Lamp Failure Control Module

[dogboy]

;) I have a 91 LS 400. One day I noticed that the lamp failure light was on. I grabbed the broom from the garage and wedged it so it would hold down the break pedal so I could determine which bulb was out. I strolled around to the back of the car and was not happy with what I saw. I did not just have one burnt out bulb but several. The third brake light and the trunk deck lights were not working. I tried switching bulbs just to make sure that all of the bulbs had not just burnt out at once. Well after some investigation I found the Lamp Failure Control Module in the trunk. The part # was 89373-50010 L. Well I opened the Lamp Failure control module and found that part of the board had burnt up. So I called the dealer to see how much this little black bocks would cost and too my surprise they only wanted $350.00 for it. Well $350.00 is less than what I would have expected to pay from a dealer but I am kind of cheep. So I set down at my bench and started to work on the burnt board. I cleaned it and set a line of solder down to make a new trace. I also ran a couple of 12 volt test on the leads to make sure that it would not send out high voltage and burn something up. I popped the Lamp Failure control module back in the car and it has work great ever since. That was about 2.5 years ago. The reason I am writing this is not to say how great I am but to find out if anyone other than me has had this problem before. I think I know what cased the problem but would like to get some feed back. So fire away.

[1990LS400]

Let me be the first to congratulate you for accomplishing this. Electrical issues can be very difficult to track down. My repair shop tried off and on for years to figure out why a dash light showing a brake light out would occasionally come on when the brake light was still working fine. I was starting to suspect the expensive lamp failure module but by chance found the real cause which was a loose connection in the trailer light wiring harness installed by the hitch company.

We need people like you with electrical skills in this forum! Welcome aboard!

[dogboy]

Thank you! BTW I am from Lenexa! I went to Shawnee Mission West. Small world.

[93LSOwner]

I just bought my 1993 LS400 and when I turn on my headlights the indicator in the instrument panel comes up that symbolized brun out brake lights, which I don't think I have any burned. Thanks to 1990LS400 my worries about that is gone, and I hope its a loose connection in the trailer light wiring harness like 1990LS400 had.

Thank you.

[VMF]

this indicator tells you not only about brake lights but about rear parkign lights as well. since you have a 7443 type of bulb in the taillight wich serves both purposes check both spirals in the bulb or just check when you turn your lights on if all the lights are on.