Q: If there is voltage showing on a meter on the negative side of an injector what does that mean?

Troubleshooting injectors if I have voltage coming in on my meter on the negative side of the injector and I have 12 votes on the positive side does that mean that I have a faulty ground Also I am trying to figure out if my ECU is badd my truck will not idle over 600 rpm even at cold start the fan clutch is not engaging and it stalls when I come to a stop after the vehicle is warm and it is automatic check engine light is on and every time that I have plugged into a computer it keeps saying that the idle air control valve is badd in or the mass airflow sensor however I have replaced both of them and they are within within a month old in were brand new And I would like to know if my truck was manufactured in 09 of 96 and it is considered a 97 the port for the computer on it is an OBD2 however every computer that I plugged into it does not register on the ECU in it is seeming as if it is still operating on obd1