5 Reasons Your Dashboard Lights Go On and off While Driving!

Every icon illuminated on your dashboard is a silent warning, alerting you to potential issues such as engine problems, oil pressure anomalies, tire pressures, or low fuel levels. But what if all dashboard lights start flickering while you drive?

To get straight into it, the problem most significantly lies in the alternator or the battery when the dashboard lights dim or flicker while driving. However, if the lights specifically go out and then a second or two later the lights come back on, another issue like loose wiring connections or ECU software glitches can cause this. I have explained this in more detail below, but first, we should explain the dashboard.

The Dashboard Explained

A car dashboard, often called the “dash,” is the control panel directly ahead of a vehicle’s driver. It is the control and monitoring center of the car, which displays real-time information through various gauges, indicators, and warning lights.

The gauges can include the speedometer (showing your car’s speed), the tachometer (displaying engine speed in revolutions per minute), the fuel gauge (indicating the fuel level), and the engine temperature gauge, among others.

In addition, you will find warning lights for various systems in your car, like the check engine light, seatbelt warning, battery charge warning, power steering light, and more. These lights illuminate to alert you of issues detected by the car’s control unit (ECU).

In modern cars, the dashboard also includes an interactive digital display showcasing navigation information, vehicle settings, and multimedia controls.

How Do Dashboard Lights Get Power?

Now the real question, which most people need clarification on, is whether the battery or alternator provides power to the dashboard.

When you enter the vehicle and turn the ignition on without starting the engine, the battery provides power to every electrical component, including the dashboard lights. 

When you start the engine, the battery provides the initial jolt of electricity to get the engine running. However, the alternator takes over when the engine fires into life. The alternator, once running, will keep charging the battery while also providing power to the dashboard lights and every vehicle component that uses electricity. You will then have the required power when you switch the car off and try to start it again.

5 Reasons Your Dashboard Lights Go On and off While Driving

Experiencing flickering dashboard lights while driving is one of the worst things. It disrupts the reliable stream of information you need as the driver and can cause quite a panic, and you may feel like the car will break down at any moment.

Alternator

As mentioned earlier, an alternator is critical to the car’s electrical system. So, it is one of the main suspects behind this issue. 

If the alternator malfunctions, it won’t charge the battery or provide enough power to illuminate components such as the dashboard lights. As a result, the dashboard lights would flicker or go dim. 

Suppose the alternator hasn’t been charging the battery for some time. In that case, you may experience many other issues, such as the car randomly switching off, all lights going off completely, and you may struggle to start the vehicle.

When the alternator is to blame, the dashboard light rarely switches off and returns to full brightness after a few seconds. So if you are experiencing the lights flickering, they start to get dimmer every time they switch back on; it will likely be the alternator at fault.  

Battery

Another potential suspect is the car battery. A weak battery won’t be able to provide a consistent power supply, which can also cause the dash lights to flicker. Although, as we mentioned, the alternator supplies the power to the dashboard lights once the engine is running, this power still “passes through” the battery. If the battery internals have failed, the power supply may struggle to get through. 

Similarly, loose or broken battery terminals could also be the culprit. An intermittent connection will mean the power supply to the dashboard lights and every component will randomly switch off and on again. Most commonly, you will also notice the radio dropping out for a moment or two at the same time as the dash lights go out.  

Loose wiring connections

The issue could stem from something as simple as loose wiring connections. If the connections to the dashboard lights are insecure, this can lead to the lights needing to be more consistent.

The only real reason an electrical connection behind the dashboard would come loose is if some other repair work was undertaken recently, such as a bulb change on the dash, and the repairer didn’t put everything back together correctly. These connections can’t work themselves loose because of the type of plugs; however, there can occasionally be a manufacturing fault where a wire wasn’t crimped correctly. 

ECU glitches

The Engine Electronic Control Unit (ECU) can have software glitches that erratically cause the dashboard lights to behave.

Since ECU controls many of the car’s functions, including the dashboard lights, if the ECU needs updating or there has been a recall, dashboard lights may turn off randomly. 

Faulty switch

If you are experiencing the dashboard lights going on and off at night with the headlights on, this could be a problem with the contacts in the switch for the headlights. When you operate the headlight switch to turn on the sidelights or low beams, the dashboard lights switch on so you can see them in the dark. Inside the switch is contacts that can fail, and the connection may become intermittent, meaning the dash lights alongside the headlights may go on and off randomly. 

How to Fix a Car Dashboard Whose Lights Go On and off While Driving?

Fixing dashboard lights that go on and off while driving can be complex for various reasons. Here’s a simple breakdown of what you should do if you encounter such a situation:

1. Check the Battery: Inspect the battery terminals. If they are corroded or loose, they are likely the source. Clean the terminals with a wire brush and apply some petroleum jelly to the terminals. Then retighten them. This is an excellent time to put the car on a battery tester to check its condition and voltages and replace it if necessary. 

2. Inspect the Alternator: Use a multimeter to check your alternator’s voltage when the car is running. Connect the voltmeter to the battery if it doesn’t supply the right amount of voltage (13.4 to 14.4 volts) when the vehicle is running; it could mean that your alternator isn’t correctly charging your battery and will need replacing.

3. Consult a professional: If you have gone through the above steps and have trouble finding a fault, booking the car with a mechanic would be best to rectify the issue. Any other problems to diagnose may involve removing the dashboard and airbags, which is not straightforward or safe to take apart without experience.

Should you drive the car with dash lights flickering? 

There are a couple of driving problems with the dash lights flickering on and off. If the cause is a battery or alternator fault, you may experience other issues. If the alternator or battery becomes really bad, the car can die while driving, and it won’t start again until you replace them. 

The other is there’s no telling how long until the dash lights switch off and never turn back on. This can be quite a big problem. It could become a bigger problem for you without knowing if the car has an engine fault light on, the fuel levels, the speed you’re traveling at, or engine temperatures.

Final Thoughts

Irregularities in the operation of dashboard lights point to an underlying issue that require immediate attention. For example, flickering or dim dash lights suggest a possible problem with your alternator or battery. If either is at fault, you may have a more severe issue, such as the car randomly switching off when driving and failing to restart again. So if you experience an issue with the dash lights switched on and off, have it checked or find the root cause of the problem and rectify it asap.