[Budge]

I am installing a set of front Laser Interceptors on my 2009 M3 sedan. For those of you familiar with this kit, there is an on/off toggle with an LED that comes with the kit. In keeping with the stealthy nature of the device, I wanted to find a location to place it that was (a) easy to reach in a hurry, and (b) somewhere that looked stock.

While searching for a solution, I found a great thread outlining how you can use Legos (no, really Legos) to make our blank stock headlight controllers function. Not only do our cars have the rear fog lights already installed, but with this easy mod, you can turn them on and off (THIS IS THE BONUS). Just don't abuse them...they are very bright at night. You can also order a new headlight controller with working buttons that are also labeled for front and rear foglights, but you don't have to.

So I used these steps to modify (or enable) the two blank switches by the headlight controller.
DIY for WilliamChang82 Rear Fog Light Mod - BMW 3-Series (E90 E92) Forum - E90Post.com

Some cars will already have at least one white piece that connects the button to the circuit board. Unfortunately, mine did not have any. No problem. So instead of using his custom piece from the link above, I used legos from this post.
Diy:: Rear Fog, Complete! Using Legos - BMW 3-Series (E90 E92) Forum - E90Post.com

Now I have working rear fog lights and a front fog light button that works (even though I don't have front fog lights installed). I can now use this button to turn on and off my Laser Interceptors (LI's), in theory. The question was how do I get a momentary switch type button to operate like the latching style switch that came with the LI's?

In steps my new hero, zerocks1. He did a great DIY here on the forum to solve this exact problem. He uses a Pulse Latching Relay Controller (PLRC) that he found on ebay. Basically, he figures out which leads from the back of the headlight controller are activated when pressing one of the buttons. He then connects one of those activated leads to the PLRC which activates the relay. Once activated, it takes 12 volts from a tapped source and sends it to whatever device you want to operate. Here's the thread.
http://www.m5board.com/vbulletin/e63-bmw-m6-forum-bmw-m6-convertible-m6board-com/164564-mod-dyi-yet-more-exterior-lighting-rear-fogs-plus.html

So I'm going to attempt this mod. I have already activate both of my fog buttons using the tutorials above. Next, I need to order the PLRC and figure out which leads are activated by the front fog button. So does anyone know where I can look this information up?

Here are some pictures.

1. The removed headlight controller.
2. The sticker with the part number from the side of the controller.
3. The circuit board
4. The inside of the controller, with the circuit board and my lego actuator.

To be continued...

 

[zerocks1]

Hi Budge, over from the M6 Board. Great research; thats exactly what I did on my M6, almost to the letter. So here's a tip, since you're 90% of the way there. Use the Pulse Latching Relay Controller (PLRC) that I described in my post. The output of the switch you wish to use should have a momentary 5v output when pressed. Normally that 5v output will feed your LMA (Light Module), but since you actually do not have front fogs, it is feeding nothing and likely does not even have a wire in the harness that plugs into your switch

If I'm right about that, you merely add a wire (reference my post) to the blank terminal of the harness and now you have that 5v output available to provide the PLRC pulse you need to activate it. What the PLRC does is; the 5v input triggers it to act as a relay, to provide you a close circuit to whatever you wish to use it for. Push again, and it disengages, thereby opening the relay if you would.

The wiring of the PLRC is below. What I did once I Had that 5v output from my unused switch, was to grab a 12v Ign On wire from the OBDI connector under the drivers footwell covering. (It won't interfere with the OBDI use), and a ground from the same harness. Now you have the power and a ground to run to the LI's. Either or both, dependent on how you choose to wire th LI's



There are full vehicle wiring diagrams at this site, in case the M3's are wired different than the 6's.

Good luck with it. You're almost there.

wiring diagrams WDS BMW Wiring Diagram System - Model Selection

 

[Budge]

For anyone interested in this mod, skip the Legos and use something else. The thin 3-dot Lego piece I used as a base actually fits over the little rubber nubs that you need to push in order to activate the switch. It works, but you lose that nice feedback "bounce" when you press the button. So instead, I took the plastic shaft from a ballpoint pen and cut it. Then I cut up an old credit card into 4 matching square pieces with a notch that fit in the space. I glued those pieces together, then test fit the pen shaft and base in the controller. I started long and just kept shaving off part of the pen until the button felt perfect. I think one of the links above shows this process.

Also, I get a nice rear fog light symbol in the tach area when I turn them on. But as you said, I don't think there are any wires leading from the front fog switch, so no front fog symbol on the dash. Oh well.

Just FYI.

 

[Gustav]

Thanks for updating us!

 

[Budge]

I can't get any of the wiring diagrams to come up on that website for a BMW E90. Is it just my computer? I did a search for fog lights, but none of the pictures will show even after downloading Java.

 

[zerocks1]

I can't get any of the wiring diagrams to come up on that website for a BMW E90. Is it just my computer? I did a search for fog lights, but none of the pictures will show even after downloading Java.

Try a different browser. Had difficulty with IE and Flock myself. I believe Chrome and/or Firefox works

 

[Budge]

OK, found this diagram. But I don't understand it. I can see 5 volts coming into the switch on pin 5 by the green wire. And there are three outgoing pins associated with the front and rear fogs (7, 9, and 11). The gray box below the switch box in the diagram is back to the footwell module. That gray box doesn't exactly show which leads coming from the control switch are controlling which lights. Or does it?

 

[zerocks1]

Budge, here's what you have to do

With the light switch plugged in but accessible with a meter, you need to check the output of pin 5. That should be your 5v in from the footwell module (Light Module). Then check pins 7,9, and 11 with the Ign on and your new LI button NOT pressed. Then recheck the same three pins with your new button pressed.

