Help with troubleshooting LED headlights

[fpvsportsguy]

Hi guys, I'm having issues with the LED headlights on my 2014 F13 M6 and could really use your help.

The driver side low beam and high beam have both stopped working. When I turn it on, it turns on for about a second, and then turns off, and the dash gives me the low beam malfunction error, same when I tried to turn on high beam. Code reader gives me "LED main light module left, low-beam headlight faulty", and a similar message for high-beam. So I took off both driver and passenger headlights, swapped the main LED control module and the adaptive control module, put them back, error is still on the driver's side.

So I thought then something in the headlight housing must be faulty, so I ponied up way too much money for a good condition used one without modules, then put my old modules in, but still got the same error.

Could this be a wiring harness issue? Or a footwell module issue? I don't see any corrosions on the pins, and don't see any obvious issues with the portion of wiring that's visible. Do I need to code the used headlight even though it's using my original modules? Really appreciate any help on this. Thanks in advance.

[Hoa]

Your module is most likely faulty from moisture. It's the one at the bottom that's faulty

[fpvsportsguy]

Originally Posted by Hoa

Your module is most likely faulty from moisture. It's the one at the bottom that's faulty

That's what I had thought at first. But I swapped that module between the left and right headlights, the error did not follow the module and fault stayed on the left. Did the same with the vertical adaptive module as well, same result. That's why I was confused.

[Hoa]

Originally Posted by fpvsportsguy

That's what I had thought at first. But I swapped that module between the left and right headlights, the error did not follow the module and fault stayed on the left. Did the same with the vertical adaptive module as well, same result. That's why I was confused.

Try to clear the codes with ISTA and then scan it again to see if the fault comes back. If headlight comes on for a second, it is getting power. Fault may still be there and is causing it to turn off.

[fpvsportsguy]

Originally Posted by Hoa

Try to clear the codes with ISTA and then scan it again to see if the fault comes back. If headlight comes on for a second, it is getting power. Fault may still be there and is causing it to turn off.

I have a foxwell code reader and was able to clear the codes in the FRM module. Just tried it, still same result. I have a kcan cable but have not gotten around to install ISTA yet. Does ISTA have a different way of clearing codes? My scanner let me run diagnostic tests on the headlights, but it only just to turn them on temporarily. Turning on the faulty one definitely makes a different noise though. The light comes on for a second, then makes a groaning noise, and then points downwards before turning off. The working one does not make a groaning noise, just an electrical hum.

I dug around a little more, and portions of the wiring harness looks like it's caked in dirt. Can this cause issues? Is it possible that the power wire to the headlight LED is corroded and have increased impedance, so when it's powered on it does not supply enough current?

[fpvsportsguy]

Originally Posted by fpvsportsguy

I have a foxwell code reader and was able to clear the codes in the FRM module. Just tried it, still same result. I have a kcan cable but have not gotten around to install ISTA yet. Does ISTA have a different way of clearing codes? My scanner let me run diagnostic tests on the headlights, but it only just to turn them on temporarily. Turning on the faulty one definitely makes a different noise though. The light comes on for a second, then makes a groaning noise, and then points downwards before turning off. The working one does not make a groaning noise, just an electrical hum.

I dug around a little more, and portions of the wiring harness looks like it's caked in dirt. Can this cause issues? Is it possible that the power wire to the headlight LED is corroded and have increased impedance, so when it's powered on it does not supply enough current?

Does anyone by any chance have experience diagnosing wiring harness for the headlight? If I can find where the harness ends, I can get my multimeter to test each wire and see if any wires are shot.

[Hoa]

Originally Posted by fpvsportsguy

I have a foxwell code reader and was able to clear the codes in the FRM module. Just tried it, still same result. I have a kcan cable but have not gotten around to install ISTA yet. Does ISTA have a different way of clearing codes? My scanner let me run diagnostic tests on the headlights, but it only just to turn them on temporarily. Turning on the faulty one definitely makes a different noise though. The light comes on for a second, then makes a groaning noise, and then points downwards before turning off. The working one does not make a groaning noise, just an electrical hum.

I dug around a little more, and portions of the wiring harness looks like it's caked in dirt. Can this cause issues? Is it possible that the power wire to the headlight LED is corroded and have increased impedance, so when it's powered on it does not supply enough current?

Those code readers are no good. You will need ISTA to do any serious diagnostic. It will let you know much more detailed diagnostic and can clear codes better than any scanner. The groan noise could be the adaptive motor that is making the noise. You can try to disconnect it to rule it out. The normal hum on the good headlight is the cooling fan.

Wiring harness rarely get damaged unless it is exposed to the element.

[fpvsportsguy]

Thanks for the guidance Hoa, I'll set up ISTA tonight then and give it a shot. Good thing I already bought the kcan cable.

