Q: Headlights coming on and draining battery

asked by on January 28, 2016

The headlights in my car are coming on while my car is off, draining the battery. Even if I go out and turn them back off, they come on by themselves again.

It sounds like there could be a short in the wiring that controls your automatic headlight system. When the automatic light system is selected the vehicle uses a ambient light sensor usually located on the dash to detect how much ambient light there is. If the sensor sees that it is getting dark at a certain point the light will turn on, as well as if there’s enough light they will shut off. This command to turn the light on or off is controlled by the body control module. When the car is shut off and the doors are locked in some cases the lights will stay illuminated for a set amount of time until the body control module shuts off and turns the lights off. If the body control module is malfunctioning the module can stay on and eventually kill the battery. A parasitic draw test should be performed to pinpoint the cause of the unnecessary draw of power.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Convertible stuck open

Hello. This commonly happens on this vehicle for a number of reasons. Most of the time, it is because of a battery voltage loss. It can also happen if one of the sensors are not reading correctly. When either of...

Car won't start, but it still has stereo on

Hello. If the stereo is on then the vehicle should have some power but the battery should still be load tested. It is common for the battery to have just enough power to provide some power but not enough to...

Car keeps dying & wont turn on once turned off. Alternator was tested & it's fine.What else could it be? A new battery was also bought.

Hi, it sound like you have a ground to chassis issue. What this does is complete a circuit and will slowly drain your battery. A couple of quick and easy checks is look at your black negative battery cable and...

Related articles

How to Check the Voltage of a Car Battery
There are few things more frustrating than discovering that your car won’t start because the battery is dead. A mechanic can measure...
What Is Key-Off Battery Drain?
Many Many things in your car continue to work even after your vehicle is turned off – radio presets, security alarms, emissions computers and clocks are just a few. They continue to draw power from your car battery, and the...
Do High Beams Use Separate Bulbs?
Your headlights have two settings – high and low. High beams are used when you’re driving at night on a...