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ciclo wrote: Thu Mar 28, 2019 11:16 am Hi,
- read this thread in its entirety.
- Laser 3932 Terminal Tool or similar https://www.ebay.co.uk/sch/i.html?_from ... ol&_sop=15
- https://drive.google.com/drive/folders/ ... GFIXzhsQ3c

Hi ciclo. I followed the instructions in this thread, and have installed the dimmer switch unit in my GT TSI. I have also isolated the license plate lights from the circuit.

I am facing a peculiar problem after installation. When the headlight switch is in the pilot lights mode, the backlights in the instrument cluster, HU, and AC display turn off completely after I rotate the dimmer scroller to about 50%, and remain off for the rest of the range up to the minimum brightness position. This problem disappears in the headlight mode. The other lights (e.g. cigarette lighter, DSG gear selection, window switches) work perfectly in all modes.

I am using an AliExpress headlight switch (with inbuilt light sensor), and thought that may be the reason. But when I tried with the stock headlight switch, I faced the same problem. Can you help me? It seems to me that the dimmer switch is not supplying enough current in the pilot lights mode.

TheLizardKing wrote: Wed Aug 28, 2019 6:37 am

ciclo wrote: Thu Mar 28, 2019 11:16 am Hi,
- read this thread in its entirety.
- Laser 3932 Terminal Tool or similar https://www.ebay.co.uk/sch/i.html?_from ... ol&_sop=15
- https://drive.google.com/drive/folders/ ... GFIXzhsQ3c

Hi ciclo. I followed the instructions in this thread, and have installed the dimmer switch unit in my GT TSI. I have also isolated the license plate lights from the circuit.

I am facing a peculiar problem after installation. When the headlight switch is in the pilot lights mode, the backlights in the instrument cluster, HU, and AC display turn off completely after I rotate the dimmer scroller to about 50%, and remain off for the rest of the range up to the minimum brightness position. This problem disappears in the headlight mode. The other lights (e.g. cigarette lighter, DSG gear selection, window switches) work perfectly in all modes.

I am using an AliExpress headlight switch (with inbuilt light sensor), and thought that may be the reason. But when I tried with the stock headlight switch, I faced the same problem. Can you help me? It seems to me that the dimmer switch is not supplying enough current in the pilot lights mode.

Hi The LizardKing, its normal, thats how it works. Even mine also works like you described.

Once you switch to headlight mode, it is understood by the headlight switch that its already dark and dimmer switch provides
illumination from minimum to maximum the way you set.
But when you switch to park mode, the dimmer switch has to be set at a minimum level for ambient lighting to work.

Headlight mode= Dimmer works full mode.
Park mode= Dimmer works partially.
Thats my understanding, let's see what experts opine.

I have never checked the Dimmer operation with the light switch in Side lights position, or at least I don't remember.
(note: Parking lights are activated with Left stalk - the symbol is there - 'PE' )

What should I understand by headlights switch in Pilot lights mode?

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https://www.rac.co.uk/drive/advice/driv ... ng-lights/

Parking lights


Side lights

ciclo wrote: Wed Aug 28, 2019 9:45 am What should I understand by headlights switch in Pilot lights mode?

Sorry for the confusion. I mean the above position of the headlight switch.

Ok, I'll check the Dimmer operation in the side lights position.
I'm curious since you've asked the question.

Well, in my 6R (PQ25 BCM Max) the Dimmer works for all interior lights (IC, A/C, HU Nav, switches) exactly the same in all three light switch positions (AUTO, Side lights, Dipped lights).

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Dimmer IN, T6/3 = 58 signal
Dimmer OUT, T6/5 = 58d signal.

With BCM Max, signal 58 is supplied by the BCM, T73b/1 or T73b/4. (with BCM control, and modifiable)
With BCM High, signal 58 is supplied by the light switch. (without BCM control)

VW manufactures a wide variety of light switch models for the PQ25 platform around the world, according to the equipment and laws of each country (check ETKA).
Knowing the differences or how all these light switches are manufactured internally would be a gigantic and useless task.

The only ones that really matters are the ones that have the AUTO function.

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TheLizardKing, if you want, with your original light switch installed, make two voltage measurements in T17/16 (= T6/3) contact terminal, one in Side lights position and the other in Dipped lights position.

ciclo wrote: Wed Aug 28, 2019 7:41 pm With BCM Max, signal 58 is supplied by the BCM, T73b/1 or T73b/4. (with BCM control, and modifiable)
With BCM High, signal 58 is supplied by the light switch. (without BCM control)
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TheLizardKing, if you want, with your original light switch installed, make two voltage measurements in T17/16 (= T6/3) contact terminal, one in Side lights position and the other in Dipped lights position.

Thank you, ciclo. I will make these measurements and let you know.

