
Black plate (80,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
10-80 Vehicle Care
Notice:Storing an aluminum
wheel with a flat tire under your
vehicle for an extended period of
time or with the valve stem
pointing up can damage the
wheel. Always stow the wheel
with the valve stem pointing
down and have the wheel/tire
repaired as soon as possible.
Store the tire under the rear of the
vehicle in the spare tire carrier.A. Flat or Spare Tire (Valve Stem Pointed Down)
B. Hoist Assembly
C. Hoist Cable
D. Tire/Wheel Retainer
E. Hoist Shaft
F. Hoist End of Extension Tool
G. Hoist Shaft Access Hole
H. Wheel Wrench
I. Jack Handle Extensions
J. Spare Tire Lock (If Equipped)
1. Put the tire on the ground at the rear of the vehicle with the valve
stem pointed down, and to
the rear.
2. Pull the cable and spring through the center of the wheel.
Tilt the wheel retainer plate
down and through the center
wheel.
Make sure the retainer is fully
seated across the underside of
the wheel.
3. Attach the wheel wrench (H) and
extensions (I) together, as
shown.
4. Insert the hoist end (F) throughthe hole (G) in the rear bumper
and onto the hoist shaft.
Do not use the chiseled end of
the wheel wrench.

Black plate (1,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
INDEX i-1
A
Accessories andModifications . . . . . . . . . . . . . . . . . 10-3
Accessory Power . . . . . . . . . . . . . . 9-27
Active Fuel Management
®. . . . . 9-30
Add-On Electrical Equipment . . . . . . . . . . . . . . . . . . 9-101
Adding a Snow Plow or Similar Equipment . . . . . . . . . . . 9-101
Additional Information OnStar
®. . . . . . . . . . . . . . . . . . . . . . 14-5
Adjustable Throttle and Brake Pedal . . . . . . . . . . . . . . . . . . 9-23
Adjustments Lumbar, Front Seats . . . . . . . . . . . 3-4
Air Cleaner/Filter, Engine . . . . . 10-15
Air Vents . . . . . . . . . . . . . . . . . . . . . . 8-10
Airbag System
Check . . . . . . . . . . . . . . . . . . . . . . . . 3-37
How Does an AirbagRestrain? . . . . . . . . . . . . . . . . . . . 3-26
Passenger Sensing System . . . . . . . . . . . . . . . . . . . . . . 3-31
What Makes an Airbag Inflate? . . . . . . . . . . . . . . . . . . . . . . 3-26 Airbag System (cont'd)
What Will You See after an
Airbag Inflates? . . . . . . . . . . . . . 3-26
When Should an Airbag
Inflate? . . . . . . . . . . . . . . . . . . . . . . 3-24
Where Are the Airbags? . . . . . . 3-22
Airbags Adding Equipment to theVehicle . . . . . . . . . . . . . . . . . . . . . . 3-35
Light On-Off . . . . . . . . . . . . . . . . . . 5-18
On-Off Light . . . . . . . . . . . . . . . . . . 5-18
On-Off Switch . . . . . . . . . . . . . . . . 3-28
Passenger Status Indicator . . . 5-19
Readiness Light . . . . . . . . . . . . . . 5-17
Servicing Airbag-Equipped Vehicles . . . . . . . . . . . . . . . . . . . . . 3-35
System Check . . . . . . . . . . . . . . . . 3-20
Alarm
Vehicle Security . . . . . . . . . . . . . . 2-10
AM-FM Radio . . . . . . . . . . . . . . . . . . 7-10
Antenna Satellite Radio . . . . . . . . . . . . . . . . 7-16
Antilock Brake
System (ABS) . . . . . . . . . . . . . . . . 9-50
Warning Light . . . . . . . . . . . . . . . . . 5-24 Appearance Care
Exterior . . . . . . . . . . . . . . . . . . . . . 10-91
