Silverado Volt Guage

[GUEST]

I took my new 2011 Silverado 5.3 to the coast;the volt guage started reading 15+ for 10 minutes then 12 flat for a while then back and forth. On the way back it behaved normally. Is there anything other than the Voltage Regulator that could cause this?
Thanks
Richard

[carriedi]

the alternator is run by the ECM. the alternator field duty cycle signal circuit is a pulse width modulation signal of 128 Hz with a cycle of 0 to 100%

10% - 11V
100% - 15.5V

the information is sent to the BCM. the BCM sends the signal to the dash.

Since it is working normally now it may be difficult to find out what happened. If it was something on going you could measure the battery voltage at the battery to see if the gauge matches up with the actual battery voltage. If the alternator output voltage matches the battery voltage.

the ecm, bcm, battery current sensor, alternator, gauge and any connection between those and the battery could cause a problem in the circuit. But if it working normally now it probably won't show anything. You could use a scanner and see if the charging system shows a code for the battery voltage jump and drop.

[guest]

The battery Voltage matches the gauge at idle and a bit higher. It repeated the same sequence yesterday, over 15 V for 10 minutes then 12.5 for a while. I took it to the dealership ,they analyzed and said nothing wrong. Am I correct that over 15V will eventually damage the battery and alternator?
The battery current sensor is cheap and seems like a suspect.
Thanks
Richard

[carriedi]

15v won't damage the alternator but it could do harm to the battery if it is done a lot over time.

if the sensor is inexpensive and easy to replace I would say to try it. Why not? It can't hurt. the 12.5 to 15.5 is within the operating range I just don't know why your computer is activating the alternator the way yours is acting.