1999 GMC ENVOY transmission

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AUTO 4WD: This setting is ideal for use when road
conditions are variable. When driving your vehicle in
AUTO 4WD, the front axle is engaged, but the vehicle's
power is sent to the rear wheels. When the vehicle
senses a loss of traction, the system will automatically
engage four
-wheel drive. Driving in this mode results in
slightly lower fuel economy than 2HI.
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,
and climbing or descending steep hills.
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.
CAUTION:
Shifting the transfer case to NEUTRAL can
cause your vehicle to roll even if the transmission
is in PARK (P). 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.
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.
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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.
Shifting to 2HI
Press and release the 2HI switch. This can be done at
any speed.
Shifting to 4LO
To shift to 4LO, the vehicle's engine must be running
and the vehicle must be stopped or moving less than 3
mph (4.8 km/h) with the transmission in NEUTRAL
(N). The preferred method for shifting into 4LO is to
have your vehicle moving 1 or 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.
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 less than 3 mph (4.8 km/h) and the
transmission is in NEUTRAL (N). After 30 seconds, the
transfer case will return to the setting last chosen.Shifting Out of 4LO
To shift from 4LO to 4HI, AUTO 4WD or 2HI your
vehicle must be stopped or moving less than 3 mph
(4.8 km/h) with the transmission in NEUTRAL (N) and
the engine running. The preferred method for shifting
out of 4LO is to have your vehicle moving 1 or 2 mph
(1.6 to 3.2 km/h). Press and release the 4HI, AUTO
4WD or 2HI switch. You must wait for the 4HI, AUTO
4WD or 2HI indicator light to stop flashing and remain
illuminated before shifting your transmission into gear.
If the 4HI, AUTO 4WD or 2HI switch is pressed when
your vehicle is in gear and/or moving, the 4HI, AUTO
4WD or 2HI indicator light will flash for 30 seconds but
will not complete the shift unless your vehicle is moving
less than 3 mph (4.8 km/h) with the transmission in
NEUTRAL (N).
Shifting to NEUTRAL
To shift the transfer case to NEUTRAL first make sure
the vehicle is parked so that it will not roll:
1. Set the parking brake.
2. Start the vehicle.
3. Connect the vehicle to the towing vehicle.
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4. Put the transmission in NEUTRAL (N).
5. Shift the transfer case to 2HI.
6. Simultaneously press and hold the 2HI and 4LO
buttons for 10 seconds. The red NEUTRAL light
will come on when the transfer case shift to
NEUTRAL is complete.
7. Shift the transmission to REVERSE (R) for one
second, then shift the transmission to DRIVE (D)
for one second.
8. Turn the ignition to OFF.
9. Place the transmission shift lever to PARK (P).
10. Release the parking brake prior to towing.
Shifting Out of NEUTRAL
To shift out of NEUTRAL:
1. Set the parking brake and apply the regular
brake pedal.
2. Start the vehicle with the transmission in PARK (P).3. Press the button for the desired transfer case shift
position (2HI, 4HI, AUTO 4WD or 4LO).
4. Put the transmission in NEUTRAL (N).
5. Shift the transmission lever to the desired position.
After the transfer case has shifted out of NEUTRAL,
the red light will go out.
6. A re
-engagement sound is normal when shifting out
of NEUTRAL.
Parking Brake
To set the parking brake, hold the regular brake pedal
down with your right foot. Push down the parking brake
pedal with your left foot. If the ignition is on, the brake
system warning light will come on.
To release the parking brake, hold the regular brake
pedal down.
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2-28 Torque Lock
If you are parking on a hill and you don't shift your
transmission into PARK (P) properly, the weight of the
vehicle may put too much force on the parking pawl in
the transmission. You may find it difficult to pull the
shift lever out of PARK (P). This is called ªtorque lock.º
To prevent torque lock, set the parking brake and then
shift into PARK (P) properly before you leave the
driver's seat. To find out how, see ªShifting Into
PARK (P)º in the Index.
When you are ready to drive, move the shift lever out of
PARK (P) before you release the parking brake.
If torque lock does occur, you may need to have another
vehicle push yours a little uphill to take some of the
pressure from the parking pawl in the transmission, so
you can pull the shift lever out of PARK (P).
Shifting Out of PARK (P)
CAUTION:
Before shifting out of PARK (P) you must fully
apply your regular brakes. Your vehicle can roll.
If you have left the engine running, the vehicle
can move suddenly. You or others could be
injured. If you're pulling a trailer, see ªTowing a
Trailerº in the Index.
Your vehicle has a Brake-Transmission Shift Interlock
(BTSI). You have to fully apply your regular brake
before you can shift from PARK (P) when the ignition is
in RUN. See ªAutomatic Transmission Operationº in
the Index.
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If you cannot shift out of PARK (P), ease pressure on
the shift lever
-- push the shift lever all the way into
PARK (P) as you maintain brake application. Then
move the shift lever into the gear you want. You must
press the shift lever button on the shift lever.
If you ever hold the brake pedal down but still can't
shift out of PARK (P), try this:
1. Turn the key to OFF.
2. Apply and hold the brake until the end of Step 4.
3. Shift the transmission to NEUTRAL (N).
4. Start the vehicle and then shift to the drive gear
you want.
5. Have the vehicle fixed as soon as you can.Parking Over Things That Burn
CAUTION:
Things that can burn could touch hot exhaust
parts under your vehicle and ignite. Don't park
over papers, leaves, dry grass or other things that
can burn.
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There is a delay in the transition between the daytime
and nighttime operation of the Daytime Running Lamps
(DRL) and the automatic headlamp systems so that
driving under bridges or bright overhead street lights
does not affect the system. The DRL and automatic
headlamp system will only be affected when the light
sensor sees a change in lighting lasting longer than
the delay.
To idle your vehicle with the automatic headlamp
system off, set the parking brake while the ignition is
off. Then start your vehicle. The automatic headlamp
system will stay off until you release the parking brake.
As with any vehicle, you should turn on the regular
headlamp system when you need it.
Lamps On Reminder
A reminder chime will sound when your headlamps or
parking lamps are manually turned on and your ignition
is in OFF, LOCK or ACCESSORY. To disable the
chime, turn the thumbwheel all the way down. In the
automatic mode, the headlamps turn off once the
ignition key is in OFF.
Daytime Running Lamps (If Equipped)
Daytime Running Lamps (DRL) can make it easier for
others to see the front of your vehicle during the day.
DRL can be helpful in many different driving
conditions, but they can be especially helpful in the
short periods after dawn and before sunset.
The DRL system will make your high
-beam headlamps
come on at reduced brightness when:

