1998 GMC ENVOY Owners Manual

Driving On Grades
Reduce speed and shift to a 1owe.r gear Iwfow you start
down a long or steep downgrade.
If you don’t shift
down. you might have to use your brakes
so much that
they would get hot and no longer work well.
On
a long uphill grade, shift down and reduce your
speed to around
45 mph (70 km/h) to reduce the
possibility of engine and transmission overheating.
You should use DRIVE
(D) 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.
When towing at high altitude
on steep uphill grades,
consider the following: Engine coolant
will boil at a lower
temperature than at normal altitudes.
If you twn your
engine off imnlediately after towing at high altitude on
steep uphill grades, your vehicle may show signs similar to
engine overheating.
To avoid this, let the engine run while
parked (preferably on level ground)
with the automatic
transmission
in PARK (PI for a few minutes before turning
the engine off.
If you do get the overheat warning. see
”Engine Overheating”
in the Index.
Parking on Hills
You really should not park your vehicle, with a trailer
attached.
on a hill. If‘ something goes wrong, your rig
could start
to move. People can be injured, and both
your vehicle and the trailer can be damaged.
But
if you ever have to park your rig on a hill, here‘s
how
to do it:
1.
-. 3
3.
4.
5.
Apply your regular brakes, but don’t shift into
PARK
(P) yet. Then turn your wheels into the curb
if facing downhill or into traffic if facing uphill.
Have someone place chocks under the trailer wheels.
When the wheel chocks are
in place, release the
regular brakes
until the chocks absorb the load.
Reapply the regular brakes. Then apply your parking
brake, and then shift into PARK
(P).
Release the regular brakes.
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When You Are Ready to Leave After
Parking on a Hill
1. Apply your regular brakes and hold the pedal down
while you:
0 Start your engine;
Shift into a gear; and
0 Release the parking brake.
2. Let up on the brake pedal.
3. Drive slowly until the trailer is clear of the chocks.
4. Stop and have someone pick up and store the chocks.
Maintenance When Trailer Towing
Your vehicle will need service more often when you’re
pulling
a trailer. See the Maintenance Schedule for more
on this. Things that are especially important in trailer
operation are automatic transmission fluid (don’t
overfill), engine
oil, axle lubricant, belt, cooling system
and brake adjustment. Each of these is covered in this
manual, and the Index will help you find them quickly.
If you’re trailering, it’s
a good idea to review these
sections before you start your trip.
Check periodically to see that all hitch nuts and bolts
are tight.
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Trailer Wiring Harness
The heavy-duty trailer wiring is an eight-wire harness
assembly. The harness is stored under the vehicle, on the
driver’s side corner frame rear crossmember. The
heavy-duty trailer wiring has a 30-amp feed wire
with
an in-line fuse located by the junct.ion block. See “Fuses
and Circuit Breakers”
in the Index. The harness does not
have a cannector and should be wired by
a qualified
electrical technician. The technician can use the
following color code chart when connecting the wiring
harness
to your trailer.
0
0
0
0
0
0
0
0
Dark Blue: Use for electric trailer brakes or
auxiliary wiring.
Red: Use for battery charging;
it connects to the
starter solenoid.
Light Green: Back-up lamps.
Brown: Taillamps and parking lamps.
Yellow: Left stoplamp and turn signal.
Dark Green: Right stoplamp
and turn signal.
White (Heavy Gage): Ground wire.
White (Light Gage): Auxiliary stoplamp.
Securely attach the harness to the trailer, then tape or
strap
it to your vehicle’s frame rail. Be sure you leave it
loose enough so the wiring doesn’t bend or break, but
not
so loose that it drags on the ground. Store the
harness
in its original place. Wrap the harness together
and tie
it neatly so it won’t be damaged.
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Section 5 Problems on the Road
Here you’ll find what to do about some problems that can occur on the road.
