Voltage changes 12 to 14 volts constantly

I did a little more browsing in the service manual and came across this DTC
I'm not sure if it applies since it says it is monitored above 1157 RPM.

P2503-CHARGING SYSTEM OUTPUT LOW

POSSIBLE CAUSES

EXCESSIVE RESISTANCE IN THE BATTERY POSITIVE CIRCUIT
EXCESSIVE RESISTANCE IN THE CASE GROUND
(K20) GEN FIELD CONTROL CIRCUIT SHORTED TO VOLTAGE
(K20) GEN FIELD CONTROL CIRCUIT OPEN
(K20) GEN FIELD CONTROL CIRCUIT SHORTED TO GROUND
(Z20) GEN GROUND CIRCUIT OPEN
GENERATOR
PCM