headlight bulbs go out repeatedly

JeffB55 · Post by **JeffB55** » 23 May 2016, 21:28

The driver's side headlight on our '98 S70 blew out (the low beam, but not the high beam). No problem: I ordered a pair of H7 bulbs, cheap, on eBay. I popped one in, and it worked fine--for about 15 seconds! Once again, the high beam was fine, the low beam dead. I replaced it with the other new bulb--good for another 15 seconds. It's like I bought flashbulbs instead of headlight bulbs.
I didn't touch the bulbs, honest. Besides, I don't know that they even got hot enough for the oils on my fingers to burn them out. The wires and connectors look fine. What am I missing?

Post by **scot850** » 23 May 2016, 23:02

It can be several things and I don't know all the answers.

Check:

1) The light switches on these cars had a known fault and do fail. Junkyard is your friend on this.
2) The dip switch may be shorting out on the column, but I'd expect that to affect both lights.
3) There are relays in the circuit but I can't recall where they are situated

You need to get a wiring diagram and see what only affects the light on the LHS of the car.

Neil.

Post by **BEJinFbk** » 23 May 2016, 23:53

So - You had a low beam that lasted a reasonably long time?
It blew, and you bought some cheap ones on eBay?
They both fried instantly?

Maybe try a better lamp?
Just sayin'...

Personally, I like Sylvania Silver Star Ultras.
They cost a little more, but they throw Great light
and generally go for a couple of years before heading
of to that big H7 graveyard in the sky. FWIW, I run my
headlights AUTO-ON, so if I'm driving, they're working.

It's also worth taking a minute and putting a meter on
the hot lead to that lamp, but I suspect you'd be having
a LOT more troubles if you were running overvoltage.
One headlight would be the least of your problems.

Best of Luck!

kaneelschep · Post by **kaneelschep** » 25 May 2016, 05:47

i agree fully with the previous post.
Why would you ever get these lights of ebay?
They sell em everywhere for quite cheap and then you know what you actually get..
Get some good brand like philips or osram etc. Cant be more than 10 euros..
Mine worked for ever now and are always on too.

I once had both, left and right normal beams simultaniously quit on me on my benz.
After measuring all, checking fuses, cables and relays, since thay could surely not just happen at once...
I swapped them for better ones and it worked.

Post by **MadeInJapan** » 30 May 2016, 08:36

Sylvania high end bulbs burned out on me constantly. Changed to bottom of the line Philips and no more issue...but then I went HID and really no issues at all after that!!

Post by **BEJinFbk** » 30 May 2016, 11:34

MadeInJapan wrote:Sylvania high end bulbs burned out on me constantly. Changed to bottom of the line Philips and no more issue...but then I went HID and really no issues at all after that!!

Sorry to hear that, but FWIW, short lamp life with
the SS and SS Ultra has not been an issue for my car.

Post by **chrafael** » 30 May 2016, 13:08

Seems like I read in the Sylvania catalog that the high end bulbs are only rated for about half the lifespan of the standard bulbs.

Azik09 · Post by **Azik09** » 30 May 2016, 13:36

I think the reason is bad quality of lamps, or delivering company was not careful enough... And if you have problems with wiring or switches or relay etc. it should affect both lamps or burn the fuse.

Post by **mecheng** » 31 May 2016, 07:32

There is a intermediate wire on my S70 that adds resistance to lengthen the build life. I bypassed it in the winter when its dark, I may add it back in the summer when its bright out. Also, heat is the enemy of the bulb.

Post by **erikv11** » 31 May 2016, 07:49

mecheng wrote:There is a intermediate wire on my S70 that adds resistance to lengthen the build life. I bypassed it in the winter when its dark, I may add it back in the summer when its bright out. Also, heat is the enemy of the bulb.

FWIW, I always unplug these wires right away when I get a new P80, and I don't have issues with bulb longevity.