DIY: E32/E34 LKM mod for HID/LED. Fix Bulb Failure Warning

[ZenitramNaes]

Now mine is a little different. Am I wrong assuming the following?
Attachment 477768

[sse34]

Now mine is a little different. Am I wrong assuming the following?
<img src="http://forums.bimmerforums.com/forum/attachment.php?attachmentid=477768"/>

Buy this http://www.theretrofitsource.com/pro...roducts_id=238

No more error afterwards

[sse34]

I had bought something similar from DMM tuning and then realized if I could avoid resistors I would.

These don't catch on fire like ddm's

But to each his own

[EEDegreeToDrive]

Thank you SO MUCH for this thread ! No longer am I reminded every single day that my (dead, cracked, held-on-by-duct-tape) fog lights fell offa my car on a bumpy dirt road several years ago.

One hair-splitting technical point, though. The chips labeled A and B merely monitor several (8) digital inputs and send them on in serial form. Q : Where do these inputs come from ? A : From the output of another chip ! In particular, from the AD2201-2 chips also on the LKM circuit board. These are the chips that do the analog job of sensing the presence/absence of a bulb filament.

So if you simply ground one of the inputs (say chip A, pin 1 for front fog lights) you are also grounding an output of the partner AD2201-2 chip. The result is likely to be gonna be a hot, possibly destroyed output transistor. Since the purpose of this mod is to ignore the output, probably nobody cares. But in the off chance the failure mode of the AD2201-2 is less pleasant, or (even less likely) that some day somebody wants to undo the mod, it is probably a good idea to be more careful.

What I did was to verify that chip A, pin 1 was indeed the signal I wanted to ignore. Then I cut/scraped away 1mm or so of the PCB trace leading into pin 1. (Verify that it comes from an output of an AD2201-2 chip !). Then I grounded the pin 1 with a short jumper wire to pin 8, as in the original method.

Again, this hardly matters in any practical way. But one of the joys of having a perfect E34 is the ability to switch on your fog lights at any time. In place of that joy, I have the (even greater ?) joy of knowing that a teeny,tiny unwanted transistor could in theory be used again !

In this thread for a Low Beam fail cancel I shorted the output pin of the AD22201 chip responsible for the hot-monitoring half of the circuit. It has an internal pull up resistor, so shorting the pin to ground has no ill effects.
Also in that thread, I attempted to identify several of the other bulb monitoring circuits so folks could do what they wanted with respect to fog lights, parking lights, license plate bulbs, etc.
Over a year after I provided the guidance to a forum member to do a Low Beam fail cancel, I finally got around to performing the mod myself. (I decided to put a 'spare' HID kit in my E34.)

[Binjammin]

Don't know why people dont just buy a set of error eliminators from theretrofitsource

Because it's a twenty cent fix to hack the LKM versus... whatever the error eliminators cost? At the same time, you don't have the load with the error eliminators versus pulling down a pin on a muxer?

[ZenitramNaes]

These don't catch on fire like ddm's

But to each his own

I didn't mean to put off your idea. Yes, I have heard of DMM's "exploding" due to their reverse polarity. The ones that I got from them don't seem as nice as the ones you link. I might go with those after all..

[sugaki]

Mine looks different... Any schematics available for this version ??

To update this thread, I just defeated the parking light warning and low-beam on this LKM-L US (91 M5), with some help from the Japanese DIY site.

The two chips say TC4021BP, which in the pic above are the two chips to the top and right (the ones that are folding down).



Compare to this pic below, and you'll see that chip A is on the left, chip B is on the right. I ground 14 to 8 for the parking, 1 to 8 for low beam.

[DrCharles]

My E38 and E39 both have aftermarket HID low beams installed... Does anyone know what maximum value of resistance will keep the error message from showing up and minimize wasted power dissipated in the load resistor?

Those "error eliminators" are 6 ohms, which at 12 volts is 2 amps, and will waste 24 watts each! Does it really take 2+ amps draw to set the AD2201 comparator output?

[DrCharles]

Look closely at the IC's... there is either a small "notch" on one end of the package, or a dot next to pin 1.

Pins are numbered counterclockwise like this, looking at the top of the package, not the solder side:

16 15 14 13 12 11 10 09
>
01 02 03 04 05 06 07 08

Hope that helps.

[straight6pwr]

DrCharles, thank you thats what I needed. Do me one last favor and check my work to make sure it matches what the OP intended.

Look closely at the IC's... there is either a small "notch" on one end of the package, or a dot next to pin 1.

Pins are numbered counterclockwise like this, looking at the top of the package, not the solder side:

16 15 14 13 12 11 10 09
>
01 02 03 04 05 06 07 08

Hope that helps.

[juhony]

DrCharles, thank you thats what I needed. Do me one last favor and check my work to make sure it matches what the OP intended.

I installed HID's a while back and was looking for a way to fix only the low beam error. Though not the original pictures, this picture helped me out a ton. This is for LKM-L (61.35-8 350 377), US spec. The pin-out for each IC is indeed correct HOWEVER the labeling of chip A & B are incorrect. Chip A is low beam lights (dip beams) and Chip B is fog lights.

[straight6pwr]

I installed HID's a while back and was looking for a way to fix only the low beam error. Though not the original pictures, this picture helped me out a ton. This is for LKM-L (61.35-8 350 377), US spec. The pin-out for each IC is indeed correct HOWEVER the labeling of chip A & B are incorrect. Chip A is low beam lights (dip beams) and Chip B is fog lights.

you are correct. I performed the mod just a couple weeks ago and found the same thing. (forgot to come here and update.)

[shogun]

Here a Japanese language info with pics http://dd.jpn.org/BMW_HP/20040911/index.shtml
including schematic circuit diagram drawing http://dd.jpn.org/BMW_HP/20040911/LKM376.pdf

[scott540i]

you are correct. I performed the mod just a couple weeks ago and found the same thing. (forgot to come here and update.)

Hello,

Thanks for the info on the Low Beam and Fog light warning cancel mod. I wanted to share my findings on the Fog lights with High beam mod.
I'll admit, I was pretty stressed about playing around with the LKM, but I'm so happy it worked out. (so far)
I used a Butane touch soldering iron which was great. One quick touch - done with solder.
My Fogs are now driving beams as I changed my lenses to clears. Now the hot spot is centered instead of dispersed. Bi-xenon is next, but I
won't get into details here.

my jumper wires:
Attachment 622036

Fog Jumper is from Pin 24 (Ground with blue mark) to a pin on the Fog relay. see pics below...
Found the Ground via Bentley Manual and this forum.
Attachment 622037

the diagram from the original poster with my updates. I found the high beam trigger pin on the fog light relay by accident when using a test light on each pin.
I confirmed my LKM part# LKM USA-L 61.35-8 350 377


Attachment 622383

The money shot:

Attachment 622039

thanks and enjoy!

scott