GMC Yukon XL Denali Owner's Manual page 328

10-12 Vehicle Care
Change the fluid and filter at the
scheduled maintenance intervals
listed in Maintenance Schedule on
page 11 3. Be sure to use the
transmission fluid listed in
Recommended Fluids and
Lubricants on page 11 12.
How to Check Automatic
Transmission Fluid
Notice: Too much or too little
fluid can damage the
transmission. Too much can
mean that some of the fluid could
come out and fall on hot engine
parts or exhaust system parts,
starting a fire. Too little fluid
could cause the transmission to
overheat. Be sure to get an
accurate reading if checking the
transmission fluid.
Before checking the fluid level,
prepare the vehicle as follows:
1. Start the engine and park the
vehicle on a level surface. Keep
the engine running.
2. Apply the parking brake and
place the shift lever in P (Park).
3. With your foot on the brake
pedal, move the shift lever
through each gear range,
pausing for about three seconds
in each range. Then, move the
shift lever back to P (Park).
4. Allow the engine to idle
(500 800 rpm) for at least
one minute. Slowly release the
brake pedal.
5. Keep the engine running and
press the Trip/Fuel button or trip
odometer reset stem until
TRANS TEMP (Transmission
Temperature) displays on the
Driver Information Center (DIC).
6. Using the TRANS TEMP
reading, determine and perform
the appropriate check
procedure. If the TRANS TEMP
reading is not within the required
temperature ranges, allow the
vehicle to cool, or operate the
vehicle until the appropriate
transmission fluid temperature is
reached.
Cold Check Procedure
Use this procedure only as a
reference to determine if the
transmission has enough fluid to be
operated safely until a hot check
procedure can be made. The hot
check procedure is the most
accurate method to check the fluid
level. Perform the hot check
procedure at the first opportunity.
Use this cold check procedure to
check fluid level when the
transmission temperature is
between 27°C and 32°C (80°F
and 90°F).