Right front fog stopped working

[diz]

Hi, used apps to enable 'DRL with fog lights' and 'Fog Lights with Auto Lights' last week.  Yesterday noticed right front fog was off.  Thinking the 2 apps werent playing nice I turned each off.  Right front fog still didnt work.  Attached are Leuchte13NL RB5 and 12NL LB45 - which both are same.  I checked wiring to fog and appeared secure.  Any other ideas to troubleshoot or might I have a bad led fog or have blown it??

Car is 2021 GTI SE.

Appreciate any help, ideas.
Thanks.

[dv52 (Australia)]

diz :Hi.

As you say "both [leuchte-sets] are [the] same" - so nothing obviously wrong from a coding perspective!

Normally when faced with the findings above - I would suggest testing the physical equipment (wires, connectors and lamps)- but there is something very odd about this car!

MQB platform vehicles (like this GTI) closely monitor the operation of the 35 x exterior lamps. So a failed fog-light would normally cause an error message. But you do NOT mention in your post that there is an error-message on the dashboard about a failed fog-light.

Very strange because a failed lamp WITHOUT an accompanying error-message normally means that the central electrics module is happy for the lamp to not operate - which usually means a coding problem!!


Very odd indeed - maybe you can provide more words about the back-story for these fog-lights?

Don

[diz]

Don, thanks for reply.  I see your posts all over these boards and in searching for info have found them really educational - thanks for what you do.

The backstory:

• 6/15 - Brought car home from dealer. 
• 6/16 - Ran scan, cleared some faults then coded (using apps) DRL with Fog Lights and Fog Lights with Auto Lights.  I also coded Start/Stop System Deactivation v2 (attached history shows everything)
• 6/17 - 6/18 - Realized Start/Stop System Deactivation v2 wasnt working - in looking into why I found consensus is VAG no longer allows this.  Not 100% sure but my understanding.  I dont think relevant to my fog light issue but calling out for completeness.
• 6/19 - First I reverted Start/Stop System Deactivation v2.  Then coded Urban Joke.  Followed by running a full scan.  In looking at history I now realize that 'U101400 - Control module incorrectly coded' fault showed however I cleared it on 6/19.  Also unsure if fault was from coding on 16th or 19th.
• 6/19 - later same day realized right front fog was out and rolled back DRL with Fog Lights and Fog Lights with Auto Lights. 

Since rolling back DRL with Fog Lights and Fog Lights with Auto Lights on 19th I have run several scans and no faults have been found since.  No errors on dash appear.  

This is my 2nd GTI so have some experience w/ OBDEleven and apps.  My intentions were to code some of what I had on previous car.  Also I am using the old white version of adapter.

Attached history here:
history.txt (49.38 KB)

Unless some of these apps stepped on each other I am unsure what might have happened.  Are there any other leuchte modules that would effect front led operation?    

Thanks again.
Diz

 

[dv52 (Australia)]

diz : Thanks for providing the additional clarifications and for your generous opening words!!

OK - again, this is a strange problem for the reasons stated in my previous reply!!

Let me make a couple of observations from your history records (it's good that you added the history.txt file to your response without me asking).

First: I suggest that you enable Freeze-frame data on your account- see HERE. There's lots of extremely relevant diagnostic information about error messages in SCAN reports that you are currently NOT accessing. I have no idea why the deities on the OBD11 mother-ship don't activate Freeze-frame as default - but it's a mandatory facility when fault finding IMO!

So, your SCANs identify that the central electrics module on this car is the series-version with P/N and S/N 5Q0-937-085. I'm not completely sure, but my strong suspicion is that you are from the land-of-the-free and that this is a North-America-Region (NAR) model Golf! Is my deductive guess correct?

My other observation from your SCANs is that this car has Light Control Modules (LCMs) - which are the modules @ address D7 & D6, and 39 & 29. Whenever I see SCAN reports that contain LCMs, it invariably means that ALL lamps in the headlight fittings are factory fitted LEDs - is this correct?

If you are not sure, you can confirm how this car was built by accessing the vehicle data label -see example below

Look at the PR code numbers on this car and use the decoding information HERE (see PR codes in the "8l" range). Also use the search term "fog" in the decoding information to find the version front fog-lights factory installed in this car

The importance of LCMs in this instance are two-fold:

1. OBD11 cannot access coding in these modules
2. cars fitted with these modules normally do NOT use the central electrics module to control many of the lamps in the car front. This usually means that lots of the Leuchte-sets in the 09 module are factory disabled. My hunch (I'm guessing) is that maybe the Leuchte-sets for the 2 x front fog-light on this car were originally factory disabled and somehow they have been activated (perhaps by the One-Click-App)?

Again for emphasis- I'm guessing, but I'm forced to consider unusual diagnostic options because of the strange nature of this problem!! If I'm correct, changing Leuchte-set values on this car will do nothing because the wires to the physical fog-light lamps are NOT terminated on the sockets on the central electrics module (instead, the lamp wires are connected to the LCMs).

So, maybe try an experiment to confirm (or not) my suspicion? Disable the fog-light leuchte-command (and dimming-level) for the working left-side fog-light and then turn-on the fog-light. After the change, if the central electrics module does control these fog-lights, the left-side lamp should NOT turn-ON. If indeed the change does alter how the left fog-light works - revert the 2 x channel values back to their original settings to restore the fog-light operation.

