Interesting Taillight Out Code

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Sunday I got a warning code on my 1998 LS400 saying "Taillight Out" or something similar to that. After a while, it went out. I checked my taillights and a 5W side bulb was out. You could barely notice that it was out. Replaced it and everything is ok. Tonight the same warning came on and then went out in about 20 minutes. When we got to our destination we checked the taillights and all the bulbs were working fine. I'm not gonna lose sleep over this but is there something going on I need to know about?
 
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If you can't identify another bulb that is out, pull and reseat all of the bulbs in their sockets. After a long time, corrosion can develop on the contacts, increasing the resistance. The circuit that is checking the bulbs works by checking their resistance.
 
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Originally Posted by atikovi
Just the fact the bulb is new could mean the resistance is different from the others. Let it break in for a few days.
I can't say I've ever heard of a break-in period for a light bulb... Maybe exists for some sort of mercury or arc lamp or some other exotic thing that I wouldn't expect to find on an automobile? shrug
 
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Originally Posted by wag123
If you can't identify another bulb that is out, pull and reseat all of the bulbs in their sockets. After a long time, corrosion can develop on the contacts, increasing the resistance. The circuit that is checking the bulbs works by checking their resistance.
Would you spray anything in the sockets? WD-40?
 
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Originally Posted by Gebo
Originally Posted by wag123
If you can't identify another bulb that is out, pull and reseat all of the bulbs in their sockets. After a long time, corrosion can develop on the contacts, increasing the resistance. The circuit that is checking the bulbs works by checking their resistance.
Would you spray anything in the sockets? WD-40?
I'd burnish the contacts and then use bulb grease.
 
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Originally Posted by atikovi
I guess you could ohm a new vs. used bulb and see if there is any difference.
True that. Although I'd compare the same bulb as the slight difference between bulbs might matter; I have to wonder if a 4 wire measurement would be better. And measuring ambient temperature as I do believe light bulbs have a positive tempco to their resistance (might not matter at room temp though).
 
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Never heard of "bulb grease." I replaced this 5 watt bulb with a non OEM bulb. Could this be a problem? I'm an OEM guy but I didn't think 🤔 a 5watt bulb could make a difference. That is, however, the first bulb I have ever replaced in this car. It's not the third brake light.
 
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Originally Posted by Gebo
Originally Posted by wag123
If you can't identify another bulb that is out, pull and reseat all of the bulbs in their sockets. After a long time, corrosion can develop on the contacts, increasing the resistance. The circuit that is checking the bulbs works by checking their resistance.
Would you spray anything in the sockets? WD-40?
Electrical contact cleaner. From personal experience, I have found that this is the best product... https://www.amazon.com/MG-Chemicals-Contact-Cleaner-Aerosol/dp/B001U3X3PA/, but there are a number of other less expensive products available.
 
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Originally Posted by Gebo
Never heard of "bulb grease." I replaced this 5 watt bulb with a non OEM bulb. Could this be a problem? I'm an OEM guy but I didn't think 🤔 a 5watt bulb could make a difference. That is, however, the first bulb I have ever replaced in this car. It's not the third brake light.
I don't know what you mean by "non-OEM" bulb. Lexus/Toyota does not manufacture light bulbs. Yes, the wrong light bulb will make a difference because, if the wattage is different, the resistance will be different. But, light bulbs are standard generic items that you can purchase at any auto parts store and will perform exactly the same as the bulbs that came from the factory if they are the same number.
 
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Originally Posted by wag123
Originally Posted by Gebo
Never heard of "bulb grease." I replaced this 5 watt bulb with a non OEM bulb. Could this be a problem? I'm an OEM guy but I didn't think 🤔 a 5watt bulb could make a difference. That is, however, the first bulb I have ever replaced in this car. It's not the third brake light.
I don't know what you mean by "non-OEM" bulb. Lexus/Toyota does not manufacture light bulbs. Yes, the wrong light bulb will make a difference because, if the wattage is different, the resistance will be different. But, light bulbs are standard generic items that you can purchase at any auto parts store and will perform exactly the same as the bulbs that came from the factory if they are the same number.
I bought a 5W 12 V bulb from Amazon that fits in the socket. The Lexus bulb was a 5W 12 V bulb. I didn't buy it from Lexus. Yep, I know they don't make their parts and was just wondering "their" part is somehow different in some freaky way. The internals do not look the same. But of course 1998 bulb vs 2019 bulb, I wouldn't expect them to look the same. LOL Im gonna drive a few more times and see if I get the warning light.
 
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Originally Posted by atikovi
Best stuff out there. [Linked Image from images-na.ssl-images-amazon.com]
Got a can. Be here Monday. This looks like it would be good for electrical connections with sound equipment. Sound board, bass, microphones, etc
 
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Check the bulb for the front light? I had cases where the warning was for any bulb not just the rear bulb despite it says "back".
 
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Originally Posted by JMJNet
Check the bulb for the front light? I had cases where the warning was for any bulb not just the rear bulb despite it says "back".
I will. It did reference "taillight" but I will take your advice and check them all out.
 
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