GMC C-SERIES 1999 Service Manual

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CAUTION:
Never do this.
Here a child is sitting in a seat that has a
lap
-shoulder belt, but the shoulder part is behind
the child. If the child wears the belt in this way, in
a crash the child might slide under the belt. The
belt's force would then be applied right on the
child's abdomen. That could cause serious or
fatal injuries.
Wherever the child sits, the lap portion of the belt
should be worn low and snug on the hips, just touching
the child's thighs. This applies belt force to the child's
pelvic bones in a crash.
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Safety Belt Extender
If the vehicle's safety belt will fasten around you, you
should use it.
But if a safety belt isn't long enough to fasten, your
dealer will order you an extender. It's free. When you go
in to order it, take the heaviest coat you will wear, so the
extender will be long enough for you. The extender will
be just for you, and just for the seat in your vehicle that
you choose. Don't let someone else use it, and use it
only for the seat it is made to fit. To wear it, just attach it
to the regular safety belt.
Checking Your Restraint Systems
Now and then, make sure the safety belt reminder light
(if your vehicle has one) and all your belts, buckles,
latch plates, retractors and anchorages are working
properly. Look for any other loose or damaged safety
belt system parts. If you see anything that might keep a
safety belt system from doing its job, have it repaired.
Torn or frayed safety belts may not protect you in a
crash. They can rip apart under impact forces. If a belt is
torn or frayed, get a new one right away.
Replacing Restraint System Parts
After a Crash
If you've had a crash, do you need new belts?
After a very minor collision, nothing may be necessary.
But if the belts were stretched, as they would be if worn
during a more severe crash, then you need new belts.
If belts are cut or damaged, replace them. Collision
damage also may mean you will need to have safety belt
or seat parts repaired or replaced. New parts and repairs
may be necessary even if the belt wasn't being used at
the time of the collision.
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2-
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Section 2 Features and Controls
Here you can learn about the many standard and optional features on your vehicle, and information on starting,
shifting and braking. Also explained are the instrument panel and the warning systems that tell you if everything is
working properly
-- and what to do if you have a problem.
2
-2 Keys
2
-4 Door Locks
2
-5 Theft
2
-5 New Vehicle ªBreak-Inº
2
-6 Ignition Positions
2
-7 Starting Your Gasoline Engine
2
-10 Starting Your Diesel Engine
2
-13 Engine Checks Before Operating
2
-15 Engine Coolant Heater (If Equipped)
2
-16 Diesel Engine Exhaust Brake
2
-17 Two-Speed Rear Axle Electric Shift Control
(If Equipped)
2
-20 Automatic Transmission Operation
2
-22 Manual Transmission Operation
2
-23 Parking
2
-29 Parking Over Things That Burn
2
-29 Engine Exhaust2
-30 Running Your Engine While You're Parked
(Automatic Transmission)
2
-30 Windows
2
-31 Tilt Wheel (If Equipped)
2
-32 Turn Signal/Multifunction Lever
2
-39 Trailer Brake Hand Control Valve (Option)
2
-40 Inter-Axle Differential Lock Control
(If Equipped)
2
-41 Rear Axle Differential Lock Control
(If Equipped)
2
-42 Engine Air Control (If Equipped)
2
-43 Exterior Lamps
2
-46 Interior Lamps
2
-46 Mirrors
2
-50 Instrument Panel
2
-52 Instrument Panel Cluster
2
-55 Warning Lights, Gages and Indicators
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Keys
CAUTION:
Leaving children in a vehicle with the ignition
key is dangerous for many reasons. A child or
others could be badly injured or even killed.
They could operate the controls or even make the
vehicle move. Don't leave the keys in a vehicle
with children.
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The square-head key is for
the ignition switch only.
The oval-head key is for
the doors.If you have the optional one
-key system, the oval key
will operate all locks, including the ignition switch.
When a new vehicle is delivered, the dealer removes the
plugs from the keys and gives them to the first owner.
Each plug has a code on it that tells your dealer or a
qualified locksmith how to make extra keys. Keep the
plugs in a safe place. If you lose your keys, you'll be
able to have new ones made easily using this code.
NOTICE:
Your vehicle has a number of new features that
can help prevent theft. But you can have a lot of
trouble getting into your vehicle if you ever lock
your keys inside. You may even have to damage
your vehicle to get in. So be sure you have
extra keys.
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Door Locks
CAUTION:
Unlocked doors can be dangerous.
Passengers -- especially children -- can easily
open the doors and fall out. When a door is
locked, the inside handle won't open it.
Outsiders can easily enter through an unlocked
door when you slow down or stop your vehicle.
This may not be so obvious: You increase the
chance of being thrown out of the vehicle in a
crash if the doors aren't locked. Wear safety belts
properly, lock your doors, and you will be far
better off whenever you drive your vehicle.
To lock your door from
the inside, slide the lock
control down.
To unlock the door, slide the lock control up.
Power Door Locks (If Equipped)
Push the switch marked
LOCK to lock both doors
at once.
Push the switch marked UNLOCK to unlock both doors.
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2-5 Leaving Your Vehicle
If you are leaving the vehicle, take your keys, open your
door and set the locks from inside. Then get out and
close the door.
Theft
Vehicle theft is big business, especially in some cities,
and even commercial vehicles are no exception. Although
your vehicle has a number of theft
-deterrent features, we
know that nothing we put on it can make it impossible to
steal. However, there are ways you can help.
Key in the Ignition
If you leave your vehicle with the keys inside, it's an
easy target for joy riders or professional thieves
-- so
don't do it.
Remember to remove your key and take it with you.
Always do this. When you take your key with you, your
ignition will be locked. Also remember to lock the doors.
New Vehicle ªBreak-Inº
NOTICE:
Your vehicle doesn't need an elaborate
ªbreak
-in.º But it will perform better in the long
run if you follow these guidelines:

