Chevrolet 2004 Monte Carlo Owner's Manual page 149

Voltmeter Gage
If the gage reads less than 12 volts or more than
16 volts while the engine is running, and it stays there,
you may have a problem with the electrical charging
system.
Also, when your gage reads less than 11 volts or more
than 16 volts, your battery life indicator will be
illuminated in the message center. For more information
see Battery Warning Message on page 3-45.
If your vehicle is equipped
with the 3800 V6 engine it
has a voltmeter gage
that indicates battery
voltage.
Brake System Warning Light
Your vehicle's hydraulic brake system is divided into
two parts. If one part isn't working, the other part can
still work and stop you. For good braking, though,
you need both parts working well.
If the warning light comes on, there is a brake problem.
The LOW BRAKE FLUID message in the message
center will also appear when there is a brake problem.
See Low Brake Fluid Warning Message on page 3-50.
Have your brake system inspected right away.
United States Canada
3-35