2001 GMC ENVOY service indicator

2-32
Electronic Transfer Case (If Equipped)
If your four-wheel-drive
vehicle has the electronic
transfer case, the transfer
case switches are to the
right of the steering wheel
on the instrument panel.
Use these switches to shift into and out of four
-wheel
drive. You can choose among three driving settings:
2HI: This setting is for driving in most street and
highway situations. Your front axle is not engaged in
two
-wheel drive. When this lamp is lit, it is about
one
-half as bright as the others.
4HI: 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: 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 switches 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 switch. This can be done at
any speed, and the front axle will lock automatically.
Shifting from 4HI to 2HI
Press and release the 2HI switch. This can be done at
any speed, and the front axle will unlock automatically.
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
ProCarManuals.com

2-33
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 switch.
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 switch 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 switch. 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.Shifting from 4LO to 4HI or 2HI
To shift from 4LO to 4HI or 2HI, your vehicle must
be stopped or moving less than 3 mph (4.8 km/h) with
the transmission in NEUTRAL (N) or the clutch pedal
engaged. The preferred method for shifting out of
4LO is to have your vehicle moving 1 to 2 mph
(1.6 to 3.2 km/h). Press and release the 4HI switch.
You must wait for the 4HI indicator light to stop
flashing and remain illuminated before shifting your
transmission into gear or releasing the clutch pedal.
If the 4HI switch is pressed when your vehicle is in
gear and/or moving, the 4HI indicator light will flash
for 30 seconds but not complete the shift unless the
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 4HI, your transmission
indicator switch may require adjustment. With your
transmission in NEUTRAL (N), press and release the
4HI switch. While the 4HI indicator light is flashing,
shift your transmission into PARK (P). Wait until the
4HI indicator light remains illuminated before shifting
your transmission into gear. This will get you into 4HI,
but you should take your vehicle in for service to restore
normal operation.
ProCarManuals.com

2-35
4HI: Use 4HI when you need extra traction, such as
on snowy or icy roads or in most off
-road situations.
This setting also engages your front axle to help drive
your vehicle.
4LO: This setting also engages your front axle and
delivers extra torque. You may never need 4LO. It sends
maximum power to all four wheels. You might choose
4LO if you are driving off
-road in deep sand, deep mud,
deep snow and climbing or descending steep hills.
CAUTION:
Shifting the transfer case to NEUTRAL can cause
your vehicle to roll even if the transmission is in
PARK (P), or if you have a manual transmission,
even if you are in gear. You or someone else could
be seriously injured. Be sure to set the parking
brake before placing the transfer case in
NEUTRAL. See ªParking Brakeº in the Index.
NEUTRAL: Shift the vehicle's transfer case to
NEUTRAL only when towing your vehicle. See
ªRecreational Vehicle Towingº or ªTowing Your
Vehicleº in the Index for more information.
Indicator lights in the switches show 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
to your dealer for service. An indicator light will
flash while shifting the transfer case. It will remain
illuminated when the shift is complete. If for some
reason the transfer case cannot make a requested shift,
it will return to the last chosen setting.
If the SERVICE 4WD light stays on, you should take
your vehicle to your dealer for service. See ªService
4WDº in the Index for further information.
Shifting to 4HI or AUTO 4WD
Press and release the 4HI or AUTO 4WD switch.
This can be done at any speed, and the indicator light
will flash while shifting. It will remain illuminated when
the shift is complete.
ProCarManuals.com

2-81
Full-Size Console
This device complies with Part 15 of the FCC Rules.
Operation is subject to the following two conditions:
(1) this device may not cause harmful interference,
and (2) this device must accept any interference received,
including interference that may cause undesired operation.
This device complies with RSS
-210 of Industry Canada.
Operation is subject to the following two conditions:
(1) this device may not cause interference, and (2) this
device must accept any interference, including interference
that may cause undesired operation of the device.
Changes and modifications to this system by other than
an authorized service facility could void authorization to
use this equipment.
Programming the Transmitter
Do not use the HomeLink Transmitter with any garage
door opener that does not have the ªstop and reverseº
feature. This includes any garage door opener model
manufactured before April 1, 1982.
Be sure that people and objects are clear of the garage
door you are programming.
Your vehicle's engine should be turned off while
programming the transmitter. Follow these steps to
program up to three channels:
1. If you have previously programmed a transmitter
channel, proceed to Step 2. Otherwise, hold
down the two outside buttons on the HomeLink
Transmitter until the indicator light begins to flash
rapidly (after 20 seconds). Then release the buttons.
This procedure initializes the memory and erases any
previous settings for all three channels.
2. Decide which one of the three channels you want to
program. Hold the end of the hand
-held transmitter
about 1 to 3 inches (3 to 8 cm) away from the
surface of the HomeLink Transmitter so that you
can still see the indicator light.
ProCarManuals.com

