One headlamp works on Chevy truck

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rdj@shaw.ca - 08 Oct 2005 02:38 GMT

I've got a 2002 K3500 and have had lots of problems with my headlamps.
it all started about 2 years ago, when I realized that my fog lamps
didn't work anymore. I didn't think it was a big deal, because they
weren't much use anyways. Then about 1 year ago, my left side daytime
headlamp stopped working. Somewhere around this time, one of the
leftside clearance lights on my fender (dually) gave up the ghost too.
I can't help but notice that there are many Chev/GMC tucks running
around with only one headlamp working during the daytime, so I'm
wondering if this is a natural occurrence, and wonder if anyone has
come across the problem and found the cure. Now just last week, the
left side headlamp (low beam only)quit. The high beam still works, but
people are flashing me when I put them on. I checked the fuses,
everything is OK. I haven't checked the bulb since the night time
headlamp stopped working, but when it was just the daytime lamp, the
bulb was found to be OK. Anyone come across this issue, and do you know
what the fix is? I have also moved around the relays in the fuse box,
same results, so I don't think that the relay is the cause.

Any suggestions?

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Raymond J. Henry - 08 Oct 2005 06:12 GMT

>I've got a 2002 K3500 and have had lots of problems with my headlamps.
>it all started about 2 years ago, when I realized that my fog lamps
[quoted text clipped - 15 lines]
>
>Any suggestions?

First, check the bulb(s) in question. Never assume that other vehicles
with a bulb out are related to your problem. Second, check for power
to the bulb. Third, check the ground.

Process of elimination....

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James C. Reeves - 08 Oct 2005 13:33 GMT

> First, check the bulb(s) in question. Never assume that other vehicles
> with a bulb out are related to your problem. Second, check for power
> to the bulb. Third, check the ground.
>
> Process of elimination....

A three-year-old truck...my bet is that the bulbs are starting to burn out.
His observation about "one-eyed" GM trucks seems consistent with my
observation though. I also see quite a few relatively new GM vehicles
(primarily) with brake lights out too...often more than one out on the same
car. I wonder who supplies GM the bulbs they use?

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Daniel J. Stern - 08 Oct 2005 13:57 GMT

> His observation about "one-eyed" GM trucks seems consistent with my
> observation though. I also see quite a few relatively new GM vehicles
> (primarily) with brake lights out too...often more than one out on the
> same car. I wonder who supplies GM the bulbs they use?

It's not the bulbs, they get those from the same major makers who supply
all the rest of the world's carmakers. It's GM's persistent insistence on
excessively-high voltage regulator setpoints (edging up towards 15.5v!).
Bulb life is affected as the *THIRTEENTH* power of voltage change, which
is why high-voltage GM vehicles eat bulbs like popcorn. In typical
fashion, rather than correct the problem and set their voltage regulators
to 13.8 to 14.2, GM commissioned a couple of new bulb types rated at 14v
rather than 12.8. *eyeroll*

DS

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HLS@nospam.nix - 08 Oct 2005 16:50 GMT

. It's GM's persistent insistence on

> excessively-high voltage regulator setpoints (edging up towards 15.5v!).
> Bulb life is affected as the *THIRTEENTH* power of voltage change, which
[quoted text clipped - 4 lines]
>
> DS

How long has this been going on, Daniel?

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Comboverfish - 09 Oct 2005 00:12 GMT

> It's not the bulbs, they get those from the same major makers who supply
> all the rest of the world's carmakers. It's GM's persistent insistence on
[quoted text clipped - 4 lines]
> to 13.8 to 14.2, GM commissioned a couple of new bulb types rated at 14v
> rather than 12.8. *eyeroll*

Somewhat off-topic, but recently our warranty clerk was asking around
for a mechanic to "burn up" an 1157 bulb because someone forgot to tag
a bad bulb during warranty replacement. I was in a hurry, so I series
wired a 9.6 volt battery pack along with the battery in the car I was
working on to a spare bulb socket. After about 10 - 15 minutes at ~23
volts and some intense glowing I decided to tap on the bulb, which
finally did the trick of causing it to fail. Anyhoo, I was surprised
at how long it held up. BTW, only the bright filament was powered.

Toyota MDT in MO

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