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5-2
5-3
5-7
5-11
Hazard Warning Flashers
Other Warning Devices
Jump Starting
Towing
Your Vehicle
Engine Overheating Engine
Fan Noise
If a Tire Goes Flat
Changing a Flat Tire
If You’re Stuck: In Sand, Mud,
Ice or Snow
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I’ :---d Warning Flashers
Your hazard warning flashers let you warn others. They
also let police know you have a problem. Your front and
rear turn signal lamps will flash
on and off. Press the button
on top of
the steering
column all the
way down to make your
front and rear turn signal
lamps flash on and
off.
Your hazard warning flashers work no matter what
position your key
is in, and even if the key isn’t in.
To turn
off the flashers, press the button until the first
click and release.
When the hazard warning flashers
are on, your turn
signals won’t work.
Other Warning Devices
If you carry reflective triangles, you can set one up at
the side of the road about
300 feet (100 m) behind
your vehicle.
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Jump Starting
If your battery has run down, you may want to use
another vehicle and some jumper cables to start your
vehicle.
But please use the following steps to do
it safely.
Batteries can hurt you. They c..-- be
dangerous because:
They contain acid that can burn you.
They contain gas that can explode or ignite.
They contain enough electricity to
If you don’t follow these steps exactly, some or all
burn
you.
’ of these things can hurt you.
NOTICE:
Ignoring these steps could result in costly damage
to your vehicle that wouldn’t be covered by
your warranty.
Trying to start your vehicle
by pushing or pulling
it won’t work, and it could damage
your vehicle.
1. Check the other vehicle. It must have a 12-volt
battery with a negative ground system.
NOTICE:
If the other system isn’t a 12-volt system with a
negative ground, both vehicles can be damaged.
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2. Get the vehicles close enough so the jumper cables
can reach, but be sure
the vehicles aren’t touching
each other.
If they are, it could cause a ground
connection you don’t want.
You wouldn’t be able to
start your vehicle, and the bad grounding could
damage
the electrical systems.
To avoid the possibility of the vehicles rolling, set
the parking brake firmly on each vehicle. Put your
vehicle
in PARK (P).
3. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or the accessory power outlets. Turn
off all
lamps that aren’t needed as well as radios. This will
avoid sparks and help save both batteries. In
addition, it could save your radio!
NOTICE:
If you leave your radio on, it could be badly
damaged. The repair wouldn’t be covered by
your warranty.
L
4. Open both hoods and locate the batteries. Find the
positive
(+) and negative (-) terminals on
each battery.
A
Using a match near a battery can cause battery
gas to explode. People have been hurt doing this,
and some have been blinded. Use
a flashlight if
you need more light.
Be sure the battery has enough water.
You don’t
need
to add water to the ACDelco Freedom’
battery installed in every new
GM vehicle. But if
a battery has filler caps, be sure the right amount
of fluid is there. If it is low, add water to take care
of that first. If you don’t, explosive gas could
be present.
Battery fluid contains acid that can burn you.
Don’t get it
on you. If you accidentally get it in
your eyes or on your skin, flush the place with
water and get medical help immediately.
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5. Check that the jumper cables don’t have loose or
missing insulation.
If they do. you could get a shock.
The vehicles could be damaged too.
Before
you connect the cables, here are some basic
things you should know. Positive
(+) will go to
positive
(+) and negative (-) will go to a metal
engine part. Don’t connect positive
(+) to
negative
(-) or you’ll get a short that would damage
the battery and maybe other parts too.
6. Connect the red
positive
(+) cable to the
positive
(+) terminal of
the vehicle with the
dead battery.
7. Don’t let the other end
touch metal. Connect
it
to the positive (+)
terminal of the
good battery.
8. Now connect the black
negative
(-) cable to
the good battery’s negative
(-) terminal.
Don’t let the other end
touch anything
until the
next step. The other end
of the negative cable
doesn’t go
to the dead
battery. It goes to
a heavy
unpainted metal
part on
the engine
of the vehicle
with the dead battery.
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