light GMC YUKON 1999 Repair Manual

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4-54
Additional Heavy-Duty Wiring
An eight
-wire harness is stored under the rear bumper of
your vehicle. The five
-wire light-duty harness is located
at the left hand rear inner lower quarter panel. The
additional heavy
-duty wiring is located forward of the
rear bumper and is attached to the center of the rear
crossmember or the forward vertical surface of the
platform hitch.
This harness has a 30 amp battery feed wire and no
connector, and should be wired by a qualified electrical
technician. After choosing an aftermarket mating
connector pair, have the technician attach one connector tothe eight
-wire trailer harness and the other connector to the
wiring harness on the trailer. Be sure that the wiring
harness on the trailer is strapped to the trailer's frame and
leave it loose enough so that the wiring doesn't bend or
break, but not so loose that it drags on the ground. The
technician can use the following color code chart when
connecting the wiring harness to your trailer.

Brown: Rear Lamps

Yellow: Left Stoplamp and Turn Signal

Dark Green: Right Stoplamp and Turn Signal

White (Heavy Gauge): Ground

Light Green: Back
-up Lamps

White (Light Gauge): Center High
-Mounted Stop
Lamp (If Equipped)

Blue: Auxiliary/Electric Trailer Brake Circuit
(If Equipped)

Orange: Fused Auxiliary Circuit (If Equipped)
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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5-3
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.
CAUTION:
Batteries can hurt you. They can be dangerous
because:

They contain acid that can burn you.

They contain gas that can explode or ignite.

They contain enough electricity to
burn you.
If you don't follow these steps exactly, some or all
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.
The ACDelco Freedom battery in your vehicle
has a built-in hydrometer. Do not charge, test or
jump start the battery if the hydrometer looks
clear or light yellow. Replace the battery when
there is a clear or light yellow hydrometer and a
cranking complaint.
Trying to start your vehicle by pushing or pulling
it won't work, and it could damage your vehicle.

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5-4
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.
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 both vehicles involved in
the jump start procedure. Put an automatic
transmission in PARK (P) or a manual transmission
in NEUTRAL (N) before setting the parking brake.
Be sure the transfer case is not in NEUTRAL (N).3. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or accessory power outlets. Turn off all lamps
that aren't needed as well as radios. This will avoid
sparks and help save both batteries. And it could
save your radio!
NOTICE:
If you leave your radio on, it could be badly
damaged. The repairs wouldn't be covered by
your warranty.

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5-5
4. Open the hoods and locate the batteries. Find the
positive (+) and negative (
-) terminals on
each battery.
CAUTION:
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.
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 heavy
unpainted 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.
CAUTION:
Fans or other moving engine parts can injure you
badly. Keep your hands away from moving parts
once the engine is running.

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5-33
NOTICE:
Spinning your wheels can destroy parts of your
vehicle as well as the tires. If you spin the wheels
too fast while shifting your transmission back
and forth, you can destroy your transmission.
For information about using tire chains on your vehicle,
see ªTire Chainsº in the Index.
Rocking Your Vehicle To Get It Out
First, turn your steering wheel left and right. That will
clear the area around your front wheels. Shift the
transfer case into 4HI. Then shift back and forth
between REVERSE (R) and a forward gear, spinning the
wheels as little as possible. Release the accelerator pedal
while you shift, and press lightly on the accelerator
pedal when the transmission is in gear. By slowly
spinning your wheels in the forward and reverse
directions, you will cause a rocking motion that may
free your vehicle. If that doesn't get you out after a few
tries, you may need to be towed out. Or, you can use
your recovery hooks if your vehicle has them. If you do
need to be towed out, see ªTowing Your Vehicleº in
the Index.
Using the Recovery Hooks
Your vehicle is equipped with recovery hooks. The
recovery hooks are provided at the front of your vehicle.
You may need to use them if you're stuck off
-road and
need to be pulled to some place where you can
continue driving.

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6-7
CAUTION:
If you get gasoline on yourself and then
something ignites it, you could be badly burned.
Gasoline can spray out on you if you open the
fuel filler cap too quickly. This spray can happen
if your tank is nearly full, and is more likely in
hot weather. Open the fuel filler cap slowly and
wait for any ªhissº noise to stop. Then unscrew
the cap all the way.
Be careful not to spill gasoline. Clean gasoline from
painted surfaces as soon as possible. See ªCleaning the
Outside of Your Vehicleº in the Index.When you put the cap back on, turn it to the right
(clockwise) until you hear a clicking sound. Make sure
you fully install the cap. The diagnostic system can
determine if the fuel cap has been left off or improperly
installed. This would allow fuel to evaporate into the
atmosphere. See ªMalfunction Indicator Lampº in
the Index.
NOTICE:
If you need a new cap, be sure to get the right type.
Your dealer can get one for you. If you get the
wrong type, it may not fit properly. This may cause
your malfunction indicator lamp to light and your
fuel tank and emissions system may be damaged.
See ªMalfunction Indicator Lampº in the Index.

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6-31
NOTICE:

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 ªAppearance Careº in
the Index.
Brake Wear
Your vehicle has front disc brakes and rear drum 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 pushing on the brake pedal firmly).
CAUTION:
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.
Some driving conditions or climates may cause a brake
squeal when the brakes are first applied or lightly
applied. This does not mean something is wrong with
your brakes.

