I've been trying to find the install drawing for this...  do any of you have one that I can look at?

Harness is P/N 71602358924

https://shop.maxbmw.com/fiche/PartsDetails.aspx?source=catalog&vid=52635&brand=BMW%23&diagram=LI_LEDADDON

- Identify the wires (pos and neg) by testing on a battery or 12 volt source. You can't damage it. I can only see a black wire and I'm not willing to bet that it's the earth wire
- Take the cover off the tail hump
- connect the earth wire to the brown wire
- connect the positive wire to the slate/yellow wire (grey with a yellow tracer, if you like)

Job done.

If you're talking about physically mounting it,

- see where the bracket sits in relation to the lower edge of the numberplate with the light along the lower edge of the numberplate
- mark the mudguard
- offer up the bracket to the same position
- drill holes as necessary
- you may need to drill the numberplate too to put bolts through both items and ensure it will sit back where it came from
-- alternatively, mount the bracket to the mudguard using dome head allen bolts because they are fairly low profile
-- remount the numberplate with double-sided tape which should be thick enough to clear the dome heads

[Edited in line with Duck's correction. Gah. I blame the 10yo port and the fact that I couldn't be bothered to find my glasses when looking at the wiring diagram]

Gray/Black is the tail light

Gary/Yellow is the brake light

If you want it to flash and then go solid I use these for my add-on LED brake lights:

https://www.ebay.com/itm/174157628360

Thanks Dai and Duck...  Figured it out with the bench battery..

Red and Brown were obvious.. (Pwr & Grnd) .

Grey/White was the tail lamp and the Yellow/White wire the brake light.

I basically hooked up the red and  Grey White together to the tail light then ran the ground to the ground to the assy. ground...  Paralleled the brake light with the existing circuit.   No issues with the BMU after install.

Duck, thanks for the link to the modulator  may use that on the brake light LED circuit..

Interesting that on my other K I have the same unit (but with red cover over white LED's) that I bought when these first came out and it pulses for a while then goes steady...  This new just goes on.  It has a white lens and red led's...

Got this from MAX's BMW.