1998 GMC ENVOY transmission

Torque Lock Shifting Out of Park (P)
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 “torque lock.”
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 “Shifting Into PARK
(P)” 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). 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 “Automatic Transmission Operation”
in
the Index.
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 console 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 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.
2-23
ProCarManuals.com

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 4L0, the vehicle must be
stopped
or moving less than 3 mph (4.8 kmh) with the
transmission
in NEUTRAL (N). The preferred method
for shifting into 4LO is to
have your vehicle moving 1 to
2 mph (1.6 to 3.2 kmh). 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 slower than 3 mph (4.8 kdh) and the
transmission is in NEUTRAL
(N).
If your transfer case does not shift into 4L0, 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 4L0, but you should take your vehicle in for service
to restore normal operation.
2-27
ProCarManuals.com

Shifting from 4LO to 4HI or 2HI
To shift from 4LO to 4H1 or 2H1, your vehicle must be
stopped or moving less than
3 mph (4.8 kdh) with the
transmission in NEUTRAL
(N). The preferred method
for shifting out of 4LO is to have your vehicle moving
1 to 2 mph (1.6 to 3.2 kdh). Press and release the 4HI
switch.
You must wait for the 4H1 indicator light to stop
flashing and remain illuminated before shifting your
transmission into gear.
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 kmh) and the
transmission
is in NEUTRAL (N).
If your transfer case does not shift into 4H1, 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 4H1, but you should take your vehicle
in for service
to restore normal operation.
Windows
Power Windows
The controls for the power windows are on each of the
side doors. The switches control
the windows when the
ignition is on or when Retained Accessory Power (RAP)
is present. (See “Retained Accessory Power” in the
Index.) The driver’s door has
a switch to control the
passenger windows as well.
2-28
ProCarManuals.com

3.
4.
Decide which one of the three channels you want to
program. Using both hands, press the hand-held
transmitter button and the desired button
on the
universal transmitter. Continue
to hold both buttons
through Step
4.
Hold down both buttons until you see the red light
on the universal transmitter flash rapidly. The rapid
flashing, which could take up to
90 seconds,
indicates that the universal transmitter has been
programmed. Release both buttons once the light
starts
to flash rapidly.
If you have trouble programming the universal
transmitter, make sure that you have followed the
directions exactly as described and that the battery
in the
hand-held transmitter is not dead. If you still cannot
program
it, rotate the hand-held transmitter end over end
and try again. The universal transmitter may not work
with older garage door openers that do not meet current
Federal Consumer Safety Standards.
If you cannot
program the transmitter after repeated attempts, consult
your
GMC dealer. Be
sure to keep the original hand-held transmitter
in case you need to erase and reprogram the
universal transmitter.
Operating the Transmitter
Press and hold the appropriate button on the universal
transmitter. The red light comes on while the signal is
being transmitted.
Note that the effective transmission range of the
universal transmitter may differ from the hand-held
transmitter and from one channel to another.
2-55
I
ProCarManuals.com

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
0
0
0
0
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 depressed 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 r7ot do if you stall, or are
about to stall, when going up
a hill.
0 Never attempt to prevent a stall by shifting into
NEUTRAL
(N) to “rev-up” 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.
0 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.
4-21
I
ProCarManuals.com

