I have a 89 LX that will give no data. Everytime you hook up the computer to it to try to get codes it will not give anything except with key on engine off. Once you go into the part of the test where you need to start the car it gets to the point where it is suppose to rev up the motor and hold the RPM's at 1500 it revs up and goes right back to idle. The only codes that come up is when its key on engine off and you get an EGR code which is normal because theres not one on the car. We tried acomputer A9L out of a 92 stang and it did pretty much the same thing with the exception of when you started it when it would get to the part where it is suppose to rev up and hold the RPM's it would rev up a little and actually hold the RPM's around 11-1200 but the test would still not complete itself. So I got a harness off of a 90 and hooked it up last night and only to find out that the car would not start. I have been informed that the 90 is only good on the 90 it will not work on a 89 w/out some serious modifying. So I dont know what to do. I am tired of spending money on stuff that doesn't work. So with all that being said do I really have a harness issue or a computer issue that I cant retreive any data?