Rear Fog Light Constantly On - Coding Issue? Or Wiring?

[Fitz]

You might have to select the Z4 G29 in Bimmercode to see more modules.
The Supra only has a very limited selection.
I had to use the G29 to do some coding.

Yeah. That's what I did. I've seen YouTube videos of people coding things on their Supra using the Z4 G29 chassis option so tried to look in there.

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[itzTang]

its one of the settings in expert mode if anything

 

[S2k]

I can’t offer anything concrete as the only BimmerCode thing I have done so far is to make the flat screen display brighter. But, looking at BMW in general it looks like you can do all sorts of stuff with fog lights (set them always on, link it to the break etc) This post talks about the process, but, obviously not Supra specific:

https://f48.bimmerpost.com/forums/showthread.php?t=1628029

Saying that, I would imagine it will be a similar setting/location where you are looking for words like: nebelschlusslicht (Rear fog light), Nebelschlussl (Fog key) in the expert menus. (Or do a search for Nebel in bimmerlink which should flag up anything with fog in it)

Maybe if you can locate the relevant parts and paste some screen shots here, someone may have a few pointers on what to set/unset.

Good luck! ?

 

[MK5_Ger]

I can’t offer anything concrete as the only BimmerCode thing I have done so far is to make the flat screen display brighter. But, looking at BMW in general it looks like you can do all sorts of stuff with fog lights (set them always on, link it to the break etc) This post talks about the process, but, obviously not Supra specific:

https://f48.bimmerpost.com/forums/showthread.php?t=1628029

Saying that, I would imagine it will be a similar setting/location where you are looking for words like: nebelschlusslicht (Rear fog light), Nebelschlussl (Fog key) in the expert menus. (Or do a search for Nebel in bimmerlink which should flag up anything with fog in it)

Maybe if you can locate the relevant parts and paste some screen shots here someone may have a few pointers on what to set/unset.

Good luck! ?

This will only work with F series cars that have the REM.
The Supra doesn't have the REM.

I searched a year ago but didn't find anything similar. With F Series cars I was able to code anything with the fog lights. Even as coming home light.
With G series this is not available unfortunately.

 

[Fitz]

I can’t offer anything concrete as the only BimmerCode thing I have done so far is to make the flat screen display brighter. But, looking at BMW in general it looks like you can do all sorts of stuff with fog lights (set them always on, link it to the break etc) This post talks about the process, but, obviously not Supra specific:

https://f48.bimmerpost.com/forums/showthread.php?t=1628029

Saying that, I would imagine it will be a similar setting/location where you are looking for words like: nebelschlusslicht (Rear fog light), Nebelschlussl (Fog key) in the expert menus. (Or do a search for Nebel in bimmerlink which should flag up anything with fog in it)

Maybe if you can locate the relevant parts and paste some screen shots here, someone may have a few pointers on what to set/unset.

Good luck! ?

One of the first things I did was look through Youtube and various forums on what options people were using for foglight coding and then searching for them in Bimmercode (like Nebelschlussl/Nebel etc.) But, as MK5_Ger mentioned, those options are only on cars with the REM (Rear Electronic Module) of which the Supra doesn't have. We have the BDC (Body Domain Controller).

I just sat down with a friend of mine who codes BMW cars etc. and he reset the BDC back to factory settings however, the problem still persists.

Can any UK/EU/Aus owners (when they get time) put your car into diagnostics mode and tell me which lights, if any come on. My rear fog comes on (obviously) and the front DRL's. The rear DRL's don't come on - so curious as to if someone can confirm what their one does.

 

[MK5_Ger]

Can any UK/EU/Aus owners (when they get time) put your car into diagnostics mode and tell me which lights, if any come on. My rear fog comes on (obviously) and the front DRL's. The rear DRL's don't come on - so curious as to if someone can confirm what their one does.

When pressing the start button 3 times to enter diagnostics mode, the front DRL will light up and if the light sensor senses it's dark, then the low beams and tail lights are on.

Did you check if there is any additional cable going towards the fog light?

 

[Fitz]

When pressing the start button 3 times to enter diagnostics mode, the front DRL will light up and if the light sensor senses it's dark, then the low beams and tail lights are on.

Did you check if there is any additional cable going towards the fog light?

Thanks for that. It seems to be what mine does, with the addition of the fog light.

I had the car on a lift and we managed to check the wiring and plug connector for the reverse/fog light, everything looks standard, no spliced wires, no crimping etc.

I'm now wondering if a replacement BDC could solve the issue if all else fails? I imagine it would need some form of coding for it to work on my car.

 

[BrettMRC]

I'm wondering if it could have simply been wired in with the rest of the lighting circuit, if it's simply had it's feed switched to an always live one then it wouldn't necessarily look different to standard. (Especially if you haven't got another car to compare it with directly)

Given we are in the UK, and it's a small A90 community, any chance of tracking down the previous owner and asking? (Could be on one of the FB groups?)

 

[BMWAF]

I'm now wondering if a replacement BDC could solve the issue if all else fails? I imagine it would need some form of coding for it to work on my car.

This may be a long shot but try deleting your driver profile and creating a new one. I know it's a pretty nuclear solution as you will have to redo all your settings, but I've discovered that the profile can store gremlins. This fixed some electrical issues I was having but of course, YMMV. ?‍

 

[Fitz]

I'm wondering if it could have simply been wired in with the rest of the lighting circuit, if it's simply had it's feed switched to an always live one then it wouldn't necessarily look different to standard. (Especially if you haven't got another car to compare it with directly)

Given we are in the UK, and it's a small A90 community, any chance of tracking down the previous owner and asking? (Could be on one of the FB groups?)

Yeah - that's my next thought is that it's been hard wired in (for whatever reason). I've tried to track down the owner who had it before me with now joy but have found the owner before him and it seems my issue was not present during his ownership.

I've had the BDC flashed back to factory settings and now also updated to the latest software revision and the issue still persists. I'll give BMWAF's suggestion with the driver profile a go but failing that, it will be going to Toyota.

I spoke with a Toyota Dealer today and explained the issue and he recommended booking it in as it's still under warranty until March 2026.

 

[Fitz]

Just to close the loop on this, I took the car to Toyota to get them to investigate and it turns out that the fog light had been hardwired in by the previous owner (no idea why). Wiring replaced, the issue is now resolved.

 

[BrettMRC]

Glad you got it sorted!

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