Sticky MQB Light Configuration Case Study

[Somnus]

NOTE: Once again, take this with a grain of salt, this information is for educational purposes only and most likely only useful to people much smarter than myself

So I was curious how the "Light Configuration" that exists as a single Channel on the newer BCMs and consists of a really big *expletive* number, like this:

IDE05145-Light configuration, 0C 34 00 14 02 00 64 00 00 00 00 00 00 00 00 00 0C 3E 00 15 04 00 64 00 00 00 00 00 00 00 00 00 08 00 00 45 08 00 64 00 00 00 00 00 00 00 00 00 08 00 00 46 08 00 64 00 00 00 00 00 00 00 00 00 09 48 00 43 14 00 64 06 00 80 08 00 1F 00 00 00 09 4C 00 44 14 00 64 07 00 80 08 00 1F 00 00 00 0B 36 00 1A 0B 00 64 00 00 00 00 00 00 00 00 00 0B 40 00 1B 0C 00 64 00 00 00 00 00 00 00 00 00 0A 37 00 1C 0D 0F 64 00 00 00 00 00 00 00 00 00 0A 41 00 1D 0E 0F 64 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 06 38 00 22 12 00 7F 00 00 00 00 00 00 00 00 00 06 42 00 23 13 00 7F 00 00 00 00 00 00 00 00 00

differs from the older style of having multiple adaptation channels



One thing I noticed is that some of the "Bytes" (for lack of a better term) repeat.
Out of curiosity, I split that large string up into chunks every time it repeated and ended up with 14 rows of 16 Byte "Chunks"

IDE05145-Light configuration
0C 34 00 14 02 00 64 00 00 00 00 00 00 00 00 00
0C 3E 00 15 04 00 64 00 00 00 00 00 00 00 00 00
08 00 00 45 08 00 64 00 00 00 00 00 00 00 00 00
08 00 00 46 08 00 64 00 00 00 00 00 00 00 00 00
09 48 00 43 14 00 64 06 00 80 08 00 1F 00 00 00
09 4C 00 44 14 00 64 07 00 80 08 00 1F 00 00 00
0B 36 00 1A 0B 00 64 00 00 00 00 00 00 00 00 00
0B 40 00 1B 0C 00 64 00 00 00 00 00 00 00 00 00
0A 37 00 1C 0D 0F 64 00 00 00 00 00 00 00 00 00
0A 41 00 1D 0E 0F 64 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
06 38 00 22 12 00 7F 00 00 00 00 00 00 00 00 00
06 42 00 23 13 00 7F 00 00 00 00 00 00 00 00 00

Now, with a little more digging, it seems that each "Chunk" corresponds to one of the "leuchte" channels, starting from Leuchte0 and ending on leuchte13, which is also conveniently all the channels for the front of the vehicle

For example, lets take the first chunk and it's matching channel, Leuchte0.

Byte 0, 1 and 3 match with the Lasttyp, Defektbitposition and Error Location Byte of a specific Leuchte channel respectively

0C 34 00 14 02 00 64 00 00 00 00 00 00 00 00 00

0C - converted from hex to decimal gives us 12, which matches up with the number assignment for Blinkleuchten

ENG116936-ENG115873-Leuchte 0 BLK VL B36-Lasttyp 0, 12 - Blinkleuchten

34 - matches up perfectly with the Lampendefektbit for Leuchte0

ENG116936-ENG116547-Leuchte 0 BLK VL B36-Lampendefektbit Position 0, 34

14 - Matches the Fehlerort Byte for leuchte0

ENG116936-ENG115875-Leuchte 0 BLK VL B36-Fehlerort mittleres Byte DTC-DFCC 0,14

Byte 4 and 5 of the chunk

0C 34 00 14 02 00 64 00 00 00 00 00 00 00 00 00

seems to correlate to the "Light Function A" and "Light Function B" channel of the Leuchte set