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6-44 Uniform Tire Quality Grading
The following information relates to the system
developed by the United States National Highway
Traffic Safety Administration, which grades tires by
treadwear, traction and temperature performance. (This
applies only to vehicles sold in the United States.) The
grades are molded on the sidewalls of most passenger
car tires. The Uniform Tire Quality Grading system does
not apply to deep tread, winter
-type snow tires,
space
-saver or temporary use spare tires, tires with
nominal rim diameters of 10 to 12 inches (25 to 30 cm),
or to some limited
-production tires.
While the tires available on General Motors passenger
cars and light trucks may vary with respect to these
grades, they must also conform to Federal safety
requirements and additional General Motors Tire
Performance Criteria (TPC) standards.
Treadwear
The treadwear grade is a comparative rating based on
the wear rate of the tire when tested under controlled
conditions on a specified government test course. For
example, a tire graded 150 would wear one and a half
(1 1/2) times as well on the government course as a tire
graded 100. The relative performance of tires dependsupon the actual conditions of their use, however, and
may depart significantly from the norm due to variations
in driving habits, service practices and differences in
road characteristics and climate.
Traction
-- AA, A, B, C
The traction grades, from highest to lowest, are AA, A,
B, and C. Those grades represent the tire's ability to stop
on wet pavement as measured under controlled
conditions on specified government test surfaces of
asphalt and concrete. A tire marked C may have poor
traction performance. Warning: The traction grade
assigned to this tire is based on straight
-ahead braking
traction tests, and does not include acceleration,
cornering, hydroplaning, or peak traction characteristics.
Temperature
-- A, B, C
The temperature grades are A (the highest), B, and C,
representing the tire's resistance to the generation of
heat and its ability to dissipate heat when tested under
controlled conditions on a specified indoor laboratory
test wheel. Sustained high temperature can cause the
material of the tire to degenerate and reduce tire life, and
excessive temperature can lead to sudden tire failure.
The grade C corresponds to a level of performance
which all passenger car tires must meet under the

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6-54
GM Vehicle Care/Appearance Materials
PART NUMBERSIZEDESCRIPTIONUSAGE
99495423 in. x 25 in.Polishing Cloth ± Wax TreatedExterior polishing cloth
105017216 oz. (0.473 L)Tar and Road Oil RemoverRemoves tar, road oil and asphalt
105017316 oz. (0.473 L)Chrome Cleaner and PolishUse on chrome, stainless steel, nickel, copper and brass
105017416 oz. (0.473 L)White Sidewall Tire CleanerRemoves soil and black marks from whitewalls
105021432 oz. (0.946 L)Vinyl CleanerCleans vinyl tops, upholstery and convertible tops
105042723 oz. (0.680 L)Glass CleanerRemoves dirt, grime, smoke and fingerprints
1052918**8 oz. (0.237 L)Armor All
ProtectantProtects leather, wood, acrylics, Plexiglas
, plastic,
rubber and vinyl
105292516 oz. (0.473 L)Multi-Purpose Interior
CleanerCleans carpets, seats, interior trim, door panels
and floor mats
105292916 oz. (0.473 L)Wheel CleanerSpray on and rinse with water
10529308 oz. (0.237 L)Capture Dry Spot RemoverAttracts, absorbs and removes soils on fabric
123457212.5 sq. ft.Synthetic ChamoisShines vehicle without scratching
1234572512 oz. (0.354 L)Silicone Tire ShineSpray on tire shine
12377964*16 oz. (0.473 L)Finish EnhancerRemoves dust, fingerprints and surface contaminants
12377966*16 oz. (0.473 L)Cleaner WaxRemoves light scratches and oxidation and protects finish
12377984*16 oz. (0.473 L)Surface CleanerRemoves contaminants, blemishes and swirl marks
See your General Motors Parts Department for these products. * For exterior use only.
See ªRecommended Fluids and Lubricantsº in the Index. ** Not recommended for use on instrument panels.

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6-57 Fuses and Circuit Breakers
The wiring circuits in your vehicle are protected from
short circuits by a combination of fuses, circuit breakers
and fusible thermal links in the wiring itself. This
greatly reduces the chance of fires caused by electrical
problems. See ªFuses and Circuit Breakersº in the Index
for more information.
Look at the silver
-colored band inside the fuse. If the
band is broken or melted, replace the fuse. Be sure you
replace a bad fuse with a new one of the identical size
and rating.
If you ever have a problem on the road and don't have a
spare fuse, you can borrow one that has the same
amperage. Just pick some feature of your vehicle that
you can get along without
-- like the radio or cigarette
lighter
-- and use its fuse, if it is the correct amperage.
Replace it as soon as you can.Instrument Panel Fuse Block
The fuse block access door
is on the driver's side edge
of the instrument panel. Pull
off the cover to access the
fuse block.
You can remove fuses with
a fuse extractor. The fuse
extractor is mounted to the
fuse block access door.
To remove fuses, if you don't have a fuse extractor, hold
the end of the fuse between your thumb and index finger
and pull straight out.
You may have spare fuses attached to the inside of the
fuse block access door. These can be used to replace a
bad fuse. However, make sure that it is the
correct amperage.