Got a 1995 Camaro 3.4, car runs and drives just fine. Although often it is somewhat hard to start... just have to keep cranking it. Once started runs fine. Also when driving the service engine soon light comes on and off constantly. NOT blinking, just off and on all the time. Ive used a scanner capable of OBD1/OBD2 reading, with 2 different OBD2 cables, and also tried an OBD1 cable with jumpers going to the correct pins on the DLC. I cant get to read to pull any codes. Also I just fixed an exhaust leak by replacing the egr adapter gasket and put in a new fuel filter. I thought that might have taken care of the issue but guess not. Also not sure if this is normal but the electric fan randomly seems to run at times before the car is even up to operating temp, often when the car is first started up. Also theres a loud whining sound that increases with RPM that seems to come from the alternator, volts on gauge read ~15.5 or so

 

You really need to get the communication problem fixed. Then get the codes.