touch halogen, lose low beams if installing

Okay, before the snow storm, noticed left headlight was out.
Just the low beam, not its high beam.
Thought, there are spares in the car.
Simple Phillips Halogens for a 94 Plymouth Voyager.
Not fun driving in the dark in a snowstorm.
Really not funny.
Where is the damn road?

Found it hard to take out in the cold and dark.
But undid the clamp holding the socket to the bulb.
Never could get back on the holding plastic nut knob on tight.
It's a large plastic nut that holds the bulb in.
So just sandwiched it in with a plastic shopping bag.
So far so good until I can get some daylight to see better
and look in the manual.

Within minutes, the new halogen's low also blew.
Not its high. Just the low beams on othe new bulb, same as the old
bulb.

Hmmm. Thought of the discussion here.
Aha, the relay or the switch.

But the fellow at Pep Boys - dealer was closed and was in a part of the
state where I did not see any other parts stores and was not familiar
and was past 5-6 pm when most other stores are closed. Just wanted to
discuss this.

The fellow suggested that touching the bulb could predispose it to
burning out.
I said, heh, I remember that from halogens, but usually they explode.
And he said, it IS a halogen.
Duh, me.
But these don't explode, just ruins the bulb.

So clean it with a rag and some 70% isopropyl alcohol and use latex
gloves?
I think I used toilet paper and alcohol to install my floor lamp's
halogen.

I guess it makes sense. Oil on the bulb would create, theoretically, a
superheated hotspot which might cause the low light's filament to
prematurely expire? I gather the low filament is closer to the outer
edge? Just guessing. After I get some sleep, I'll inspect the bulb and
all and try a new bulb.

I gather the relay or switch is a double-throw, so if it burned out, I
would have both lows out? Not just one? Makes sense.

Relieved if this is true. Not a good time to take apart the dash,
assuming one takes apart the dash for the relay or switch. Although
that poster who suggested wiring one to the other. Hmmm, remembered
that. Would need just the hot wire for the low? That's assuming the
Ground and the other hot are good. Just guessing again. After I send
this post I'll get out the Chrysler factory shop manual and see if this
is discussed in detail. My little owner's manual does not mention
replacing the headlamps. I guess it's too technical, but dash it, it's
extremely important. I didn't realize it until there's a howling
snowstorm and I am many miles from home with needing to use country
roads, unfamiliar ones, in the dark. Nest time I keep the shop manual
in the car as I used to.

wrote:
> The fellow suggested that touching the bulb could predispose it to
> burning out.
> I said, heh, I remember that from halogens, but usually they explode.
> And he said, it IS a halogen.
> Duh, me.
> But these don't explode, just ruins the bulb.
>
> So clean it with a rag and some 70% isopropyl alcohol and use latex
> gloves?
> I think I used toilet paper and alcohol to install my floor lamp's
> halogen.
>
> I guess it makes sense. Oil on the bulb would create, theoretically, a
> superheated hotspot which might cause the low light's filament to
> prematurely expire? I gather the low filament is closer to the outer
> edge? Just guessing. After I get some sleep, I'll inspect the bulb and
> all and try a new bulb.

Although I like to avoid responding to my own post, it's been over 12
hours (okay, okay, people have to sleep and found the answer in the
shop manual. Big, bold capital letters, the manual states do not touch
the bulb with the fingers because "REDUCED LIFE" will ensue. I would
say < 20 minutes of [on low] bulb life is, ahem, reduced life. Yes,
indeed.

I guess I forget these bulbs are halogens and this is my first time
replacing a halogen headlamp bulb. I'm kind of slow in that regard. And
the previous vehicles used non-halogen bulbs before. Not bad, just more
than 10 years behind the curve, at a very minimum.


> I gather the relay or switch is a double-throw, so if it burned out, I
> would have both lows out? Not just one? Makes sense.