Interior . . . . . . . . . . . . . . . . . . . . . . 10-94
Armrest Storage . . . . . . . . . . . . . . . . 4-1
Ashtrays . . . . . . . . . . . . . . . . . . . . . . . 5-10
Assistance Program, Roadside . . . . . . . . . . . . . . 13-7, 13-11
Audio Players . . . . . . . . . . . . . . . . . 7-17 CD . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-17
CD/DVD . . . . . . . . . . . . . . . . . . . . . . 7-23
Audio System
Fixed Mast Antenna . . . . . . . . . . 7-16
Radio Reception . . . . . . . . . . . . . . 7-15
Rear Seat (RSA) . . . . . . . . . . . . . 7-47
Theft-Deterrent Feature . . . . . . . . 7-2
Automatic
Door Locks . . . . . . . . . . . . . . . . . . . . 2-7
Headlamp System . . . . . . . . . . . . . 6-3
Transmission . . . . . . . . . . . . . . . . . 9-32
Transmission Fluid . . 10-10, 10-12
Automatic Transmission
Manual Mode . . . . . . . . . . . . . . . . . 9-36
Shift Lock ControlFunction Check . . . . . . . . . . . 10-32

Black plate (2,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
i-2 INDEX
AuxiliaryDevices . . . . . . . . . . . . . . . . . . . . . . . 7-33
Roof Mounted Lamp . . . . . . . . . . . 6-6
Axle, Front . . . . . . . . . . . . . . . . . . . . 10-29
Axle, Rear . . . . . . . . . . . . . . . . . . . . 10-30
B
Battery . . . . . . . . . . . . . . . . . . . . . . . 10-27 Jump Starting . . . . . . . . . . . . . . . 10-82
Load Management . . . . . . . . . . . . . 6-9
Power Protection . . . . . . . . . . . . . . 6-9
Voltage and ChargingMessages . . . . . . . . . . . . . . . . . . . 5-37
Blade Replacement, Wiper . . . 10-33
Bluetooth . . . . . . . . . . . . . . . . . . . . . . 7-49
Brake Pedal and AdjustableThrottle . . . . . . . . . . . . . . . . . . . . . . 9-23
System Warning Light . . . . . . . . 5-23
Brakes . . . . . . . . . . . . . . . . . . . . . . . . 10-24 Antilock . . . . . . . . . . . . . . . . . . . . . . . 9-50
Assist . . . . . . . . . . . . . . . . . . . . . . . . . 9-52
Fluid . . . . . . . . . . . . . . . . . . . . . . . . 10-25
Parking . . . . . . . . . . . . . . . . . . . . . . . 9-51
System Messages . . . . . . . . . . . . 5-38 Braking . . . . . . . . . . . . . . . . . . . . . . . . . 9-3
Break-In, New Vehicle . . . . . . . . . 9-23
Bulb Replacement . . . . . . . . . . . . 10-38
Center High-MountedStoplamp (CHMSL) and
Cargo Lamp . . . . . . . . . . . . . . . 10-37
Fog Lamps . . . . . . . . . . . . . . . . . . . . 6-6
Halogen Bulbs . . . . . . . . . . . . . . 10-34
Headlamp Aiming . . . . . . . . . . . 10-34
Headlamps . . . . . . . . . . . . . . . . . 10-34
Headlamps, Front Turn
Signal, Sidemarker, and
Parking Lamps . . . . . . . . . . . . 10-35
License Plate Lamps . . . . . . . 10-37
Pick-up Box Identification and Fender Marker
Lamps . . . . . . . . . . . . . . . . . . . . 10-35
Taillamps . . . . . . . . . . . . . . . . . . . 10-36
Taillamps, Turn Signal, Stoplamps, and
Back-up Lamps . . . . . . . . . . . 10-36
Buying New Tires . . . . . . . . . . . . . 10-65
C
Calibration . . . . . . . . . . . . . . . . . . . . . . 5-5
California Fuel Requirements . . . . . . . . . . . 9-66
Perchlorate MaterialsRequirements . . . . . . . . . . . . . . . 10-3
Warning . . . . . . . . . . . . . . . . . . . . . . 10-2
Camera, Rear Vision . . . . . . . . . . 9-60
Canadian Vehicle Owners . . . . . . . . iii
