One of the most common tests regarding automotive diagnostics is checking short to ground.
Thankfully, your job can be made a lot easier with a digital multimeter.
Several multimeters are specifically designed for automotive diagnostics, but any multimeter that can measure resistance in Ohms (usually displayed as Ω on your multimeter dial) can do this simple job.
If you’re looking for a digital multimeter, look at our several comparison posts.
Although it’s not hard to check short to ground with a multimeter (For this task, we recommend using Fluke 3340 multimeter), it takes a bit of knowledge to get it right.
In this blog post, we’ll briefly discuss the theory behind checking a short-to-ground and then provide a detailed overview of the exact steps you need to take to check short-to-ground with your digital multimeter.
Once you know how to check short to ground with a multimeter, you’ll be able to find this common problem and take your first steps to fix small electrical problems in your appliances or cars.
Ohms and resistance
You need to measure resistance to check short to ground with a multimeter. Electrical resistance is the difficulty that electricity has in getting through a component called a conductor.
The more resistance, the harder it is for a current to pass through the conductor. To measure resistance, you have to find the voltage of an object and divide it by the current. Voltage is the object's capacity, whereas the current indicates how much of that capacity is used.
The more current loss compared to the capacity, the more resistance is measured. The proportion between volts and current is measured in Ohms, so you’ll need a multimeter that measures Ohms to check short to ground.
Luckily, a digital multimeter will automatically do all this math for you, but it’s always helpful to understand the dynamics behind a measurement to know what’s going on.
You can also watch this video for a better understanding of resistance and Ohm's law:
What is short to ground?
Short to the ground is a particular type of electrical problem (that is most common in automotive problems). In short, when you’ve got a short to ground, it means that a live wire is touching something it shouldn’t and is accidentally grounded. An electrical appliance in your house will trip the breaker, and you won’t be able to reset it until the problem is fixed.
In practical terms, there is a leak in your electrical circuit somewhere. If your electrical circuit is a simple plumbing pipe with water flowing through it, a short to ground is comparable to a big hole somewhere in the pipe that leaks out all the water before it ever gets to its destination.
How to check short to ground with a multimeter?
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To check a short to ground with a multimeter, you’ll need to set the dial of your multimeter to Ohms or another setting that allows you to measure resistance. Simply adjust the dial if you have any digital multimeters designed for automotive diagnostics, such as the Innova 3340 (your digital multimeter). Still, most other multimeters will also have a Ω setting. All the digital multimeters we discuss on our website have the option to measure resistance.
Now that you know how to check short to ground with a multimeter, it’s time to put your knowledge to the test. Remember that if there isn’t a short-to-ground problem with the component or circuit you’re testing, you will measure something other than infinite resistance. Take some components in your car and ensure you get some reading, and you’ll know the difference when a problem arises.