GMC 2007 Yukon XL Owner's Manual page 447

Then, without shutting off the engine, follow
these steps:
See Engine Compartment Overview on page 436
for more information on location.
1. Flip the handle up and then pull out the
dipstick and wipe it with a clean rag or
paper towel.
2. Push it back in all the way, wait three seconds
and then pull it back out again.
The transmission
dipstick handle with this
graphic is located at
the rear of the engine
compartment, on
the passenger's side of
the vehicle.
3. Check both sides of the dipstick, and read the
lower level. The fluid level must be in the
COLD area, below the cross-hatched area, for
a cold check or in the HOT or cross-hatched
area for a hot check. Be sure to keep the
dipstick pointed down to get an accurate
reading.
4. If the fluid level is in the acceptable range,
push the dipstick back in all the way; then
flip the handle down to lock the dipstick
in place.
447