Door Jamb Switch

What is a door jamb switch and where is it located?

Door jamb switches, also referred to as door jamb light switches or door ajar switches, are used to activate the interior dome light when you open your car’s doors. In newer cars they also signal the vehicle’s computer if a door is not closed completely, which in turn turns the warning light signal and the door ajar warning alarm on. 

There are a few different locations these switches could be found in and a couple of different ways they could function. Some door ajar switches are located in the front of the door frame, near the hinge side of the door. These switches get pressed when the door is opened and are released when the door is closed. Some switches are found at the rear door jamb at the swinging end of the door. These are pressed in when the door is closed and released when the door is opened. Other door ajar switches, confusingly, are not found in the door frame at all, but are attached to the door latch mechanism, behind the interior door handle. Wherever the switch is located, it will be set up to activate the interior dome light when the door is opened, and shut it off when the door is closed. In newer vehicles, it will also activate the dashboard light and the sound that warns you that your door is ajar, if the door is not latched completely. 

You will find one (or more) switches for each door. Some vehicles may use separate switches for the interior lights and the door ajar warning. 

How do I know if my door jamb switch needs to be replaced?

These switches can fail due to high use (especially in the driver door), shorting out due to bad weatherstripping, or damaged due to a faulty door hinge. If something goes wrong with the door ajar switch, you may experience problems with your interior lights or your door ajar warning. A faulty door jamb switch may cause the interior lights to fail to activate or may cause the light and door ajar alarm to activate improperly.

An interior light that will not turn on is largely a nuisance. One that stays on even when all the doors are closed tightly can be dimmed or turned off with your interior lighting controls. A door ajar alarm that keeps sounding, though, cannot be turned off, since it is intended to be a safety feature. This is not only an annoyance and a distraction, but also a drain on the battery. If you are experiencing these problems, you’ll want to replace your door jamb switch.  

Before replacing one of these switches, you’ll have to determine which door and which switch is at fault. If your problem is that the light will not come on when you open one of the doors, then you’ll just have to check if it comes on when you open the other doors. If only one door is affected, then you need to replace that switch. If the switch is stuck in the on position, this will be more difficult to pinpoint. You may be able to test the associated circuits with an electronic probe tool. A mechanic with a diagnostic scan tool may also be able to determine the exact source of your problem. 

Can I replace a door jamb switch myself?

Fortunately, you should be able to fix your switch and get your lights on and off when they’re supposed to be with just a little bit of time and effort. You’ll just have to unbolt the old switch, disconnect its wiring, and connect and bolt on the new one. A switch at the rear of the door frame will be easy to access. One at the front near the hinges will of course require a bit more contortion on your part. A door ajar switch located near the door latch will require you to remove the door panel. Be sure to disconnect the battery before working with electrical parts. 

Need a door ajar switch replacement?

If your interior lights are not working because of a defective door jamb switch, then you have come to the right place! At 1A Auto, we carry a large selection of aftermarket door ajar switches for many makes and models, and at great prices. They are just what you need to get your vehicle in good working order again!

At 1A Auto, we also make shopping for a replacement door jamb light switch for your car, truck, SUV or van easy - we're here to help you select the right part for your vehicle! Call our customer service toll free at 888-844-3393 if you have any questions about our door jamb switches, warranty, compatibility or to purchase, or you can buy online.