I have a 2002 Jeep Grand Cherokee Laredo. 6 Cyl/4.0. I am having a strange charging problem that I hope some one can help me with. It has a new alternator already, and the battery tested ok.
Here's what it's doing. Upon startup, the voltage gauge is fairly stable, it fluctuates slightly. As the vehicle warms up, it gets worse, and will vary between a little above 14 on the gauge, to almost down to 9 on the gauge, It does this continuoulsy back and forth, almost as if it's "Hunting". I'm questioning the PCM I guess, as well as the Battery Temp Sensor.
Also, sometimes at idle, the voltage will fall real quick, and the engine changes in sound, almost as if there was a sudden load put on the alternator. When this happens, I get a good amount of engine noise through a subwoofer I have in the vehicle.
Sorry for a long post, just trying to remember all the info I can for you. Thanks in advance.