Truck Repair: 2007 freightliner century fault codes

Question
I am getting 2 fault codes: inst volts low 140 168 01, and Low 137s004 01, do you know what these codes mean? I am also noticing a voltmeter problem. at idle my voltmeter is around 14 amps. while driving it drops to 13.25-13.50. could this be a bad alternator?

Answer
I tried to google your codes and it doesn't really bring anything up. With key on engine off it should show 12 volts. with engine running should show 14 volts. when you turn your lights on it should dip down for a second then pop back up to 14 volts anything over or under is usually a issue with a alternator regulator which is internal of the alternator. If your wanting to tackle it yourself first thing I would do is get you a battery load tester. undo your battery cables and load test your batteries to make sure none of those are bad and giving you a bad reading. Then with the engine running load test your batteries again. Most load testers have a feature to load test to check if the alternator is putting out the proper volts.
As for your codes call a freightliner dealer I've always had good luck with telling them the code and them telling me what it means without charging you for it.