1999 GMC SONOMA wheel

5-18
Engine Fan Noise
This vehicle has a clutched engine cooling fan. When
the clutch is engaged, the fan spins faster to provide
more air to cool the engine. In most everyday driving
conditions the clutch is not engaged. This improves fuel
economy and reduces fan noise. Under heavy vehicle
loading, trailer towing and/or high outside temperatures,
the fan speed increases when the clutch engages. So you
may hear an increase in fan noise. This is normal and
should not be mistaken as the transmission slipping or
making extra shifts. It is merely the cooling system
functioning properly. The fan will slow down
when additional cooling is not required and the
clutch disengages.
You may also hear this fan noise when you start the
engine. It will go away as the fan clutch disengages.
If a Tire Goes Flat
It's unusual for a tire to ªblow outº while you're driving,
especially if you maintain your tires properly. If air goes
out of a tire, it's much more likely to leak out slowly.
But if you should ever have a ªblowout,º here are a few
tips about what to expect and what to do:
If a front tire fails, the flat tire will create a drag that
pulls the vehicle toward that side. Take your foot off the
accelerator pedal and grip the steering wheel firmly.
Steer to maintain lane position, and then gently brake to
a stop well out of the traffic lane.
A rear blowout, particularly on a curve, acts much like a
skid and may require the same correction you'd use in a
skid. In any rear blowout, remove your foot from the
accelerator pedal. Get the vehicle under control by
steering the way you want the vehicle to go. It may be
very bumpy and noisy, but you can still steer. Gently
brake to a stop
-- well off the road if possible.
If a tire goes flat, the next part shows how to use your
jacking equipment to change a flat tire safely.

5-19
Changing a Flat Tire
If a tire goes flat, avoid further tire and wheel damage
by driving slowly to a level place. Turn on your hazard
warning flashers.
CAUTION:
Changing a tire can cause an injury. The vehicle
can slip off the jack and roll over you or other
people. You and they could be badly injured.
Find a level place to change your tire.
To help prevent the vehicle from moving:
1. Set the parking brake firmly.
2. Put an automatic transmission shift lever in
PARK (P) or shift a manual transmission to
FIRST (1) or REVERSE (R).
3. Turn off the engine.
4. Put the wheel blocks at the front and
rear of the tire farthest away from the
one being changed. That would be the
tire on the other side of the vehicle, at
the opposite end.The following steps will tell you how to use the jack and
change a tire.
Removing the Spare Tire and Tools
The jacking equipment you'll need is stored inside the
plastic jack cover which is behind the front seats, either
on the center of the wall (extended cab) or on the
passenger's side of the wall (regular cab).

5-20
This is the jack cover for the extended cab.
The cover for the regular cab is similar. To remove
it, turn the plastic wing nut counterclockwise.
Remove the jack cover.
Turn the wing nut counterclockwise and remove the
wheel blocks, jack and wheel wrench.
Your spare tire is stored underneath the rear of your
vehicle. See ªCompact Spare Tireº later in this section
for more information about the compact spare.
NOTICE:
Never remove or store a tire from/to a storage
position under the vehicle while the vehicle is
supported by a jack. Always tighten the tire
fully against the underside of the vehicle when
storing it.
Insert the chisel end
of the wheel wrench, on
an angle, into the hole in
the rear bumper.
Be sure the chisel end of the wheel wrench connects into
the hoist shaft.

5-21
Turn the wheel wrench counterclockwise to lower the
spare tire. Keep turning the wheel wrench until the spare
tire can be pulled out from under the vehicle.
When the tire has been completely lowered, tilt the
retainer at the end of the cable and pull it through the
wheel opening. Pull the tire out from under the vehicle.
NOTICE:
To help avoid vehicle damage, do not drive the
vehicle before the cable is restored.
Put the spare tire near the flat tire.The tools you'll be using include the jack (A) and wheel
wrench (B). Your vehicle may also have an optional hub
cap removal tool.

5-22
Position the bent end of your hub cap removal tool
(shown), or the chisel end of your wheel wrench, in the
notch of the hub cap and pry off the hub cap.
Some of the molded plastic hub caps have imitation
wheel nuts molded into them. The wheel wrench won't
fit these imitation nuts, so don't try to remove them with
the socket end of the wheel wrench.If you have individual wheel nut caps that cover each
nut, they must be removed in order to get to the wheel
nuts. Use the socket end of the wheel wrench to remove
the wheel nut caps.
Your wheel nut caps may attach your hub cap to the
wheel. Remove these wheel nut caps before you take off
the hub cap.

5-23 Removing the Flat Tire and Installing
the Spare Tire
1. Using the wheel wrench, loosen all the wheel nuts.
Don't remove them yet.
2. Turn the jack handle clockwise slightly to raise the
jack lift head.
3. Fit the jack into the appropriate hole nearest
the flat tire.
A. Front Frame Hole
B. Rear Frame Hole (ZR2)
C. Spring Hanger Hole (Standard Pickups)

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CAUTION:
Getting under a vehicle when it is jacked up is
dangerous. If the vehicle slips off the jack, you
could be badly injured or killed. Never get under
a vehicle when it is supported only by a jack.
CAUTION:
Raising your vehicle with the jack improperly
positioned can damage the vehicle and even
make the vehicle fall. To help avoid personal
injury and vehicle damage, be sure to fit the jack
lift head into the proper location before raising
the vehicle.4. Raise the vehicle by turning the jack handle clockwise.
Raise the vehicle far enough off the ground so there is
enough room for the spare tire to fit.
5. Remove all the wheel nuts and take off the flat tire.

5-25
6. Remove any rust or dirt
from the wheel bolts,
mounting surfaces and
spare wheel.
CAUTION:
Rust or dirt on the wheel, or on the parts to
which it is fastened, can make the wheel nuts
become loose after a time. The wheel could come
off and cause an accident. When you change a
wheel, remove any rust or dirt from the places
where the wheel attaches to the vehicle. In an
emergency, you can use a cloth or a paper towel
to do this; but be sure to use a scraper or wire
brush later, if you need to, to get all the rust
or dirt off.
CAUTION:
Never use oil or grease on studs or nuts. If you
do, the nuts might come loose. Your wheel could
fall off, causing a serious accident.
7. Place the spare on the wheel mounting surface.
8. Put the nuts on by
hand. Make sure
the cone
-shaped
end is toward
the wheel.