How to Tell if a Car Fuse is Bad.
How to Tell if a Car Fuse is Bad
Before we get into how to diagnose bad fuses, it’s important to understand what role they play in a car. Fuses act as protection for electrical circuits. If an abnormal condition occurs in the system, such as a short circuit, the fuse will trip and break the circuit, preventing damage to components.
Electrical Device Problems.
The first and most obvious sign of a bad fuse is problems with the electrical devices in the car. For example, if the headlights don’t light, the radio doesn’t turn on, or the climate control doesn’t work, this could indicate a blown fuse.
These devices aren’t always directly related. For example, if the fuse that controls the headlights is blown, it doesn’t mean it will affect the stereo, but it’s still a sign worth checking. Pay attention to the consistency of symptoms: no voltage to multiple devices could indicate a common fuse.
Visually Inspecting Fuses.
Another way to diagnose a bad fuse is to visually inspect the device itself. Most cars have a set of fuses, usually located in the engine compartment or under the dashboard. To check the fuses, follow these steps.
First, access the fuses. Open the hood or open the cover under which the fuse box is located.
There is usually a diagram on the cover that shows which fuse is responsible for what.
Remember to disconnect the battery before working on the electrical system to avoid short circuits.
After removing the fuse, carefully inspect it for damage (how to replace (remove) a fuse). If the fuse seems intact, but you still have problems with electrical devices, the cause may lie in other components.
Checking with a multimeter.
If the visual inspection does not yield any results, you will need to use a multimeter to more accurately determine the condition of the fuse. Set the multimeter to resistance mode and touch both terminals of the fuse. If the multimeter shows infinite resistance, the fuse is faulty.
You can also set the tester to continuity mode (usually the icon looks like a sound wave).
Then touch the multimeter probes to the contact pads of the two fuses. If the circuit is OK, the tester will beep.
