Doom(Dome) Light Not Working

[V(35)Powarh!]

Hi guys seems like I never learn! first problem I had was with the white switch not working when I changed to led lights got that fixed and the other day I changed the led lights again this time I forgot to turn the switch to off from door mode amd I seem the led light up once now my dome light only works when I manually click in on and off but the auto dimming when door open and closes and when I lock/unlock doesnt work!! Super sad tried disconnecting battery still no luck...I've been researching and it maybe a bcm issue? Please if anyone could help itd be much appreciated havent had the best w.e tthinking about it!!! Thanks

[The Max]

I almost gave up trying to decipher your message. Seriously dude, use a little punctuation next time so that we can hopefully better understand you!

Now to check if I understood you correctly (which I doubt I have), you've changed your dome light to LEDs and since then, you've had problems. Is this correct? If so, have you tried putting your original dome light's bulb back in to see how it performs? If it doesn't exhibit any trouble, then clearly it's a case of your aftermarket LEDs not being compatible with that particular light control design, so the BCM cannot drive it unless it has the full 12V.

[V(35)Powarh!]

Sorry mate just typing on the phone aint my forte... anyways I have tried using the normal globes and same thing is happening. It turns on when I press the lights but not when I switch the button to door... so I've lost my auto dimming feature since I changed to led lights..

[INSANITI]

I dont even turn mine on. Its better when its off hehe.

[The Max]

It's cool. Practice makes perfect, so the longer you type on your phone, the better you'll get at it.

Anyway, if the auto-dimming has begun to malfunction since you attempted to use the LED replacements and replacing it with the conventional/stock globes isn't resolving it, then something may have happened to the switch or the less likely case of the BCM as a result. Without knowing what year model you have, I've been looking at the FSM for a 2005 G35 which shows the BCM having direct control of the lamps when the switch is in door mode.

Again, interpreting what you're saying, you haven't actually lost auto-dimming. Rather, you have lost total functionality of your interior/map lighting when the switch is in door mode. Let's be clear about this because there's a big difference as to what could be happening here. In the very least, you may need to explain this clearly to an auto electrician if you can't diagnose and resolve the problem yourself. If you don't, an unclear explanation may confuse the situation and cost you more time and money. I'm not trying to be grammar nazi on you (though I am quite militant about communication). I'm simply making sure that this gets resolved for you efficiently.

If you only lost the auto-dimming, so that the interior/map lights were coming on when the switch is set to "Door", that would suggest that the BCM has gone faulty as it's either completely on or off, indicating that the MOSFET driver within the BCM controlling the grounding of the lamps has malfunctioned and needs replacing.

But in your case, if the lights remain off even with the door open, then it's more than likely that your switch is buggered. Easy way to find out is to disassemble your map light assembly so that you can get access to the switch and check that it is functioning as it's meant to with a multimeter on continuity or the lowest resistance setting. See if the switch has continuity between the pins on the switch which carry both the BCM connection and the ground leg of the lamps. I don't have the complete FSM loaded but it should be easy enough to work out. In the very least, you should be able to determine if the switch shows continuity between the BCM leg of the switch and the ground leg of the lamps if you can't determine which pin on the switch itself is meant for this ground leg of the lamps.

The other thing to do is to check the door switches themselves and whether or not they still have continuity to the BCM. Best way to check this is to check pins 12 and 62 (according to the 2005 FSM) are grounding when the doors are opened. Pin 12 is the passenger side door and pin 62 is the driver's door. Of course, this is a US FSM so this order could be the reverse. Again, this is from a 2005 model so it may not be a match for yours. Find the FSM which is and follow its diagram.

If the the door switches and the map light switch looks like it's doing its job, then check for continuity between pin on the BCM (pin 48 in the 2005 schematic) and the pin on the interior/map lamp switch which the BCM is meant to connect to. If this is OK, then my guess will be that you didn't successfully test the map light switch and it's more than likely that the switch or the wiring leading to the switch is buggered or maybe the connector for the switch isn't properly seated - particularly because the problem only arose when you performed the work only in this area.

In short, I reckon you broke it and you need to retrace your steps to find what has physically broken.

Edited December 15, 2013 by The Max

[mushilea]

I attempted a switch to LEDs before and the same thing happened. I bought a dome light from the US and replaced it. Simple plug and play and everythings working again.

I believe the switches have a fuse which the LEDs burn out.

Cheers,
Martin.

[V(35)Powarh!]

Hey man I bought a new unit at the wreckers and tried plugging it in that one same thing happens light turns on when I press the buttons but when I open doors it still dont work im just gonna leave em cant be arsed anymore lol thanks 4 the input guys

[The Max]

Sounds like the connection between the BCM and your done light assembly has gone bad.

If the wiring shows continuity, then since you eliminated my theory about the connectivity to the dome light switch, it is probably the MOSFET in the BCM has been damaged due to excessive current draw.

Easiest way to check is to ground pin 48 on the BCM and see if the lights come on. If they do, then that's definitely the problem.

You might not be arsed now but you will be later because they're your interior lights.