Originally Posted by mkultra
95 LS400 headlights, brake lights and signals all work... but my fog lights which have been modded as parking lights and tail lights do not come on...
First thing check your fuses.
Second thing check your modded fog lights wires where they are connected to the parking lights again for any shorts or issues.
Third thing you should do is check your light bulbs if they are burn or the soldering points at the bottom that are melted and replace them.
Fourth thing you should do is look and inspect your tail light socket harness where the light bulb goes it to see if your sockets inside the tail light socket harness are burn or have any shorts. If your tail lights socket harness are burn i suggest you change them. <------(this is very common I have two different lexus ls400 that I had and changed the tail light socket harness because the tail lights wont turn on at the back but the front headlights work fine)
Fifth thing you should do is check your Lamp Failure Sensor located in your trunk underneath your trunk latch, you'll need to take off those cover pieces to get to it. Gently unplug the harness to the Lamp Failure Sensor and pop the Lamp Failure Sensor open with a flat or something pointy to see if the soldering on the chip is burn, if it's burn the color should be grayish or black or it will look like a fuse that just have a cut in between the soldering or ohms solder to the chip. If you see anything like that then you'll need to replace it.
Same thing happen to my car I check my fuse and they were good. I bought new light bulbs and found there was a short in both of my tail light socket harness so I replaced it with the ones I picked up from the junkyard and the brake light works but the tail lights wont turn on. Then I found the Lamp Failure Sensor relay at the back and popped it open to look at and there was my problem it was burn so I went back to the junkyard and pick up one and replaced it and now everything works perfectly like it's suppose to.
I hope this will help you and many of those other guys who have this problem with your tail lights not working when you turn on your light switch and your front headlights work but your tail lights doesn't turn on. Good luck.