1999 CHEVROLET SILVERADO climate control

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2-40
Running Your Engine While You're
Parked (Automatic Transmission)
It's better not to park with the engine running. But if
ever you have to, here are some things to know.
CAUTION:
Idling the engine with the climate control
system off could allow dangerous exhaust into
your vehicle (see the earlier Caution under
ªEngine Exhaustº).
Also, idling in a closed-in place can let deadly
carbon monoxide (CO) into your vehicle even if
the fan switch is at the highest setting. One place
this can happen is a garage. Exhaust
-- with
CO
-- can come in easily. NEVER park in a
garage with the engine running.
Another closed-in place can be a blizzard.
(See ªBlizzardº in the Index.)
CAUTION:
It can be dangerous to get out of your vehicle if
the shift lever is not fully in PARK (P) with the
parking brake firmly set. Your vehicle can roll.
Don't leave your vehicle when the engine is
running unless you have to. If you've left the
engine running, the vehicle can move suddenly.
You or others could be injured. To be sure your
vehicle won't move, even when you're on fairly
level ground, always set your parking brake and
move the shift lever to PARK (P).
Four-wheel drive vehicles with the transfer case in
NEUTRAL (N) will allow the vehicle to roll, even if
your shift lever is in PARK (P). So, be sure the transfer
case is in a drive gear
-- not in NEUTRAL (N). Always
set your parking brake. Follow the proper steps to be
sure your vehicle won't move. See ªShifting Into
PARK (P)º in the Index.
If you're pulling a trailer, see ªTowing a Trailerº in
the Index.

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6-50 Uniform Tire Quality Grading
The following information relates to the system
developed by the United States National Highway
Traffic Safety Administration, which grades tires by
treadwear, traction and temperature performance. (This
applies only to vehicles sold in the United States.) The
grades are molded on the sidewalls of most passenger
car tires. The Uniform Tire Quality Grading system does
not apply to deep tread, winter
-type snow tires,
space
-saver or temporary use spare tires, tires with
nominal rim diameters of 10 to 12 inches (25 to 30 cm),
or to some limited
-production tires.
While the tires available on General Motors passenger
cars and light trucks may vary with respect to these
grades, they must also conform to Federal safety
requirements and additional General Motors Tire
Performance Criteria (TPC) standards.Treadwear
The treadwear grade is a comparative rating based on
the wear rate of the tire when tested under controlled
conditions on a specified government test course. For
example, a tire graded 150 would wear one and a half
(1 1/2) times as well on the government course as a tire
graded 100. The relative performance of tires depends
upon the actual conditions of their use, however, and
may depart significantly from the norm due to variations
in driving habits, service practices and differences in
road characteristics and climate.
Traction -- AA, A, B, C
The traction grades, from highest to lowest, are AA, A,
B, and C. Those grades represent the tire's ability to stop
on wet pavement as measured under controlled
conditions on specified government test surfaces of
asphalt and concrete. A tire marked C may have poor
traction performance. Warning: The traction grade
assigned to this tire is based on straight
-ahead braking
traction tests, and does not include acceleration,
cornering, hydroplaning, or peak traction characteristics.

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6-66
NAME Usage
L BODY Retained Accessory Power Relay
LOCK Power Door Locks
DRV UNLOCK Power Door Lock RelayNAME Usage
LOCK Power Door Lock Relay
HVAC 1 Climate Control System
CRUISE Cruise Control, Instrument Cluster
IGN 3 Ignition, Power Seats
4WD Four
-Wheel Drive System,
Auxiliary Battery
CRANK Starting System
INT PRK Parking Lamps, Sidemarker
Lamps, Interior Lamps
L DOOR Power Door Lock Relay
BRAKE Anti
-Lock Brake System
RR WIPER Not Used
ILLUM Interior Lamps
SEAT Power Seat Circuit Breaker

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6-67
NAME Usage
TURN Exterior Lamps, Turn Signals,
Hazard Lamps
UNLOCK Power Door Locks
HTR A/C Climate Control System
WS WPR Windshield Wipers
IGN 1 Ignition, Instrument Panel
AIR BAG Air Bag
MIR/LOCK Power Mirrors, Power Door Locks
DR LOCK Power Door Locks
PWR WDO Power Window Circuit BreakerNAME Usage
UNLOCK Power Door Lock Relay
IGN 0 PRND321 Display, Odometer,
VCM/PCM
SEO IGN Special Equipment Option,
Ignition, Manual Selectable Ride
SEO ACCY Special Equipment Option
Accessory, Cellular Telephone
RAP #1 Retained Accessory Power Relay
RDO 1 Audio System
RAP #2 Not Used

