GMC 2010 Yukon/Yukon XL Owner's Manual page 253

The speedometer shows the vehicle's speed in both
kilometers per hour (km/h) and miles per hour (mph).
The odometer shows how far the vehicle has been
driven, in either kilometers (used in Canada) or miles
(used in the United States).
The trip odometer can show how far the vehicle has
been driven since the trip odometer was last set to zero.
Press the reset button, located on the instrument panel
cluster next to the trip odometer display, to toggle
between the trip odometer and the regular odometer.
Holding the reset button for approximately one second
while the trip odometer is displayed resets it.
To display the odometer reading with the ignition off,
press the reset button.
The tachometer displays the engine speed in
revolutions per minute (rpm).
When the engine is started, a chime sounds for several
seconds to remind a driver to fasten the safety belt,
unless the driver safety belt is already buckled.
This chime and light sequence are repeated if the driver
remains unbuckled and the vehicle is in motion. If the
driver safety belt is already buckled, neither the chime
nor the light comes on.
The safety belt light
flashes for several
seconds, then comes on
solid for several more.
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