http://en.community.dell.com/support-forums/desktop/f/3514/p/17191491/17315349.aspx


......................O
.PWR LED- O O
.HDD LED- O O HDD LED+
.................... O O
.................... O O
.................... O O PWR LED+
.................... O O
...PWR SW O O PWR SW
.................... O O
.CON CNT O O CON CNT

The 2 CON CNT pins are connected by a jumper on the plug.

Take care to note the missing pin in the top corner. This marks the orientation of this diagram.This only relates to Power switch, HD, and Power LEDs.

The Dell front panel connector wiring is a Dell proprietary and undocumented.  You will have to take an ohmmeter and try to trace out what is what.