Hi I'm Jason. I joined this forum because I'm somewhat mechanically inclined but there's alot I'm still learning. I own a 2002 Dodge Ram 1500 Quad cab.....it has a 4.7 magnum gas engine with over 200,000 miles....it still runs strong...it has an automatic transmission....im having a problem with the charging system that didn't occur until after I replaced the factory radio, after I did that the alt gauge showed very little charge and the dash lights didn't work...my battery went dead on the way to work. I was wondering if anybody else had this problem and if it might be connected to changing out the radio.

 

Likely popped a fuse somewhere.

 

I rec you start by logging voltages and see if that leads to the problem. What is your static battery voltage? Should be at least 12.4v. What does the voltage drop to during start? Should be no lower than 9.6V. What is the battery voltage with engine running and gauge showing low charge?
For the new head unit, what install kit did you use? Some have those square black dongles that will draw power if they are defective.

 

Try removing the radio and leave it out and see if the truck is charging.

 

Immediately after? Pull the alternator (pretty easy on the 4.7) and take it to a parts store to be tested.