brakes GMC ENVOY 1998 Owner's Manual

Add-on Equipment
When you carry removable items, you may need to put a
limit on how many people you carry inside your vehicle.
Be sure
to weigh your vehicle before you buy and install
the new equipment.
Towing a Trailer
I NOTICE:
Your warranty doesn’t cover parts or
components that fail because of overloading.
A CAUTION:
If you don’t use the correct equipment and drive
properly, you can lose control when you pull a
trailer. For example,
if the trailer is too heavy, the
brakes may not work well
-- or even at all. You
and your passengers could be seriously injured.
Pull
a trailer only if you have followed all the
steps in this section. Ask your dealer for advice
and information about towing a trailer with
your vehicle.
I NOTICE:
Pulling a trailer improperly can damage your
vehicle and result in costly repairs not covered by
your warranty.
To pull a trailer correctly, follow
the advice in this part, and see your dealer for
important information about towing a trailer
with your vehicle.
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Safety Chains
You should always attach chains between yo~~r vehicle
and yo~lr trailer.
Cross the safety chains under the tongue
of the trailer
so that the tongue will not drop to the road
if it becomes separated from the hitch. Instructions
about safety chains may be provided by the hitch
manufacturer
or by the trailer manufxturer. Follow the
manufacturer's recommendation
for attaching safety
chains and do not attach them to the bumper. Always
leave just enough slack
so you can turn with your rig.
And, never
allow safety chains to drag on the ground.
Trailer Brakes
If your trailer weighs mcxe than 1,000 Ibs. (450 kg)
loaded, then
it needs its own brakes -- and they must be
adequate.
Be sure to read and follow the instructions for
the trailer brakes
so you'll be able to install. adjust and
maintain them properly. Your
trailer-s brake system can tap into the vehicle's
hydraulic brake system only if:
0 The trailer parts can withstand 3,000 psi
(20 650 kPa) of pressure.
0 The trai1er.s brake system will use less than
0.02 cubic inch (0.3 cc) of fluid from your vehicle's
master cylinder. Otherwise, both braking systems
won't
work well. You could even lose your brakes.
If everything checks out this fir, then make the brake
fluid tap at the port on the master cylinder that sends
fluid to the rear brakes. But don't
LIS~ copper tubing for
this.
If you do, it will bend and finally break off. Use
steel brake tubing.
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Driving with a Trailer
A CAUTION: I
0
0
0
If you have a rear-most window open and you
pull a trailer with your vehicle, carbon monoxide
(CO) could come into your vehicle. You can’t see
or smell
CO. It can cause unconsciousness or
death. (See ‘(Engine Exhaust” in the Index.) To
maximize your safety when towing a trailer:
Have your exhaust system inspected for
leaks, and make necessary repairs before
starting on your trip.
Keep the rear-most windows closed.
If exhaust does come into your vehicle
through a window in the rear or another
opening, drive with your front, main
heating or cooling system on and with the
fan on any speed. This will bring fresh,
outside air into your vehicle.
Do not use
RECIRCULATION because it only
recirculates the air inside your vehicle. (See
“Comfort Controls” in the Index.)
Towing a trailer requires a certain amount of experience, ~
Before setting out for the open road, you’ll want to get
to know your rig. Acquaint yourself with the feel of
handling and braking with the added weight of the
trailer. And always keep in mind that the vehicle you
arc
driving is now a good deal longer and not nearly as
responsive as your vehicle is by itself.
Before you
start, check the trailer hitch and platform
(and attachments), safety chains, electrical connector,
lamps, tires and mirror adjustment. If the trailer has
electric brakes, start your vehicle and trailer moving and
then apply the trailer brake controller by hand to be sure
the brakes are working. This lets you check your
electrical connection at the same time.
During your trip, check occasionally to
be sure that the
load is secure, and that the lamps and any trailer brakes
are still working.
Following Distance
Stay at least twice as far behind the vehicle ahead as you 1
would when driving your vehicle without a trailer. This
can help you avoid situations that require heavy braking
and sudden turns.
