I have code P1594 which refers to the charging system. When I check the battery voltage it shows 12.5 volts. With the engine running, the voltage at the battery shows 13.5 volts. This is not too high. What else could cause this code?

Any solution ??

 

It's your alternator. It's getting ready to go out on you.

 

Voltage regulator in the alternator. You can change that yourself if you feel like it. Take the alternator to a shop they can fix it cheaper than buying one from auto parts store.

 

Check the voltage at the big stud off the back of the alternator. See if it matches the voltage at the battery. It's probable your alt is failing but dirty battery cables and corroded wiring between the battery and alternator can cause this symptom too.

 

Reset the PCM my unhooking the battert for a few minutes, if it comes back on you have a problem for sure.

In the winter and when its cold my Volt meter reads about 14.5v, and my multimeter agrees with it, I havn't throw a code ever.

 

With the Magnum engines Dodge put the voltage regulator inside the PCM computer...which makes it an expensive repair....and there is also a battery temperature sensor underneath the battery tray whose signal is used by the PCM to dial back the voltage in hot weather and ramp it up in cold weather. An out of whack battery temp sensor could cause the voltage to be unacceptable to the PCM computer.