I own a 2010 Avalanche with a towing package and a 5.3 Ltr v-8. I love the vehicle. I noticed lately that the voltage gauge on my dash shows 1 bit over 14 volts when I start it up and then after maybe 10 miles of driving, it slowly drops off to 12.8 volts. I have had an auto parts store put a tester on the battery and they said it was good. They also loaded down the alternator from the battery posts as well and the alternator produced 14.4 volts.
If while the dash voltmeter shows 12.8 I shut the engine off and immediately start it, the voltage shows 14+ volts and starts the process all over again.
I never noticed this before. Do I possibly have this in "towing Mode"?
I replaced the belt and tensioner pulley but voltage drop was confirmed with a good voltmeter at the battery.
I do have the engine package that switches between 4-8 cylinders.
Whether I am in 4 or 8 cylinder mode, it seems to make no difference on the voltage drop...
It can run for days fixed on the 14 volt reading and then like this morning, drops off the 12.8.
I did notice that it was coming back up to 14 after being fixed at the 12 volt voltage.
Should the voltage swing like this or do I have a regulator going bad.?
Any help would be appreciated..
Jerry
