GMC 2005 Envoy Owner's Manual page 175

United States
This light should come on briefly when you turn the
ignition key to RUN. If it doesn't come on then, have
it fixed so it will be ready to warn you if there's a
problem.
If the light comes on while you are driving, pull off the
road and stop carefully. You may notice that the pedal
is harder to push. Or, the pedal may go closer to
the floor. It may take longer to stop. If the light is still
on, have the vehicle towed for service. See Towing
Your Vehicle on page 4-50.
Canada
CAUTION:
{
Your brake system may not be working
properly if the brake system warning light is
on. Driving with the brake system warning
light on can lead to an accident. If the light
is still on after you have pulled off the road
and stopped carefully, have the vehicle towed
for service.
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