1997 GMC SIERRA service

Electronic Transfer Case (If Equipped)
If your four-wheel-drive vehicle has the electronic
transfer case, the transfer case switches are below and
to
the left of the climate control system.
Use these switches to shift into and out
of four-wheel
drive. You can choose among three driving settings:
.
2HI: This setting is for driving in most street and
highway situations. Your front axle is not engaged
in
two-wheel drive.
4HI: This setting engages your front axle to help
drive your vehicle. Use
4HI when you need extra
traction, such as
on snowy or icy roads, or in most
off-road situations.
4LO: This setting also engages your front axle to give
you extra traction. You may never need
4LO. It sends
the maximum power to all four wheels. You might
choose
4LO if you were driving off-road in sand, mud
or deep snow and climbing or descending steep hills.
Indicator lights in the switches show you which setting
you are in. The indicator lights will come
on briefly
when you turn on the ignition and the last chosen setting
will stay on. If the lights do not come on, you should
take your vehicle in for service. An indicator light will
flash while shifting. It
will remain illuminated when
the shift is completed. If for some reason the transfer
cannot make a requested shift,
it will return to the last
chosen setting.
ProCarManuals.com

Safety Belt Reminder Light
When the key is turned to RUN or START, a tone will
come on for about eight seconds to remind people to
fasten their
safety belts, unless the driver’s safety belt is
already buckled.
The safety belt light will
also come on and stay on
for about
20 seconds,
then it will flash for about
55 seconds. If the driver’s
belt is already buckled,
neither the tone nor the
light will come on.
Air Bag Readiness Light
There is an air bag readiness light on the instrument panel,
which shows
AIR BAG. The system checks the air bag’s
electrical system for malfunctions. The light tells you if there is an electrical problem. The system check includes the
air bag sensors, the air bag module, the wiring and the
diagnostic module.
For more information on the air bag
system,
see “Air Bag” in the Index.
AIR
BAG
This light will come on
when you start your engine,
and it will
flash for a few
seconds. Then the light
should go out. This means
the system is ready.
If the air bag readiness light stays on after you start the
engine or comes on when you are driving, your air bag
system may not work properly. Have your vehicle
serviced right away.
The air bag readiness light should flash for
a few
seconds 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.
2-67
ProCarManuals.com

/I CAUTION: I
If the air bag readiness light ever comes on when
you have turned
off the air bag, it means that
something may be wrong with the air bag system.
The right front passenger’s
air bag could inflate
even though the switch is
off. If this ever
happens, don’t secure a rearfacing child
restraint in your vehicle until you have your
vehicle serviced.
Charging System Indicator Light
This light should come on
briefly when you
turn on the
ignition, before starting the
engine, as a check to show
you it is working.
After the engine starts, the light should go out.
If it stays
on or comes on while you are driving, you may have a
problem with your charging system. It could indicate a
problem with the generator drive belt, or some other
charging system problem. Have it checked right away.
Driving while this light is on could drain your battery.
If you must drive a
short distance with this light on, it
helps to turn
off all your accessories, such as the radio
and the air conditioner.
2-69
ProCarManuals.com

Voltmeter
When your engine is not
running, but the ignition is
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.
2-70
ProCarManuals.com

Brake System Warning Light
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.
This 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.
I
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.
When the ignition is on, the brake system warning light
will also 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.
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 “Towing Your Vehicle”
in the Index.)
2-71
ProCarManuals.com

Anti-Lock Brake System Warning Light
ANTI -
LOCK
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
“Brake System Warning Light” 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
Ill This gage shows the engine
1
*\\I‘
00
%,
0
260
coolant temperature.
It also provides an indicator
of how hard your vehicle is
working. During a majority of the operation, the gage
will read 210°F
(lOO°C) or less. If you are pulling a
load or going up hills, it is normal for
the temperature to
fluctuate and approach the
260°F (125°C) mark. If the
gage reaches the 260°F ( 125 “C) mark, it indicates that
the cooling system is working beyond its capacity.
In “Problems on the Road,” this manual shows what to
do. See “Engine Overheating” in the Index.
2-72
ProCarManuals.com

Malfunction Indicator Lamp (Service
Engine Soon Light) (Gasoline Engine)
SERVICE
ENGINE
SOON
Your vehicle is equipped
with a computer which
monitors operation of the
fuel, ignition and emission
control systems.
This system is called OBD
II (On-Board
Diagnostics-Second Generation) and is intended to assure
that emissions are at acceptable levels for the life
of the
vehicle, helping to produce a cleaner environment. (In
Canada,
OBD II is replaced by Enhanced Diagnostics.)
The SERVICE ENGINE SOON light comes on to
indicate that there is a problem and service is required.
Malfunctions often will
be indicated by the system before
any problem is apparent.
This may prevent more serious
damage to your vehicle. This system is
also designed
to assist your service technician in correctly diagnosing
any malfunction.
NOTICE:
If you keep driving your vehicle with this light
on, after a while, your emission controls may not
work as well, your fuel economy may not be as
good and your engine may not run as smoothly.
This could lead to costly repairs that may not be
covered by your warranty.
This light should come on, as a check to show you it is
working, when the ignition is on and the engine is not
running. If the light doesn’t come on, have it repaired.
This light will also come on during a malfunction in one
of two ways:
0 Light Flashing -- A misfire condition has been
detected. A misfire increases vehicle emissions and
may damage the emission control system on your
vehicle. Dealer or qualified service center diagnosis
and service is required.
Light On Steady -- An emission control system
malfunction has been detected on your vehicle.
Dealer or qualified service center diagnosis and
service may be required.
2-73
ProCarManuals.com

If the Light Is Flashing If the Light Is On Steady
The following may prevent more serious damage to
your vehicle:
0 Reducing vehicle speed.
0 Avoiding hard accelerations.
0 Avoiding steep uphill grades.
0 If you are towing a trailer, reduce the amount of
cargo being hauled as soon as it is possible.
If the light stops flashing and remains on steady, see “If
the Light Is On Steady” following.
If the light continues to flash, when
it is safe to do so,
stup the vehicle. Find a safe place to park your vehicle.
Turn the key off, wait at least
10 seconds and restart the
engine. If the light remains on steady, see “If the Light
Is On Steady” following. If the light is still flashing,
follow the previous steps, and drive the vehicle to your
dealer or qualified service center for service. You
may be able to correct the emission system
malfunction by considering the following:
Did you recently put fuel into your vehicle?
If
so, reinstall the fuel cap, making sure to fully install
the cap. The diagnostic system can determine if the fuel
cap has been
left off or improperly installed. A loose or
missing fuel cap
will allow fuel to evaporate into the
atmosphere.
A few driving trips with the cap properly
installed should turn the light off.
Did you just drive through a deep puddle of water?
If
so, your electrical system may be wet. The condition
will usually be corrected when the electrical system
dries out.
A few driving trips should turn the light off.
Are you low on
fuel?
As your engine starts to run out of fuel, your engine may
not run as efficiently as designed since small amounts of
air are sucked into the fuel line causing a misfire. The
system can detect this. Adding fuel should correct this
condition. Make sure to install
the fuel cap properly. It
will take a
few driving trips to turn the light off.
2-74
ProCarManuals.com