Dome light bulb burned out yet it tests ok for continuity.....

[Guest Kitskaboodle]

My dome light bulb has me confused. I was working inside the car yesterday evening when my dome light suddenly went out. I pulled the cover off, took a look at the filament but it seemed ok.

(not broken or anything) So, I put an ohmmeter on it and I got continuity. I thought perhaps it was simply loose in its holder but after fiddling with it(and cleaning the contacts) it still didnt work.

So, I went to the auto store, bought a new bulb and voila the dome light worked again!

I thought as long as the bulbs filament was not broken it should light up. Why then did it test

good for continuity? (I realize there is greater "resistance" right before a filament breaks but shouldnt the bulb still have lit up?

Thanks, Kit

[jonlabree]

Rge dome light only stays on for a short time. I automaticly goes off.

[Guest F14CRAZY]

That is true. I believe it turns off after 20 minutes or so to conserve battery life.

[ikesleeping]

Did you test for power 12v at the socket?

[Guest Kitskaboodle]

It goes off after 20 minutes? Heck, I'm learning new things about this car all the time!

As for the additional voltage measuring, no I didnt do that since it was getting late and I needed to get to the auto store before it closed. (needed to pick up some 194 bulbs so I thought I might as well pick up a new dome light bulb too since it looked tired) After I got back home, I plugged it in and voila!

Kit <img src="http://forums.aaca.org/images/graemlins/smile.gif" alt="" />

[Guest CL_Reatta]

Most of my burned bulb's tested ok for continuity also, but after replacing them with new bulb's I would get light. someone told me once that car light's can do that because of the constant movement from bumps and the bulb's usually get tiny cracks on the filament just enough to not light. don't know if that's true or not.