I've been having trouble out of my charging system. I put a volt meter on it at work The battery read 12.6v with the truck off. With the truck on it read 12.4v. It has a brand new battery and a I've tried two different alternators. I checked the wires going from my alternator to the regulator and noticed 4 wires that had been cut and spliced together two are yellow on the other two appear to be black but one of those is the charging wire on the alternator. Now when I run the truck my volt meter in the cab drops way down when I turn the lights on or the blower. And when the blinkers are on the Gage will move with the blinkers it's never done that before. I can post pics of the wiring and everything described. Thank you for any help

 

first thing I would check is your grounds to engine block and frame.
also there is a small one off the battery to the radiator support.
a another one under the bed past the axle on drivers side ,frame.

 

You have already started a discussion/thread on this same subject. I would go down to that thread and report what you have found and we can work on it with a little history in mind.