You may be able to read the codes by putting the ECM into diagnostic mode and reading the ECU flashes. Using an LED takes a bit more work as that thread explains. It's not just an LED with a couple of wires attached to it.
But, since you found that thread you are on your way. Let us know if you have questions.
Gone, out doing soft recreational past time with overpowered boat!
ALABAMA'S #1 BANDWAGON FAN!! AND DOESN'T WANT TO WAIT UNTIL 2014 TO PLAY THE ONE AND DONE CREW!!!