Just to clarify: LCD = Liquid Crystal Display, LED = Light Emitting Diode.
I just read the codes out on my '93 SPFI Loyale, so I hope this helps. Connect the read (White) connectors under your hood and return to the passenger compartment. You are looking for a hole with an LED in it, not an LCD. When you are looking at the mounted ECU (under the dash) it's going to be on the the side that points towards the driver (my LED is red, I'm not sure if all of them are this color). You will have to remove a few screws & plastic clips to get the panel that's directly under the steering wheel off. There will probably be a black plastic hose/duct that is attached to it, that's for your A/C / heater - leave it attached and let the whole panel dangle. To actually count the flashing on the LED, I had to get on my knees, outside of the car and lean under the steering wheel, while turning the ignition to the "on" position (do not start). Count the number of long and short flashes from the LED from the ECU under the dash and check it against this list: http://www.troublecodes.net/Subaru/
I have a bad EGR valve/solenoid, so the code, looked something like this:
"_ _ _ ...." which translates to "34"