Chevrolet 2003 Silverado 1500 Pickup Owner's Manual page 217

SERVICE BRAKE SYSTEM
If there is a problem with the brake system, this
message will be displayed on the DIC. If this message
appears, stop as soon as possible and turn off the
vehicle. Restart the vehicle and check for the message
on the DIC display. If the message is still displayed,
or appears again when you begin driving, the brake
system needs service.
SERVICE BRAKE BOOSTER
If your vehicle has vaccum assist power brakes, this
message will be displayed on the DIC when there is a
problem with the Supplemental Brake Assist system.
If the message is displayed immediately after starting
the vehicle or the message appears while driving,
your Supplemental Brake Assist system needs service.
See Brake System Warning Light on page 3-40.
YOL. brake system may ..-t be working
properly if the SERVICE BRAKE BOOSTER
message is displayed.
If the brake system warning light
is also on, you
should have the vehicle towed for service. See
"Brake System Warning Light" in the Index.
If the brake system warning light isn't on, you
still have brakes, but the supplemental brake
assist system may not operate properly. In the
event of a vacuum loss, you may not have
vacuum power assist for braking. The brake
pedal will be harder to push and it will take
longer to stop. If you continue to drive with
this
message displayed it can lead to a crash. Have
the brake system serviced as soon as possible.
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