LED Tail light problems
02-23-15, 12:35 AM
#31
Driver School Candidate
Thread Starter
Error on dash just came up...
Lights still work...
But now sometimes the front lights stopps working...
So just wen you turn the lights on sometimes only the left or right one works, sometimes nothing, sometimes both
Lights still work...
But now sometimes the front lights stopps working...
So just wen you turn the lights on sometimes only the left or right one works, sometimes nothing, sometimes both
02-23-15, 01:36 AM
#32
Lead Lap
iTrader: (4)
Join Date: May 2006
Location: FRANCE
Posts: 489
Likes: 0
Received 0 Likes
on
0 Posts
Send me a PM if you want more information. My french writing is better than my english writing ;-)
12-14-15, 05:26 PM
#33
I just recieved some LED taillights from another seller, I'm not sure if they are the same but I figure they might be. My problem is that only the lower portion lights up, the top portion of the lights never come on. The top and bottom should be lit up. Any ideas?
01-09-16, 07:17 PM
#34
Moderator
Sorry for bumping up an old question. Do you still need a good idea to prevent it? 
I have an idea to deal with the error dash light without adding any ridiculously big high power resistors that dissipate too much heat.
My idea is just to modify the current sensors in the computer board for a JDM UCF30/31 of early models (2001-2002). I don't know this idea is effective for non-JDM models or not, but it's much better than to use high-wattage external resistors if OK for non-JDMs.
I have already posted another idea for UCF20/21s at below.
https://www.clublexus.com/forums/ls-...cf20-21-a.html
There sometimes came requests to me from owners of UCF30/31 and I have been analysing the board and now I found the idea.
I have an idea to deal with the error dash light without adding any ridiculously big high power resistors that dissipate too much heat.
My idea is just to modify the current sensors in the computer board for a JDM UCF30/31 of early models (2001-2002). I don't know this idea is effective for non-JDM models or not, but it's much better than to use high-wattage external resistors if OK for non-JDMs.I have already posted another idea for UCF20/21s at below.
https://www.clublexus.com/forums/ls-...cf20-21-a.html
There sometimes came requests to me from owners of UCF30/31 and I have been analysing the board and now I found the idea.
01-31-16, 07:53 AM
#36
Moderator
In case of a JDM UCF30 and 31 of earlier models that have conventional bulbs, the failure sensor circuit is in the “Multiplex Rear Junction Computer”.
As is shown in the photo, there are following current sensing resistors and the voltage drop at each resistors are checked by the comparator and the processor.
R81 = 0.1Ω for tail lights (5Wx2) used at the trunk lid.
R89 = 0.1Ω for tail lights (5Wx2) used at the rear fenders.
R82 = 0.02Ω for outer brake lights (21Wx2)
R85 = 0.02Ω for inner brake lights (21Wx2)
R87 = 0.1Ω for tail lights built in outer brake lights (5Wx2)
R83 = 0.1Ω for tail lights built in inner brake lights (5Wx2)
R121 = 0.04Ω for 3rd brake light
Increasing the resistance of these resistors, you will not have the brake light warning.
For an example, use a 0.2Ω instead of a 0.02Ω for a R82, if the current becomes 1/10 when you use the LED brake light for an outer brake lights. If the current is 1/5, use a 0.1Ω.
The new resistor can be calculated easily in accordance with Ohm's law.
As is shown in the photo, there are following current sensing resistors and the voltage drop at each resistors are checked by the comparator and the processor.
R81 = 0.1Ω for tail lights (5Wx2) used at the trunk lid.
R89 = 0.1Ω for tail lights (5Wx2) used at the rear fenders.
R82 = 0.02Ω for outer brake lights (21Wx2)
R85 = 0.02Ω for inner brake lights (21Wx2)
R87 = 0.1Ω for tail lights built in outer brake lights (5Wx2)
R83 = 0.1Ω for tail lights built in inner brake lights (5Wx2)
R121 = 0.04Ω for 3rd brake light
Increasing the resistance of these resistors, you will not have the brake light warning.
For an example, use a 0.2Ω instead of a 0.02Ω for a R82, if the current becomes 1/10 when you use the LED brake light for an outer brake lights. If the current is 1/5, use a 0.1Ω.
The new resistor can be calculated easily in accordance with Ohm's law.
Last edited by Yamae; 02-05-16 at 04:23 PM.
The following users liked this post:
rizwan01 (06-21-21)
02-03-16, 09:57 AM
#38
Instructor
LSDoc: I was thinking the opposite - now that Yamae has provided the exact details on how the taillamp failure detection circuit works, all LS430 owners can now replace all the incandescent bulbs with LEDs. This is a significant discovery.
I'm not fully convinced that LEDs have better lumen output than normal bulbs due to the various LED firing patterns and none of those patterns being particularly optimized for the incandescent reflector housings. Also not fully convinced LEDs will last longer than incandescents.
Anyway, with this new circuit information, when my old bulbs die out, I just might test some LEDs and modification of the detection circuit.
I'm not fully convinced that LEDs have better lumen output than normal bulbs due to the various LED firing patterns and none of those patterns being particularly optimized for the incandescent reflector housings. Also not fully convinced LEDs will last longer than incandescents.
Anyway, with this new circuit information, when my old bulbs die out, I just might test some LEDs and modification of the detection circuit.
02-05-16, 05:11 PM
#40
Moderator
Will someone check and confirm my analysis result on a USDM?
I hope StanVanDam would do it since he is the first gentleman who quickly understand my analysis result. I only did it on a JDM since I live in Japan and I can't try on a USDM.
