I did some bios updates on toughbooks some years ago, but since my last ultimate fail (I bricked a CF-M34 mk2 thanks to a bad version of the bios update), i didnt try again.
Anyhow, if my memory still works good, the EC update works the same way as the bios update.
What i did was this:
take a spare harddrive (the smaller the better, example 2 or 3 gigs)
format on another computer with MS-DOS 6.2 or so.
put both the EC update and BIOS update in 2 seperate directories (to make sure you do NOT mix them up)
insert harddrive in your CF-17
go to the directory of the EC-update, run the ec-update (its a .BAT or .COM .EXE file.....)
i think, after the update the CF-17 reboots.
then run the BIOS update.
Maybe some other members of this forum know more about this .
Update: I found this information that is the solution for your problem:http://toughbook.wikispaces.com/message ... 4/32850336
of course you have to use the EC and BIOS update for your CF-17 and not for the CF-M34.