ENG116936-ENG115876-Leuchte 0 BLK VL B36-Lichtfunktion A 0, Blinken links Hellphase
ENG116936-ENG115877-Leuchte 0 BLK VL B36-Lichtfunktion B 0, not active

in this example 02 would be for "Blinken links Hellphase" and 00 would be "not active". here is a list that shows all of the functions that I have been able to correlate

02	Blinken links Hellphase
03	Blinken links Dunkelphase
04	Blinken rechts Hellphase
05	Blinken rechts Dunkelphase
06	Blinken links aktiv (beide Phasen)
07	Blinken rechts aktiv (beide Phasen)
08	Standlicht allgemein (Schlusslicht: Positionslicht: Begrenzungslicht)
09	Parklicht links (beidseitiges Parklicht aktiviert li & re)
0A	Parking light right
0B	Abblendlicht links
0C	Abblendlicht rechts
0D	Left high beam
0E	Right high beam
0F	Lichthupe generell
12	Nebellicht links
13	Nebellicht rechts
14	Daytime running lights
18	Brake light
19	Rueckfahrlicht
31	Ambience lighting

Byte 6 matches with the Dimmwert AB channel

0C 34 00 14 02 00 64 00 00 00 00 00 00 00 00 00

64 - converted from HEX to decimal is 100

ENG116936-ENG115878-Leuchte 0 BLK VL B36-Dimmwert AB 0, 100

this pattern seems to repeat for channels C, D, E, F, G, and H as well

byte 7 - Light Function C
byte 8 - Light Function D
byte 9 - Dimmwert CD
byte 10 - Light Function E
byte 11 - Light Function F
byte 12 - Dimmwert EF
byte 13 - Light Function G
byte 14 - Light Function H
byte 15 - Dimmwert GH

I still have yet to figure out how the Dimming DIrection channels factor into the above information.


Edit (originally posted by TBAx): Dimming Direction (maximize/minimize) is encoded in the brightness byte, as far as I see. Everyting below $80 is "maximize" (0-127 [$00-$7F]). Everything from this value on is "minimize" (0-127 [$80-$FF]). At least this is what I consider when looking at Somnus posted configuration for the DRLs - I suspect they turn while signal indicator is active on that specific side...?

 

[DV52]

^^^ hmm..........in the current version BCM s, the 665 x Lighting configuration channels in the older hex09 modules has been reduce to just one very long hex-string - IDE05145-Light configuration

Not sure if it helps, or hinders - but here's an extract from an early primer that I wrote many years ago about these mystical channels.

"Of the 35 x channel-sets in the BCM of my 103TSI, 10 x channels-sets are not active. Of the 25 channel-sets that are active, 6 x channels-sets appear to have a close correlation between the Leuchte channels and the Light configuration channels. The remaining 19 x "active" channel-sets do not appear to have this correlation.
The close correlation channels are: Low Beam Headlamp, Front Turn Indicator and Daytime Running Lamp (left and Right lamps in each case). The only linking aspect for these lights is that they are all part of the front headlight assembly albeit the High beam lamp is missing from the list. Whenever a stored valued of a Leutche channel is changed for these lamps, the corresponding stored value of the Lighting configuration channel automatically changes to the altered value.
At the time of writing, the purpose of the Lighting configuration channels is not known. However, my initial suspicion is that each Lighting Configuration channel-set records the set-up parameters for the power supply circuits of the exterior light that is defined in its twin Leuchte channel-set. "​

Don

 

[Somnus]

Don,

Your primer is actually what made me interested in how the configuration was handled in the newer BCMs.

It looks loke there are actually THREE configuration channels in the BCM

IDE05145-Light configuration
ENG141661-Leuchtenkonfiguration_Aussenlich_Heck
ENG141662-Leuchtenkonfiguration_Sonstiges

that handle Front (Leuchte 0-13), Rear (Leuchte 18-29), and Miscellaneous (Leuchte 16, 17, 30-35) respectively


(WARNING: completely hypothetical comment ahead!)

It makes sense to condense the configuration into three channels however, as it may be used by ODIS to adapt the lighting section of the BCM rather rapidly, since it only has to write three channels to populate the data in many more.

