Why Do Different Bulbs Keep Burning Out?

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In the last 2 weeks, I have had right rear marker, left front marker, left rear brake bulbs burn out. The only work I have done on my LS400 is about a month ago I had my alternator replaced with a Toyota OEM.

Is this some underlying symptom of a 22 year old car developing old age problem? Should I check anything out ?
 
Hook up a voltmeter and monitor while driving. My first thought is, perhaps overcharging, although perhaps it is intermittent. I would think about tacking across the battery (use a fuse if running a wire to your DMM). But maybe I'm wrong and the voltage is high at idle and/or when rev'd up. I'd start by testing at idle, give the throttle a goose and go from there.

You could monitor cig lighter voltage too, that might be enough to monitor while driving.

Alternatively, as you say, it's 22 years old. It's just possible that they all decided to quit at the same time.
 
Originally Posted by CT8
Are the bulbs original?


Yes. That's what has gotten me thinking. Maybe it's just time. Sorta weird.

2 month old Lexus 84 month battery and 1 month old OEM alternator and new OEM serpentine belt.
 
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Like I stated in your other thread, you might want to consider replacing ALL of the light bulbs given the fact that you had two of them burn out within such a short time period and they are all the same age. Light bulbs are consumable parts with a limited lifespan, it's time.
At least you got 22 years out of them. I have a bone to pick with Mercedes, they also have a sensitive light bulb failure warning system, but they use light bulbs from a supplier that only last 4 or 5 years, and many of them are extremely difficult to replace.
 
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If you have time on your hands chase it.

I think 3x/year per same $5 bulb then I would give it some more thought and analysis. 22 year car is be happy it works!
 
Your alternator may be overcharging and or your battery is weak and unable to correctly filter the spikes add or bad ground wires. Also some alternators use avalanche diodes, and some of the cheap china replacement units use regulator diodes. Avalanche diodes limit voltage spikes.

Some cheap regulators do not have effective voltage control, slow to respond, oscillate (sometimes with non led lights you can see them pulsing) overshoot etc. I would check voltage while driving. A cheap needle voltmeter from harbor freight is under $10.00. needle is better in this case than digital since you can see the needle wiggle when a LCD digital display never shows anything.

Rod
 
Originally Posted by madRiver
If you have time on your hands chase it.

I think 3x/year per same $5 bulb then I would give it some more thought and analysis. 22 year car is be happy it works!



I'm afraid you are making sense. I have time to chase it but I don't feel like it. I'm gonna give it another week or two.

The one bulb that we may have initially missed was the lower left brake light. The story can get complicated so I'll just stop here.
 
Originally Posted by wag123
Like I stated in your other thread, you might want to consider replacing ALL of the light bulbs given the fact that you had two of them burn out within such a short time period and they are all the same age. Light bulbs are consumable parts with a limited lifespan, it's time.
At least you got 22 years out of them. I have a bone to pick with Mercedes, they also have a sensitive light bulb failure warning system, but they use light bulbs from a supplier that only last 4 or 5 years, and many of them are extremely difficult to replace.


IF one more blows out, I will go to Lexus and buy all the exterior bulbs.
 
305k and original bulbs? Good run I'd say.

I am of the opinion that Toyota has excellent electrical control. I had to never replace a tail light in my Scion XB, Corolla, or Matrix.

My 16 Ford already needed tail/brake bulb replacement at 30k.
 
If the new alternator is putting out too high of a voltage the bulbs will not last long.

Have someone with a background in electronics rig up a connector that plugs into your 12 volt receptacle (the round one that looks like what older cars plugged the cigarette lighter use to plug into) so the rigged plug provides wires to connect to a digital volt meter they can lend you, and monitor the voltage while the vehicle is being driven. Record the highest voltage, (some digital volt meters will save the highest reading) and do a little research to see if that value is too high.

The problems started after you replaced the alternator, so the new alternator is most likely the problem and is putting out too high of a voltage.
 
Drive it for a couple of weeks, and see if the trend of burning the bulb continue with the NEW bulb.
If the same bulb went bad in the span of time you mention, then the alt may be the issue.
I am assuming it is different ORIGINAL bulb that is more than its intended life cycle.

It is not a trend yet.
 
Regardless of the mileage/age of the car, I agree that it's related to the alt replacement.
After confirming the output of the alternator, I'd check (clean and seal) the grounds for the alternator and battery etc.
 
I have a 93 Lexus SC400 that eats tail light bulbs due to moisture in the sockets causing corrosion. Always garaged, never driven in the rain. Had to replace some sockets. My 01 Tacoma still has most of it's original bulbs, pretty amazing really. Always outside, driven rain or shine! 250K, bought it new.

20180429_154259.jpg


Lexus, Kathy, 2011 003.JPG
 
It's also possible your old alternator was giving slightly less but sufficient charge for several years giving the bulbs an "easy" life. And a return to like new voltages was a bit much for them. Anyways 22 years is a great run for lights.
 
Originally Posted by rekit
I have a 93 Lexus SC400 that eats tail light bulbs due to moisture in the sockets causing corrosion. Always garaged, never driven in the rain. Had to replace some sockets.


Check the housings for seam splits and reseal those. Dielectric grease in the socket and the socket-housing interface. Then again, it's 27 years old. If you replaced with equal/OEM quality sockets, it may never be an issue for the remaining lifespan of the vehicle.
 
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I know on some headlights there is a vent, not sure on the tails. Lots more heat on the heads. There was some condensation on the rears. Probably seal leaking. Just don't understand why the issue was more prevalent on this car...never an issue on 5 Celica's we owned, from 1971 to 1985, and various Camrys.
 
I've had pairs of headlight bulbs, installed at identical times, burn out within a week or two of each other. Bulbs just have a finite life, and its not unreasonable for some of them to have reached EOL.
 
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