The change for this experiment is:

Leuchte12NL LB45 

• Lichtfunktion A 12 > not active (existing value = Nebellicht links)
  
• Dimmwert AB 12 > 0 (existing value = 127)

Report-back your findings - please!

Don

[diz]

Hello.  Reporting back the findings ...
Your deductive guess is correct - I am in the US.
I took a look at the PR codes and the only code in '8I' range is 8IX 'LED headlamps with cornering light (separate daytime running lights with special class-A surface)'.  There is no corresponding fog light specific code.  However, I am nearly certain all lights are factory fitted. 
I did run your experiment and it disabled the left side fog - so this confirms the central electronics module does control them.

Thanks again.

[dv52 (Australia)]

diz : If the LCMs on this car control 8lX version headlights- then yes, the central electrics module does manage the fog-lights!

So, I'm fast running out of suggestions - as I have said, because there are no error-codes, it seems that the central electrics module on this car is perfectly happy to operate the fog-light on just one car-side!! 

Since it appears from your History data that this situation is NOT the result of manual coding,  I can only conclude that the OCAs that you implemented are the cause of the problem. But I don't know what changes were made by the OCAs, or why!

My only remaining suggestion is to post-up a Backup of the 09 module - so I can see how it's coded! It's a long-shot, but I can't think of anything else - I'm stumped!

Don

[diz]

Don, attached is the backup requested.  Fingers crossed there is something there to go on :-) Thanks again.

I'll mention this as well.  In googling for answers I found a post on a diff forum that indicated person ran into similar problem (a fog out) after coding urban joke v2.  As luck would have it you responded to that post and provided stock and the urban joke v2 config if done w/o apps.  I compared stock to my config (after disabling urban joke altogether) and notice a difference. Leuchte20BR LA71/Lichtfunktion E 20 is not active on my car.  What you provided showed Standlicht allgemein.  Might be nothing but wanted to call out in case triggers anything as I did code then revert urban joke v2.

Also, I turned off/disabled all apps on my car except dotted dashboard theme and window function w/ remote.  I dont expect these are in anyway related but if feel value in disabling as test let me know.

Diz

Attachments:

GTI Central EU Backup.txt (149.85 KB)

[dv52 (Australia)]

diz: Alas, I can find nothing obvious in your Backup data!! 

However, I provide a copy of the equivalent module values from another "Yankee" vehicle that has the same 5Q0-937-085-CF module as this car. The information comes from my MQB platform database - I suggest that you look through the values - you might find a difference related to the fog-lights ("fog"="Nebel" in German). My file is sourced from VCDS, so it might look different - but the channel data is the same as OBD11

My final long-shot suggestion is to temporarily remove the negative battery lead for about 5 minuted. This should have the effect of resetting the modules. Expect a number of errors to be generated when the battery lead is re-fitted - these errors should self clear after a short drive. Again, long-shot suggestion!

Don

5Q0-937-085-CF module.xlsx (71.64 KB)

[diz]

Don, thanks again. So I took the settings you provided, formated the export of mine to be same - and they are identical! Removing the negative battery terminal didn't help either. So next stop is dealership I think.

Will dealer be able to see the history to know I made some changes using apps and then troubleshot using the leuchte sets? Or can they only see current state (mine being stock based on comparison I did)?

There is still and hasn't been any error shown in console. Would you definitely expect that to be present if fog was out? Everything I've found online talks about it for driving lights and seems to differentiate from fog. So it isn't clear to me if fog malfunction would trigger.

Diz

[dv52 (Australia)]

Diz: OK, I didn't have much confidence in my battery reset suggestion - as I said, long-shot!! Again - mighty odd indeed!

To answer your questions:

Dealers have access to VW's central servers (called "FAZIT") which hold a duplicate copy of the factory software for every MQB platform vehicle that has ever rolled-off the production line. So yes a dealer can detect that coding changes are made - but to do this, they need to invoke a particular process. Normally dealers don't bother with this check because they aren't usually interested and in this case, the values in the Leuchte-sets for the fog-lights appear to be the same as factory settings

As for your second question, notice that each Leuchte-set has the following 2 x channels:

• Lampendefektbitposition
  
• Fehlerort mittleres Byte DTC-DFCC
  

Translated to English, these channels mean:

• Lamp defect bit position .
  
• Error location middle byte DTC-DFCC
  • DTC = Diagnostic Trouble Code
  • DFCC = the 4-6 digit code that is typically listed before a VW fault code  (example: 32333 -  P060C 00 - Main Processor Performance)
    

These two channels set-up the address details in fault memory for the result of the lamp monitoring function in each Leuchte-set. These channels can be shut down - but they are not on this car!!

I guess the final check before you go to a dealer is to actually check the operation of right-side fog-light. I'm not sure if you are aware how to test a LED lamp - but from your words "I took the settings you provided, formatted the export of mine to be same", my hunch is that you are a resourceful person!

So, using a pair of temporary wires hooked-up to the battery, or a charger (maybe with an in-line fuse) - unplug the right side fog-light connector and test if you can illuminate the lamp. If you don't know, LEDs are polarized - meaning that the lamp will ONLY illuminate if the +ve/-ve wires from the battery are correctly arranged. If the lamp doesn't illuminate - swap the placement of the wires and test again.

Of course the other way to test the LED lamp is with a multi-meter - see YouTube for instructions!

Don