Quick ECU question

Ok, i just slapped my autometer tach on my 1990 integ ls, the problem is that i dont know which pin on the ecu to connect my wire to.... can anyone with a helms or a good mind on 2nd gen ecu diagrams tell me which wire pin controls the tachometer????????????

dont all integras have tachs already?
anyways, when i got my car the monster tach was hooked up to the black wire from the plug that has the blue/black and black wire, but then when i checked for thrown coeds a electrical load was detected, but it didnt make the CEL come on.

monster tach was hooked up to the black wire from the plug that has the blue/black and black wire

where would this plug be located at ..... by the ecu?...... ohh yea and yes my integ has a tach already i just slapped a monster tach on too

its by the distributor, and mine only had one cuz the car idnt but i swapped in a cluster with one and then i took it out.

always wondered, what exactly is "ECU"................yes i am a newb

my guess is electronic control unit, not sure though

Thanx for the help got my tach up and running ..... just spliced the blue wire by the dist.