the ignition is on,

the headlamp switch is in automatic headlamp mode,

the light sensor detects daytime light,

the transmission is not in PARK (P), and

the parking brake is released.
When the DRL are on, only your high
-beam headlamps
will be on. The taillamps, sidemarker and other lamps
won't be on. The instrument panel won't be lit up either.
When it begins to get dark, the high
-beam headlamps
will automatically switch from DRL to the regular
low
-beam headlamps.
To idle your vehicle with the DRL off, put your
vehicle's transmission in PARK (P). The DRL will stay
off until you shift out of PARK (P).
As with any vehicle, you should turn on the regular
headlamp system when you need it.
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NOTICE:
If you keep driving your vehicle with this light
on, after a while, your emission controls may not
work as well, your fuel economy may not be as
good and your engine may not run as smoothly.
This could lead to costly repairs that may not be
covered by your warranty.
NOTICE:
Modifications made to the engine, transmission,
exhaust or fuel system of your vehicle or the
replacement of the original tires with other than
those of the same Tire Performance Criteria
(TPC) can affect your vehicle's emission controls
and may cause the SERVICE ENGINE SOON
light to come on. Modifications to these systems
could lead to costly repairs not covered by your
warranty. This may also result in a failure to pass
a required Emission Inspection/Maintenance test.
This light should come on, as a check to show you it is
working, when the ignition is on and the engine is not
running. If the light doesn't come on, have it repaired.
This light will also come on during a malfunction in one
of two ways:

Light Flashing
-- A misfire condition has been
detected. A misfire increases vehicle emissions and
may damage the emission control system on your
vehicle. Dealer or qualified service center diagnosis
and service may be required.

Light On Steady
-- An emission control system
malfunction has been detected on your vehicle.
Dealer or qualified service center diagnosis and
service may be required.
If the Light Is Flashing
The following may prevent more serious damage to
your vehicle:

Reducing vehicle speed.

Avoiding hard accelerations.

Avoiding steep uphill grades.

If you are towing a trailer, reduce the amount of
cargo being hauled as soon as it is possible.
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Q:What should I do if my vehicle stalls, or is about
to stall, and I can't make it up the hill?
A:If this happens, there are some things you should
do, and there are some things you must not do.
First, here's what you should do:

Push the brake pedal to stop the vehicle and keep it
from rolling backwards. Also, apply the parking brake.

If your engine is still running, shift the transmission
to REVERSE (R), release the parking brake, and
slowly back down the hill in REVERSE (R).

If your engine has stopped running, you'll need to
restart it. With the brake pedal pressed and the
parking brake still applied, shift the transmission to
PARK (P) and restart the engine. Then, shift to
REVERSE (R), release the parking brake, and
slowly back down the hill as straight as possible in
REVERSE (R).

As you are backing down the hill, put your left hand
on the steering wheel at the 12 o'clock position. This
way, you'll be able to tell if your wheels are straight
and maneuver as you back down. It's best that you
back down the hill with your wheels straight rather
than in the left or right direction. Turning the wheel
too far to the left or right will increase the possibility
of a rollover.Here are some things you must not do if you stall, or are
about to stall, when going up a hill.

Never attempt to prevent a stall by shifting into
NEUTRAL (N) to ªrev-upº the engine and regain
forward momentum. This won't work. Your vehicle
will roll backwards very quickly and you could go
out of control.
Instead, apply the regular brake to stop the vehicle. Then
apply the parking brake. Shift to REVERSE (R), release
the parking brake, and slowly back straight down.

Never attempt to turn around if you are about to stall
when going up a hill. If the hill is steep enough to
stall your vehicle, it's steep enough to cause you to
roll over if you turn around. If you can't make it up
the hill, you must back straight down the hill.
Q:Suppose, after stalling, I try to back down the
hill and decide I just can't do it. What should
I do?
A:Set the parking brake, put your transmission in
PARK (P) and turn off the engine. Leave the vehicle
and go get some help. Exit on the uphill side and stay
clear of the path the vehicle would take if it rolled
downhill. Do not shift the transfer case to NEUTRAL
when you leave the vehicle. Leave it in some gear.
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