OBD2 not communicating

[punkieys17]

On a 2003 W203 C200 Kompressor the check engine light came on.

I connnected an IBM T30 with Xentry and tried to use a Memoscan multiplexer (bought used) but I could not get it to communicate.

The multiplexer kight up both lights - but neither flashed - which i understand inidcates data.

The Xentry started and began opening the communication layer but failed when it could not find the connection - it said it could not find 12v on circuits 30 or 31??

I guessed this may be a fuse problem but the only fuse referenced also services the dipped headlights - which works.

So 2 questions,

1) are there any other fuses I need to check
2) is there any other port (dedicated to the engine?)

Any help greatly appreciated

Julian