Car Lights Malfunction May Drain The Batteries

You might have noticed that the car components may malfunction, and it may happen to anyone even if they take care of the car very regularly and systematically. Car lights may also not function properly at times, and it could be due to many reasons apart from being very old. 

Now, there are many lights in a vehicle, and all use the same car battery but are meant for different purposes and places in the vehicle. Here are some lights and the reasons for their malfunctioning.

Headlights Are The Most Significant Drain On Battery

The headlights may continue to be on even after you have turned off the engine. There is usually an engine timer in modern cars that automatically turns off the headlights within seconds once you switch off the car.

If not, then it could be that this engine timer may malfunction. You can diagnose this by simply turning off the lights before the engine, and if it succeeds and the lights switch off, the reason is clear.  

Sometimes only one headlight may remain even after the car is switched off. The lights may not be in sync, and one switch off and one do not. It could also be that one lightbulb is dead, and both are malfunctioning.

The light bulb may need replacement before you can identify the problem. The burn-out of the light bulb may also be due to some fault in the lighting mechanism, so after changing the bulb, you must take it to a mechanic if the problem persists. 

Many cars these days come with an automatic system that allows lights to turn on when the surrounding ambient lights are low. The system is automatic, but if it stops functioning properly, then the lights may stay on even when the lights are bright or when the car is switched off. 

To diagnose the issue, you can try using the parking brake and turning off the headlights. If that happens, then the system of automatic lights may need repair or replacement. 

The lights may also malfunction if the electrical signals are not receiving the correct signals. The relay system is in the hood of the car, and you can check it gently to see if their movement leads to the flickering of headlights and then change the relays if needed.

The Interior Lights May Also Malfunction

The interior lights may not switch off even after the car is switched off, and this may happen if the control knob is still active or it is stuck. You use the dome light individual switch to reduce the light’s power or switch it off. The battery will keep getting drained, so if the light does not switch off, you can remove the bulb with care until it is repaired.

This light may also remain bright if the door switch is broken, which controls its functioning by switching the interior light on when any doors open. Find the door switch in all the doors and find the malfunctioning one by switching on and off all the buttons one by one. 

Parking Lights May Also Remain Switched On

There are two scenarios here. The parking light must switch off when you switch off the car or use a switch to do that. The switch may be located in different places in the different vehicles, but usually, it is on the steering wheel. You can switch off the lights using this switch. The circuit of parking lights may be crossed, and the lighting system may go haywire in the system. 

You can easily identify the cause if all the other lights are also malfunctioning. For example, the parking lights may remain on, and the dashboard and headlights malfunction. A simple diagnosis is available to find if the circuits are crossed. You check the parking light is on while the brake light is still on, and if this is the case, then the circuit is crossed. 

The automatic lighting system may malfunction

The lights malfunction due to the automatic system at times. Some people feel that the old, mechanized way of switching the lights on and off was simpler. But now, almost all models have sensors, and automatic systems as these conserve more battery. But if the sensor cannot receive the right signals, it may not work properly; it may assume that it is dark, and the light will remain on.  

The turn signal or the relay signals may be stuck in the position. If this is the case look for professional help. He can easily find the relay system and repair the relay timer, and the lights will start receiving signals properly. The turn signal may be stuck or have a broken part.  

Save the Battery

If the lights remain on, the battery will drain off very quickly. This situation can lead to major trouble, where you won’t be able to move your car and take it to a mechanic for repair. So it is better to get your car checked or you can carefully disconnect the battery cables using protective gear and the right tools. 

You must disconnect the negative cables followed by the positive wires. In case you already know the whole process, just follow the steps and complete the task. In each scenario, the car does need to be repaired, and this can just be a stopgap arrangement. Get the headlights, interior lights, or brake lights repaired as early as possible. You can remove the bulbs carefully until you take the car to a mechanic. 


There are many reasons that the car lights do not switch off when you turn off the engine. But the fact remains that they will drain off the engine unless you take care of the same as soon as possible.

You can follow the methods to diagnose the reason behind this malfunction or take it immediately to a mechanic. But if there is going to be a delay, remove the bulbs or disconnect the wires and signals if you can. 

Liam Dare

As CEO of, my passion for the automotive world motivates me to build online businesses that provide information and entertainment to users. I am proud to contribute in a positive way to the automotive community.