Driving Downhill
When off-roading takes you uownhill, you'll want to
consider
a number of things:
0
0
0
0
How steep is the downhill'? Will I be able to maintain
vehicle control?
What's the surface like'? Smooth'? Rough'? Slippery'?
Hard-packed dirt'? Gravel?
Are there hidden surface
obstacles'! Ruts?
Logs? Boulders'?
What's at the
bottom of the hill'! Is there a hidden
creek bank
or even a river bottom with large rocks?
If you decide you can go down a hill safely. then try to
keep your vehicle headed straight down. and use
a low
they won't have to do
all the work. Descend slowly,
keeping your vehicle under control at
all times.
b "ear. This way, engine drag can help your brakes and
0
0
A CAUTION:
Heavy braking when going down a hill can cause
your brakes
to overheat and fade. This could
cause
loss of control and a serious accident.
Apply the brakes lightly when descending a hill
and use a low gear to keep vehicle speed
under control.
Are there some things
I should not do when
driving down a hill?
A: Yes! These are important because if you ignore
them you could lose control and have
a
serious accident.
When driving downhill, avoid turns that take you
across the incline of the
hill. A hill that's not too
steep to drive down may be too steep to drive ~CI-OSS.
You could roll over
if you don't drive straight down.
Never
go downhill with the transmission in
NEUTRAL (N). This is crdled "free-wheeling." Your
brakes
will have to do all the work and could
overheat and fade.
4-22
ProCarManuals.com

0
0
Keep your vehicle in good shape. Check all fluid
levels and also the brakes, tires, cooling system and
transmission. These parts can work hard on
mountain roads.
Know how to go down hills. The most important
thing to know is this: let your engine
do some of the
slowing down. Shift to a lower gear when you go
down a steep or long hill.
‘ A CAUTION:
If you don’t shift down, your I brakes could get so
hot that they wouldn’t work well. You would then
have poor braking or even none going down a
hill. You could crash. Shift down to let your
engine assist your brakes on a steep
downhill slope. 0
0
/I CAC rION:
Coasting downhill in NEUTRAL (N) or with the
ignition
off is dangerous. Your brakes will have to
do all the work of slowing down. They could get
so hot that they wouldn’t work well. You would
then have poor braking or even none going down
a hill. You could crash. Always have your engine
running and your vehicle in gear when you
go downhill.
0
Know how to go uphill. You may want to shift down
to a lower gear. The lower gears help cool your
engine and transmission,
and you can climb the
hill better.
Stay in your own lane when driving on two-lane
roads in hills or mountains. Don’t swing wide or cut
across the center
of the road. Drive at speeds that let
you stay in your own lane.
As you go over the top of a hill, be alert. There could
be something in your lane, like a stalled car or
an accident.
4-35
I
ProCarManuals.com

Every vehicle is ready for some trailer towing. If yours
was built with trailering options, as many are, it’s ready
for heavier trailers. But trailering is different than just
driving your vehicle by itself. Trailering means changes
in handling, durability and fuel economy. Successful,
safe trailering takes correct equipment, and
it has to be
used properly.
That’s
the reason for this part. In it are many
time-tested, important trailering tips and safety rules. Many
of these are important for your safety and that of
your passengers.
So please read this section carefully
before you pull a trailer.
If You Do Decide To Pull A Trailer
If you do, here are some important points:
0
0
There are many different laws, including speed limit
restrictions, having to do with trailering. Make sure
your rig will be legal, not only where you live but
also where you’ll be driving.
A good source for this
information can be state or provincial police.
Consider using a sway control if your trailer
will
weigh 2,000 lbs. (900 kg) or less. You should always
use a sway control if your trailer will weigh more
than
2,000 Ibs. (900 kg). You can ask a hitch dealer
about sway controls.
0
0
0
Don’t tow a trailer at all during the first 500 miles
(800 km) your new vehicle is driven. Your engine,
axle or other parts could be damaged.
Then, during the first
500 miles (800 km) that you
tow a trailer, don’t drive over 50 mph (80 km/h) and
don’t make starts at full throttle. This helps your
engine and other parts of
your vehicle wear in at the
heavier loads.
You should use DRIVE
(D) (or, as you need to, a
lower gear) when towing a trailer. Operating your
vehicle
in DRIVE (D) when towing a trailer will
minimize heat buildup and extend the life
of
your transmission.
Three important considerations have to
do with weight:
the weight of the trailer,
0 the weight of the trailer tongue
0 and the weight on your vehicle’s tires.
4-44
ProCarManuals.com