The 5v into the switch from the footwell module feeds the switch and then depending what light switch is on, passes that same 5v back to the footwell module to light whatever light, the switch position is in at the time.

One of the pin outputs will have 5v only when you press the new button you've put in. Now, I'm assuming your new button has the proper contacts behind it as you described to close the circuit within the switch. Whichever of the three pins has 5V only when you press the new button, is the one that you need to route to that PLRC described. Thats the 'Trigger' pulse.

Don't be surprised that one of the pins has no wire in it. Since you really don't have front fogs, if its like the 6, it will be a blank spot. You add a wire best you can. I shoved one in far enough and tight enough with a tie wrap that will hold itself in. The pin configuration is noted both on the plug and the switch assembly, so you can find each wire number

Post if that works.

 

[Budge]

Wow, thanks. One more question. My voltmeter has the positive and negative electrodes. I know the positive one is used to test the wires. What do I use for the ground electrode?

 

[zerocks1]

Any ground you can find. Best bet, open your hood and place the negative lead directly on a battery terminal or a good solid chassis connection with an alligator clip or other creative means. Black wire

 

[Budge]

Just an update. I got sidetracked by another project for awhile. I just installed some OSS led angel eyes! :wroom: Since I had to remove my bumper, I went ahead and installed my laser interceptors and a front camera. Once I get it all wired up and make sure it works, I will find the 5 volt power for the relay and order it. I will let you know as soon as I get the relay.

By the way, does anyone know if there is switched 12 volt underneath the steering wheel that I can access?

 

[zerocks1]

Budge, there is a switched (Known as #15 wire), on the wiring at the OBDI connector. There is a ground there as well.

Good luck

 

[Budge]

Budge, there is a switched (Known as #15 wire), on the wiring at the OBDI connector. There is a ground there as well.

Thanks. I just heard back from Cliff at LI and he suggests using a completely unused 12 volt source. He also said I cannot tap into the bluetooth speaker either. So I guess I'm going all the way across the dash to the fuse box. No problem.

 

[Budge]

Zerocks, I finally got around to searching for that 5 volt trigger on lead 7, 9, and 11. If the color chart from the WDS BMW Wiring Diagram system is correct, then I do have wires coming from 7, 9, and 11. But I can't be sure because I cannot see where the wired connect. As you can see, the wires connect to a cartridge that slides into the main connector. I haven't figured out how to remove the cartridge. Do you know how?

 

[zerocks1]

Budge, your connector is different than mine on the M6. I don't have that cartridge piece. Why don't you put the + lead of your meter in each of the wires where the metal connector is, down in that plug (Use a sewing needle if the probe cannot reach), and while the plug is plugged in, look for that 5v signal when you press the button you plan on using for the relay. Then you'll know for sure

+ meter lead to the wire in the connector
- meter lead to a ground (- battery is best)

And back to your earlier post about a 'pure 12v source'. That is always preferred, however I use the 12v Ign on at the OBDI connector without issue, and have been for at least a year problem free.

P.S. the colors of the wires are the clue as well. Look at the wiring diagram again, #7, #9 and #11 are colro coded using a German abbreviation GE (Green), BR (Brown). I forget the rest but a google search will interpret them for you. Then you'll know what color goes to what pin#

 

[Budge]

OK, your needle trick worked great! I tested lead 5 to make sure it was providing 5 volts and that I had a good ground (I cannot reach the battery...it's in the trunk). Once 5 volts was established, I tested lead 7. It has a baseline voltage of 2 volts, and jumps to 5 volts when the front fog light is pressed and 3.67 volts when the rear fog is pressed. Sounds promising...could be the front fog trigger. Then I tested lead 9. It has a baseline of 2 volts and jumps to 3 volts when the front fog light is pressed. It also jumps to 5 volts when the rear fog light is pressed. This could be the rear fog lead. I could not reach lead 11.

So what do you think? Is lead 7 my front fog trigger?

 

[zerocks1]

The reason the voltage is different when you press the front and then rear fog switches is feedback within the Light Module. So to trigger that relay system you are getting, (The PLRC), use pin #7 voltage for the trigger. Fuse it with a 2a in line fuse. Now when you press the front fogs, it will trigger (5v) the PLRC and get you the 12v you want for power. Pressing again, will remove the 5v trigger and deactivate the PLRC. Make sure you specify to the manufacturer how you want the 'last state' of the PLRC to remain once the car is turned off. Suggestion is to have it revert to off position.

 

[Budge]

Out of curiousity, what is the fuse for, and do i need one for the 12 volt line as well?

Sent from my Nook Color (zoom2) using Tapatalk

 

[zerocks1]

Out of curiousity, what is the fuse for, and do i need one for the 12 volt line as well?

Sent from my Nook Color (zoom2) using Tapatalk

Yes and yes. Yes you need a fuse for the 12v input to your LI, because no matter how you connect a fuse with an amperage smaller than the amperage in the fuse box that provides the 12v is an additional layer of safety and if a fuse blows, the smaller amperage fuse will blow first making it easier to change and nothing else on that 12v source line will go out.

The reason for the fuse on the 5v line feeding your PLRC is to protect the Lamp Module itself where you are pulling that 5v from. Highly unlikely a 5v short, should it occur, will cause the entire Lamp Module to fail. But it is one very expensive item, so why take a chance?

 

[Budge]

zerocks1, did you notice a baseline voltage on your front headlight switch like I did (about 2v)? I got an email from Baker Electronix and he's not sure his relay will work if the momentary switch in the car doesn't go from 0v to 5v when pressed.