GMC C-Series 2001 Owner's Manual page 152

Driving too fast through large water puddles or even
going through some vehicle washes can cause problems,
too. The water may affect your brakes. Try to avoid
puddles. But if you can't, try to slow down before you
hit them.
4-18
CAUTION:
Wet brakes can cause accidents. They won't work
as well in a quick stop and may cause pulling to
one side. You could lose control of the vehicle.
After driving through a large puddle of water or
a vehicle wash, apply your brake pedal lightly
until your brakes work normally.