 

[DV52]

^^^ hmm...................... perhaps your hypothesis is correct, but the other possible explanation is that at about the same time the already high channel count in this module started to increase dramatically (particularly with the incorporation of the software switches in the BCM's long-code string).

The length of IDE05145-Light configuration the is about 169 Bytes (my rough count)- which means that 469 Bytes (i.e. (35 x 19) -169)) in the old module are missing. Which means that 469 settings were superfluous in the old BCM. Which means that 664 adaptation channels (i.e. (35 x 19) -1) were not needed - at all!

So- perhaps the change was due to the boffins in Germany simply applying an age-old engineering principal to generational improvement to this module - that is, they were attempting to make this massive module more efficient - maybe?

Don

 

[Somnus]

Don,

I believe you are most likely correct in your assumption that they were trying to optimize the BCM.
What makes that more evident is the fact that in the MK7.5 vehicles, most of the headlight control is handed off to the 4B: Multifunction Module and the related leuchte channels are completely zeroed out (with the exception of the dipped beam and the rear lighting)

 

[TBAx]

Thanks for your research, Somnus.

I also belive that modifications to the front lights in cars with LCMs (or with module 4B) is hidden somewhere in these channels. However since I don't own such a car, I never got the chance to experiment with this. When your original research is correct there is an easy test; find the byte string "02 00 64" which roughly translates left turn signal on full brightness and replace it with "02 14 64". This should - if there is any correlation to the actual lighting functions - add the left turn signal as a daytime running light (DRL).

Maybe it will work, maybe it won't. If you don't see a change, please cycle ignition.

@DV52: I see your point with the probably missing configuration values when compared to the old/classic MQB BCMs. However I belive, that they existed for the same reason we now can't modify front lights. It was planned to use them in combination with LCMs; however there was either a problem with the method used there, or it was deemed to simple to be modified, as they know, people here in europe love to add so called US lights to their cars.

These light configuration channels appear to be, in a way, seem related to the BCM light configuration in PQ35 cars ("beware of Byte 18"). Also Somnus research fits pretty good to what an adphex of my Octavia 3 RS looks like (reordered for numeric correctness in the channel positions starting at $0550):

