Why can't the car headlights be turned off?
2 Answers
Car headlights cannot be turned off due to the relay sticking. Headlight combination switch: In electrical control circuits, it is often used as a power introduction switch to directly start or stop small-power motors or to reverse the motor's rotation direction. It is also commonly used to control local lighting circuits. Combination switches come in single-pole, double-pole, triple-pole, and quadruple-pole types, with rated continuous currents ranging from 10A, 25A, 60A, to 100A. Headlight button: The car combination switch usually has the lighting controls on the right side. Turning it one position activates the low beam, and turning it two positions activates the high beam. Lifting it from the original state briefly activates the high beam (used for passing or as a warning light).
When encountering the issue of car headlights not turning off, first consider if the switch is stuck. Many car headlight switches wear out over time, causing the button to stay depressed or internal contacts to stick, resulting in the lights staying on. The relay could also be problematic—for example, burnt contacts may fail to break the circuit, allowing current to flow continuously. Wiring shorts are not uncommon, especially in the front section where wires may degrade or have their insulation chewed by rodents, leading to a short circuit against metal parts. Vehicles with automatic headlights are prone to misjudging ambient light due to faulty sensors, keeping the headlights on. In such cases, try turning off the engine and restarting it—sometimes minor faults reset automatically. Check the headlight fuse in the fuse box for melting or looseness; if that doesn’t help, visit a professional shop to diagnose the circuit with a scanner. Don’t delay too long to avoid draining the battery (preventing engine starts) and increasing driving risks. Temporarily removing the fuse to cut power and protect the battery before repairs is advisable.