Capacities and Specifications . . . . . . . . . . . . . . . . 12-2
Carbon Monoxide Engine Exhaust . . . . . . . . . . . . . . . 9-31
Tailgate . . . . . . . . . . . . . . . . . . . . . . . . 2-9
Winter Driving . . . . . . . . . . . . . . . . 9-12
Cargo Lamp . . . . . . . . . . . . . . . . . . . . 6-7
Cautions, Danger, and
Warnings . . . . . . . . . . . . . . . . . . . . . . . . iv
CD Player . . . . . . . . . . . . . . . . . . . . . 7-17
CD/DVD Player . . . . . . . . . . . . . . . . 7-23
Center Console Storage . . . . . . . . 4-2
Center High-Mounted Stoplamp (CHMSL) and
Cargo Lamp . . . . . . . . . . . . . . . . . 10-37
Center Seat . . . . . . . . . . . . . . . . . . . . 3-3
Chains, Tire . . . . . . . . . . . . . . . . . . 10-70

Black plate (4,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
i-4 INDEX
DrivingCharacteristics and
Towing Tips . . . . . . . . . . . . . . . . . 9-71
Defensive . . . . . . . . . . . . . . . . . . . . . . 9-3
Drunk . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3
For Better Fuel Economy . . . . . 1-33
Highway Hypnosis . . . . . . . . . . . . 9-11
Hill and Mountain Roads . . . . . . 9-11
If the Vehicle is Stuck . . . . . . . . . 9-14
Loss of Control . . . . . . . . . . . . . . . . 9-5
Off-Road . . . . . . . . . . . . . . . . . . . . . . 9-5
Off-Road Recovery . . . . . . . . . . . . 9-4
Vehicle Load Limits . . . . . . . . . . . 9-15
Wet Roads . . . . . . . . . . . . . . . . . . . 9-10
Winter . . . . . . . . . . . . . . . . . . . . . . . . 9-12
Dual Automatic Climate
Control System . . . . . . . . . . . . . . . . 8-5
Dual Tire Rotation . . . . . . . . . . . . . . . . . . . . 10-63
DVD Rear Seat Entertainment
System . . . . . . . . . . . . . . . . . . . . . . 7-38
DVD/CD Player . . . . . . . . . . . . . . . . 7-23E
E85 Fuel . . . . . . . . . . . . . . . . . . . . . . . 9-68
Electrical Equipment, Add-On . . . . . . . . . . . . . . . . . . . . . 9-101
Electrical System Engine CompartmentFuse Block . . . . . . . . . . . . . . . . 10-39
Fuses and Circuit Breakers . . . . . . . . . . . . . . . . . . 10-39
Instrument Panel Fuse Block . . . . . . . . . . . . . . . . . . . . . . 10-43
Overload . . . . . . . . . . . . . . . . . . . 10-38
Emergency OnStar
®. . . . . . . . . . . . . . . . . . . . . . 14-2
Engine Air Cleaner/Filter . . . . . . . . . . . 10-15
Check and Service Engine
Soon Light . . . . . . . . . . . . . . . . . . 5-21
Compartment Overview . . . . . . . 10-5
Coolant . . . . . . . . . . . . . . . . . . . . . 10-17
Coolant Heater . . . . . . . . . . . . . . . 9-28
Coolant Temperature Gauge . . . . . . . . . . . . . . . . . . . . . . 5-15 Engine (cont'd)
Cooling System . . . . . . . . . . . . . 10-16
Cooling System Messages . . . 5-39
Drive Belt Routing . . . . . . . . . . . . 12-6
Exhaust . . . . . . . . . . . . . . . . . . . . . . 9-31
Fan . . . . . . . . . . . . . . . . . . . . . . . . . 10-22
Oil Life System . . . . . . . . . . . . . . . 10-9
Oil Messages . . . . . . . . . . . . . . . . . 5-40
Oil Pressure Gauge . . . . . . . . . . 5-14
Overheated Protection
Operating Mode . . . . . . . . . . . 10-22
Overheating . . . . . . . . . . . . . . . . 10-20
Power Messages . . . . . . . . . . . . . 5-40
Pressure Light . . . . . . . . . . . . . . . . 5-26
Running While Parked . . . . . . . . 9-32