Leuchte 0 BLK VL B36,0550,16,0C 34 00 14 02 00 64 00 00 00 00 00 00 00 00 00 
Leuchte1BLK VRB20,0551,16,0C 3E 00 15 04 00 64 00 00 00 00 00 00 00 00 00 
Leuchte2SL VLB10,0552,16,04 48 00 4A 08 09 23 1E 00 23 14 00 64 00 00 00 
Leuchte3SL VRB21,0553,16,04 4C 00 4C 08 0A 23 1E 00 23 14 00 64 00 00 00 
Leuchte4TFL LB4,0554,16,01 3A 00 49 08 09 7F 1E 00 7F 14 00 7F 00 00 00 
Leuchte5 TFL RB32,0555,16,01 44 00 4B 08 0A 7F 1E 00 7F 14 00 7F 00 00 00 
Leuchte6ABL LC5,0556,16,03 36 00 1A 0B 0F 7F 1E 00 80 00 00 00 00 00 00 
Leuchte7ABL RB1,0557,16,03 40 00 1B 0C 0F 7F 1E 00 80 00 00 00 00 00 00 
Leuchte8FL LB39,0558,16,0A 4E 00 24 12 16 64 00 00 00 00 00 00 00 00 00 
Leuchte9FL RB2,0559,16,0A 4F 00 25 13 17 64 00 00 00 00 00 00 00 00 00 
Leuchte10SHUTTER LB23,055A,16,02 37 00 1E 0D 0F 7F 00 00 00 00 00 00 00 00 00 
Leuchte11SHUTTER RB22,055B,16,02 41 00 1F 0E 0F 7F 00 00 00 00 00 00 00 00 00 
Leuchte12NL LB45,055C,16,0A 38 00 22 12 00 64 00 00 00 00 00 00 00 00 00 
Leuchte13NL RB5,055D,16,0A 42 00 23 13 00 64 00 00 00 00 00 00 00 00 00 
Leuchten14AL LB6,055E,16,00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
Leuchte15AL RB44,055F,16,00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
Leuchte16BLK SLB35BLK SL KC9,0560,16,25 35 00 17 08 09 64 1E 00 64 00 00 00 00 00 00 
Leuchte17TFL R BLK SRB3TFL R BLK SR KC3,0561,16,25 3F 00 19 08 0A 64 1E 00 64 00 00 00 00 00 00 
Leuchte18BLK HLA60,0562,16,0C 08 00 16 02 00 64 00 00 00 00 00 00 00 00 00 
Leuchte19BLK HRC31,0563,16,0C 18 00 18 04 00 64 00 00 00 00 00 00 00 00 00 
Leuchte20BR LA71,0564,16,22 09 00 2B 18 00 64 00 00 00 1E 00 00 00 00 00 
Leuchte21BR RC8,0565,16,22 19 00 2D 18 00 64 00 00 00 1E 00 00 00 00 00 
Leuchte22BR MA57,0566,16,22 29 00 2C 18 00 64 00 00 00 00 00 00 00 00 00 
Leuchte23SL HLC10,0567,16,20 0A 00 29 08 09 64 1E 14 64 00 00 00 00 00 00 
Leuchte24SL HRA65,0568,16,20 1A 00 2A 08 0A 64 1E 14 64 00 00 00 00 00 00 
Leuchte25KZL HA59,0569,16,2B 28 00 30 08 1E 7F 00 00 00 00 00 00 00 00 00 
Leuchte26NSL LA72,056A,16,09 0C 00 2E 1A 00 64 00 00 00 00 00 00 00 00 00 
Leuchte27NSL RC6,056B,16,09 1C 00 2F 1A 00 64 00 00 00 00 00 00 00 00 00 
Leuchte28RFL LC11,056C,16,09 0B 00 31 19 00 64 00 00 00 00 00 00 00 00 00 
Leuchte29RFL RA64,056D,16,09 1B 00 32 19 00 64 00 00 00 00 00 00 00 00 00 
Leuchte30FR LC72,056E,16,2B 00 00 02 2B 00 64 00 00 00 00 00 00 00 00 00 
Leuchte31AMBL 1C61,056F,16,00 00 00 03 2D 00 64 00 00 00 00 00 00 00 00 00 
Leuchte32AMBL 2C35,0570,16,00 00 00 04 2E 00 64 00 00 00 00 00 00 00 00 00 
Leuchte33AMBL 3C36,0571,16,00 00 00 05 2F 00 64 00 00 00 00 00 00 00 00 00 
Leuchte34AMBL 4C37,0572,16,00 00 00 06 30 00 64 00 00 00 00 00 00 00 00 00

...or maybe, there is an ENG141660-Leuchtenkonfiguration_Aussenlicht_Front that is simply not documented in the ASAM/ROD data as of today, but who knows.

Edit: Dimming Direction (maximize/minimize) is encoded in the brightness byte, as far as I see. Everyting below $80 is "maximize" (0-127 [$00-$7F]). Everything from this value on is "minimize" (0-127 [$80-$FF]). At least this is what I consider when looking at Somnus posted configuration for the DRLs - I suspect they turn while signal indicator is active on that specific side...?

 

[DV52]

TBAx :my mental meanderings in my extract above were just musings at a time when I was desperately trying to understand how Leuchte-sets operated (my learnings were greatly enhance by your writings on the motor-talk de. forum - for which I thank you).

More than happy to adopt your hypothesis as a working assumption -until we have more definitive information. And you are probably better placed to get better data - alas for me the tyranny of distance and language are problematic!!

Don

 

[Somnus]

TBAx,

You are correct on changing a byte in the light config does cause an immediate change to the Leuchte channel it is assigned to.

As a test, I changed the Light Function A byte for the left fog light from 12 to 18 and, after checking the related Light Function A channel it now displays Brake Light

EDIT: The information you provided related to the Dimming direction makes perfect sense. Thank you for sharing it.

