Assistance Needed for Programming BCM for LED Fog Lights on VW Golf MK7 (2014 TDI to

[ak77]

I am seeking assistance with programming the BCM module on my 2014 VW Golf TDI to enable LED fog lights after retrofitting a 2015 VW Golf GTI front bumper. Despite extensive troubleshooting and multiple attempts to configure the BCM using VCDS, the LED fog lights remain non-functional. Below are the details of my setup, the steps I’ve tried, and the current state of the system:
Vehicle and BCM Information​
Original Vehicle: 2014 VW Golf TDI
Donor Vehicle (Front Bumper): 2015 VW Golf GTI
BCM Part Number: 5Q0 937 084 AC
BCM Component: BCM MQBAB M H16 0124
Coding: 03101842C24102FB4BE4400000040308100000000000000000 0000000000
Dataset Number: 5G0063v____ 0001
What Works​
The LED fog light modules were tested manually with a direct 12V power source and function correctly.
The wiring harness delivers a confirmed 12V at both fog light connectors when activated.
Steps Tried So Far​
Wiring and Voltage Testing:
Verified that the wiring harness adapters are correctly connected:
Left Fog Light → Leuchte12NL LB45.
Right Fog Light → Leuchte13NL RB5.
Confirmed that both connectors supply ~12V when fog lights are activated.
Adaptation Changes in VCDS:
Updated "Lasttyp" (Load Type) for both fog light channels:
Tried settings:
6 - LED Lichtmodul (LED Light Module).
32 - allgemeine LED bis 12W (General LED up to 12W).
37 - allgemeine LED bis 12W.
40 - allgemeine LED.
Set "Dimmwert AB" (Dimming Value) to 127 for maximum brightness.
Disabled "Kaltüberwachung aktiv" (Cold Monitoring Active) where available.
Error Location Evaluation Adjustments:
Set "Fehlerort mittleres Byte DTC-DFCC" to 0 or "Not Active" for both fog light channels.
Long Coding Adjustments:
Modified Byte 18 in Long Coding Helper:
Set Byte 18 to 20 (binary: 00100000) to activate Bit 5 for LED-specific settings.
Output Tests via VCDS:
Ran output tests for both fog light channels in Module 09.
Fog lights did not activate during output tests.
Ground and Continuity Checks:
Verified ground connections at both fog light connectors.
Tested continuity between BCM and fog light connectors—no issues found.
BCM Compatibility Check:
Confirmed that BCM model 5Q0 937 084 AC should support LED lighting based on manufacturer specifications.
No firmware updates have been applied yet.
Current Status​
The LED fog lights remain non-functional despite confirmed power supply and functional modules.
No fault codes appear in VCDS after clearing, but the lights still do not activate.
Questions for Assistance​
Are there additional coding or adaptation changes required for this specific BCM (5Q0 937 084 AC) to enable LED fog lights?
Could this be a firmware limitation of the BCM? If so, is there a recommended firmware update or replacement model (e.g., 5Q0 937 084 DD)?

Are there any hidden parameters or advanced settings in VCDS that I may have overlooked?
Should I consider using ODIS or another diagnostic tool to reprogram the BCM?
Could this issue be related to dependencies between halogen headlights and LED fog lights?


Any insights or guidance would be greatly appreciated! Thank you in advance for your time and expertise.

[DV52]

ak77: Hi.

Color me confused!!! I am absolutely flabbergasted to read that a 084 series BCM (which is used on MQB platform cars in Australia, England and Europe) have an active Byte 18!!!

Yes, when polled by VCDS, these 084 modules report a massive 30 x Bytes on the long-code string - but they have only 18 x active Bytes (meaning that the last active Byte is Byte17)! That's why Byte 18 -> Byte 29 are ALWAYS a zero-string on 084 series BCMs

And also yes, Byte 18, Bit 5 is a software switch for the fog-light - but I don't believe that this is correct for a Golf mk7 (or any MQB platform car). The VW models that use BCMs that have the dreaded Byte 18 active are PQ35 platform cars - like the Golf mk5 and Golf mk6. The BCMs on these earlier model Golfs also have a long-code string with 30 x Bytes, but AFAIK, ALL the Bytes are active

I have no idea what happens when a Bit on Byte 18 is forced - I would have thought that nothing happens, but I'm not sure

OK - back to your problem (and my confusion). I may be mis-reading your words, but in saying "Confirmed that both connectors supply ~12V when fog lights are activated" - do you mean that when the center turret on the rotary light switch is pulled-out to the first position, ~12V appears at the fog-light connector - but the LEDs do not illuminate?

If so, then doesn't sheer logic dictate that the problem is down-stream of the connector - meaning either,

1. LED polarity is incorrect,
2. The LEDs do not like the form of PWM that the BCM outputs
3. The LEDs are cactus
4. The lamps have an earthing problem?

Again, if so - a supply source at the connectors when the fog-light switch is energized is conclusive proof that the coding is OK.

Don
PS: Perhaps post-up a URL link to the seller of these fog-lights