The instructions for the relay were, well, I'm still looking for them.
The index said go to 8L-3. And then 8L-3 says to go to 8-E for the
instrument panel. Uh oh, this is what I was afraid of, taking apart the
dashboard. But since I cannot find exactly the headlamp switch, no
problem! It's likely not the switch or whatever allows the current to
get to the headlamp since only one is gone. It would not make economic
sense to have a left and right relay or switch. Not much logical sense,
but would do I know. I messed up replacing a simple halogen bulb.

On Mon, 16 Jan 2006, wrote:

> The fellow suggested that touching the bulb could predispose it to
> burning out.

<snip>

Years ago, halogen bulbs (known then as "quartz Iodine" or just "quartz"
bulbs) were made out of fused quartz. If you touch fused quartz, skin oil
gets on it. When skin oil is heated to the high temperatures found on an
operating bulb, it devitrifies the quartz. The result is an opaque
fingerprint-shaped spot, or a blister on the bulb, or a severely balooned
area of the bulb, or a shattered bulb. Which thing happens depends on the
type of bulb and how hot it is.

And so we were all carefully taught never to touch the bulb. Never touch
the bulb! If you do, clean it with alcohol! Never touch the bulb or it'll
fail quickly! Never touch the bulb or it'll explode! Never touch the bulb!

Thing is, most automotive halogen bulbs are now made out of hardglass, not
quartz. Hardglass doesn't devitrify or do anything else untoward if you
touch it and then light the lamp. No opaque spots. No blisters. No
shattering, no ballooning, no exploding, no shortened life. Hardglass does
not know or care it's been touched by human hands. So, from a bulb-health
perspective, the "don't touch!" warning is thoroughly obsolete.

It's still not a great idea to get the bulb all oily before installing it,
because the oil will burn off and the oilsmoke will condense as dirt on
the inside of the reflector and lens. But that's a different matter.

So, no, you didn't cause short bulb life by touching the bulb. There are
several causes of short bulb life (low bulb quality, high or spiky line
voltage, insecure bulb mounting, etc.). Take a close look at the failed
filaments: Are the ends broken cleanly off, or are there little round
globs of molten metal either at the broken ends or rattling around inside
the bulb?

> I guess it makes sense. Oil on the bulb would create, theoretically, a
> superheated hotspot which might cause the low light's filament to
> prematurely expire?

No.

> I gather the relay or switch is a double-throw, so if it burned out, I
> would have both lows out? Not just one?

No. The left bulb does not know or care the condition of the right bulb.

> assuming one takes apart the dash for the relay or switch.

Headlamp switches and relays are usually not difficult to replace.

> that poster who suggested wiring one to the other

Very, very stupid idea. The headlamp wiring in most Mopars made in the
last few decades is thoroughly pathetic (long lengths of 18ga and 20ga
wire). If you tap into the left low beam wire to feed the right low beam,
for instance, or do anything similar, you'll be making a bad situation
even worse, aggravating the portion of your vehicle's poor headlamp
performance that is caused by the marginal factory wiring and throwing a
100% overload on sizeable sections of the headlamp circuit.

> That's assuming the
> Ground and the other hot are good.

Depending on the model and year, you may not have two hots and a ground.
Chrysler uses ground-switched circuitry on some models.

DS

On Tue, 17 Jan 2006, wrote:

> Although I like to avoid responding to my own post, it's been over 12
> hours (okay, okay, people have to sleep and found the answer in the
> shop manual. Big, bold capital letters, the manual states do not touch
> the bulb with the fingers because "REDUCED LIFE" will ensue.

Nope. That warning's been in there since the very first halogen
replaceable bulb appeared on a US-built Chrysler product in 1969. Back
then, with quartz bulbs, it was applicable. It no longer is.

> < 20 minutes of [on low] bulb life is, ahem, reduced life. Yes, indeed.

You did not cause this by touching the bulb.

