GMC 2010 Sierra 1500 Crew Cab Owner's Manual page 273

Here are some situations owners can experience with
the fuel gauge. None of these indicate a problem with
the fuel gauge.
At the gas station, the fuel pump shuts off before
the gauge reads full.
It takes a little more or less fuel to fill up than the
fuel gauge indicated. For example, the gauge may
have indicated the tank was half full, but it actually
took a little more or less than half the fuel tank's
capacity to fill it.
The gauge goes back to empty when the ignition is
turned off.
For a diesel engine, see Fuel Gauge in the Diesel
Engine Supplement.
This light and a chime comes on when the fuel tank is
low on fuel. The Driver Information Center also displays
a FUEL LEVEL LOW message. See
When fuel is added this light and message should go
off. If it does not, have the vehicle serviced by your
dealer.
This light, under the fuel
gauge, comes on briefly
while the engine is being
started.
for more information.
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