how do i read the ecu code?

i have an 89 240sx with single cam ka, automatic

when it warms up it misfires.. i've changed maf, tps, temp sensor and i'd just like to know if it's throwing a code.. there is no CEL on the dash (at least not one that i can see)

what do i have to hook up or which wires do i have to jump to get the ecu to flash a code at me?

you pull out the ecu from under the pass. kickpanel, and on one side, there is a hole, with a red led inside, and what looks like, a flathead screw, you turn the screw all the way to the right and hold for a couple seconds, and then turn the screw all the way to the left and hold. And if the key is in the ON position, it should start reading codes.

to set it back to normal, do the same thing again, and that will take you out of diagnostic mode.