I inflated 1 tire (BMW 2017) and it worked great. Switched to the 2nd bus but it won't turn on. The tired block on the cigarette lighter of my concern (MB) did not turn on. A spare fuse was supplied with the unit so I attempted to replace the fuse. The fuse is located in the cigarette lighter module. I open it and find a blown fuse. I couldn't put the pieces together because it's spring loaded and it would be VERY difficult to put everything together. Also, I had no idea if the second fuse would blow as well. return of the device. We easily charge mobile phones, MP3 players and other devices using the cigarette lighter. Bad block or just bad design.