Let your engine warm up before you
operate your vehicle under load.

Keep your speed at 55 mph (88 km/h) or
less for the first 500 miles (805 km).

Don't drive at any one speed
-- fast or
slow
-- for the first 500 miles (805 km).
Don't make full
-throttle starts.

Avoid making hard stops for the first
200 miles (322 km) or so. During this time
your new brake linings aren't yet broken
in. Hard stops with new linings can mean
premature wear and earlier replacement.
Follow this breaking
-in guideline every
time you get new brake linings.
NOTICE: (Continued)
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NOTICE: (Continued)

Use the lowest gear you can when you start
a loaded vehicle in motion and when going
up hills to avoid overloading the engine.

Check and adjust engine and transmission
fluid levels often and be sure tires are properly
inflated for the load you're carrying.

If you have a Caterpillar
 diesel engine,
see the Caterpillar Operation &
Maintenance Manual.
Ignition Positions
CAUTION:
Leaving children in a vehicle with the ignition
key is dangerous for many reasons. A child or
others could be injured or even killed. They could
operate power windows or other controls or even
make the vehicle move. Don't leave the keys in
the vehicle with children.
Use your square-head key to start your vehicle (unless it
has the single
-key option, where one oval-head key
works everything, including the ignition). You can turn
the ignition switch to five different positions.
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ACCESSORY (A): This position lets you use
accessories when the engine is off. To use
ACCESSORY, push in the key and turn it toward you.
LOCK (B): This position locks your ignition. You will
be able to remove your key only when the switch is in
this position.
OFF (C): This position lets you turn off the engine, but
the key can't be removed.
RUN (D): This is the position for driving and activating
the CAT diesel air inlet heater (if equipped).
START (E): This position starts your engine.
Engine Starter Over-Crank Protection
(If Equipped)
Some vehicles have an engine starter over-crank
protection system. This system includes a built
-in
temperature limiting switch to prevent internal damage
to the starter. If the starter motor overheats and shuts
off due to over
-cranking, the motor must cool down
before the switch will reset and allow you to operate the
starter. It can take up to six minutes before the starter
will work again.
Starting Your Gasoline Engine
Engines start differently. The 8th digit of your Vehicle
Identification Number (VIN) shows the code letter for
your engine. (See ªVehicle Identification Numberº in
the Index.) Follow the proper steps to start the engine.
To start a diesel engine, see ªStarting Your Diesel
Engineº in the Index.
Automatic Transmission
Set the parking brake and move your shift lever to
NEUTRAL (N) or PARK (P) if so equipped. Your
engine won't start in any other position
-- that's a
safety feature.
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2-8 Manual Transmission
Set the parking brake, shift your gear selector to
NEUTRAL and hold the clutch pedal to the floor while
starting the engine.
Starter Motor Operation
1. The starter motor will disengage if you release
the key or the engine reaches a predetermined
engine speed.
2. To prevent overheating, the starter motor will
disengage after continuously operating for 15 seconds.
You must release the key from the start position to
re
-engage the starter.
3. The starter motor will not engage if the engine is
already running.
4. The starter motor will disengage if, after two
seconds, the starter pinion gear does not engage the
flywheel or there is no engine rpm signal from the
engine speed sensor.
Starting Your Engine
1. Without pushing the accelerator pedal, turn your
ignition key to START. When the engine starts, let
go of the key. The idle speed will go down as your
engine gets warm.
2. If the engine doesn't start in 10 seconds, push the
accelerator pedal all the way down and crank the
engine for five more seconds, unless it starts sooner.
3. If your engine still won't start (or starts but then
stops), it could be flooded with too much gasoline.
Wait 15 seconds to let the starter motor cool down.
Do Steps 1 through 3 again.
When the engine starts, let go of the key and the
accelerator pedal.
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