1999 GMC C-SERIES warning light

yellowblue
6-18
CAUTION:
Gasoline Engines Only: Operating the engine
with the air cleaner/filter off can cause you or
others to be burned. The air cleaner not only
cleans the air, it stops flame if the engine
backfires. If it isn't there, and the engine
backfires, you could be burned. Don't drive with
it off, and be careful working on the engine with
the air cleaner/filter off.
NOTICE:
Gasoline Engines Only: If the air cleaner/filter is
off, a backfire can cause a damaging engine fire.
And, dirt can easily get into your engine, which
will damage it. Always have the air cleaner/filter
in place when you're driving.
Your vehicle may also be equipped with an optional
Filterminder gage. See ªWarning Lights, Gages and
Indicatorsº in the Index.
Automatic Transmission Fluid
When to Check
A good time to have it checked is when the engine oil is
checked. See your Allison Automatic Transmission
Operator's Manual to find out when to change your
transmission fluid and filters.
How to Check and What to Use
The Allison Automatic Transmission Operator's Manual
that came with the vehicle shows how to check the
automatic transmission fluid and what fluid to use.
NOTICE:
Too much or too little fluid can damage your
transmission. Too much can mean that some of
the fluid could come out and fall on hot engine
parts or exhaust system parts, starting a fire. Be
sure to get an accurate reading if you check your
transmission fluid.
ProCarManuals.com

yellowblue
6-23
Engine Coolant (Gasoline Engine)
The cooling system in your vehicle is filled with
DEX
-COOL
engine coolant. This coolant is designed
to remain in your vehicle for 5 years or 150,000 miles
(240 000 km), whichever occurs first, if you add only
DEX
-COOL
extended life coolant.
The following explains your cooling system and how to
add coolant when it is low. If you have a problem with
engine overheating, see ªEngine Overheatingº in
the Index.
A 50/50 mixture of clean, drinkable water and
DEX
-COOL
coolant will:

Give freezing protection down to
-34F (-37C).

Give boiling protection up to 252F (122C).

Protect against rust and corrosion.

Help keep the proper engine temperature.

Let the warning lights and gages work as
they should.
NOTICE:
When adding coolant, it is important that you
use only DEX
-COOL (silicate-free) coolant.
If coolant other than DEX-COOL is added to
the system, premature engine, heater core or
radiator corrosion may result. In addition, the
engine coolant will require change sooner
-- at
30,000 miles (50 000 km) or 24 months,
whichever occurs first. Damage caused by the
use of coolant other than DEX
-COOL is not
covered by your new vehicle warranty.
ProCarManuals.com

yellowblue
6-26
Surge Tank (Caterpillar
Diesel Engines)
When your engine is cold, the coolant level should be at
the COLD level, or a little higher, on the coolant
recovery tank with the gasoline engine, or at the COLD
FULL mark, visible through the surge tank, with the
diesel engine.
If this light comes on and
stays on, it means you're
low on engine coolant.
See ªLights, Low Coolant Warning Lightº in the Index
for further information.
Adding Coolant
If you need more coolant, add the proper DEX
-COOL

coolant mixture at the coolant recovery tank or the
surge tank.
ProCarManuals.com

yellowblue
6-29 What to Use
To determine what kind of fluid to use, see
ªRecommended Fluids and Lubricantsº in the Index.
NOTICE:
When adding power steering fluid or making a
complete fluid change, always use the proper
fluid. Failure to use the proper fluid can cause
leaks and damage hoses and seals.
If your power steering fluid level is low, this can
cause the PRIMARY BRAKE or AUX BRAKE
warning lights to come on. If either light remains
on after you have added power steering fluid to
the proper level, then shut off the engine for
10 seconds. This should reset the brake warning
lights. If one or both lights stay on, though,
then see ªHydraulic Brake Warning Lightsº in
the Index.
Windshield Washer Fluid
What to Use
When you need windshield washer fluid, be sure to read
the manufacturer's instructions before use. If you will be
operating your vehicle in an area where the temperature
may fall below freezing, use a fluid that has sufficient
protection against freezing.
Adding Washer Fluid
Open the cap labeled WASHER FLUID ONLY.
Add washer fluid until the tank is full.
ProCarManuals.com

