hey guys, i unplugged the O2 sensor to check the voltage so i let the truck warm up and while the sensor was warming up i noticed that the SES light never came on is this normal does the obd1 not check?? or is there a problem with my pcm?? its L98 350 TPI out of a 91 Formula

 

ok answered my own question lol drove while the O2 was unplugged and got check engine light code 13.