1999 GMC SONOMA warning

2-58 Voltmeter Gage
When your engine is not
running, but the ignition is
on (in RUN), this gage
shows your battery's state of
charge in DC volts.
When the engine is running, the gage shows the
condition of the charging system. Readings between the
low and high warning zones indicate the normal
operating range.
Readings in the low warning zone may occur when a
large number of electrical accessories are operating in
the vehicle and the engine is left at an idle for an
extended period. This condition is normal since the
charging system is not able to provide full power at
engine idle. As engine speeds are increased, this
condition should correct itself as higher engine speeds
allow the charging system to create maximum power.You can only drive for a short time with the reading in
either warning zone. If you must drive, turn off all
unnecessary accessories.
Readings in either warning zone indicate a possible
problem in the electrical system. Have the vehicle
serviced as soon as possible.
Shift Light
You have the shift
light if you have a
manual transmission.
Shifting when the indicator light is on will help you get
the best fuel economy. See ªShift Lightº in the Index.

2-59 Brake System Warning Light
When the ignition is on, the brake system warning light
will come on when you set your parking brake. The light
will stay on if your parking brake doesn't release fully.
If it stays on after your parking brake is fully released, it
means you have a brake problem.
Your vehicle's hydraulic brake system is divided into
two parts. If one part isn't working, the other part can
still work and stop you. For good braking, though, you
need both parts working well.
If the warning light comes on, there could be a brake
problem. Have your brake system inspected right away.
United States CanadaThis light should come on briefly when you turn the
ignition key to RUN. If it doesn't come on then, have it
fixed so it will be ready to warn you if there's a problem.
If the light comes on while you are driving, pull off the
road and stop carefully. You may notice that the pedal is
harder to push. Or, the pedal may go closer to the floor.
It may take longer to stop. If the light is still on, have the
vehicle towed for service. (See ªTowing Your Vehicleº
in the Index.)
CAUTION:
Your brake system may not be working properly
if the brake system warning light is on. Driving
with the brake system warning light on can lead
to an accident. If the light is still on after you've
pulled off the road and stopped carefully, have
the vehicle towed for service.

2-60 Anti-Lock Brake System Warning Light
With the anti-lock brake
system, this light will come
on when you start your
engine and may stay on
for several seconds.
That's normal.
If the light stays on, or comes on when you're driving,
your vehicle needs service. If the regular brake system
warning light isn't on, you still have brakes, but you
don't have anti
-lock brakes. If the regular brake system
warning light is also on, you don't have anti
-lock brakes
and there's a problem with your regular brakes. See
ªBrake System Warning Lightº earlier in this section.
The anti
-lock brake system warning light should come
on briefly when you turn the ignition key to RUN. If the
light doesn't come on then, have it fixed so it will be
ready to warn you if there is a problem.
Engine Coolant Temperature Gage
United States Canada
This gage shows the engine coolant temperature.
If the gage pointer moves into the red area, your engine
is too hot!
It means that your engine coolant has overheated. If you
have been operating your vehicle under normal driving
conditions, you should pull off the road, stop your
vehicle and turn off the engine as soon as possible.
The ªProblems on the Roadº section of this manual
shows you what to do. See ªEngine Overheatingº in
the Index.

2-65 Security Warning Light
This light will come on
briefly when you turn the
key toward START. The
light will stay on until the
engine starts.
If the light flashes, the Passlock

system has entered a
tamper mode. If the vehicle fails to start, see ªPasslockº
in the Index.
If the light comes on continuously while driving and
stays on, there may be a problem with the Passlock
system. Your vehicle will not be protected by Passlock,
and you should see your dealer.
Also see ªContent Theft
-Deterrentº in the Index for
additional information regarding the SECURITY light.
Service Four-Wheel-Drive Warning Light
If your vehicle is equipped with the Automatic
Four
-Wheel-Drive Transfer Case, it has a computer
which controls the four
-wheel-drive system.
This light should come on
briefly when you turn on the
ignition, as a check to show
you it is working.
The SERVICE 4WD light comes on to indicate that
there may be a problem with the four
-wheel-drive
system and service is required. Malfunctions can be
indicated by the system before any problem is apparent,
which may prevent serious damage to the vehicle. This
system is also designed to assist your service technician
in correctly diagnosing a malfunction.

2-66 Check Gages Light
If this light comes on
and stays on while you
are driving, check your
coolant temperature
and engine oil pressure
gages to see if they are
in the warning zones.
Fuel Gage
When the ignition is on, the
fuel gage tells you about
how much fuel you
have remaining.Here are four things that some owners ask about.
None of these show a problem with your fuel gage:

At the gas station, the gas pump shuts off before the
gage reads F (Full).

