The courtesy light is the lamp on the interior of the vehicle that turns on when the vehicle's doors are opened. It is usually mounted on the roof of the vehicle’s interior, near the rearview mirror. When the door is opened the switch activates the courtesy light to illuminate the interior of the vehicle for the passengers. The courtesy light switches found on some vehicles are also wired to a timer that will dim the lights automatically after a predetermined period of time. While the courtesy lamp and switch might not be components critical to the safety or performance of the vehicle, they do provide a feature that makes the driving experience more convenient for the passengers. When the switch has a problem, it can disable the switch and remove this convenient feature for the passengers. Usually a bad or failing switch will produce a few symptoms that can alert the driver of a potential problem that should be serviced.
1. Dome light does not come on
One of the most common symptoms of a possible problem with the courtesy light switch is an inoperable dome light. The switch is designed to route power to the courtesy light once the vehicle doors are opened, and will leave the courtesy lamp inoperable if it fails.
2. Flickering courtesy light
Another common symptom of a problem with the courtesy light switch is a flickering courtesy light. Courtesy light switches are activated every single time someone enters and exits the vehicle and are susceptible to wearing out. A flickering light usually indicates that the electrical contacts inside the switch are worn out and are no longer able to make a clean connection. Usually a flickering switch is approaching the end of it’s service life.
3. Dome light stays on
Another less common symptom of a potential issue with a courtesy light switch is a courtesy or dome light that remains on at all times. If the courtesy light switch shorts it can cause power to be allowed to the courtesy light, even when the doors of the vehicle are closed. Depending on the exact wiring setup, this may cause the dome light to remain on even with the key out, which will drain the battery.
The courtesy light and switch are not necessarily components that play an important role in the safety or performance of the vehicle, but they do provide a useful feature for the passengers and can be an inconvenience when they fail. For this reason, if you suspect that your vehicle may be having an issue with the courtesy light or its switch, have the vehicle inspected by a professional technician, such as one from YourMechanic. They will be able to replace your courtesy light switch if necessary.
This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Courtesy Light Switch and was authored by Ed Ruelas.