Chevrolet 2004 Blazer Owner's Manual page 96

4HI (Four-Wheel High): This setting engages your
front axle to help drive your vehicle. Use 4HI when you
need extra traction, such as on snowy or icy roads,
or in most off-road situations.
4LO (Four-Wheel Low): This setting also engages
your front axle to give you extra traction. You may never
need 4LO. It sends the maximum power to all four
wheels. You might choose 4LO if you were driving
off-road in sand, mud or deep snow and climbing
or descending steep hills.
Indicator lights in the buttons show you which setting
you are in. The indicator lights will come on briefly when
you turn on the ignition and one will stay on. If the
lights do not come on, you should take your vehicle in
for service. An indicator light will flash while shifting.
It will remain illuminated when the shift is completed.
Shifting from 2HI to 4HI
Press and release the 4HI button. This can be done at
any speed, and the front axle will lock automatically.
Shifting from 4HI to 2HI
Press and release the 2HI button. This can be done at
any speed, and the front axle will unlock automatically.
2-30
Shifting from 2HI or 4HI to 4LO
To shift from 2HI or 4HI to 4LO, the vehicle must be
stopped or moving less than 3 mph (4.8 km/h) with the
transmission in NEUTRAL (N) in vehicles equipped
with an automatic transmission or the clutch pedal
engaged in vehicles equipped with a manual
transmission. The preferred method for shifting into 4LO
is to have your vehicle moving 1 to 2 mph (1.6 to
3.2 km/h). Press and release the 4LO button. You must
wait for the 4LO indicator light to stop flashing and
remain illuminated before shifting your transmission into
gear or releasing the clutch pedal.
If the 4LO button is pressed when your vehicle is in
gear and/or moving, the 4LO indicator light will flash for
30 seconds and not complete the shift unless your
vehicle is moving slower than 3 mph (4.8 km/h) and the
transmission is in NEUTRAL (N) or the clutch pedal
engaged.
On automatic transmission equipped vehicles, if your
transfer case does not shift into 4LO, your transmission
indicator switch may require adjustment. With your
transmission in NEUTRAL (N), press and release the
4LO button. While the 4LO indicator light is flashing, shift
your transmission into PARK (P). Wait until the 4LO
indicator light remains illuminated before shifting
your transmission into gear. This will get you into 4LO,
but you should take your vehicle in for service to
restore normal operation.