LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

How to modify the tail lights failure sensor for UCF20/21

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Old 08-06-14, 11:28 AM
  #16  
Caniac14
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I'm not sure of the brand tbh. I got them off amazon for around $400.

They look like this.

Old 08-06-14, 10:54 PM
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Shmee
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Look like the depo ones I have. Did they come with resistor boxes? Mine did and the dash light was out up until I replaced my trunk lid and now it's on... I need to check the resistances of my resistor boxes and if my little red box is properly connected since they shaved my antenna and emblems...
Old 09-20-14, 08:59 PM
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Big Steve
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I hate to bump old threads, but I just did this mod with my Insurance Group LED Tail lights and the error message went away. Thank you Yamae for this!
Old 09-30-14, 01:13 PM
  #19  
Caniac14
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Originally Posted by Shmee
Look like the depo ones I have. Did they come with resistor boxes? Mine did and the dash light was out up until I replaced my trunk lid and now it's on... I need to check the resistances of my resistor boxes and if my little red box is properly connected since they shaved my antenna and emblems...
I didn't use the resistors that came with it because I heard they get really really hot and could be a potential fire hazard. I love your shaved trunk and antenna btw. Wish I would get rear ended. lol.
Old 09-30-14, 01:31 PM
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Originally Posted by Big Steve
I hate to bump old threads, but I just did this mod with my Insurance Group LED Tail lights and the error message went away. Thank you Yamae for this!
stranger danger! wuddup steve .
Old 10-01-14, 04:54 PM
  #21  
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Originally Posted by Yamae
Here it goes. Lift or cut the leg of the resistor indicated by X.
Now I think I'd better change the title, but I can't do that. Will a moderator or someone, please change it. May be "How to modify the tail lights failure sensor for UCF20/21" would be better.
Originally Posted by Caniac14
I did this and my tail-light out thing still comes up my dash.
yamae, it looks like this didn't work. i will try this soon on my 97 but since caniac was not successful, i am hesitant to do it.
Old 10-01-14, 10:24 PM
  #22  
Yamae
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Originally Posted by timmy0tool
yamae, it looks like this didn't work. i will try this soon on my 97 but since caniac was not successful, i am hesitant to do it.
More than 30 JDM models were all successful on this end. An old guy initially failed but it turned out to be his poor eyes that caused him a mistake.
Old 10-06-14, 03:07 PM
  #23  
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Originally Posted by Yamae
More than 30 JDM models were all successful on this end. An old guy initially failed but it turned out to be his poor eyes that caused him a mistake.
my US-spec 97 is equivalent to a 95-96 celsior i believe. i was referring to your second picture for a early generation UCF20. is the 30 successful JDM models all 95-96 early gen UCF20s?

sorry for the many questions, i am just trying to understand before i risk this mod.
Old 10-06-14, 03:11 PM
  #24  
cgawelko
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Do we have a fix like this for 89-94?? I hate that stupid light...
Old 10-07-14, 05:00 PM
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91LS400vgb
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I also would like to know how to bypass the taillight failure indicator on the UCF10/11's (90-94). Yamae, if you're watching, do you have a fix for those as well?
Old 10-07-14, 06:05 PM
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Yamae
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Originally Posted by 91LS400vgb
I also would like to know how to bypass the taillight failure indicator on the UCF10/11's (90-94). Yamae, if you're watching, do you have a fix for those as well?
Sorry that I have never analyzed the one for UCF10/11. There isn't any UCF10/11 around here any more. They were all gone already. The law here requires old car owners to pay extra tax and they give up keeping those cars still running well. I hate the law but I have to obey and I'm keeping a 16 years old car.

I would analyze the unit if a UCF10/10 were here.
Old 10-07-14, 07:02 PM
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91LS400vgb
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Default Disabling UCF10/11 Taillight Failure Sensor

That's okay. I'm sure it is very similar to the 95 unit. I will have a look at it when I get the chance. I see that pin 4 goes to the Light Failure Warning Light as per the wiring diagram in the service manual so I'll trace it backwards from there and see if it makes sense to me.

Old 10-08-14, 12:29 AM
  #28  
cgawelko
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Originally Posted by Yamae
Sorry that I have never analyzed the one for UCF10/11. There isn't any UCF10/11 around here any more. They were all gone already. The law here requires old car owners to pay extra tax and they give up keeping those cars still running well. I hate the law but I have to obey and I'm keeping a 16 years old car.

I would analyze the unit if a UCF10/10 were here.
Your more than welcome to examine my car lol
Old 10-08-14, 12:56 AM
  #29  
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One of the simple and easy ways is to cut the wire connected to the pin #4 in the drawing kindly provided by 91LS400vgb. This line enables the warning bulb to light up. I don't think there would be no side effect cutting it.

The best way is to remove or lift up a resistor used at the comparator circuit in the unit but without the actual board, I have no idea to show you the exact one.
Old 10-08-14, 05:38 AM
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cgawelko
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too many boards to show lol there is the two that are in the trunk lid for the inner lights and then the others idk where they are


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