2-92
You can only drive for a short time with the reading in
either warning zone. If you must drive, turn off all
unnecessary accessories.
Readings in either warning zone indicate a possible
problem in the electrical system. Have the vehicle
serviced as soon as possible.
Shift Light
You have the shift light
on the instrument panel
cluster if you have a
manual transmission.
Shifting when the indicator light is on will help you get
the best fuel economy. See ªShift Lightº in the Index.
Brake System Warning Light
When the ignition is on, the brake system warning light
will come on when you set your parking brake. The light
will stay on if your parking brake doesn't release fully.
If it stays on after your parking brake is fully released,
it means you have a brake problem.
Your vehicle's hydraulic brake system is divided into
two parts. If one part isn't working, the other part can
still work and stop you. For good braking, though, you
need both parts working well.
If the warning light comes on, there could be a brake
problem. Have your brake system inspected right away.
United States Canada
ProCarManuals.com

2-94
Engine Coolant Temperature Gage
United States Canada
This gage shows the engine coolant temperature.
If the gage pointer moves into the red area, your engine
is too hot!
It means that your engine coolant has overheated.
If you have been operating your vehicle under normal
driving conditions, you should pull off the road, stop
your vehicle and turn off the engine as soon as possible.
See ªEngine Overheatingº in the Index for
more information.
Malfunction Indicator Lamp
(Service Engine Soon Light in the United
States or Check Engine Light in Canada)
United States Canada
Your vehicle is equipped with a computer which
monitors operation of the fuel, ignition and emission
control systems.
This system is called OBD II (On
-Board
Diagnostics
-Second Generation) and is intended to
assure that emissions are at acceptable levels for the life
of the vehicle, helping to produce a cleaner environment.
The SERVICE ENGINE SOON or CHECK ENGINE
light comes on to indicate that there is a problem and
service is required. Malfunctions often will be indicated
by the system before any problem is apparent. This may
prevent more serious damage to your vehicle. This system
is also designed to assist your service technician in correctly
diagnosing any malfunction.
ProCarManuals.com

3-47
If your vehicle is equipped with the AM-FM Stereo with
Cassette Tape Player:
1. Turn the ignition to RUN or ACCESSORY.
2. Turn the radio on.
3. Insert the scrubbing action cleaning cassette.
4. Within five seconds, press and hold the REV and
FWD buttons at the same time for three seconds.
The tape symbol on the display will flash, showing
that the broken tape detection feature is no
longer active.
5. Eject the cleaning cassette after the manufacturer's
recommended cleaning time.
If your vehicle is equipped with the AM
-FM Stereo with
Cassette Tape Player and Automatic Tone Control:
1. Turn the ignition to RUN or ACCESSORY.
2. Turn the radio off.
3. Press and hold the TAPE AUX button for five
seconds. The tape symbol on the display will flash
for two seconds.4. Insert the scrubbing action cleaning cassette.
5. Eject the cleaning cassette after the manufacturer's
recommended cleaning time.
When the cleaning cassette has been ejected, the broken
tape detection feature is active again.
You may also choose a non
-scrubbing action, wet-type
cleaner which uses a cassette with a fabric belt to clean
the tape head. This type of cleaning cassette will not
eject on its own. A non
-scrubbing action cleaner may
not clean as thoroughly as the scrubbing type cleaner.
The use of a non
-scrubbing action, dry-type cleaning
cassette is not recommended.
After you clean the player, press and hold EJECT for
five seconds to reset the CLN indicator. The radio will
display
--- to show the indicator was reset.
Cassettes are subject to wear and the sound quality
may degrade over time. Always make sure the cassette
tape is in good condition before you have your tape
player serviced.
ProCarManuals.com

6-4
Be sure the posted octane is at least 87. If the octane is
less than 87, you may get a heavy knocking noise when
you drive. If it's bad enough, it can damage your engine.
If you're using fuel rated at 87 octane or higher and
you hear heavy knocking, your engine needs service.
But don't worry if you hear a little pinging noise when
you're accelerating or driving up a hill. That's normal,
and you don't have to buy a higher octane fuel to get
rid of pinging. It's the heavy, constant knock that means
you have a problem.
If your vehicle is certified to meet California Emission
Standards (indicated on the underhood emission control
label), it is designed to operate on fuels that meet
California specifications. If such fuels are not available
in states adopting California emissions standards, your
vehicle will operate satisfactorily on fuels meeting
federal specifications, but emission control system
performance may be affected. The malfunction indicator lamp on your instrument
panel may turn on and/or your vehicle may fail a
smog
-check test. See ªMalfunction Indicator Lampº
in the Index. If this occurs, return to your authorized
GM dealer for diagnosis to determine the cause of
failure. In the event it is determined that the cause of
the condition is the type of fuels used, repairs may not
be covered by your warranty.
Some gasolines that are not reformulated for low
emissions may contain an octane
-enhancing
additive called methylcyclopentadienyl manganese
tricarbonyl (MMT); ask your service station operator
whether or not the fuel contains MMT. General Motors
does not recommend the use of such gasolines.
If fuels containing MMT are used, spark plug life
may be reduced and your emission control system
performance may be affected. The malfunction indicator
lamp on your instrument panel may turn on. If this
occurs, return to your authorized GM dealer for service.
ProCarManuals.com