DS

Thanks Daniel, very informative (as usual)

---Greg---

> Years ago, halogen bulbs (known then as "quartz Iodine" or just "quartz"
> bulbs) were made out of fused quartz. If you touch fused quartz, skin oil
> gets on it. When skin oil is heated to the high temperatures found on an
> operating bulb, it devitrifies the quartz. The result is an opaque
> fingerprint-shaped spot, or a blister on the bulb, or a severely balooned
> area of the bulb, or a shattered bulb. Which thing happens depends on the
> type of bulb and how hot it is.
>
> And so we were all carefully taught never to touch the bulb. Never touch
> the bulb! If you do, clean it with alcohol! Never touch the bulb or it'll
> fail quickly! Never touch the bulb or it'll explode! Never touch the bulb!
>
> Thing is, most automotive halogen bulbs are now made out of hardglass, not
> quartz. Hardglass doesn't devitrify or do anything else untoward if you
> touch it and then light the lamp. No opaque spots. No blisters. No
> shattering, no ballooning, no exploding, no shortened life. Hardglass does
> not know or care it's been touched by human hands. So, from a bulb-health
> perspective, the "don't touch!" warning is thoroughly obsolete.

Daniel J. Stern wrote:
> So, no, you didn't cause short bulb life by touching the bulb. There are
> several causes of short bulb life (low bulb quality, high or spiky line
> voltage, insecure bulb mounting, etc.). Take a close look at the failed
> filaments: Are the ends broken cleanly off, or are there little round
> globs of molten metal either at the broken ends or rattling around inside
> the bulb?

I did a quick peak at the bulb. I am waiting to put in another new bulb
tomorrow. I'm having trouble getting the plastic hold-down screw nut to
screw back in. To my surprise, both filaments seem intact. This is a
Phillips 9004. I will put in a Sylvania 9004LL tomorrow. The filaments
in the Sylvania, to my uneducated eye, appear somewhat more robust and
not so flimsy.

The bulb may have failed not because I touched it (as you pointed out)
but because it is not secure in place with the screw nut. It's not
coming out and appears to be stuck but maybe my jostling it around
around messed it up. Or keeping it in the little drawer under the
passenger seat for 4-5 years probably did not help matters. The length
of time and the bumps and vibrations of all those year probably
weakened the filaments? But the highs work, so don't know. The high's
filament looks about the same as the low's filament so one would think
they both would be bad.

> No. The left bulb does not know or care the condition of the right bulb.

> Headlamp switches and relays are usually not difficult to replace.

That's good to know because I could not glean this info from the
factory manual with a first glance. I was hoping it was just a relay or
some such which I could grab from beneath the dash - but that was on
cars built long ago.

> Depending on the model and year, you may not have two hots and a ground.
> Chrysler uses ground-switched circuitry on some models.
>
> DS

There are three wires leading to the socket so I guessed two hots, low
and high, and a ground. I don't know what ground-switch circuitry is.
The ground completes the circuit so acts like a switch then? Instead of
switch the hots, one switches the grounds? Interesting.

Thanks for your informative reply.

wrote:

> I did a quick peak at the bulb. I am waiting to put in another new bulb
> tomorrow. I'm having trouble getting the plastic hold-down screw nut to
> screw back in. To my surprise, both filaments seem intact. This is a
> Phillips 9004...

Sometimes filaments break, with the two ends at the break staying so
close together that you can't tell by looking at them that there is a
break - this will often be the case if the filament broke due to shock
rather than burning in two. If it is in fact broken, check the filament
with a multimeter for continuity - if this is the case, you might even
get an intermittent connection by shaking the bulb around a bit with the
meter connected thru it. If the filament is solid good but not lighting
in the vehicle, then the problem is elsewhere (connector, wiring, whatever).

> The bulb may have failed not because I touched it (as you pointed out)
> but because it is not secure in place with the screw nut. It's not
> coming out and appears to be stuck but maybe my jostling it around
> around messed it up. Or keeping it in the little drawer under the
> passenger seat for 4-5 years probably did not help matters. The length
> of time and the bumps and vibrations of all those year probably
> weakened the filaments?

