GMC YUKON XL 2003 Manual page 302

The following steps must be performed on each of the
push-pins to remove the air dam:
1. Insert a tool into the
push-pin slot and pull
downward until the
push-pin snaps loose.
2. While continuing to pull
downward on the
push-pin, squeeze and
turn the expandable
end of the push-pin
with a tool until it
releases from the
retainer.
I
3. Pull the push-pins and
lower air dam assembly
away from the
retainers until the lower
air dam is free.
When you're back on roads, though, be sure to replace
the air dam.
Notice: Operating your vehicle for extended
periods without the front bumper lower air dam
installed can cause improper air flow to the engine
and may allow things like fog lamps or tow hooks
on the front of your vehicle to be damaged. Always
be sure to replace the front bumper air dam when
you're finished off-road driving.
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