The PCM has other 12 volt hot wires to it plus 12 volt key on wires so it will still know battery voltage but maybe not as accurate as the blue sense wire may be. But as a Mopar tech for many years most all of the ones in the 80's through the early 2000's just used the battery wire to the PCM for battery reference volts. So I would think you will be fine but you will know if you put a load on the system and the alt puts out more/enough amps to keep the system supplied and the battery at the reference volts. Ron