Starting . . . . . . . . . . . . . . . . . . . . . . . 9-25
Entry Lighting . . . . . . . . . . . . . . . . . . . 6-8
Equipment, Towing . . . . . . . . . . . . 9-89
Event Data Recorders . . . . . . . . 13-19
Exit Lighting . . . . . . . . . . . . . . . . . . . . 6-8
Extender, Safety Belt . . . . . . . . . . 3-19
Exterior Lamp Controls . . . . . . . . . 6-1
Exterior Lamps Off Reminder . . . 6-2

Black plate (7,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
INDEX i-7
Lamps (cont'd)Exterior Lamps Off
Reminder . . . . . . . . . . . . . . . . . . . . 6-2
License Plate . . . . . . . . . . . . . . . 10-37
Malfunction Indicator . . . . . . . . . 5-21
Messages . . . . . . . . . . . . . . . . . . . . 5-41
Pick-up Box Identification
and Fender Marker . . . . . . . . 10-35
Reading . . . . . . . . . . . . . . . . . . . . . . . 6-8
Taillamps . . . . . . . . . . . . . . . . . . . 10-36
Lap Belt . . . . . . . . . . . . . . . . . . . . . . . 3-18
Lap-Shoulder Belt . . . . . . . . . . . . . 3-13
LATCH System Replacing Parts after a
Crash . . . . . . . . . . . . . . . . . . . . . . . 3-54
LATCH, Lower Anchors and Tethers for Children . . . . . . . . . . 3-45
Lighter, Cigarette . . . . . . . . . . . . . . . 5-9
Lighting
Entry . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8
Exit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8
Illumination Control . . . . . . . . . . . . 6-7
Lights
Airbag On-Off . . . . . . . . . . . . . . . . . 5-18
Airbag Readiness . . . . . . . . . . . . . 5-17
Antilock Brake System(ABS) Warning . . . . . . . . . . . . . . 5-24 Lights (cont'd)
Brake System Warning . . . . . . . 5-23
Charging System . . . . . . . . . . . . . 5-20
Cruise Control . . . . . . . . . . . . . . . . 5-28
Engine Oil Pressure . . . . . . . . . . 5-26
Flash-to-Pass . . . . . . . . . . . . . . . . . . 6-3
Four-Wheel-Drive . . . . . . . . . . . . . 5-25
Front Fog Lamp . . . . . . . . . . . . . . 5-28
High-Beam On . . . . . . . . . . . . . . . . 5-28
High/Low Beam Changer . . . . . . 6-2
Low Fuel Warning . . . . . . . . . . . . 5-27
Safety Belt Reminders . . . . . . . . 5-16
Security . . . . . . . . . . . . . . . . . . . . . . 5-27
StabiliTrak
®OFF . . . . . . . . . . . . . 5-25
Tire Pressure . . . . . . . . . . . . . . . . . 5-26
Tow/Haul Mode . . . . . . . . . . . . . . . 5-25
Traction Control System (TCS)/StabiliTrak
®. . . . . . . . . . 5-26
Locking Rear Axle . . . . . . . . . . . . . 9-55
Locks Automatic Door . . . . . . . . . . . . . . . . 2-7
Delayed Locking . . . . . . . . . . . . . . . 2-7
Door . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Lockout Protection . . . . . . . . . . . . . 2-8
Power Door . . . . . . . . . . . . . . . . . . . . 2-7
Safety . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
Loss of Control . . . . . . . . . . . . . . . . . 9-5 Low Fuel Warning Light . . . . . . . . 5-27
Lower Anchors and Tethers
for Children (LATCH
System) . . . . . . . . . . . . . . . . . . . . . . 3-45
Lumbar Adjustment . . . . . . . . . . . . . 3-4 Front Seats . . . . . . . . . . . . . . . . . . . . 3-4
M
MaintenanceRecords . . . . . . . . . . . . . . . . . . . . .11-16
Maintenance Schedule Recommended Fluidsand Lubricants . . . . . . . . . . . . .11-12
Transfer Case . . . . . . . . . . . . . . . . 9-38
