I have an 04 F150 with the 5.4l. Recently my voltmeter either reads high or low once in awhile. Do I replace the alternator or just the voltage regulator? No other issues have been happening electrically. Not to mention, where the heck is the voltage regulator? Somebody please send a pic of the regulator. Waaaay too much info on the internet lately. Thanks

 

The regulator is internal to the alternator and is controlled by the PCM.

 

^ exactly what glc said.

There is a 3 pin connector on your alternator for this.

 

Before replacing ANYTHING, get one of those voltmeters you can plug into the lighter. You need to know if you have an actual problem with the voltage or if you have a METER problem in the cluster.