Are you talking about the cigarette lighter? Have you checked with a test light that there is definitely no power at the base of the lighter, with the test light grounded, then check the side of the lighter is providing an earth. Key must be in "on" position.

If definitely no power, I wouldn't be swapping the cable. It's probably the fuse, I'd be checking that first.

 

The fuse is ok.
I swapped the whole tray - it didn't help. But it lights up, so it means earth is ok.
Why you're not suggesting to swap the cables?

 

The cigarette lighter is always hot. This is why the BMW I-bus battery tender is plugged into this socket. On the MOST bus vehicles the socket powers down after the ingnition is turned off.

As far as reversing the power leads, the light would most likely be on all of the time and the socket would only receive power if the lights are on.

OP how did you confirm the no power condition? If you used a power adapter it may be making poor contact or, as many of them are fused, the adapter's fuse could be blown. As stated by M5 Sydney a test light or better a DMM is your friend. Good luck.

 

As far as reversing the power leads, the light would most likelynbe on all of the time and the socket would only receive power if the lights are on.

I wouldn't be swapping due to the above. Also I'm guessing the power for the light is supplied by the Light Control Module, and I'm guessing you wouldn't want to draw any more power through it than was intended!

I'd say it's better to get to the source of the actual problem than a dodgy repair. As stated above, I assume you've checked that you definitely have no power and it's not just a bad connection of the device into the socket? If fuse is OK, is there definitely power at the fuse? On both sides when the fuse is in place? Is it definitely the right fuse? If there's power at the fuse and none at the socket, you have some sort of continuity problem between the two. I'm sure someone can post a wiring diagram.

I'm not that good with electrics so if it wasn't too obvious I'd leave the console apart and take it to an auto electrician who could probably identify the issue in 20 minutes! I know when I'm beaten : )

 

It was fuse #7 in the glove box. I was checking #52 and #39 according to instructions below.
I didn't know #7 was responsible for cigarette lighter until I checked WDS

Thank you all! I appreciate your help.