It takes a little more or less fuel to fill up than the gage
indicated. For example, the gage may have indicated
the tank was half full, but it actually took a little more
or less than half the tank's capacity to fill the tank.

The gage moves a little when you turn a corner
or speed up.

The gage doesn't go back to E (Empty) when you
turn off the ignition.
Low Fuel Light
This light comes on briefly
when you start your engine.
This light comes on when the fuel tank is low on fuel.
To turn it off, add fuel to the fuel tank. See ªFuelº
in the Index.

4-7
Avoid needless heavy braking. Some people drive in
spurts
-- heavy acceleration followed by heavy
braking
-- rather than keeping pace with traffic. This is a
mistake. Your brakes may not have time to cool between
hard stops. Your brakes will wear out much faster if you
do a lot of heavy braking. If you keep pace with the
traffic and allow realistic following distances, you will
eliminate a lot of unnecessary braking. That means
better braking and longer brake life.
If your engine ever stops while you're driving, brake
normally but don't pump your brakes. If you do, the
pedal may get harder to push down. If your engine
stops, you will still have some power brake assist. But
you will use it when you brake. Once the power assist is
used up, it may take longer to stop and the brake pedal
will be harder to push.
Anti-Lock Brakes (ABS)
Your vehicle has anti-lock brakes (ABS). ABS is an
advanced electronic braking system that will help
prevent a braking skid.
When you start your engine and begin to drive away,
your anti
-lock brake system will check itself. You may
hear a momentary motor or clicking noise while this test
is going on. This is normal.
If there's a problem with the
anti
-lock brake system, this
warning light will stay on.
See ªAnti
-Lock Brake
System Warning Lightº in
the Index.

4-13
Loss of Control
Let's review what driving experts say about what
happens when the three control systems (brakes, steering
and acceleration) don't have enough friction where the
tires meet the road to do what the driver has asked.
In any emergency, don't give up. Keep trying to steer and
constantly seek an escape route or area of less danger.
Skidding
In a skid, a driver can lose control of the vehicle.
Defensive drivers avoid most skids by taking reasonable
care suited to existing conditions, and by not ªoverdrivingº
those conditions. But skids are always possible.
The three types of skids correspond to your vehicle's
three control systems. In the braking skid, your wheels
aren't rolling. In the steering or cornering skid, too
much speed or steering in a curve causes tires to slip and
lose cornering force. And in the acceleration skid, too
much throttle causes the driving wheels to spin.
A cornering skid and an acceleration skid are best
handled by easing your foot off the accelerator pedal.If your vehicle starts to slide, ease your foot off the
accelerator pedal and quickly steer the way you want the
vehicle to go. If you start steering quickly enough, your
vehicle may straighten out. Always be ready for a
second skid if it occurs.
Of course, traction is reduced when water, snow, ice,
gravel or other material is on the road. For safety, you'll
want to slow down and adjust your driving to these
conditions. It is important to slow down on slippery
surfaces because stopping distance will be longer and
vehicle control more limited.
While driving on a surface with reduced traction, try
your best to avoid sudden steering, acceleration or
braking (including engine braking by shifting to a lower
gear). Any sudden changes could cause the tires to slide.
You may not realize the surface is slippery until your
vehicle is skidding. Learn to recognize warning
clues
-- such as enough water, ice or packed snow on
the road to make a ªmirrored surfaceº
-- and slow down
when you have any doubt.
Remember: Any anti
-lock brake system (ABS) helps
avoid only the braking skid.

4-30
Hydroplaning usually happens at higher speeds.
There just isn't a hard and fast rule about hydroplaning.
The best advice is to slow down when it is raining.
Driving Through Deep Standing Water
NOTICE:
If you drive too quickly through deep puddles
or standing water, water can come in through
your engine's air intake and badly damage your
engine. Never drive through water that is slightly
lower than the underbody of your vehicle. If you
can't avoid deep puddles or standing water, drive
through them very slowly.
Driving Through Flowing Water
CAUTION:
Flowing or rushing water creates strong forces.
If you try to drive through flowing water, as you
might at a low water crossing, your vehicle can
be carried away. As little as six inches of flowing
water can carry away a smaller vehicle. If this
happens, you and the other vehicle occupants
could drown. Don't ignore police warning signs,
and otherwise be very cautious about trying to
drive through flowing water.
Some Other Rainy Weather Tips

Turn on your low-beam headlamps -- not just your
parking lamps
-- to help make you more visible to others.

Besides slowing down, allow some extra following
distance. And be especially careful when you pass
another vehicle. Allow yourself more clear room
ahead, and be prepared to have your view restricted
by road spray.

Have good tires with proper tread depth.
(See ªTiresº in the Index.)