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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 6 Service and Appearance Care
Here you will find information about the care of your vehicle. This section begins with service and fuel information,
and then
it shows how to check important fluid and lubricant levels. There is also technical information about your
vehicle, and a part devoted
to its appearance care.
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Service
Fuel
Fuels in Foreign Countries
Filling Your Tank
Filling a Portable
Fuel Container
Checking Things Under the Hood
Engine Oil
Air Cleaner
Automatic Transmission Fluid
Rear Axle
Four- Wheel Drive
Engine Coolant
Radiator Pressure Cap
Thermostat
Power Steering Fluid
Windshield Washer Fluid
Brakes Battery
Bulb Replacement
Windshield Wiper Blade Replacement
Tires
Appearance Care
Cleaning the Inside
of Your Vehicle
Care of Safety Belts
Cleaning the Outside of Your Vehicle
Appearance Care Materials Chart
Vehicle Identification Number (VIN)
Service Parts Identification Label
Electrical System
Replacement Bulbs
Capacities and Specifications
Air Conditioning Refrigerants
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Brakes
Brake Fluid
have your brake system fixed, since a leak means that
sooner or later your brakes won't work well, or won't
work at all.
So, it isn't a good idea to "top off' your brake fluid.
Adding brake fluid won't correct
a leak. If you add fluid
when your linings are worn, then you'll have too much
fluid when you get new brake linings. You should add
(or remove) brake fluid,
as necessary, only when work
is done
on the brake hydraulic system.
Your brake master cylinder reservoir is here.
It is filled
with DOT-3 brake fluid.
There are
only two reasons why the brake fluid level in
the reservoir might go down. The first is that the brake
fluid goes down
to an acceptable level during normal
brake lining wear. When new linings are
put in, the fluid
level goes back up. The other reason
is that fluid is
leaking out
of the brake system. If it is, you should
If you have too much brake fluid, it can spill
on the engine. The fluid will burn
if' the engine
is hot enough.
You or others could be burned,
and your vehicle could be damaged. Add brake
fluid only when work is done on the brake
hydraulic system.
Refer to the Maintenance Schedule to determine when to
check your brake fluid. See "Periodic Maintenance
Inspections"
in the Index.
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Checking Brake Fluid What to Add
You can check the brake
fluid without taking off
the cap.
Just look at the brake fluid reservoir. The fluid level
should be above
MIN. If it isn’t, have your brake system
checked to see if there is a leak.
After work is done
on the brake hydraulic system,
make sure
the level is above the MTN but not over
the
MAX mark or the top of the window on the side
of the reservoir. When
you do need brake fluid, use only
DOT-3
brake fluid -- such as Delco Supreme 11 @ (GM Part
No.
12377967). Use new brake fluid from a sealed
container only.
Always clean the brake fluid reservoir cap and the
area
around the cap before removing it. This will help keep
dirt from entering the reservoir.
A CAUTION:
With the wrong kind of fluid in your brake
system, your brakes may not work well, or they
may not even work at
all. This could cause a
crash. Always use the proper brake fluid.
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NOTICE:
0 Using the wrong fluid can badly damage
brake system parts. For example, just
a few
drops of mineral-based oil, such as engine
oil, in your brake system can damage brake
system parts
so badly that they’ll have to be
replaced. Don’t let someone put in the
wrong kind of fluid.
If you spill brake fluid on your vehicle’s
painted surfaces, the paint finish can be
damaged. Be careful not to spill brake fluid
on your vehicle.
If you do, wash it off
immediately. See “Appearance Care” in
the Index.
Brake Wear
Your vehicle has four-wheel disc brakes.
Disc brake pads have built-in wear indicators that
make a high-pitched warning sound when the brake
pads are worn and new pads are needed. The sound
may come and
go or be heard all the time your vehicle
is moving (except when you are pushim on the brake
pedal firmly).
A CAU‘
The brake wear warning sound means that soon
your brakes won’t work well. That could lead to
an accident. When you hear the brake wear
warning sound, have your vehicle serviced.
NOTICE:
Continuing to drive with worn-out brake pads
could result
in costly brake repair.
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