yellowblue
7-26
Engine Cooling System Service
Inspect the hoses and have them replaced if they are
cracked, swollen or deteriorated. Inspect all pipes,
fittings and clamps; replace as needed. Clean the outside
of the radiator and air conditioning condenser. To help
ensure proper operation, a pressure test of the cooling
system and pressure cap is recommended at least once
a year.
Exhaust System Check
Be alert for any changes in the sound of the exhaust
system or any smell of fumes. These are signs the
system may be leaking. Have it checked and/or repaired
at once. Refer to ªEngine Exhaustº and ªRunning Your
Engine While You're Parkedº in the Index.
Windshield Wipers and Washers Check
Check operation and condition of the wiper blades.
Check the flow of the washer spray.
Defroster Check
Move the control to the defrost symbol and the fan to HI
or the high symbol. Then check the airflow from the
ducts at the inside base of the windshield.Mirrors and Sun Visors Check
Check that friction joints hold mirrors and sun visors
in place.
Seat Adjuster Check
When adjusting a manual seat, be sure seat adjusters
latch by attempting to move the seat after latching.
Lamps Check
Check panel lighting, warning lights, indicator lights
and interior lamps. On the outside, check: license plate
lamps, sidemarker lamps, reflectors or lights on outside
mirrors, headlamps, parking lamps, identification and
clearance lamps, taillamps, brake lamps, turn signals,
backup lamps and hazard warning flashers. Have
headlamp aim checked at once if beams seem
improperly aimed.
Glass, Mirrors, Lamps and/or Reflectors
Condition Check
Look for broken, scratched, dirty or damaged glass,
mirrors, lamps or reflectors that could reduce the view
or visibility or cause injury. Replace, clean or
repair promptly.
ProCarManuals.com

9-yellowblue
9-1
Section 9 Index
A
ir
Brake System Warning Light 2-59 . . . . . . . . . . . . . . . . . . . .
Cleaner 6-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cleaner Filter 6-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compressor Filter 6-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Conditioning 3-5, 6-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Conditioning Refrigerants 6-77 . . . . . . . . . . . . . . . . . . . . . .
Dryer 6-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filter Restriction Indicator 6-17 . . . . . . . . . . . . . . . . . . . . . .
Suspension 2-19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Brake Systems 6-33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Dryer 6-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alcohol Injector 6-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Moisture Ejector 6-33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alcohol Injector 6-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Alignment and Balance, Tire 6-51 . . . . . . . . . . . . . . . . . . . . . .
AM-FM Stereo 3-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AM-FM Stereo with Remote Cassette Tape Player 3-10 . . . . .
Antenna 3-12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Antifreeze 6-23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Anti-Lock
Brakes 4-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake System Warning Light 2-61, 4-7 . . . . . . . . . . . . . . . .
Appearance Care 6-59 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appearance Care Materials 6-66 . . . . . . . . . . . . . . . . . . . . . . . Apply Park Brake Warning Light 2
-60 . . . . . . . . . . . . . . . . . .
Ashtray 2-47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Audio Systems 3-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Automatic Transmission Fluid 6-18 . . . . . . . . . . . . . . . . . . . . .
Automatic Transmission Shift Indicator Check 7-25 . . . . . . . .
Auxiliary Power Jacks 2-48 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Axle, Rear 6-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Airshift Control 2-19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Differential Lock Control 2-41 . . . . . . . . . . . . . . . . . . . . . . .
Fluid Capacity 6-76 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shift Motor 6-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tw o-Speed Electric Shift Control 2-17 . . . . . . . . . . . . . . . .
Towing 5-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Battery 6-42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Battery, Jump Starting 5-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake
Adjustment 6
-33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Brake Systems 6-33 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Air Parking Brake 2-26 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electric/Hydraulic Parking Brake 2-25 . . . . . . . . . . . . . . . .
Electric/Hydraulic Parking Brake Fluid 6-36 . . . . . . . . . . . .
Exhaust 2-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluid 6-30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ProCarManuals.com

