Tail light bulbs blowing - dealership says it's the bulb socket $400!?!

kaichu dento

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My friends just had me look at the tail light on their '99 Jeep so I could keep an eye out for one in the wrecking yards.

The dealership told them that it was a bad lamp socket that was causing bulbs to blow out on such a regular basis that there's no assurance that you can make it through a single trip in town before having to replace it again.

Looking inside at the socket, it appears brand new and it seems that a problem of this sort would have to be something further upstream inside the wiring going to the tail light.

Does this sound familiar to anyone else? If anyone has any ideas or had an experience like this please let me know what worked for you.
 

TooManyGizmos

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~

Ha ! ..... I'd be tellin JEEP

Hey ... You Designed it ..... You Made it !

If it's Faulty ... you need to replace it !


UNDER WARRANTY ...... of course !

Ask em .. what did the owner DO to cause it ?

I'd be FURIOUS with em ......

Sound like a LAME excuse to me !

~
 

Lynx_Arc

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sounds more like a voltage spike or them being overdiven and jarred while the filament is very hot. I would check your electrical system while they are in operation to see if they are getting 16v or something.
 

HotWire

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Ford had a similar problem with the high mounted stop lights. The 921 bulbs would over-heat and burn the socket and the light would go out! I found that all the replacement parts in the junkyard were burned, but found some that were not too bad. I installed them and then large red LED clusters in the place of bulbs. No problems since. On the Jeep you could check for voltage at the bulbs/sockets and if not too high install "long-life" bulbs available from parts stores. I would also check the alternator voltage under various speeds/load conditions. Also check the ground with a multimeter. Good luck! It will end up being something simple, but hard to find!
 

-Virgil-

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This is an all-plastic commodity socket which can be bought for about $3.00 at any NAPA or similar auto parts store. But the socket is probably not causing the problem.
 

kaichu dento

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A couple points that really add to the confusion are that the socket looks good as new and the only bulb blowing is the left rear turn/brake light.

I'll have to try checking the ground and also do a voltage meter test if nothing else, but I like your suggestion of the long-life bulbs.
 

-Virgil-

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I don't think a long-life bulb is the answer. Something is causing the bulb on that one side to fail. Could be a mechanically-induced failure (socket loose in the housing or bulb loose in the socket, bulb rattles around and filament shakes apart).
 

Illum

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Unfortunately it's been out of warranty for over a decade and the voltage spike sounds right, but where could it be coming from?

Alternator, regulator, battery post corrosion etc. The battery of a running car acts in a way like a huge capacitor that helps to limit spikes, but as the battery gets old, it slowly loses this ability due to increased internal resistance. Ignition makes noise, alot of noise, but usually doesn't add up to blowing lamps.
 

-Virgil-

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Alternator, regulator, battery post corrosion etc.

Probably not. Remember, only one bulb is blowing. If it were an electrical system problem such as you suggest, all the bulbs would be blowing.
 

kaichu dento

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I know mechanical failure needs to be considered, although I'm leaning towards something causing a spike.

The bulb is perfectly tight in the socket and appearance is as new. I really think the guys at the dealership took a lazy way out of trying to actually identify the problem.
 

-Virgil-

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It would be helpful if you had some of the burned-out bulbs to look closely at. Do they show signs of overvoltage (blackened glass, melted filament ends) or is it clearly a mechanical/vibration failure (clean/sharp broken filament ends or pieces shaking around inside the bulb)?

The more I think about this, the more I think it's probably mechanical/vibration. What model of Jeep is this, by the way?
 

N8N

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I'm thinking possibly water intrusion? That could easily do it...
 

-Virgil-

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Well, yeah, if the bulbs are coming out with broken glass. I had a car once (Ford Maverick...LONG time ago!) with a leak path into the left tail lamp. If I drove it in the rain, the bulb would blow the first or second time I hit the brakes. They don't get hot enough in tail mode, but in brake mode they get hot enough, fast enough, for a drop of water to shatter the glass.

Come to think of it, this problem could be nothing more than a batch of low-quality replacement bulbs. Maybe the first bulb died of natural causes and then was replaced by a low-quality bulb, and each replacement might be the same lousy quality. If there's no clear evidence of why the bulbs are burning out, try switching the bulbs right/left and see if the fast burnouts move to the other side.
 

HotWire

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I discussed this problem with a buddy of mine and he suggested that a bad ground from the battery could be to blame. He said that their should be a clean ground from the battery to the engine, from the battery to the chassis, and from the chassis to the engine. His theory is that electricity is taking the "long way round" to something else--like the starter, headlights, or fuel pump.... Just another thought....
 

PhotonWrangler

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I'm also guessing a bad ground between the lamp socket and the chassis. If it's intermittent it could be placing stress on the filament. It could also be a bad contact inside the flasher module.
 

BobDeLaLuz

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Its very odd that its just one light that consistently blows. Not being able to see the bulb makes it even harder to guess what is going on. Water intrusion would mean that water is getting in every time you drive (possible but unlikely). A bad ground means that the bulb will not light up but typically the bulb will not be burned out. It would be simple to change out the socket with a cheap $3 aftermarket socket just to see what happens. Since its only the left bulb, it seems more likely that there is something else failing, on that side of the car, that is spiking the bulb, it just happens to be the first to fail noticeably. There could a an electric fuel pump, rear window defroster, rear wiper or other electrical accessory that is failing and spiking on the ground path. They could have a poor ground connection and by poor design, they could be flowing their ground path through the bulb, burning it out.

Some of the Jeeps in the 90s came with defective sockets (the contacts were microscopically too deep so they just barely contacted the bulb, causing all the current to go through one tiny spot, the spot would overeat and burn out the bulb. Sometimes the problem is severe enough that you can see a small amount of melting behind the contacts, but not always. An inexpensive socket replacement would eliminate this issue because they are manufactured by a different company and have different tolerances. Some Jeeps have a defect in the lamp housing where the ground tabs barely make contact with the socket. This may be why the dealer wants to replace everything. If the $3 socket replacement does not work, get a junk yard lamp assembly that shows no signs of overheating and try that. You could try to pry up the contacts very carefully yourself but if one breaks during the process, then you'll have no lights and will have to replace the entire lamp assembly anyway.
 

Illum

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Probably not. Remember, only one bulb is blowing. If it were an electrical system problem such as you suggest, all the bulbs would be blowing.

Good point :)

I discussed this problem with a buddy of mine and he suggested that a bad ground from the battery could be to blame.

That would tie in to what Scheinwerfermann said, if that was the case all the lamps would be affected. However this does raise a point, have you tried measuring the resistance between the lamp socket and the chassis? Perhaps an intermittent spike originated from the socket vibrating between connect and disconnect on the return line?
 
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