Q: When I open my doors the interior lights don't come on.

Hello. Without knowing the make and model of your vehicle, it hard to definitively give insight on the exact component that has failed.

In general, when the door is opened, the switch turns on the interior lights. If the lights are not coming on, then its possible the switch has failed. It also possible there is a short between the fuse and the door switch.

Does your vehicle have a door ajar warning light, and if so does it turn on when you open the door? The door switch in question would be responsible for this warning as well, and if its not working this would indicate that the switch has gone bad or is not receiving power. The switch is used and impacted often enough that it is more likely to fail than any other component in the circuit.

You will need to test the available voltage at the door switch, and what the voltage is after the door switch is supposed to turn on. If there is available voltage before the switch, and no voltage after, you will need to replace the door switch as necessary.

If you’re unable to fix the issue, have a certified technician, like one from YourMechanic, come to your location and diagnose the electrical issue and firsthand.