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6-71
Name Usage
STUD #1 Accessory Power/Trailer Wiring
Feed
ABS Anti
-Lock Brakes
IGN A Ignition Switch
AIR A.I.R. System
RAP #1 Retained Accessory Power, Power
Mirrors, Power Door Locks,
Power Seat(s)
IGN B Ignition Switch
RAP #2 Not Used
STUD #2 Accessory Power/Trailer Wiring
Brake Feed
TRL R TRN Right Turn Signal Trailer Wiring
TRL L TRN Left Turn Signal Trailer Wiring
IGN 1 Ignition, Fuel Controls
INJ B Ignition, Fuel Controls (Relay)
STARTER Starter (Relay)
PARK LP Parking Lamps
FRT HVAC Climate Control System
STOP LP Exterior Lamps, Stoplamps
ECM 1 VCM/PCM
CHMSL Center High Mounted Stoplamp
VEH STOP Stoplamps, Cruise ControlName Usage
TRL B/U Backup Lamps Trailer Wiring
INJ A Fuel Controls, Ignition
RR HVAC Not Used
VEH B/U Vehicle Backup Lamps
ENG 1 Engine Controls, Canister Purge,
Fuel System
ETC Electronic Throttle Control
IGN E A/C Compressor Relay, Rear
Window Defogger, Daytime
Running Lamps, A.I.R. System
B/U LP Backup Lamps, BTSI
ATC Automatic Transfer Case
RR DEFOG Rear Window Defogger, Heated
Mirrors (Relay)
RR PRK Right Rear Parking Lamps
ECM B VCM/PCM
F/PMP Fuel Pump (Relay)
O2 A Oxygen Sensors
O2 B Oxygen Sensors
LR PRK Left Rear Parking Lamps
RR DEFOG Rear Window Defogger, Heated
Mirrors
HDLP Headlamps (Relay)

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6-72
Name Usage
TRL PRK Parking Lamps Trailer Wiring
RT HDLP Right Headlamps
DRL Daytime Running Lamps (Relay)
HTD MIR Heated Mirrors
LT HDLP Left Headlamps
A/C Air Conditioning
AUX PWR Cigarette Lighter, Auxiliary
Power Outlets
SEO 2 Special Equipment Option Power,
Power Seats, Aux Roof Mnt Lamp
SEO 1 Special Equipment Option Power,
Aux Roof Mnt Lamp, Cell Phone
DRL Daytime Running Lamps
A/C A/C (Relay)
FOG LP Fog Lamps
FOG LP Fog Lamps (Relay)
RADIO Audio System, Instrument Cluster,
Climate Control System
CIGAR Cigarette Lighter,
Auxiliary Power OutletsName Usage
RT TURN Right Turn Signals
BTSI Brake
-Transmission
Shift Interlock
LT TURN Left Turn Signals
FR PRK Front Parking Lamps,
Sidemarker Lamps
W/W PMP Windshield Washer Pump
HORN Horn (Relay)
IGN C Ignition Switch, Fuel Pump,
PRND321 Display, Crank
RDO AMP Not Used
HAZ LP Exterior Lamps, Hazard Lamps
EXP LPS Not Used
HORN Horn
CTSY LP Interior Lamps
RR WPR Not Used
TBC Body Control Module, Remote
Keyless Entry, Headlamps

