Can you not get a adjustable regulator? I know in my jeep the CPU controlled what my alt would charge at so I had to get an external an bypass it or is that what you already had? I might have missed it.
I looked into it but it's not recommended for me they said .
Page 5-31 of 2011 owner's manual:
The normal battery voltage range
is 11.5 to 15.5 volts. You can monitor
battery voltage on the DIC by
pressing the vehicle information
button until Battery Voltage is
Also from GM service information: 90% duty cycle of alternator will result in 15.5 volt output. 10% = 11volts. This is controlled by the ECM.
Sent from my iPhone using Tapatalk