If someone has a BMW 5 Series E39 model, it may have this fault. A headlight fault tends to show up somewhere between the 1998 and 1999 model years. It appears to be a problem with the off-set main beam headlight staying on permanently whether you have the ignition on or off and the headlight switch in the full off position. .
When I had this problem I had the lights on for a bit and when I stopped and went to turn the lights off again I found that the main light just wouldn’t turn off. I went into the house where I had to go to do some work, but when I got back in the car about 10 minutes later the battery was dead. After calling the breakdown service the man restarted the car and after a lot of gossiping he simply said “yeah well it’s a BM dude it could be anything but it’s probably just a relay or something that’s stuck”. As a quick measure, I took out the lightbulb to get home and pondered the puzzle all night.
The next morning I decided it had to be a relay that was to blame, so I looked around the car for relays for the lights. I checked the manual for the location of it. I took out panels here and there, literally removed every fuse and relay I could find, took them all out and put them back. And guess what the light still wouldn’t go out. So I started looking for answers on the web. I visited most of the BMW forums I could find and found a few owners who seemed to have the same problem. Some of the responses that came in were pretty similar, some people said it had to be a relay, someone suggested removing the battery for 10 minutes then plugging it back in and everything should reset and everything should be fine. that didn’t work either. So over the next week I went back on the web again and finally someone said they had tried those things and finally gave up and took their car to a BMW dealer. After parting with a wad of cash to pay BMW for their services, BMW said that there are no relays to control the lights and all the lights are controlled by the “LCM”.
Now the “LCM” is the light control module that controls all the lights. If this LCM fails, you just have to replace it. Easy! Apart from the LCM it is only a BMW main dealer part and the cost is over £200. At the time £200 was not an option in my pocket, so I drove for the next few months with the bulb still unplugged. Then the day of the technical inspection began to approach and there was still no pocket money to buy the LCM. So I called my cousin desperate to ask him if he had any idea how to get the car through ITV.
He said to me, “Why don’t you cut the positive wire from the offending light and then connect a new wire from the other light that works so they both run on the same supply? What a great idea! So I did exactly what you suggested. The car sailed through MOT and another 6 months down the line it is still running to this day which is better because the £200 is still not there.