Low voltage

Check your voltage at the dash. Is the dash gauge going bad.
1 Bad battery.

My truck holds steady at 14.2 volts. I would buy an alternator along the way. To have it and Change when I get delivered.
What motor, year. Your unit may not tolerate lower voltage charging and shut down. Maybe this thread has some information. Good luck'

.Low voltage warning | TruckersReport.com Trucking Forum | #1 CDL Truck Driver Message Board (thetruckersreport.com)

 

I’m having a similar issue. 2008 freightliner century with 14L 60 series. So, I have one more issue that I’m trying to figure out. Do you know which wire goes to the plug for the voltage gauge? I’ve tested and cleaned everything. I’m getting the same voltage at the batteries, the jump post, the back of the alternator, and the starter. Usually 14.2 while engine is running and 12.7 while engine is off. But for whatever reason, the voltage gauge reads 9-10 and I have a message on the dash that says warning, low voltage. I’m thinking maybe the wire going to the ecm or dash cluster maybe the culprit. Any help would be greatly appreciated! Thanks