You need to get a scanner for your personal use. Ebay and Amazon usually have the Actron CP9145 scanner, which does obd1 and obd2 cars, for around $140. It not only scans for codes but does running sensor data scans, that can be helpful in diagnosing running problems.
Since you own a 94 with a 12 pin dlc connector, you would also have to buy the Actron CP9127 adapter for about $30
Another alternitive would be to turn your laptop into a powerful scan tool. You will need a special cable to connect car's dlc to usb port on laptop. You can get at this site ALDL OBD1 OBD cable OBDI OBD2 engine codes $60 for cable. For your program you can use the trial version of DataMaster available at TunerCat Gives you 20 free data logs and unlimited data playback. DataMaster is an excellent scan program and you can playback your sensor scans in realtime. That way if you need help, you can upload to web for members to view your sensor data.
Another good scan program is freescan. The site is currently down, but if you want freescan, pm me with your e-mail address, and I'll send it to you. Freescan, as name implies, is free for life.
DataMaster, if you wish to scan after the 20 free ones, is about $90
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