ANOTHER EDIT: Uwe, If TBAx doesnt mind, would you quote his Dimming Direction information in the first post?

 

[Uwe]

ANOTHER EDIT: Uwe, If TBAx doesnt mind, would you quote his Dimming Direction information in the first post?

I'm not sure I understand this request.

-Uwe-

 

[TBAx]

Oh, wait, so that was all? We now know, how to modify front lights in newer gen BCMs?
(Yes, I don't mind adding the information to the first post)

 

[Somnus]

Uwe,

apologies, that was a little scatterbrained on my part

would you add this quote

Edit: Dimming Direction (maximize/minimize) is encoded in the brightness byte, as far as I see. Everyting below $80 is "maximize" (0-127 [$00-$7F]). Everything from this value on is "minimize" (0-127 [$80-$FF]). At least this is what I consider when looking at Somnus posted configuration for the DRLs - I suspect they turn while signal indicator is active on that specific side...?

to the first post? or should it remain where it is.

 

[Somnus]

Oh, wait, so that was all? We now know, how to modify front lights in newer gen BCMs?
(Yes, I don't mind adding the information to the first post)

That is what it seems, at least on my vehicle specifically. I believe more testing would be required for a definitive answer. It looks like a step in the right direction, however.

Although, some of the changes I made had a tendency to set a "Control Module Incorrectly Coded" DTC, but reverting to the original value allowed the DTC to clear

 

[Uwe]

Uwe,

apologies, that was a little scatterbrained on my part

would you add this quote

to the first post? or should it remain where it is.

Done.

-Uwe-

 

[Somnus]

I can confirm that any changs that I made to the Light Configuration channel including:

Dimming Value
Light Function
Light Type

are reflected in the Leuchte channels after an ignition cycle and the same is true in reverse (changes made to the Leuchte channel reflect into the Light Configuration channel)

EDIT: See Post# 16 for an example

 

[TBAx]

But does it change, what exterior lights are illuminated?

 

[Somnus]

But does it change, what exterior lights are illuminated?

As an example, I modified the Lighting Configuration channel to change my GTI's Left U-light (Leuchte4TFL) to act as a turn signal

Starting with the unmodified Lighting Configuration string

IDE05145-Light configuration,21 34 00 14 02 00 7F 00 00 00 00 00 00 00 00 00 21 3E 00 15 04 00 7F 00 00 00 00 00 00 00 00 00 04 48 00 4A 14 00 64 06 00 80 08 09 1A 00 00 00 04 4C 00 4C 14 00 64 07 00 80 08 0A 1A 00 00 00 01 3A 00 49 14 00 7F 06 00 9A 08 09 7F 00 00 00 01 44 00 4B 14 00 7F 07 00 1A 08 0A 7F 00 00 00 03 36 00 1A 0B 0F 7F 00 00 00 00 00 00 00 00 00 03 40 00 1B 0C 0F 7F 00 00 00 00 00 00 00 00 00 24 35 00 26 08 09 7F 00 00 00 00 00 00 00 00 00 24 3F 00 27 08 0A 7F 00 00 00 00 00 00 00 00 00 02 37 00 1E 0D 0F 7F 00 00 00 00 00 00 00 00 00 02 41 00 1F 0E 0F 7F 00 00 00 00 00 00 00 00 00 06 38 00 22 12 00 7F 00 00 00 00 00 00 00 00 00 06 42 00 23 13 00 7F 00 00 00 00 00 00 00 00 00 ,224

