Bought a new alternator and battery still won' charge

Hello, The voltage regulator inside the powertrain control module (PCM) may be to blame, but when the issue is undercharging, installing a new regulator will not assist with the issue. The PCM limits power, so if resistance is too high, the power coming out is already below the threshold of the new voltage regulator. So, what I suggest is to measure the voltage output from the PCM where the original voltage regulator is installed, then measure the output at the bolt-on wire connection on the back of the alternator. Alternator should be putting out slightly more than the PCM. Now, if the PCM is receiving less voltage than the alternator is putting out, time to look at fusible links. If the PCM is putting out more than is arriving at the battery, time to look at fusible links. Long story short: follow the charging voltage from the alternator and see where you are losing voltage. The voltage drop will tell the story of the failed part.