2004 4.8iS Headlight ALC Module Question

[80stech]

What do you mean you can by pass modules by turning on with DIS?. LCM still needs to be functioning to light on right? Sounds like maybe the light is shorting when the auto level is dipping them and the LCM picks up the fault and shuts off the light. When you activate with DIS and there is no dip the light stays on. LCM is maybe not the problem. Drawing double the power from the other side could be a problem for the driver in the LCM though ;(

[BimmerE38E53]

Originally Posted by 80stech

What do you mean you can by pass modules by turning on with DIS?. LCM still needs to be functioning to light on right? Sounds like maybe the light is shorting when the auto level is dipping them and the LCM picks up the fault and shuts off the light. When you activate with DIS and there is no dip the light stays on. LCM is maybe not the problem. Drawing double the power from the other side could be a problem for the driver in the LCM though ;(

Let me start with I am by no means a DIS/GT1 expert lol. So the auto level function works fine. The adaptive functions in both headlights work fine. Using DIS you can either do an entire systems check which runs through the LCM or you can individually select each light in each headlight and turn them on. Now, while you're testing each light in either headlight I assumed DIS was bypassing the LCM and AHL modules and only relying on the ballast, ALC and Ignitor. I may be completely wrong but just seemed logical to me how the modules and other hardware work with BMWs. Below is a picture of he error found using DIS in my LCM Module.

Because I can individually make the all bulbs turn on using DIS I know that the ALC, ballast and Ignitor are all fine. I trust the computer as it was absolutely right on everything else I have tried to trouble shoot in all 3 of my vehicles. This is only a temporary fix anyway. I eventually will replace the LCM and take care of all the errors.

[80stech]

I don't think your bypassing the LCM by turning lights on with DIS, only bypassing the light switch and maybe not activating the lights dipping when they first turn on. Maybe I'm wrong, anyone else ??

[BimmerE38E53]

Originally Posted by 80stech

I don't think your bypassing the LCM by turning lights on with DIS, only bypassing the light switch and maybe not activating the lights dipping when they first turn on. Maybe I'm wrong, anyone else ??

Are you talking about the initial startup dip and height adjustment? Both headlights function properly and dip and adjust on their own with the drivers jumped right now. If that helps at all??

[80stech]

You said that you lost power to the light as soon as the auto level process(dip) started and that the problem started after you had the lights apart right ?

[BimmerE38E53]

Originally Posted by 80stech

You said that you lost power to the light as soon as the auto level process(dip) started and that the problem started after you had the lights apart right ?

Yes and yes

[80stech]

Originally Posted by 80stech

What do you mean you can by pass modules by turning on with DIS?. LCM still needs to be functioning to light on right? Sounds like maybe the light is shorting when the auto level is dipping them and the LCM picks up the fault and shuts off the light. When you activate with DIS and there is no dip the light stays on. LCM is maybe not the problem. Drawing double the power from the other side could be a problem for the driver in the LCM though ;(

I'll stick with my original guess but I would like to take out the word "shorting" but leave in "fault".

[BimmerE38E53]

Originally Posted by 80stech

I'll stick with my original guess but I would like to take out the word "shorting" but leave in "fault".

Very true. Like I said I'm not expert using DIS. My procedure ideas will start with the small stuff and end with the LCM. For now all of the functions of the headlights work correctly but I still have a fault in the LCM module. All in all my goal was achieved. I will correct the issues in the near future. Maybe I can take apart the LCM idk. I will keep this thread updated with my findings. Thanks for all the help and advice this far.

[crystalworks]

Thank you for your findings. I will do some testing and implement that jumper if need be in the near future. Wish I could get INPA/DIS/etc. working on a damn laptop. Tried a couple of times and barely got some things working in INPA.

Anyway, almost done with the kitchen remodel... so I'll have to dive into the truck soon. Thanks again.

[crystalworks]

Just updating this thread as well as my failed driver's head light also turned out to be a failed LCM.

Oddly enough there was some water in the old ALC (I replaced it with used after cleaning out the water residue and resealing everything) module but that turned out to not be the cause of the failed driver's side low beam. Verified this by moving the driver's side to the passenger's side light and having all functions work properly. After removing the LCM it appears there was some water intrusion, probably during the torrential rains we had earlier in the year. Unfortunately these later model LCM IV's are not serviceable and so I will have to either buy new or retrofit a used one. I am also no longer able to communicate with the LCM via Carly BMW as an additional indicator.

I am going to try and do a relay (to prevent damage to passenger side circuitry in LCM) and jump the passenger side power to the driver's side so that I will at least gain full headlight functionality until I am willing to drop the $480 on a new unit or $200 on a used unit. Thoughts on feasibility of this approach? I see no problems with it, but maybe I'm not thinking of something.