bulb sensor warning light

Daniel · Post by **Daniel** » 19 Sep 2002, 07:51

my volvo 850's bulb warning sensor light keeps coming on, but turns itself off when one of the doors are shut - strange. Does anyone know how to either turn the sensor off completely or to check where the burned out bulb is? I have checked everywhere and I can't find a burned out bulb. thanks!

Post by **matthew1** » 19 Sep 2002, 13:01

Have you checked the lights that are activated specifically when you open a door? Like the dome light, driver/passenger lights on the ceiling, and the red 'side marker' type warning lights on all four doors (visible only when they're open).

Daniel · Post by **Daniel** » 23 Sep 2002, 07:57

Hi Matt,

Unfortunately, yes. I have checked all the "little bulbs" in the car, i.e. the dome lights, the passenger reading lights, the side marker lights, etc. and all of them work. However, I do notice that when one of the car's doors are shut again, the sensor light goes out, but the whole process begins again when the car is restarted! Help!

Thanks,

Daniel

rick in denver · Post by **rick in denver** » 04 Oct 2002, 21:30

That little dash light tells you that a bulb is burned out. Mine came on too, and it took me a while to find the bulb. I had to have someone else hit the brakes with the lights on while I checked---low and behold....

mdempst_79 · Post by **mdempst_79** » 21 Jan 2010, 05:50

I would suspect someone has changed a bulb somewhere with the wrong wattage.. what I mean by this is as follows:

The lamp sensor works by monitoring drain through the individual circuits, so if you have two parking lights that are different wattages then it will see the difference and iluminate the bulb warning lamp. Same for brake lamps etc..

I don't believe that the lamp will illuminate for a burnt out interior bulb, when you open the door I think it is causing a small voltage drop that evens out the detection circuit in the bulb warning system (fluke).

Take your bulbs out an compare them side to side and make sure that all lamps are the same bulb make & wattage (left turn signal & right turn signal, stop lamps, license plate lamps, running lamps etc.. they all match left side to right side).

My old 760 used to be bad for this.. if you didnt change your headlight bulbs in pairs the lamp would be on forever, except sometimes when the heater came on, or a door was opened it would turn off for a while, but always come back on.

Mark

Post by **jblackburn** » 21 Jan 2010, 08:11

+1 on the different bulbs. It shouldn't illuminate for any interior lights...the system simply doesn't care about that, but the voltage drop when a door is opened would explain that. When I first got my car, every time I touched the brakes, the bulb out light would come on. All the brake lights worked though. It drove me crazy, but I eventually found that one of the reverse lights was a 2-filament bulb, and didn't fit entirely into the socket right and was stealing current and shorting out the brake bulb under it.

rtisan · Post by **rtisan** » 16 Jan 2012, 11:35

im having the same problem. the bulb waring light comes on every time i hit the brakes. ive checked all the bulbs and everything is working. i read the post about the different wattages setting off the warning, but i havent changed any bulbs since i bought the car. ive had the car for over a year now, why would the sensor be tripped now?