Malfunction Indicator Lamp . . . . 5-21
Manual Mirrors . . . . . . . . . . . . . . . . 2-13
Manual Mode . . . . . . . . . . . . . . . . . . 9-36
Manual Windows . . . . . . . . . . . . . . 2-18
Memory Features . . . . . . . . . . . . . . 1-12
Memory Seats . . . . . . . . . . . . . . . . . . 3-6
Messages Airbag System . . . . . . . . . . . . . . . . 5-43
Battery Voltage andCharging . . . . . . . . . . . . . . . . . . . . 5-37
Brake System . . . . . . . . . . . . . . . . 5-38
Door Ajar . . . . . . . . . . . . . . . . . . . . . 5-38

Black plate (9,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
INDEX i-9
Overheated EngineProtection
Operating Mode . . . . . . . . . . . . . 10-22
Overheating, Engine . . . . . . . . . . 10-20
Overview, Infotainment
System . . . . . . . . . . . . . . . 7-3, 7-4, 7-6
P
ParkShifting Into . . . . . . . . . . . . . . . . . . . 9-28
Shifting Out of . . . . . . . . . . . . . . . . 9-30
Tilt Mirrors . . . . . . . . . . . . . . . . . . . . 2-16
Parking Assist, Ultrasonic . . . . . . . . . . . . . 9-59
Brake . . . . . . . . . . . . . . . . . . . . . . . . . 9-51
Brake and P (Park)Mechanism Check . . . . . . . . 10-33
Over Things That Burn . . . . . . . 9-30
Passenger Airbag Status Indicator . . . . . . . . . . . . . . . . . . . . . 5-19
Passenger Sensing System . . . 3-31
Perchlorate Materials Requirements, California . . . . . 10-3
Personalization Vehicle . . . . . . . . . . . . . . . . . . . . . . . 5-46 Phone
Bluetooth . . . . . . . . . . . . . . . . . . . . . 7-49
Pick-up Box Identification and Fender Marker
Lamps . . . . . . . . . . . . . . . . . . . . . . 10-35
Pickup Conversion to Chassis Cab . . . . . . . . . . . . . . . . 9-104
Power Door Locks . . . . . . . . . . . . . . . . . . . . 2-7
Mirrors . . . . . . . . . . . . . . . . . . . . . . . . 2-14
Outlets . . . . . . . . . . . . . . . . . . . . . . . . 5-9
Protection, Battery . . . . . . . . . . . . . 6-9
Retained Accessory (RAP) . . . 9-27
Seat Adjustment . . . . . . . . . . . . . . . 3-4
Steering Fluid . . . . . . . . . . . . . . . 10-23
Windows . . . . . . . . . . . . . . . . . . . . . 2-18
Pregnancy, Using Safety Belts . . . . . . . . . . . . . . . . . . . . . . . . . 3-18
Privacy Radio FrequencyIdentification (RFID) . . . . . . . 13-20
Program Courtesy Transportation . . . . 13-13
Proposition 65 Warning, California . . . . . . . . . . . . . . . . . . . . . 10-2
R
Radio Frequency
Identification (RFID) . . . . . . . . 13-20
Statement . . . . . . . . . . . . . . . . . . 13-20
Radios AM-FM Radio . . . . . . . . . . . . . . . . . 7-10
CD/DVD Player . . . . . . . . . . . . . . . 7-23
Reception . . . . . . . . . . . . . . . . . . . . 7-15
Satellite . . . . . . . . . . . . . . . . . . . . . . . 7-12
Reading Lamps . . . . . . . . . . . . . . . . . 6-8
Rear Axle . . . . . . . . . . . . . . . . . . . . . 10-30 Locking . . . . . . . . . . . . . . . . . . . . . . . 9-55
Rear Doors . . . . . . . . . . . . . . . . . . . . . 2-8
Rear Seat Audio (RSA) System . . . . . . . . . . . . . . . . . . . . . . . 7-47
Rear Seat Entertainment
System . . . . . . . . . . . . . . . . . . . . . . . 7-38
Rear Seat Audio (RSA) . . . . . . . 7-47
Rear Seats . . . . . . . . . . . . . . . 3-9, 3-10
Rear Vision Camera (RVC) . . . . 9-60
