Keep blowing H4 bulb on passenger side

g-man · Post by **g-man** » Wed Dec 23, 2009 9:48 am

On my 81 Euro spec E12 528i I have Hella H1/H4 lights but a slight problem recently happened within the past week, I keep blowing the passenger side H4 bulb. I put a bulb in, turn on the headlights, and it goes on for a few seconds and then it's history. After the low beam part of the bulb blows, I turn on the high beams and of course, that portion of the bulb works. The fuse is not blowing. I've gone through three bulbs and I only got a couple left in my parts stash. My fuse box is written in German so I don't know which fuse is for my passenger side headlight. The US spec owners manual that I have says to look at the fuse box cover to identify fuses so that doesn't do me a lot of good. I pulled all the fuses out to make sure they work properly and they are all good. WTF,O! Need some help from the peanut gallery on a solution this problem.

G-Man

YouTube · Post by **Peter Florance** » Wed Dec 23, 2009 11:20 am

Hey Gordon
The fuse is to protect the wire. You ought to be able to connect the bulb right across the battery and it should light.
Maybe you have a bad batch of H4s?

If the car is running, maybe the alternator voltage is too high.

I can't use SilverStar H1's because my springs are so stiff, the filament holders break off inside. Regular H1's work fine for me. But I don't think that is your problem.

pmaronoff · Post by **pmaronoff** » Wed Dec 23, 2009 1:31 pm

Unusual to have alternator or voltage regulator affect only one side. Does it blow the bulb turning the lights on but not starting the car? Test voltage at the connector with a volt/ohm meter. You could take the known good bulb from the other side and switch them. You would know if you have a bad batch of bulbs. If you have a Carquest parts store up in Santa Barbara see if they have the bulbs. I found brake light bulbs there cheap. If problem persists the headlight switch would be suspect. It could be shorting out. Good luck.