808sinned

Don't know why my interior lights in the front stop working when I open the front doors. The dome lights work fine when I switch them to the "on"position. But when I switch them to the "door" position it doesn't work. All the fuses looks good. Bulbs are all good. When I open the front doors the car recognizes them when they are open. The lights on the doors turns on but not the dome lights.

Does anyone know where I should start to fix this problem?

randal

You have sinned 808 times my son. Repent, and your dome lights will again work. ;-)

Well, seems to me that it might be in the switch that takes you from 'on' to 'door' mode. At least that is where I would start. That switch routes the supply to the dome light either directly from 12v ('on') or switched from the door being open('door'). Might be a bad switch...maybe. What year/make do you have?

808sinned

Thanks for the reply. I noticed it stop working when I hit a bump and 1 of my puddle lights broke. Do you think I shorted something?

808sinned

Year is 99

randal

Do you remember how your dome lights would behave as they came on? Did they come up slowly and then dim back down as they went off? I believe that the domes are controlled thru a dimmer circuit and the door lights just come on full bright w/o dimming. So, it is possible that the dimmer driver is not working. I really doubt that it is related to hitting a bump but stranger things have happened. I will look and see if I can find any sort of schematic.

808sinned

I really don't remember. I got all led bulbs. I noticed that the led bulbs would glow everytime I press the gas when the switch is in the "door" position. Ohh one thing I remember is that the bulbs in the footwell would stay on and would not turn off. So I had to remove the bulb. Hope it helps

randal

whoa...wait a minute! You replaced some of the cabin bulbs with LEDs? That might explain your issues because LED's take quite a lot less current than the original incandescent bulb and the dimmer drive circuitry may not 'play' nice with them. In addition, they are 'directional', meaning they only light with a certain polarity...and you may have that reversed. That LED bit of info is very important. I would now suggest that you replace the LED bulbs with the original style bulb, then see what happens.

Yamae

You probably damaged the MPX door computer which is controlling the dome light too.
Unfortunately it can't be fixed just replacing a fuse or something similar. You need to replace the whole unit to fix. I have seen many people killing it trying to replace bulbs to LED ones.

randal

Yamae, do you happen to know the failure mode of the Multiplexer computer? Does the LED knock out some drive transistor? And finally, are there any schematics of the MPX? I would love to take a look at it.

808sinned, I would still put the incandescent bulbs back in and see what happens. If you have lived a clean life, the MPX will still be ok. Oh wait...you have sinned. Forgot.;-)

Yamae

The failure mode I know is the over current mode. The quality of some aftermarket LED bulbs are terrible. Also there often happen some mistakes caused by owners when trying to install those LED bulbs. They often cause a shorted circuit. 808sinned might had either of these, I imagine.

Regarding the schematics, any of them are not available. I only have wiring diagrams in the service manual. I always need to analyze the board by my eyes, a circuit tester, an oscilloscope and some lighting tools.

808sinned

Thanks for all your help. Dose anyone know where the part is located or where I can get it?

billydpowe

iTrader: (1)

none of this sounds like a LS400 issue.... am I out of touch?

sha4000

iTrader: (1)

Wrong forum and I'm sure your still under warranty so take it to the dealer. I'm sure you checked that the bulb was not blown right???

Tun

U can turn button clockwise on the base of speedometer rightside. will appear footlight.