1996 converted to OBDI.
I've put two different scan tools on this car and both cannot connect to PCM. When I was tuning the car I ran into intermittent connection problems as well.
I've tested port 9 (wire to PCM) to port 5 (ground) for resistence and voltage. I'm getting 1Ohm of resistence and approx 6v with the key forward (engine not running).
I followed these steps using the Chiltons manual. It does not give a voltage value. It just staes that if there is no resistence and if you see voltage then that part of the test is over. I have yet to test resistence by poking a volt meter from the data port to the PCM port though.
I am thinking there is a problem with the PCM itself. I have a SES light on and am trying to figure out what it is, but with this problem.. to no avail. I'm wondering if the PCM is throwing out bogus trouble codes and is on the verge of death...
Any suggestions or steps by those who may have gone through the same thing?

 

If anyone cares....
Come to find out all the scanners I used were OBDII only. I wasn't told that until AFTER they didn't work.
Was able to get the code using my cable and a friend's laptop.... bad knock sensor. Replaced it and the jalopy runs like a top!