[mudpaw]

I have had the same problem with my 2015 640i GC. I disconnected the headlight connector and reconnected it and it now works. I have done this a few times and each time the issue disappears for awhile. This leads me to believe it is possible corrosion or dirt contamination in the connector. I plan to disassemble the plug soon and give it a thorough cleaning/inspection. Connectors and contacts can be easily replaced if I find it defective. I do find it interesting that most of these issues I read about are the left headlight assembly.

[fpvsportsguy]

Just to update you guys, I ended up getting another replacement headlight, and this one actually worked after I swapped in my old modules. So the 1st replacement I got just had the exact same fault as my old defective one. The seller was probably none-the-wiser since the headlight itself looked good. Will be getting a refund on that one.

This is also an indication that this is not an uncommon issue. From all my reading, looks like the driver side headlight is just prone to water ingress/corrosion. All my contact pins looked good so it's probably something inside the headlight that was damaged. I was about to pull my hair out trying to diagnose it. Phew what a relief.

For the posterity - if anyone came to this thread after googling BMW F10/12/13 6 series LED headlight problems, here's your fix. There are so many things can go wrong and it's not gonna be cheap to fix. Modules are $300-600, and the headlight assembly was $1200+.

[fpvsportsguy]

Here are the common symptoms and solutions for LED headlight faults. I read through hundreds of forum posts so you don't have to:

Symptom: low/high beam out. But would turn on if left to "on" instead of "auto" on the headlight switch
Cause: fault with the headlight turning mechanism, most likely the TMS module (the vertical looking module with 2 screws). Can also be coded out (disable adaptive function) as a cheapo fix

Symptom: low/high beam out, does not turn on at all.
Cause: most likely the LED main module, located at the bottom of the headlight held with 3 screws.

Symptom: low/high beam out, but would turn on briefly for a second but then goes out again at startup
Cause: fault within the headlight assembly, most likely the LED bulb itself or the vertical aim mechanism. Need to replace the whole headlight assembly sans modules

Symptom: corning light out
Cause: corning light module, it has its own assembly and can be easily swapped out

Symptom: halo/DRL light out
Cause: most likely TMS module

Symptom: a whole bunch of faults, just about everything headlight related
Cause: footwell module might be faulty

For everything above, definitely double check all the connectors for corrosion, and swap your modules from left to right to confirm the culprit before plucking down cash for replacement. Also beware when you cheap out and buy used parts on ebay, the replacement may have the same issue as your old one and you'll be scratching your head like me. Used modules also requires coding with ISTA, so you need to know what you're doing. Hope this helps.

[dsocold]

Originally Posted by fpvsportsguy

Here are the common symptoms and solutions for LED headlight faults. I read through hundreds of forum posts so you don't have to:

Symptom: low/high beam out. But would turn on if left to "on" instead of "auto" on the headlight switch
Cause: fault with the headlight turning mechanism, most likely the TMS module (the vertical looking module with 2 screws). Can also be coded out (disable adaptive function) as a cheapo fix

Symptom: low/high beam out, does not turn on at all.
Cause: most likely the LED main module, located at the bottom of the headlight held with 3 screws.

Symptom: low/high beam out, but would turn on briefly for a second but then goes out again at startup
Cause: fault within the headlight assembly, most likely the LED bulb itself or the vertical aim mechanism. Need to replace the whole headlight assembly sans modules

Symptom: corning light out
Cause: corning light module, it has its own assembly and can be easily swapped out

Symptom: halo/DRL light out
Cause: most likely TMS module

Symptom: a whole bunch of faults, just about everything headlight related
Cause: footwell module might be faulty

For everything above, definitely double check all the connectors for corrosion, and swap your modules from left to right to confirm the culprit before plucking down cash for replacement. Also beware when you cheap out and buy used parts on ebay, the replacement may have the same issue as your old one and you'll be scratching your head like me. Used modules also requires coding with ISTA, so you need to know what you're doing. Hope this helps.

i wonder if bmw updates these designs and fixes these issues.

I have had both of my pre lci headlights replaced under warranty like 3800 each and the design was definitely different i couldnt even adjust the headlights anymore i couldnt locate the adjusters they were no longer in the same location or any location for that matter that i could see.

[Boss330]

Had to change my left headlight with the same issue. Dipped beam would intermittently work. Sometimes for a few seconds and others it would stay on for 10 minutes.
Also had oncoming traffic frequently flash at me since my left dipped beam blinded them.
This led me to believe that there is actually a mechanical issue with the LED light mechanism inside the headlight.
Only the most outward light source failed.

Seems like a quite common issue on these cars. And only on the left hand side it seems (or perhaps right hand side on LHD cars?).

