician. They may be able to identify all possible problems and tell whether they can repair it cheaply or if they have to order parts for you.

Frequently Asked Questions

Can You Test Led Backlight With Multimeter?

Yes, you can test the backlight of a LED display with a multimeter. To do this, first determine the voltage at which the backlight is operating. This will be either 5V or 3.3V. Then use a multimeter to measure the resistance between the positive and negative terminals of the backlight. If the display is using an LED driver, it should have a data sheet available that provides this information.

How Do I Know if My Led is Working With a Multimeter?

To test whether your LED is working properly, you can use a multimeter to measure the voltage and current output from the LED. If the voltage is higher than the voltage required for the LED to operate (3.3 volts for a red LED, for example), then the LED is working properly. If the current is higher than the current required for the LED to operate (0.8 amperes for a red LED, for example), then the LED is also working properly.

What Happens if You Put Too Much Voltage Through an Led?

If you put too much voltage through an LED, it may overheat and potentially burn out. LEDs are typically rated at a maximum voltage of 5 volts, but if the voltage is increased beyond this limit, the LED may heat up and eventually fail. If you are unsure about how much voltage your LED is receiving, it is safest to err on the side of caution and keep the voltage low.

Final Thoughts

It is essential to know how to test the led backlight with a multimeter to determine whether the light module can work appropriately with your model without damaging its components or causing other issues.

And repairing an electronic device can be pretty expensive, especially if you are not experienced in electronics repair and soldering.

So, take a look at this article if you want to find out how to test led backlight with multimeter before using it on your model car kit or for your home improvements project.

Leave a Comment