What the hell is going on?

Like the title says the Bulb warning light is on, but they all work. Now I did have to replace a headlight plug yesterday, got it all wired in, everything works as it's supposed to, but the light won't go out.

argh. Any suggestions??

 

That system is TOO touchy! If bulbs have any variation at all, sometimes just being a different brand, you may get that warning light. It is unfortunately an annoying Volvo feature...

 

As lev pointed out, it is a sensitive system. It basically looks for a difference in current draw between the pairs of lights. When you replaced the headlight plug, did you replace the bulb as well? Sometimes it solves the problem by replacing bulbs in pairs - making sure you have the same brand in the pair.

Also, how did you connect in the new headlight plug? I always solder my wire splices and use heat shrink tubing to seal. Make sure the new plug has a good connection. It may work ok but could cause a different current draw than the other side.

 

Thanks for the feedback guys. I did replace both bulbs at the same time but I didn't have a solder gun lying around to work with so I just crimped them instead.

If/when I can get the chance to solder I will, if not I'm not going to worry then.

But you guys are right...the system is way to picky !!!

 

the sensor can contains pairs of coils counter wound around magnetic reed relays. if any of the reeds is triggered, the bulb failure light comes on.

In each pair, one coil goes to each bulb, and the windings going opposite directions cancels the magnetic field if the current is exactly the same. old socket contacts or connectors in the wiring harness can have higher resistance, etc, and make them uneven even if the bulbs are matched.