LS - 3rd Gen (2001-2006) Discussion topics related to the flagship Lexus LS430

Tail Light Issue

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Old 08-07-24, 03:59 PM
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yp21
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Default Tail Light Issue

I started having an issue with the tail lights of my 2005 LS a little while back. Essentially the inner trunk tail lights always light up as if I'm hitting the brakes, whereas the outside lights on the quarter panels are dimmer (as they should be) unless I'm hitting the brakes. This is especially prominent on the left side of the car where both the upper and lower inner LEDs are always lit up, whereas on the right side only the top portion is as I suspect the bottom part is failing. I've attached a picture of what it looked like before and now for reference.

Coincidentally, the backup camera has also started to fail (turning into a black screen when in reverse), though I'm not sure whether that is related. The trunk release and license plate lights work without any issues.

Before


Now...



Has anyone ever experienced this? I've pulled the trunk apart and sprayed electrical connector cleaner on the inner tail light connectors, but the issue remains.

It's a minor thing but it bugs me to no end! Any thoughts on what to check or do next would be greatly appreciated!

Thanks
Old 08-10-24, 02:46 PM
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CA2WALS430
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This is NOT a minor issue! Taillights are critical to safety, and this seems to go beyond LED's malfunctioning. I'm sorry you haven't had a response and I don't have ideas, but I am commenting to bump you back up the list. Maybe try some other Google searches like "clublexus LS430 tail light". Keep it generic and see what you get.

CLUBLEXUS team, can we help our Canadian friend here??

Last edited by CA2WALS430; 08-10-24 at 03:03 PM.
Old 08-10-24, 06:44 PM
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tammap
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If you have an OBD scanner, please scan all BCMs to see if there are any B, C and U codes stored.
Old 08-10-24, 08:53 PM
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Yamae
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The LS430 04-06 has an integrated circuit board to control tail lights. It is in the luggage room and is called the JB/ECU. There is a photo here.

The JB/ECU is driving LED arrays separately and also checking the current of each. I worry that your JB/ECU is partially failed. Without investigating it myself, I can't say much but what I suspect is the rain water invaded or some soldering issues.
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Old 08-10-24, 09:51 PM
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tammap
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Originally Posted by Yamae
The LS430 04-06 has an integrated circuit board to control tail lights. It is in the luggage room and is called the JB/ECU. There is a photo here.

The JB/ECU is driving LED arrays separately and also checking the current of each. I worry that your JB/ECU is partially failed. Without investigating it myself, I can't say much but what I suspect is the rain water invaded or some soldering issues.
Agree!


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Old 08-10-24, 10:03 PM
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tammap
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I want yp21 to scan all BCMs for possible fault codes
- B2402
- B2403
Old 08-21-24, 10:31 PM
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916LS
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Default Tail lights issue

I have a similar issue. My tail lights both inner and outer were not working so I bought all new oem tail lights and when the car is off meaning engine is turned Off when I turn on the lights, they come on however as soon as I start the engine then the lights go Off and don’t come back on. When I hit the brakes only the inner lights mounted to the trunk come on but not the outer ones. I checked all the fuses and they are fine. I checked the little fuse box in the trunk but I didn’t see any relays. Is there a tail light relay anywhere?
Old 08-22-24, 04:18 AM
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Yamae
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Originally Posted by 916LS
I have a similar issue. My tail lights both inner and outer were not working so I bought all new oem tail lights and when the car is off meaning engine is turned Off when I turn on the lights, they come on however as soon as I start the engine then the lights go Off and don’t come back on. When I hit the brakes only the inner lights mounted to the trunk come on but not the outer ones. I checked all the fuses and they are fine. I checked the little fuse box in the trunk but I didn’t see any relays. Is there a tail light relay anywhere?
Tail lights are not driven by relays but by Power MOS FETs and a micro computer. Those are in the JB/ECU. You probably need to replace it or you analyze and repair it
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