hi all in Yukon 07++
This fluctuation with the RVC system is normal system operation. No repairs should be attempted. Refer to the owner manual Section 3 (Instrument Panel) Voltmeter Gage for more information.
TIP: Refer to PIT4426 for concerns with keeping a camper or trailer battery properly charged.
this is quote from GM tech link ,, because the volts is between 12.7 and 15
so if there is fluctuated volts because the car in fuel economy mode ,, so how to check the alternator ?
I think we need to exit the economy mode but I don know how ?