I Need Some Help with a Weird/Confusing Problem with X5 Xenon Headlights

[BimmerM3inGA]

I have a 2006 X5 3.0i with about 133K miles. I noticed that the driver side Xenon light wasn't working. I bought a new $100 bulb, but it didn't help. So I have decided to dig deeper but am now totally confused and frustrated.

I have a lot of experience troubleshooting and repairing BMWs, but have never run into something so illogical. I've spent several hours trying to figure this out, and I'll give an overview of everything I've tried so far.

I replaced the bulb and it didn't help, so I swapped the xenon igniters side to side - that didn't make any difference. So now I got serious. I removed the front bumper and actually swapped the entire lights side to side. Again, only the one on the passenger side worked. So it's most likely not a problem with the lights themselves.

I discovered that if I move the headlight switch between the normal on position and automatic and toggle the high beams and flash-to-pass, sometimes the driver side light will come on, but then the passenger side goes out. If I toggle and flash some more, I can get both lights working. Once they both begin to work, they will stay on.

Additionally, there are no warnings or messages in the Check Control. Although it will occasionally display a message about the low beam lights at the same time that the passenger side switches on and the driver side switches off.

If I shut the car off, I have to start all over again because the driver side light once again won’t turn on.

I have access to another X5, so I tried swapping the headlight switch to see if that was the problem. It made no difference.

Using DIS, if I enter the Activation mode, I can individually control the lights regardless of the headlight switch position. Using this test mode, I can turn on each headlight individually. Doing that, they each work every time. I can turn them on and off as much as I want and they work every time - but I can only test them one at a time. I don’t have a way to activate both lights simultaneously using DIS.

When I check the error memory, there is only one error. If I clear the error and check again, it comes right back. This is the error:

LCM Light/Check Module IV
3E LCM: Fault, ALC control unit

Based on this troubleshooting, and the nature of the error, I’m inclined to think the problem is with the light control module. But they are expensive and I don’t want to just throw one at it to see what happens. Are there any other tests I can perform to make sure the problem is the LCM?

Could the problem be something else entirely, but I’m just not seeing it because I’m focused on the LCM?