[F22 Raptor]

OK, so I finished doing the grounding cable retrofit to my taillights for pre-10/2016 vehicles:

https://www.newtis.info/tisv2/a/en/f...ter/1VnZ8zZX2B

...after my iDrive barfed telling me I had no taillights on the right side. After I opened up, all bulbs were good but the #7 pin on the eight-pin connector was fried and melted part of the connector (no ground). My BMW parts dept. sold me the repair kit for half price (nice!) and I used the new connector. I used another method for adding an additional ground since I was NOT replacing the socket housing. I can detail it for you if you ask me nicely!

My question is this: How can I make that cute little H21W bulb work with the brake lights? Or can I? I've read that's a fog light (I don't have the rear fog switch) OR it's a two-stage brake light that comes on during heavy braking. If that's true, how can I test it?

I was thinking of jumper-ing the lights together but I got cold feet thinking I might blow something else or send iDrive into a tizzy again. I still would like to make it work - I hate the fact I got empty real estate back there. Thanks

[19bis]

So long as you have front fog lights, adding rear fog lights is an easy and inexpensive (i.e., free) mod. In the headlight switch assembly, pop out the blank button underneath the front fog light button, using a trim tool. There are two nibs on the top near the front of the button and one nib on the bottom; these need to be shaved down (they function in US vehicles to prevent you from pushing the button in). Reinsert the button.

Now you need to do a little coding:
In FEM 3060 (LceMaster) NSL_Verbaut -> verbaut
In REM 3063 (LCELampMapping 2)
Mapping_Nebelschlussl_L_Output -> nsl_l (0x1C)
Mapping_Nebelschlussl_R_Output -> nsl_r (0x1D)

[da jemster]

This is on the E9x platform. The way 19bis is describing it, I think it might be the same instructions: https://www.m3post.com/forums/showthread.php?t=531296

[19bis]

Originally Posted by da jemster

This is on the E9x platform. The way 19bis is describing it, I think it might be the same instructions: https://www.m3post.com/forums/showthread.php?t=531296

Yeah, that's way too complicated. No need to take out the vent and dismantle everything, just pop out the button from the front, trim off the tabs, and reinsert the button.

[F22 Raptor]

Er, uh, I guess what I really like to know is can I make the fog bulbs work as an additional brake light? Has anyone done this? And done it without upsetting the computer?

Thanks for the comments and suggestions, especially 19bis for the lines of code - I'll use them if I go the rear fog route.

[Poochie]

On US-spec vehicles, the "Rear Fog Lights" are already used as emergency brake lights, this is BMW's description of its operation:


The Dynamic Brake Force Display show drivers behind you how heavily you're braking and allow them to react in good time. This drastically reduces the danger of a rear-end collision.

The brake lights themselves are divided into two zones. During normal braking, only one zone is illuminated. When heavy braking is detected, Brake Force Display increases the intensity of the brake lights by illuminating the second zone as well (i.e.Rear Fog Lights).




.

[F22 Raptor]

Thanks Poochie!

Now, how can I test the second stage to see if it is working?

[Poochie]

Originally Posted by F22 Raptor

Thanks Poochie!

Now, how can I test the second stage to see if it is working?

There is no way to test them unless you have someone follow you and confirm they activate, upon moderate to hard braking. If they didn't work, there would be some some sort of bulb error on the dash, indicating the second-stage brake light is out.

Also, if you did the "rear fog light" mod or have a European switch to control the rear fogs, you can code them to illuminate in a steady state.