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9-3
Inside of Your Vehicle 6-54 . . . . . . . . . . . . . . . . . . . . . . . . .
Instrument Panel 6-56 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Interior Plastic Components 6-56 . . . . . . . . . . . . . . . . . . . . .
Leather 6-56 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Outside of Your Vehicle 6-58 . . . . . . . . . . . . . . . . . . . . . . . .
Special Problems 6-55 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stains 6-55 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tires 6-60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vinyl 6-56 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wheels 6-59 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Windshield and Wiper Blades 6-57 . . . . . . . . . . . . . . . . . . .
Climate Control System 3-2, 3-3 . . . . . . . . . . . . . . . . . . . . . . .
Clock, Setting the 3-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Clutch Fluid, Hydraulic 6-24, 7-25 . . . . . . . . . . . . . . . . . . . . .
Clutch, System Check 7-20 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Comfort Controls 3-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Comfort Guides, Rear 1-41 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compact Disc Care 3-28 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Compact Disc Player 3-18, 3-22 . . . . . . . . . . . . . . . . . . . . . . .
Compact Disc Player Care 3-28 . . . . . . . . . . . . . . . . . . . . . . . .
Compass, Rearview Mirror with 2-56 . . . . . . . . . . . . . . . . . . .
Console Storage 2-63 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Content Theft-Deterrent 2-11 . . . . . . . . . . . . . . . . . . . . . . . . .
Control of a Vehicle 4-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Convex Outside Mirror 2-60 . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant 6-29, 6-75, 7-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Heater, Engine 2-19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Surge Tank 5-12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Surge Tank Pressure Cap 6-28 . . . . . . . . . . . . . . . . . .
Cooling System 5-12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Courtesy Transportation 8-8 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cruise Control 2-48 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cruise Light 2-80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cupholders 2-63 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Customer Assistance for Text Telephone Users 8
-4 . . . . . . . . .
Customer Assistance Information 8-1 . . . . . . . . . . . . . . . . . . .
Customer Satisfaction Procedure 8-2 . . . . . . . . . . . . . . . . . . . .
Damage, Finish 6-60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Damage, Sheet Metal 6-60 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Daytime Running Lamp Bulb Replacement 6-40 . . . . . . . . . .
Daytime Running Lamps 2-52 . . . . . . . . . . . . . . . . . . . . . . . . .
Dead Battery 5-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defects, Reporting Safety 8-10 . . . . . . . . . . . . . . . . . . . . . . . .
Defensive Driving 4-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defogger, Rear Window 3-6 . . . . . . . . . . . . . . . . . . . . . . . . . .
Defogging and Defrosting 3-6 . . . . . . . . . . . . . . . . . . . . . . . . .
Dolby B Noise Reduction 3-16 . . . . . . . . . . . . . . . . . . . . . . . .
Dome Lamps 2-55 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Door
Locks 2
-4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Third 2-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Downshifting 2-26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Driver Position 1-18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Driving
City 4
-35 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defensive 4-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drunken 4-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Freeway 4-36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
In a Blizzard 4-42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
In the Rain 4-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Night 4-30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Off-Road 4-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
On Curves 4-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
On Grades While Towing a Trailer 4-62 . . . . . . . . . . . . . . .
On Hill and Mountain Roads 4-38 . . . . . . . . . . . . . . . . . . . .
On Snow and Ice 4-40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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9-4
Driving (Continued)
Through Water 4-34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wet Roads 4-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Winter 4-40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
With a Trailer 4-61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drunken Driving 4-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Easy Entry Seat 1-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Equipment, Adding 2-17, 3-26, 6-70 . . . . . . . . . . .
Electrical System 6-64 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrochromic Day/Night Rearview Mirror 2-56 . . . . . . . . . .
Engine 6-10, 6-11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant 6-29, 6-75, 7-25 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Heater 2-19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Level Check 7-18 . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant Temperature Gage 2-75 . . . . . . . . . . . . . . . . . . . . .
Cooling System Capacity 6-75 . . . . . . . . . . . . . . . . . . . . . . .
Exhaust 2-39 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuse Block 6-69 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Identification 6-63 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Level Check 7-18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overheating 5-9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Running While Parked 2-40 . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications 6-74 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Starting Your 2-16, 2-18 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Underhood Electrical Center 6-69 . . . . . . . . . . . . . . . . . . . .
Engine Fan Noise 5-18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Oil 6-12, 7-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adding 6-13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Additives 6-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking 6-13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Oil Life Monitor 6
-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pressure Gage 2-79 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Used 6-16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
When to Change 6-15 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Overheated Message 2-85 . . . . . . . . . . . . . . . . . . . . . .
Exhaust, Engine 2-39 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fabric Cleaning 6-54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fan Control, Climate Control System 3-2, 3-3 . . . . . . . . . . . .
Filling a Portable Fuel Container 6-8 . . . . . . . . . . . . . . . . . . . .
Filling Your Tank 6-6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filter
Engine Air Cleaner 6
-16, 6-77 . . . . . . . . . . . . . . . . . . . . . . .
Oil 6-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Passenger Compartment Air 3-5, 6-18, 6-77 . . . . . . . . . . .
Finish Care 6-58 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Finish Damage 6-60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Flashers, Hazard Warning 5-2 . . . . . . . . . . . . . . . . . . . . . . . . .
Flat Tire, Changing 5-18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluid Capacities 6-75 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fluids and Lubricants 7-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fog Lamps 2-53 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Foreign Countries, Fuel 6-5 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Four-Wheel Drive 2-27, 6-26 . . . . . . . . . . . . . . . . . . . . . . . . .
French Language Manual ii. . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Axle 6
-27, 7-26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Axle Locking Feature 2-27 . . . . . . . . . . . . . . . . . . . . . . .
Front Axle Reserve Capacity 4-49 . . . . . . . . . . . . . . . . . . . . . .
Front Sidemarker Lamp Bulb Replacement 6-40 . . . . . . . . . . .
Front Towing 5-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Front Turn Signal Lamp Bulb Replacement 6-40 . . . . . . . . . .