The pinout below is from testing with a multi-meter. The power supply signal location is tested. Connecting the signal from PIN 8 to Ground will switch the Power on. I can't figure out what PIN 4 is for, perhaps another signal? Pins start from the top right of the receptical and continue on the top row starting the bottom row at pin 5 on the right most side.
The below table is a representation of what the female receptical would look like if you were to look at it straight on with the clip fastener on the bottom. Of course this would be flipped left to right for the cord itself (male end).
Pin 4 is reserved. System is expecting 12VDC 18A.
Dell power supply D220P-01: Except that the diagramme and chart pinout on the web page are backwards compared to the diagramme on the nameplate on the power supply. The operative info is the line "Connecting the signal from PIN 8 to Ground will switch the Power on." When you realise that his Pin 8 (Signal) is really Pin 5 (Remote) then you can jumper 5-6 and the pilot light turns from orange to green and 12v appears on pins 2,3,4. (As indicated on the nameplate.)