yellowblue
9-2
Brake (Continued)
Four-Wheel and Six-Wheel Drum 6-33 . . . . . . . . . . . . . . .
Four-Wheel Disc 6-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hydraulic Systems 4-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Master Cylinder 6-30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parking 2-23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pedal Travel 6-33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Propshaft Brake Burnish Procedure 2-24 . . . . . . . . . . . . . . .
Releasing Air-Operated Parking Brakes 5-15 . . . . . . . . . . .
Replacing System Parts 6-35 . . . . . . . . . . . . . . . . . . . . . . . .
System Check 7-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Warning Lights 2-57 . . . . . . . . . . . . . . . . . . . . . . . .
Brake, Anti-Lock 4-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Braking 4-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Braking in Emergencies 4-9 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Break-In, New Vehicle 2-5 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Capacities and Specifications 6-74 . . . . . . . . . . . . . . . . . . . .
Carbon Monoxide 2-29, 2-30 , 4-27 . . . . . . . . . . . . . . . . . . .
Cassette Tape Player Care 3-12 . . . . . . . . . . . . . . . . . . . . . . . .
Center Passenger Position 1-22 . . . . . . . . . . . . . . . . . . . . . . . .
Certification/Tire Label 4-28, 6-67 . . . . . . . . . . . . . . . . . . . . .
Changing a Flat Tire 5-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Charging System Light 2-56 . . . . . . . . . . . . . . . . . . . . . . . . . .
Chassis Lubrication 6-37 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Check Gages Light 2-67 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking Your Restraint Systems 1-36 . . . . . . . . . . . . . . . . . .
Chemical Paint Spotting 6-65 . . . . . . . . . . . . . . . . . . . . . . . . . . Child Restraints 1
-26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Securing in the Center Seat Position 1-31 . . . . . . . . . . . . . .
Top Strap 1-30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cigarette Lighter 2-47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Breaker Block, Instrument Panel 6-69 . . . . . . . . . . . . .
Cleaner, Air 6-17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning
Fabric 6
-59 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Glass 6-62 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inside of Your Vehicle 6-59 . . . . . . . . . . . . . . . . . . . . . . . . .
Instrument Panel 6-61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Outside of Your Vehicle 6-63 . . . . . . . . . . . . . . . . . . . . . . . .
Safety Belts 6-61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Special Problems 6-60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tires 6-64 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vinyl 6-61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Windshield and Wiper Blades 6-62 . . . . . . . . . . . . . . . . . . .
Clock, Setting the 3-7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Clutch Pedal Free Travel 6-37 . . . . . . . . . . . . . . . . . . . . . . . . .
Comfort Controls 3-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Component Box 6-44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Connections, Trailer 2-49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control of a Vehicle 4-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant 6-23 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Heater, Engine 2-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Recovery Tank 5-22 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Surge Tank 5-29 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ProCarManuals.com

yellowblue
9-5
Gages
Air Pressure 2-69 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Coolant Temperature 2-61 . . . . . . . . . . . . . . . . . . . .
Engine Oil Pressure 2-65 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filterminder 2-70 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel 2-68 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hourmeter 2-70 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Pressure 2-65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Speedometer 2-53 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tachometer 2-54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transmission Temperature 2-69 . . . . . . . . . . . . . . . . . . . . . .
Voltmeter 2-56 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Guide en Fran†ais ii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hazard Warning Flasher Switch 5-3 . . . . . . . . . . . . . . . . . . .
Hazard Warning Flashers 5-2 . . . . . . . . . . . . . . . . . . . . . . . . . .
Head Restraints 1-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Headlamps 2-43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High/Low Beam Changer 2-34 . . . . . . . . . . . . . . . . . . . . . .
Wiring 6-68 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Heating 3-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Highway Hypnosis 4-21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hill and Mountain Roads 4-22 . . . . . . . . . . . . . . . . . . . . . . . . .
Hood
Access Panels 6
-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking Things Under 6-9 . . . . . . . . . . . . . . . . . . . . . . . . .
Latches Check 7-27 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Horn 2-31 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hourmeter Gage 2
-70 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hydraulic Brake Warning Light 2-58 . . . . . . . . . . . . . . . . . . . .
Hydroplaning 4-18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ignition Positions 2-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inflation, Tire 6-49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inspections
Engine Cover Check 7
-27 . . . . . . . . . . . . . . . . . . . . . . . . . .
Underbody 7-27 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Instrument Panel 2-50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Breaker Block 6-69 . . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning 6-61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cluster 2-52 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Intake Heater Indicator Light 2-63 . . . . . . . . . . . . . . . . . . . . . .
Inter-Axle Differential Lock Control 2-40 . . . . . . . . . . . . . . . .
Jump Starting 5-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Keys 2-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Labels
Certification/Tire 4-28, 6-67 . . . . . . . . . . . . . . . . . . . . . . . .
Service Parts Identification 6-67 . . . . . . . . . . . . . . . . . . . . .
Vehicle Identification Number 6-67 . . . . . . . . . . . . . . . . . . .
Lamp and Bulb Data 6-74 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lamp Check 7-26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ProCarManuals.com