broken down into the individual Leuchte channels

IDE05145-Light configuration,
21 34 00 14 02 00 7F 00 00 00 00 00 00 00 00 00 
21 3E 00 15 04 00 7F 00 00 00 00 00 00 00 00 00 
04 48 00 4A 14 00 64 06 00 80 08 09 1A 00 00 00 
04 4C 00 4C 14 00 64 07 00 80 08 0A 1A 00 00 00 
01 3A 00 49 14 00 7F 06 00 9A 08 09 7F 00 00 00 
01 44 00 4B 14 00 7F 07 00 1A 08 0A 7F 00 00 00 
03 36 00 1A 0B 0F 7F 00 00 00 00 00 00 00 00 00 
03 40 00 1B 0C 0F 7F 00 00 00 00 00 00 00 00 00 
24 35 00 26 08 09 7F 00 00 00 00 00 00 00 00 00 
24 3F 00 27 08 0A 7F 00 00 00 00 00 00 00 00 00 
02 37 00 1E 0D 0F 7F 00 00 00 00 00 00 00 00 00 
02 41 00 1F 0E 0F 7F 00 00 00 00 00 00 00 00 00 
06 38 00 22 12 00 7F 00 00 00 00 00 00 00 00 00 
06 42 00 23 13 00 7F 00 00 00 00 00 00 00 00 00

I zeroed out the following lines for Leuchte4TFL

01 3A 00 49 14 00 7F 06 00 9A 08 09 7F 00 00 00

which disabled the dimming when the turn signal was activated (06 00 9A), and the Parking light and Side Light (08 09 7F).

Then I replaced Function A with "Blinken links Hellphase" with a dimming value of 127 and maximize as the dimming direction

01 3A 00 49 02 00 7F 00 00 00 00 00 00 00 00 00

after changing that code in the BCM, the U-lights only responded when I turned on the left indicator, after which they began blinking in sync with the turn signal bulb

And to show that the Leuchte channel updated as well, here is a snippet of an AdMap taken right after the Lighting Configuration channel was updated

ENG116940-ENG115958-Leuchte4TFL LB4-Dimming Direction CD 4,maximize ,16
ENG116940-ENG115962-Leuchte4TFL LB4-Dimming Direction EF 4,maximize ,16
ENG116940-ENG115966-Leuchte4TFL LB4-Dimming Direction GH 4,maximize ,16
ENG116940-ENG115953-Leuchte4TFL LB4-Dimmwert AB 4,127 ,16
ENG116940-ENG115957-Leuchte4TFL LB4-Dimmwert CD 4,0 ,16
ENG116940-ENG115961-Leuchte4TFL LB4-Dimmwert EF 4,0 ,16
ENG116940-ENG115965-Leuchte4TFL LB4-Dimmwert GH 4,0 ,16
ENG116940-ENG115950-Leuchte4TFL LB4-Fehlerort mittleres Byte DTC-DFCC 4,49 ,16
ENG116940-ENG116553-Leuchte4TFL LB4-Lampendefektbitposition 4,3A ,16
ENG116940-ENG115948-Leuchte4TFL LB4-Lasttyp 4,1 - LED Tagfahrlichtmodul Versorgung ,16
ENG116940-ENG115954-Leuchte4TFL LB4-Lichtansteuerung HD AB 4,Always ,16
ENG116940-ENG115951-Leuchte4TFL LB4-Lichtfunktion A 4,Blinken links Hellphase ,16
ENG116940-ENG115952-Leuchte4TFL LB4-Lichtfunktion B 4,not active ,16
ENG116940-ENG115955-Leuchte4TFL LB4-Lichtfunktion C 4,not active ,16
ENG116940-ENG115956-Leuchte4TFL LB4-Lichtfunktion D 4,not active ,16
ENG116940-ENG115959-Leuchte4TFL LB4-Lichtfunktion E 4,not active ,16
ENG116940-ENG115960-Leuchte4TFL LB4-Lichtfunktion F 4,not active ,16
ENG116940-ENG115963-Leuchte4TFL LB4-Lichtfunktion G 4,not active ,16
ENG116940-ENG115964-Leuchte4TFL LB4-Lichtfunktion H 4,not active ,16

 

[DV52]

Somnus: I don't suggest that you cease your investigations - but I had a little chuckle (which I had to share with you) at the dichotomy between what you are doing and the motto on your posts- the irony is palpable!!

Don

 

[Somnus]

Don,

That's how I stumble onto most of my solutions; By breaking my car to the point it is undrivable, learning how to fix it, and sharing that information here

 

[DV52]

^^^^^^

 

[DiegotheCat]

Top work guys, this makes a lot of sence.