I have been fighting this Low resolution issue for quite a while now.
I went back and wired a direct wire just behind the connector on the PCM and straight to the connector on the Intake and I still throw a Low res Code.
I have tried 2 different PCM's and 2 different optis. Well the originall GM opti got eaten by the waterpump and kicked a low and high res failure. I replaced the waterpump and I now have the Dynaspark opti. I did notice when I turn on the ignition, I only read .23 volts. Its suppose to be between 4 and 6 volts.
Any ideas???
Please dont hesitate to voice your opinion!

 

Ok, surely someone on the board has had these simular issues before.
When I disconnect the TEST connector on the Intake. It reads 5 volts when I plug it back in it only reads like .23 volts. I also checked the High res wire and it reads .23 volts aswell.

 

Have you tried Shoebox's procedure:

http://shbox.com/1/4th_gen_tech2.html#opti_test

 

Actually thats pretty much the exact way I checked it. I have a GM 1994 F Car manual at the house. I dont understand the part where shoebox describes the voltage out of the Test connector though. I though the PCM supplies a 5 volt reference to the opti. He said it should test 10volts. I test 5 volts.

 

Ok, after going back and reading Shoebox's page, thats not quite how I checked it. I didnt measure from the ICM, I measure from the PCM.
Ill give that a try tonight.
Thanks