[herrbrahms]

2014 328dx here, halogen fog lights replaced in 2021 with Diode Dynamics SL1 LED bulbs, along with their anti-flicker modules which I believe to simply be resistors wired in series in order to fool CANbus by matching halogen amp draw on the circuits.

I live in Seattle but took a road trip to visit family in the St. Louis area. The weirdest thing happened the other day. A dash warning popped up informing me that my right fog light is defective. The Foxwell scan tool that goes with me on all long trips confirmed code 804191. I thought it might be a gremlin and cleared the code.

Nope. The code came back the next time I popped the fog lights on, and it kept peppering me with that stupid bong every 1/2 mile. Meanwhile, to my eyes the fog LEDs both look to be of a similar brightness. If not for the module warning, I'd be driving along happily.

Diode Dynamics is a company based near my mother's house in St. Charles, MO, so I had a unique opportunity to do a warranty return in person. I called yesterday and spoke with a very friendly person in their customer service department. I reasoned that since the lights were both still lit, the likeliest issue was that the right anti-flicker module had burned through and shorted to full continuity, rather than providing the appropriate amount of resistance. Circuit current draw would have fallen below threshold and triggered the dash warning. She agreed and issued RMA for the relatively cheap modules.

Installation was more difficult than I had planned for, because the old module had to have its zip ties clipped out and new ones installed, along with routing the wiring. It wasn't a simple job of pulling a few bolts from the inner fender liner and bending it back; I had to remove both the liner and the wheel to do a decent job. Remember: 2100 mile trip home coming up, so don't take shortcuts. I'm also on travel tools, so I'm using my MegaPro screwdriver to drive an 8mm socket -- not ideal in a confined space.

I turned everything on before buttoning the job up. Polarity was good since the lights worked and I had paid attention before removing, wiring all looked nice and healthy with no obvious defects, and the code was cleared by my scan tool. I set the car back on the ground.

Once night fell, I took the car out for a shakedown. Nope. The stupid warning came back like I had done nothing at all. F$%k. My plan for tomorrow is to try Diode Dynamics again, but not to ask them for a warranty replacement on a $100 bulb without reason. I'm hoping that I can drive to their factory and quickly pull the right fog bulb out. That should be easier to access with less removal necessary than the anti-flicker harness. Then we can place it on an engineering test stand and compare resistance and amp draw to specifications.

In the case that the bulb tests fine, or that they aren't able to accommodate me with testing, WTF should I do? I need fog lights for the wilds of Montana so I don't hit an animal. I also need to not be annoyed to death by a false alarm that just won't go away. Is there anyone in the St. Louis area who can code this error straight to hell and ensure that it doesn't come back?

What a needy little beast this car is becoming in its second decade of life. I take care of it with all my heart, and it rewards me with continuous bing and bong annoyances. The sad thing is -- it's already 10 years old! Imagine how intolerable BMWs fresh off today's showroom floor will become once they age out.

Thanks in advance for all your advice.

[Billfitz]

Did you code the fogs for LED operation? It's mandatory. No matter what the advertising may say there's no such thing as plug and play LED for BMW.

[herrbrahms]

No, however this same setup had worked for 2 1/2 years without any previous complaint. Now I'm getting the fog lamp malfunction bong sometimes every tenth of a mile.

Diode Dynamics was not really set up to bench test the bulb, however I received some further information and advice. Apparently their anti-flicker module is not a resistor providing a dummy load as I had thought, but a capacitor (and IC) smoothing out the voltage. He suggested pulling the negative terminal from the battery for a hard reset, then driving for 20 minutes with the fog lights on in order to "teach" the front electronic module that the bulb in place is drawing the expected amount of power. Hey, maybe it'll work.

I used Carly years ago to code preferences before they invalidated my license and went to the subscription model. I swore off Carly forever at that point.

I haven't coded my modules since. It looks like my only other option is to wait around here for an OBD II Bluetooth adapter to be delivered and sign up for Bimmercode. Ugh, what a cluster.

[Billfitz]

Resistors and capacitors have different functions. Resistors provide a low resistance load similar to that of a halogen bulb so a bad bulb warning won't be triggered. It's a lousy method, as most of the current normally saved with LED is wasted as heat in the resistor. Capacitors provide smoothing of the pulsed voltage checks used with halogens that cause LEDs to flicker. Neither is necessary when the bulbs are coded to LED.

IMO Diode Dynamics probably doesn't know what they're talking about. Very few LED sellers do, as very few of them actually make LED bulbs. Most of them source them from Asia. The rest are European.

[herrbrahms]

Diode Dynamics is the exception to the general rule of foreign sourcing as one of their selling points is that they manufacture in Missouri, or at least they claim to. I haven't verified it with my own eyes. They mostly serve the custom truck market. H8 fog bulbs seem to be more of a side business for them, but their products are high quality. My car originally had some of the worst lighting on the road, but I've drastically improved the situation. When a product improves my ability to see at night without blinding others, I'm not going to pinch pennies.

The manager I spoke with at DD seemed very knowledgeable. I wish he had told me earlier that the anti-flicker module was capacitor-based rather than resistor-based, as it could have prevented some of the wild goose chase I went on. He was right, though, that pulling the battery for a half hour would retrain the FEM to accept the LED power draw as normal. But in case the module does freak out again while I'm on the road, I bought a Bluetooth dongle that I already tested with Bimmercode in Demo mode. I'd just pay for a license and flip the switch.

Thanks for your insights. I'm confident now that I'm not going to be annoyed to death on this trip by warning bongs.

[Billfitz]

Coding to LED is only one of at least a dozen mods I've done with Bimmercode. I can't imagine not having it, if only to get rid of the stupid disclaimer that comes up on the screen every time the car is started.

[LA430]

Originally Posted by Billfitz

Coding to LED is only one of at least a dozen mods I've done with Bimmercode. I can't imagine not having it, if only to get rid of the stupid disclaimer that comes up on the screen every time the car is started.

Which disclaimer. I know you can remove many of the start up disclaimers. Even the rearview camera warning.

[Billfitz]

It's been so long since I coded them off I can't remember what they were. When I start my car it goes directly to the nav map.