BMW E36 Blog

Turning Your BMW Lights On Automatically At Night . . . Main light

11th April 2008

Turning Your BMW Lights On Automatically At Night . . . Main light

posted in Do It Yourself, Electrical, Technical Info, Uncategorized |

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I wrote six articles until now about how you can make your BMW lights turn on automatically at night. I will summarize these posts for you in case you have missed them. In the first post, I proved that this should be something easy to implement inside a BMW E36 car. In the second post, I presented a circuit diagram that will help you create the electronic circuit that is supposed to control your lights and turn them on automatically when it gets dark. Of course, if you don’t know how to implement such a circuit or you simply feeling too lazy to do it, you can ask some electrician to do it for you. I’m sure he will agree if you paid him $20. In the third post, I wrote about my first attempt to implement this circuit and told you that it’s partially working but it needed some enhancements. In the fourth post, I created a video with the circuit implemented on breadboard and connected directly to my brother’s car lights. In the fifth post, I soldered the circuit on permanent board and showed you exactly how I intend to use it inside my car. In the sixth post, I posted 4 videos that I shoot while testing the auto light system. In case you didn’t see these videos I suggest you check them first before proceeding.

Aright, today, I decided to solve the last problem that I’ve mentioned in the last post, which is main lights problem. I didn’t know previously which wire(s) I should use to turn the main lights on using the auto-light circuit, so my car used to turn the angel eyes lights and the dashboard lights on automatically at night, but not the main lights. As you can see, this is good, but it’s not good enough. So, I decided to try and solve this problem today. To do that, I looked in my Bentley manual and I found the lighting system diagram for the BMW E36. I finally found that I should use the yellow wire to turn the main lights on, so now it should be a very easy task. Take a look at the new wiring diagram for the auto-light circuit. The new modifications are in red:

Please notice that I’ve introduced 4 diodes to get 4 wires out of the relay to be able to control:
1. Left angel eye light (yellow/gray).
2. Right angel eye light (purple/gray).
3. Dashboard lights (black/gray).
4. Main lights (yellow).

The diodes should serve as a precaution measure to prevent the interference between the 4 parts mentioned above.

With this new information, I thought that I’ve figured the solution to my problem, so I decided to go out and connect it to see if it’s going to work or not.

For some reason, when I connect the fourth controller to the yellow wire (main lights), the circuit started to make a buzzing sound (resulting from the relay being switched on and off very quickly) and the headlights turn on and off very quickly too. I’m not really sure about this problem and how to solve it. So, I’m going to review everything I did. The only reason I can think of right now that is causing this problem is that the relay is not suitable for the headlights some how. I’m going to try another relay with larger current limit and see if this solves the problem. If you guys have any idea why this is happening, I would appreciate your comments.

As you can see, this is still unfinished work, so if you want to implement this in your car, I suggest you wait until I figure out the solution for this problem to avoid paying for parts and work that is not proven to be 100% successful yet.


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There are currently 8 responses to “Turning Your BMW Lights On Automatically At Night . . . Main light”

Why not let us know what you think by adding your own comment! Your opinion is as valid as anyone elses, so come on... let us know what you think.

  1. 1 On April 12th, 2008, ricky said:

    In the diagram, label your relay terminals please? 85, 86, etc.

  2. 2 On April 12th, 2008, Tony Sticks said:

    Done Ricky. I also found a connection problem in the diagram. I fixed it too. Just use Ctrl+F5 to refresh your browser.

  3. 3 On April 13th, 2008, Dennis said:

    This is SO nice!
    unfortunately we have to have our headlights turned on both day and night in Denmark, so i can’t really use it (unless i want to have a fine for not driving with my lights on at day). I was thinking if it was possible to make a high-beam assistant (like the ones on the new 5-series), i don’t know if it would work using the same diagram just in reverse order: if oncoming traffic gets too close (the sensor should sense the oncoming traffic lights getting to bright), and then turn off the high beam until it gets dark again, then turn the high-beams on again.

    I know the “original” highbeam assistant, use some kind of camera and maybe some computing to figure out when to turn the high-beams on and off. Read more at the following page:

  4. 4 On April 13th, 2008, Tony Sticks said:

    Hi Dennis,

    Why you have to keep your lights on day and night in Denmark?

    About the high-beam assistance, It’s a great option! I think it can be done, but I will have to finish this first before jumping into another project 😀 . I hope I will be able to write about this soon.

  5. 5 On April 13th, 2008, Dennis said:

    Hi Tony,

    I think it’s because it’s easier to see other cars and oncoming traffic, with the headlights turned on at all times. It became a law to always have your headlight running 15 years ago or something like that. I think germany, sweden and norway must have their lights running at all time like we do.

    If you forget to turn on your lights it’s a 100$ fine.

  6. 6 On April 13th, 2008, Tony Sticks said:

    Wow!! That’s alot of money. So, I think you’re not going to need my circuit at all :p

    I should create something for you to turn your lights on automatically as soon as you start your car then 😉

  7. 7 On April 13th, 2008, Dennis said:

    Hi Tony,

    that would be nice! I don’t know if there already is some kind of relay that turns your lights on when the ignition starts? All new european cars turns their lights on when they’re started.

  8. 8 On April 13th, 2008, Tony Sticks said:

    I will try to search for it. I will let you know if it turned out to be something easy to do.