Or broke the one. That would be consistent with a break due to shock
and intermittent operation (as the broken ends move around from
vibration, jostling, etc.).

> But the highs work, so don't know. The high's
> filament looks about the same as the low's filament so one would think
> they both would be bad.

Not necessarily - not unusual that one would break and not the other.

> There are three wires leading to the socket so I guessed two hots, low
> and high, and a ground. I don't know what ground-switch circuitry is.
> The ground completes the circuit so acts like a switch then? Instead of
> switch the hots, one switches the grounds? Interesting.

Yes.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

On Tue, 17 Jan 2006, wrote:

>> So, no, you didn't cause short bulb life by touching the bulb. There
>> are several causes of short bulb life (low bulb quality, high or spiky
>> line voltage, insecure bulb mounting, etc.). Take a close look at the
>> failed filaments: Are the ends broken cleanly off, or are there little
>> round globs of molten metal either at the broken ends or rattling
>> around inside the bulb?
>
> I did a quick peak at the bulb. I am waiting to put in another new bulb
> tomorrow. I'm having trouble getting the plastic hold-down screw nut to
> screw back in. To my surprise, both filaments seem intact. This is a
> Phillips 9004.

Philips 9004s are made in Korea, not especially well. I've seen very early
failures out of them before.

> I will put in a Sylvania 9004LL tomorrow. The filaments in the Sylvania,
> to my uneducated eye, appear somewhat more robust and not so flimsy.

LL = Long Life but Less Light. Those "more robust" filaments you see
produce less light, lower-quality light, and poorer beam focus. Not a wise
choice if you're trying to squeeze the best possible performance out of
headlamps that are fairly rotten to begin with, fed by lousy wiring.

> The bulb may have failed not because I touched it (as you pointed out)
> but because it is not secure in place with the screw nut.

Well, yeah, if it's allowed to rattle around while lit, vibration-induced
failure becomes highly likely.

> It's not coming out and appears to be stuck

What's not coming out and appears to be stuck?

> The high's filament looks about the same as the low's filament so one
> would think they both would be bad.

Um...huh? How do you reach this conclusion? The high beam filament does
not know or care the condition of the low beam filament, and vice versa.

>> Depending on the model and year, you may not have two hots and a ground.
>> Chrysler uses ground-switched circuitry on some models.

> There are three wires leading to the socket so I guessed two hots, low
> and high, and a ground.

Depending on the model and year, you may not have two hots and a ground.
Chrysler uses ground-switched circuitry on some models.

> I don't know what ground-switch circuitry is.
> The ground completes the circuit so acts like a switch then? Instead of
> switch the hots, one switches the grounds?

Yes.

Bill Putney wrote:
> Sometimes filaments break, with the two ends at the break staying so
> close together that you can't tell by looking at them that there is a
> break - this will often be the case if the filament broke due to shock
> rather than burning in two. If it is in fact broken, check the filament
> with a multimeter for continuity - if this is the case, you might even
> get an intermittent connection by shaking the bulb around a bit with the
> meter connected thru it. If the filament is solid good but not lighting
> in the vehicle, then the problem is elsewhere (connector, wiring, whatever).

You're right. One circuit was open, presumably the Low which does not
work.

Thanks for all the good advice.

Daniel J. Stern wrote:
> On Tue, 17 Jan 2006, wrote:
> LL = Long Life but Less Light. Those "more robust" filaments you see
> produce less light, lower-quality light, and poorer beam focus. Not a wise
> choice if you're trying to squeeze the best possible performance out of
> headlamps that are fairly rotten to begin with, fed by lousy wiring.

That's so. Noticeable difference between the LL and the Regular for
output.
Not a lot but definitely the LL is a less bright.
Good advice to avoid the LL.