[fpvsportsguy]

Yeah all the posts I've came across was for the left driver side as well. The xenons version doesn't seem to have this problem, so must be something with the LED control mechanism, there are modules inside the housing, such a shame to having replace the whole thing for what might be a simple mechanical issue.

[biostar]

Originally Posted by mudpaw

I have had the same problem with my 2015 640i GC. I disconnected the headlight connector and reconnected it and it now works. I have done this a few times and each time the issue disappears for awhile. This leads me to believe it is possible corrosion or dirt contamination in the connector. I plan to disassemble the plug soon and give it a thorough cleaning/inspection. Connectors and contacts can be easily replaced if I find it defective. I do find it interesting that most of these issues I read about are the left headlight assembly.

Hi, May i check if you accessed the connector from the wheel well or under the bonnet?

[mudpaw]

Originally Posted by biostar

Hi, May i check if you accessed the connector from the wheel well or under the bonnet?

Under the bonnet. Remove the trim piece on the left side of the engine bay to access the connector.

[mudpaw]

Does anyone know if it is possible to code off the adaptive headlight function using Bimmer Link-Expert Mode? I see no option in the non-expert mode. If so, how do I do it?

[HeyKC]

Originally Posted by mudpaw

Does anyone know if it is possible to code off the adaptive headlight function using Bimmer Link-Expert Mode? I see no option in the non-expert mode. If so, how do I do it?

Yes. For the LEDs. I can only confirm for the pre LCI.

https://f10.m5post.com/forums/showth...3#post26120893

[bagged650.xi]

I had the same problem and after a month it corrected itself.. I was on and off so I waited a while since German cars are tricky with electronics and so far 2 months gone by and no issues 🤞

[cooltechguide]

Yes, it is possible that the issue you are experiencing with your LED headlights on your 2014 F13 M6 could be a wiring harness issue or a footwell module issue. It seems like you have already done some troubleshooting by swapping modules and replacing the headlight housing, but the error still persists.

To further diagnose the problem, it would be recommended to check the wiring harness for any signs of damage or loose connections. Make sure to thoroughly inspect the entire length of the wiring harness, including the portion that is not visible, as there could be hidden issues.

If the wiring harness appears to be in good condition, it might be worth checking the footwell module as well. It is responsible for controlling various electrical functions in the vehicle, including the headlights. You can try resetting the footwell module by disconnecting the battery for a few minutes and then reconnecting it. If that doesn't resolve the issue, it may be necessary to have the footwell module checked by a professional or dealership.

As for coding the used headlight, if you are using your original modules, it shouldn't be necessary to code the headlight. However, it's always a good idea to consult the vehicle's service manual or reach out to a BMW dealership for specific coding requirements for your particular model.

Keep in mind that electrical issues can sometimes be challenging to diagnose and may require the expertise of a qualified technician. If you are unable to resolve the problem through these troubleshooting steps, it would be recommended to seek professional assistance.

[Opie55]

Originally Posted by cooltechguide

Yes, it is possible that the issue you are experiencing with your LED headlights on your 2014 F13 M6 could be a wiring harness issue or a footwell module issue. It seems like you have already done some troubleshooting by swapping modules and replacing the headlight housing, but the error still persists.

To further diagnose the problem, it would be recommended to check the wiring harness for any signs of damage or loose connections. Make sure to thoroughly inspect the entire length of the wiring harness, including the portion that is not visible, as there could be hidden issues.

If the wiring harness appears to be in good condition, it might be worth checking the footwell module as well. It is responsible for controlling various electrical functions in the vehicle, including the headlights. You can try resetting the footwell module by disconnecting the battery for a few minutes and then reconnecting it. If that doesn't resolve the issue, it may be necessary to have the footwell module checked by a professional or dealership.

As for coding the used headlight, if you are using your original modules, it shouldn't be necessary to code the headlight. However, it's always a good idea to consult the vehicle's service manual or reach out to a BMW dealership for specific coding requirements for your particular model.

Keep in mind that electrical issues can sometimes be challenging to diagnose and may require the expertise of a qualified technician. If you are unable to resolve the problem through these troubleshooting steps, it would be recommended to seek professional assistance.

So an actual human created an account, then responded to several old threads about headlights - one at least 10 years old, all in the same stilted Chat GPT syntax. I want to meet this person.

[jubu45286]

For everything above, definitely double check all the connectors for corrosion, and swap your modules from left to right to confirm the culprit before plucking down cash for replacement. Also beware when you cheap out and buy used parts on ebay, the replacement may have the same issue as your old one and you'll be scratching your head like me. Used modules also requires coding with ISTA, so you need to know what you're doing. Hope this helps9apps