In the meanwhile, I checked with Gannu from Team BHP, and he is not facing this problem in his GT TDI. He has upgraded the BCM to part number 6R0 937 087 T, which is lower than Max. Is the above explanation true for his BCM as well?

And finally, just upgrading the BCM will have no effect unless we also modify the wiring to change the source of signal 58, right? Because if I am not mistaken, patil has the BCM Max in his GT TSI, but he is still facing the same problem as me.

TheLizardKing wrote: Thu Aug 29, 2019 6:02 am In the meanwhile, I checked with Gannu from Team BHP, and he is not facing this problem in his GT TDI. He has upgraded the BCM to part number 6R0 937 087 T, which is lower than Max. Is the above explanation true for his BCM as well?

YES

Is your light switch the same as Gannu's?
Is your 6R the same as Gannu's? NO. All vehicle models evolve, which implies that they are not the same conditions.

As I told you there are different models of light switches, and it is one of the several possible causes of this circumstance.

TheLizardKing wrote: Thu Aug 29, 2019 6:02 am And finally, just upgrading the BCM will have no effect unless we also modify the wiring to change the source of signal 58, right?

It is mandatory when upgrade to BCM Max.

TheLizardKing wrote: Thu Aug 29, 2019 6:02 am ... patil has the BCM Max in his GT TSI, but he is still facing the same problem as me.

What about the patil light switch?

And finally , to draw correct conclusions you must have all the correct and true data.

ciclo wrote: Thu Aug 29, 2019 7:10 am And finally , to draw correct conclusions you must have all the correct and true data.

That is the bottom line, indeed.

Do you think you could suggest a way for me to solve my problem while retaining my stock BCM and stock headlight switch?

- Ask Gannu what is the reference number of his light switch.
- Get one, borrowed or purchased.
- Test if it solves this circumstance.
- Tell us the result. (if you want)

ciclo wrote: Thu Aug 29, 2019 8:30 am - Ask Gannu what is the reference number of his light switch.
- Get one, borrowed or purchased.
- Test if it solves this circumstance.
- Tell us the result. (if you want)

Thank you for the suggestion. I asked Gannu, and he is using an AliExpress unit with a wired light sensor. Like this one, for example. I am using a unit from another seller, and I am facing the problem with it as well as the stock unit.

Do you think it is worthwhile for me to purchase the unit that Gannu is using to try and see if it solves the problem?

Thanks in advance.

Update on my Dimmer switch function.

Apologies for my previous post.
The Dimmer switch on my 6R is functioning correctly as it should. I posted that it is working partially in sidelight mode and fully in headlight mode, is factually incorrect. Honestly speaking, I didn't check Dimmer function after installing BCM Max until The LizardKing posted the issue.

It is true that I faced the similar issue as The LizardKing mentioned previously with my factory BCM High 087M(confirmed)and also with 087AD (not sure) which I had installed briefly for Direct TPMS installation.

May be the issue got resolved after upgrading to BCM Max, I don't know, but dimmer switch is now working perfectly as described by Master Ciclo.
My Chinese auto headlight switch and black box with light sensor is same from the beginning, I never changed it.

patil wrote: Thu Aug 29, 2019 2:49 pm May be the issue got resolved after upgrading to BCM Max, I don't know, ...

May be? not, you can be totally sure.

These wires did the job in your BCM Max,


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as I said:

ciclo wrote: Thu Aug 29, 2019 7:10 am And finally , to draw correct conclusions you must have all the correct and true data.

ciclo wrote: Thu Aug 29, 2019 3:04 pm

patil wrote: Thu Aug 29, 2019 2:49 pm May be the issue got resolved after upgrading to BCM Max, I don't know, ...

May be? not, you can be totally sure.

These wires did the job in your BCM Max,

Aye Master, Thank you for the confirmation.

ciclo wrote: Thu Aug 29, 2019 7:10 am And finally , to draw correct conclusions you must have all the correct and true data.

Aptly said.

Found something interesting,.... Maxidot cluster's inbuilt light sensor not only adjusts cluster brightness but as well as of Radio brightness depending on ambient lighting.

May be this fact is already known or I am knowing it for the first time. Thought of sharing it with everyone anyway

https://www.youtube.com/watch?v=8Dry8p4 ... e=youtu.be

patil wrote: Thu Aug 29, 2019 4:54 pm Found something interesting,.... Maxidot cluster's inbuilt light sensor not only adjusts cluster brightness but as well as of Radio brightness depending on ambient lighting.

May be this fact is already known or I am knowing it for the first time. Thought of sharing it with everyone anyway

https://www.youtube.com/watch?v=8Dry8p4 ... e=youtu.be

Thanks for sharing patil!
In my RNS510 also happen.