Regarding the UCF20/21, both a JDM and a USDM use the same sensing module and the modification for my 98 JDM Celsior was effective to a USDM LS400. I have posted it at the LS400 forum and then there came a request regarding the UCF30/31.
The circuit is mainly checking the open and the short and regarding the tolerance/accuracy of the resistor, ±30% is mostly OK. When you can't find an exact resistor which is the result of the calculation, use one which is just close.
I hope StanVanDam would do it since he is the first gentleman who quickly understand my analysis result. I only did it on a JDM since I live in Japan and I can't try on a USDM.
Regarding the UCF20/21, both a JDM and a USDM use the same sensing module and the modification for my 98 JDM Celsior was effective to a USDM LS400. I have posted it at the LS400 forum and then there came a request regarding the UCF30/31.
The circuit is mainly checking the open and the short and regarding the tolerance/accuracy of the resistor, ±30% is mostly OK. When you can't find an exact resistor which is the result of the calculation, use one which is just close.
02-10-16, 05:27 PM
#42
Moderator
I'm not fully convinced that LEDs have better lumen output than normal bulbs due to the various LED firing patterns and none of those patterns being particularly optimized for the incandescent reflector housings. Also not fully convinced LEDs will last longer than incandescents.
My first experiment was to make a bulb-like LED unit which can be simply replaced the original bulb as is shown below. This is a screen shot of my blog pages writing for good old friends in abroad with many photos expecting them to understand my limited English more. May be I can show you those related pages, if you are interested in.
04-13-16, 12:50 PM
#43
Instructor
Yamae: Let's say I want to change the W5/21W 7443 bulb in the lower rear taillight. The Philips 7443 LED bulb says it runs at 2W. The current is therefore 9.52% of original on the 21W circuit, and assuming it also runs at 2W on the 5W circuit, then current is 40% of original on the 5W circuit.
Does this mean the correct 21W-sensing resistor is 0.02 / 0.0952 = 0.210 Ohms, and the 5W-sensing resistor should be 0.1 / 0.40 = 0.250 Ohms? Would it be OK to replace all the resistors with 0.250 Ohm?
Also, if someone wants to disable the detection circuits completely, would there be any harm in changing all of the resistors out with 0.3, 0.5, or any of the commonly high 1K-1000K resistors?
Do you know where the detection circuit is for the front headlamp bulbs (ie. parking light, turn signal, side marker)? Does the foglight have failure detection?
Does this mean the correct 21W-sensing resistor is 0.02 / 0.0952 = 0.210 Ohms, and the 5W-sensing resistor should be 0.1 / 0.40 = 0.250 Ohms? Would it be OK to replace all the resistors with 0.250 Ohm?
Also, if someone wants to disable the detection circuits completely, would there be any harm in changing all of the resistors out with 0.3, 0.5, or any of the commonly high 1K-1000K resistors?
Do you know where the detection circuit is for the front headlamp bulbs (ie. parking light, turn signal, side marker)? Does the foglight have failure detection?
04-15-16, 06:03 AM
#44
Moderator
I think 0.25 Ohms would be OK. If not OK, inform me the result.
Regarding the front headlamp bulbs, I haven't had any chance to investigate those and I have no idea to answer.
Regarding the front headlamp bulbs, I haven't had any chance to investigate those and I have no idea to answer.
09-01-16, 02:51 PM
#45
Driver School Candidate
In case of a JDM UCF30 and 31 of earlier models that have conventional bulbs, the failure sensor circuit is in the “Multiplex Rear Junction Computer”.
As is shown in the photo, there are following current sensing resistors and the voltage drop at each resistors are checked by the comparator and the processor.
R81 = 0.1Ω for tail lights (5Wx2) used at the trunk lid.
R89 = 0.1Ω for tail lights (5Wx2) used at the rear fenders.
R82 = 0.02Ω for outer brake lights (21Wx2)
R85 = 0.02Ω for inner brake lights (21Wx2)
R87 = 0.1Ω for tail lights built in outer brake lights (5Wx2)
R83 = 0.1Ω for tail lights built in inner brake lights (5Wx2)
R121 = 0.04Ω for 3rd brake light
Increasing the resistance of these resistors, you will not have the brake light warning.
For an example, use a 0.2Ω instead of a 0.02Ω for a R82, if the current becomes 1/10 when you use the LED brake light for an outer brake lights. If the current is 1/5, use a 0.1Ω.
The new resistor can be calculated easily in accordance with Ohm's law.
As is shown in the photo, there are following current sensing resistors and the voltage drop at each resistors are checked by the comparator and the processor.
R81 = 0.1Ω for tail lights (5Wx2) used at the trunk lid.
R89 = 0.1Ω for tail lights (5Wx2) used at the rear fenders.
R82 = 0.02Ω for outer brake lights (21Wx2)
R85 = 0.02Ω for inner brake lights (21Wx2)
R87 = 0.1Ω for tail lights built in outer brake lights (5Wx2)
R83 = 0.1Ω for tail lights built in inner brake lights (5Wx2)
R121 = 0.04Ω for 3rd brake light
Increasing the resistance of these resistors, you will not have the brake light warning.
For an example, use a 0.2Ω instead of a 0.02Ω for a R82, if the current becomes 1/10 when you use the LED brake light for an outer brake lights. If the current is 1/5, use a 0.1Ω.
The new resistor can be calculated easily in accordance with Ohm's law.
Hi, is there is a way that I can turn off completely the Taillamp Failure Sensor ? Like cutting a cable or something? I don't really need this sensor! Thanks
LS430 2002
The following users liked this post:
BustaLS430 (01-07-21)