Check engine light came on so I checked it with a code reader and the code came up P0562, which means low voltage in the system. I have disconnect the battery to reset it which it does for a day or 2 then the code comes back. The jeep is an 08 with a 130k on it. The battery is a yellow top with about 4 years on it. There are no other issues. what are your thought s alternator? Battery? wiring? what is most common? and if it is the alternator is this a difficult job to do by one's self. if it is the alternator I would like to upgrade to heavy duty alternator. so what recommendations do you have? How can I tell for sure if it is the alternator or something else.

Pep boys gave me a 16 dollar quote whelk menace said 60 for an eval of the charging system . Is there a better way with say a multimeter? Any suggestions?
rj'sjeep is offline

 

Check the battery voltage a couple hours (24 hours would be better) after shutdown. Should be more than 12.6 volts.
Then, start it up and check the battery voltage with the engine idling. Should be about 14.3 volts.

 

So I tested the battery as it sat there with no draw a solid 14.2 turned on the motor every thing I have electric in the jeep lights, high beam radio, ac, and 800w power inverter , window wipers , and the voltage reader says 16.4 so I think this means it is not the battery or the alternator.

Question is though why am i slithering a p0562 code and the check engine light is still on?

 

So, what is the battery voltage with the engine off a few hours after shutdown, and what is the voltage with just the engine idling?

 

14.2 running at an idle seems normal, however 16.4 ( if that is the correct reading), is way too high. Sounds like the voltage regulator is shot. But then again I don't see how you are running 14.2, which is a pretty good reading, yet it jumps to 16.4 with all those components on and getting a higher reading. By the way a P0562 code is system low voltage.
And as ronjenx stated, let the battery sit for a couple hours, then check it with your multimeter with the engine NOT RUNNING. If the battery reads less than 12.6 I would say that is the culpret.
Check your connections at the battery and alternator, also the grounds.