ISTA Wiring colours/F01 brake light wiring colours

[Eddles]

Hi all,

I'm installing a new tow-bar on my 2010 F01 740i. I have an aftermarket vehicle specific towbar electrics package with CANBUS connection. Despite the CANBUS connection, it still has to be manually connected to 2 wires, as shown in steps 14 & 17 in the picture attached.

Step 14 shows that I need to connect the brown/blue wire to the brown/blue wire at the outer right rear light cluster, which I have done. Although it's a bit confusing as it mentions the 3rd brake light which is the incorrect location, so I think this is a typo. In step 17, it states I have to connect the yellow/black wire to the yellow/black wire under the scuff panel on the rear left passenger door leading to the high-level 3rd brake light. I am not really keen on having to run the wire all the way from the outer right rear light cluster to the rear left passenger door, but I'm a bit confused why this is necessary to connect to the 3rd brake light, as it should be the same as the rear brake lights? The ISTA wiring diagram shows that it's wired separately to the rear clusters, however. The space under the scuff panel is extremely tight too, not a lot of space for proper soldering work which I prefer to do.

I have spotted a yellow/black wire leading into the tailgate above the rear fuse panel (top of the picture in Step 14) however I am not certain whether this is the same black/yellow wire as the one under the scuff panel. I have found the relevant wiring diagram on ISTA, but it does not display the wiring colours. So I can't determine whether the wiring is the same.

I'd really appreciate advice on how to find the wire colours on ISTA, please.

Many thanks in advance!

[Wingman]

Hi Eddles, I was just wondering if you got this resolved. I just picked up my F01 730d last weekend and currently going through a towbar install. I too would prefer to attach to the 3rd stop light and avoid the location you've found. Any help would be appreciated.

[Eddles]

I eventually installed it as per the instructions. There is a plastic channel under the boot floor that contains many wires, in which you may find the correct wiring, but it was too difficult to look through, and I had to undo a lot of wrapping. I eventually just did what the instructions said and connected it where the picture showed. I had to remove the seat back & bottom, but it wasn't too nightmarish as I thought. Good luck!

[Wingman]

Thanks for getting back to me. I didn't want to go digging so I wired it to the left rear brake lamp supply. All appears to be working ok so far so fingers crossed.