The Xenon light/LCM problem....flickering headlight, etc...
 

So I was having some problem with my front passenger side turn signal, and after I took it to a shop I decided to buy an used LCM IV and give it a shot...

Here's the problem:

With Original LCM IV:
The front passenger side turn signal will not light up, no matter what I do(turn,hazard, etc). No error message. Everything else works fine.
Seems like the LCM unit has lost all contact with the front passenger side turn signal.

With the used LCM IV I bought:
The front passenger side turn signal work perfectly fine, but the front xenon headlight will flicker, or goes on and off from time to time.
The 'check low-beam light' message comes and goes. Sometimes the Xenon light will flicker, sometimes it will turn off/on suddenly, and sometimes it will work perfectly fine.

The LCM IV I bought does show a different HW version and SW version, however it is also pulled from a 2004 X5. Both are 'LCM IV Without LWR'.


I'm thinking that maybe both LCM IV units are faulty, or maybe the ground wire, or light socket is causing the problem with the newly purchased LCM. (Maybe because the original LCM lost contact with some of the lights, and therefore not detecting the issue that's causing the flickering with the new LCM)

Anyone had similar issues before?

Curious if you had to code the module when you replaced it.

Agreed...

Nardo, do you have a GT1 or PA Soft to recode the LCM? Lucky dog...where did you find your used LCMIV?

Thanks,

JJ

The flickering on your xenon would be an inconsistent voltage issue. Now whether it's coming from the LCM, ballast, bulb on its way out, or something else I couldn't tell you....
Do you have the tools to code? Look through that and see if something may have been turned off that shouldn't have been?

While not totally conclusive, using the old LCM didn't give him the same symptoms of flickering.

Well I did not code the module yet, and there is a red dot showing right now.

I don't know if the module is coded differently compared to my original one, but I am looking into getting a BMW scanning tool that can give me access to reading and rewriting the codes for the LCM...not sure which exact tool I should choose for that tho. :(

No JJ, I don't have GT1 or PA Soft right now, but I'm thinking about buying one, and see if that will help. How much do they usually cost?

I found my used LCM IV on eBay, it was not listed as LCM IV, but it mentioned it was from a 2004 X5 and it shows LCM IV on the pic.

Not sure if I'm lucky or not, since I haven't figure out if the LCM that I just bought if faulty or not...

Xenon is completely normal with my original LCM but the turn signal is off, with the new LCM either everything works or problems with the Xenon...I need to figure out what's going on...

I'm getting a tool to read the codes.

I don't think it's the ballast since Xenon works perfectly with my old LCM, and sometimes it work perfectly with the new LCM as well, and some other times it just flickers and turns on and off.

I have no knowledge of how the BMW lighting system works, but to me it seems like there is either something wrong with some grounding/socket/housing that's causing the problem, or the LCM is just another faulty unit.

Yes that is correct.

I read on an E46 forum that the flickering issue may be caused by bad grounding or sockets, which cause the LCM to reset and therefore flickers. But in my case the Xenon also turns on and off....:dunno:

My bad, I missed that.

While I'm still a salty boot when it comes to this coding stuff....could there be a chance that the pwm values for those particular lights are incorrect? From what I have read, it sounds like you can get funky things (like what the OP is describing) with values outside of the range of the bulb?

Either way, you may be up a creek as long as you don't have a tool to get into the module software and see whats actually going on; as its my understanding that it does need to be coded to the vehicle regardless.