Dome Light Stuck On
January 25, 2011 7:58 AM   Subscribe

My car's dome/interior light won't go off. Toyota Camry, I can't remember the year.

First, let's dispense with the obvious: It has a switch with 3 settings, ON, OFF and DOOR.

When I set it to either ON or OFF, it is on. When I set it to DOOR it is not only on, but the "door ajar" light on the dash comes on. No doors are ajar, although I will admit a door sensor (including the trunk) could be malfunctioning. However, I assume the light must be causing the false ajar reading and not vice versa because otherwise the ON and OFF settings would leave the light off.

The next most obvious problem could be the dash brightness control knob. On a previous car I had, that knob, if cranked all the way to one end, would override the dome light switch. The camry's switch doesn't work like that.

One person I described this to mentioned that her car left the light on for a while and then shut off. Mine doesn't do that. When I go out in the morning it's still on from 14 hours ago.

Nothing in particular happened to the car just before this that I know of.

I have a remote starter (Viper brand, no alarm system) installed that's been there almost a year. I changed the low batteries in the remote to see if it could be some kind of reverse-remote alert. I also went through the remote start manual to see if there was some function that might turn on the light and found nothing. I tried various random "auxiliary functions" to no avail.

It hasn't been particularly draining my battery (deep winter here and the problem has existed for a couple weeks) but it's kind of hard to see out the windows at night so I'd like to get it fixed for less than N*$100.
posted by DU to Travel & Transportation (7 answers total)
The switch in the door jamb that senses when the door is shut has failed. Replace it.
posted by Thorzdad at 8:29 AM on January 25, 2011 [2 favorites]

The switch in the door jamb that senses when the door is shut has failed. Replace it.

I just recently started having this problem, the day after I slammed my seat belt buckle in the door. So I think this is it.
posted by cashman at 8:44 AM on January 25, 2011

The switch in the door jamb that senses when the door is shut has failed. Replace it.

Then why is the light not off when I set the switch to OFF?
posted by DU at 8:46 AM on January 25, 2011

I'm guessing at how it is wired here, but the door switches may have multiple wires going through them, perhaps the door-ajar-sensing-wire is now shorted to the wire that powers the bulb, or something has shorted to the chassis.

cashman is almost certainly right that the door sensor is the most likely thing to have failed (it's a frequently operated moving part), but taking the bulb out will be the cheapest option. You may find that taking the bulb out triggers the door-ajar alarm permanently or something that will force you to replace the door switch anyway but it's worth a try.
posted by samj at 9:00 AM on January 25, 2011

The switch itself in the dome light might be bad, as well. Lacking any event that might have damaged one of the door switches, and armed with the knowledge that manipulating that domelight switch affects other things in the car, my first step would probably be to replace or diagnose the dome light switch. Perhaps just disconnect it and simulate it with a short piece of wire [A to B is "ON", all open is "OFF", B to C is "Door" or what have you]. That should confirm or deny that hypothesis.

You can probably buy a replacement dome light assembly at a pick-n-pull yard for $5.

The door switches are probably very easily accessible, so it may be worth opening them all up and shorting [or opening, depending on the switch] them so that they are for sure reading "closed". If you do that and your problem goes away, it's one of those switches and a binary search will reveal which one.

Here's a similar situation where it turned out to be a bad connection between a door-closed-switch and the car body.
posted by chazlarson at 9:34 AM on January 25, 2011 [1 favorite]

A quick, immediate fix is to remove the bulb from the fixture. The translucent lens should pop out with a smal screwdriver and then the bulb is easily removed. If it's not that simple, it's possible that the interior-colored trim bezel around the lens should come out first, but it's usually pretty straightforward.
If the "door ajar" light is coming on when no door is open, then there's a short to ground somewhere in that circuit. The door switches are normally open (with the door shut) and the switch closes when the door opens, creating a path to ground for the dash light, door and light buzzer, and dome lights.
It's also possible that the remote start/alarm is wired in such a way that it taps into the door switches. If there's something wrong with the alarm or wiring, it could be creating a short to ground in the door circuit, simulating an open door.
posted by Jon-o at 1:40 PM on January 27, 2011

Followup: Took it to the shop and they said it was "pushed up too hard". Like, against the roof. I assume that means the light itself was shorting.

To those who confidently stated it was for sure the door sensor, despite the fact that I definitely ruled that out: See?
posted by DU at 10:03 AM on March 20, 2011

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