Does anyone know how to check diagnostic codes?

[Glyph]

I have a 93 240sx vert and it's having major probs. The check engine light just came on and I'd like to read the error codes if possible. Is it? and if so how would I find out what they mean? Thanks for any help. -Glyph

[S14toRPS13]

I used the Chilton manual. I gotta double check if I can find my manual, but you gotta turn the dial on the side of the ecm counterclockwise and hold for about 5 sec. Then turn it back clockwise. The little red bulb should start flashing with codes. The manual will tell you what these codes mean.