Just put Rusty (2002 MCB, CVT) back together and got her off to the alignment shop. While reassembling, I found this wire hanging around the aft ECU cable. I don’t remember taking this off of anything and I don’t see anything in the driver’s side corner of the firewall it would attach to. The brake sensors and airbag inertia sensor are accounted for and plugged in. Any ideas? I looked in the service manual to see if there is a battery temp sensor or something else up there, but there’s nothing that jumps out.

 

@Chris In Milwaukee Looks like the harness that plugs into the other end of your CVT rotational speed sensor. (on the transmission housing)

https://www.realoem.com/bmw/enUS/sho...diagId=24_1007

 

Thanks! I’ll give it a look.

 

I checked that sensor and everything is connected properly. And that particular sensor is farther away than the plug will reach. I’ll keep looking, though. Appreciate the suggestion.

The wire naturally “falls” around where the brake hardware is but I couldn’t find anything in that opening. But there are no errors that I can see.

 

I will go out and see if i can find that on mine for you, though mines an 04 , 6spd ,s
but ille still check
if i were you I would get a top for the ecu box asap to help protect it.

 

I agree. A battery hold down would be great, too.

 

Sorry but no such cable in my car anywhere , I even have most that separator removed behind the airfilter...
possibly it it to something on or with the auto trans , maybe at sometime it got disconnected and forgot about and over time and owners or something its been routed out of its stock position.

 

No worries. Thanks for looking. No error codes that I can tell so far, so I’ll leave it until otherwise needed. When I’m under it changing out the O2 sensors this weekend I’ll take a peek from a different viewpoint.

 

If you have a wiring diagram for an automatic 2002 R50, the wiring colors should provide a clue.
Just 2 wires, red & blue? Any tracers?

 

No tracers that I noticed, but I haven't tried to pull back any tape or loom to get a better look. I've been looking through the schematics in the Bentley manual close to the ECU system and battery system since that's what the cable is close to. But I haven't turned up much. Now that you mention it, I thought I remember seeing a connector list in the manual. Maybe I can look for colors as you described. I'll give that a go. Thanks for the alternative view.