Rear Windows . . . . . . . . . . . . . . . . . 2-19
Rearview Mirrors . . . . . . . . . . . . . . 2-16 Automatic Dimming . . . . . . . . . . . 2-17
Reclining Seatbacks . . . . . . . . . . . . 3-5
Recommended Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . 9-66

Black plate (10,1)GMC Sierra Owner Manual - 2013 - crc - 8/14/12
i-10 INDEX
Recommended Fluids andLubricants . . . . . . . . . . . . . . . . . . . 11-12
Records Maintenance . . . . . . . . . . . . . . . . .11-16
Recreational Vehicle Towing . . . . . . . . . . . . . . . . . . . . . . 10-87
Reimbursement Program,
GM Mobility . . . . . . . . . . . . . . . . . . 13-7
Remote Keyless Entry (RKE) System . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Remote Vehicle Start . . . . . . . . . . . 2-4
Replacement
Glass . . . . . . . . . . . . . . . . . . . . . . . 10-34
Replacement Bulbs . . . . . . . . . . . 10-38
Replacement Parts Airbags . . . . . . . . . . . . . . . . . . . . . . . 3-37
Maintenance . . . . . . . . . . . . . . . . .11-14
Replacing Airbag System . . . . . . 3-37
Replacing LATCH System Parts after a Crash . . . . . . . . . . . 3-54
Replacing Safety Belt
System Parts after a Crash . . . 3-20
Reporting Safety Defects Canadian Government . . . . . . 13-18
General Motors . . . . . . . . . . . . . 13-18
U.S. Government . . . . . . . . . . . 13-17 Restraints
Where to Put . . . . . . . . . . . . . . . . . 3-44
Retained Accessory Power (RAP) . . . . . . . . . . . . . . . . . 9-27
Ride Control Systems Messages . . . . . . . . . . . . . . . . . . . . 5-42
Roads
Driving, Wet . . . . . . . . . . . . . . . . . . 9-10
Roadside Assistance Program . . . . . . . . . . . . . . . 13-7, 13-11
Roof
Sunroof . . . . . . . . . . . . . . . . . 2-20, 2-21
Rotation, Tires . . . . . . . . . . . . . . . . 10-61
Routing, Engine Drive Belt . . . . . 12-6
Running the Vehicle While Parked . . . . . . . . . . . . . . . . . . . . . . . 9-32
S
Safety Belts . . . . . . . . . . . . . . . . . . . 3-11
Care . . . . . . . . . . . . . . . . . . . . . . . . . . 3-19
Extender . . . . . . . . . . . . . . . . . . . . . . 3-19
How to Wear Safety BeltsProperly . . . . . . . . . . . . . . . . . . . . . 3-12
Lap Belt . . . . . . . . . . . . . . . . . . . . . . 3-18
Lap-Shoulder Belt . . . . . . . . . . . . 3-13 Safety Belts (cont'd)
Reminders . . . . . . . . . . . . . . . . . . . . 5-16
Replacing after a Crash . . . . . . 3-20
Use During Pregnancy . . . . . . . . 3-18
Safety Defects Reporting Canadian Government . . . . . . 13-18
General Motors . . . . . . . . . . . . . 13-18
U.S. Government . . . . . . . . . . . 13-17
Safety Locks . . . . . . . . . . . . . . . . . . . . 2-8
Safety System Check . . . . . . . . . . 3-19
Satellite Radio . . . . . . . . . . . . . . . . . 7-12
Scheduling Appointments . . . . . 13-12
Seats Adjustment, Front . . . . . . . . . . . . . . 3-3
Center Seat . . . . . . . . . . . . . . . . . . . 3-3
Head Restraints . . . . . . . . . . . . . . . 3-2
Heated and Ventilated Front . . . 3-8
Lumbar Adjustment, Front . . . . . 3-4
Memory . . . . . . . . . . . . . . . . . . . . . . . . 3-6
Power Adjustment, Front . . . . . . 3-4
Rear . . . . . . . . . . . . . . . . . . . . . 3-9, 3-10
Reclining Seatbacks . . . . . . . . . . . 3-5
Securing Child
Restraints . . . . . . . . 3-54, 3-56, 3-57