2008 GMC Sierra Owner ManualSeats and Restraint Systems . 1-1Front Seats . 1-3Rear Seats . 1-12Safety Belts . 1-14Child Restraints. 1-35Airbag System. 1-68Restraint System Check. 1-87Features and Controls . 2-1Keys. 2-3Doors and Locks . 2-10Windows . 2-15Theft-Deterrent Systems . 2-18Starting and Operating Your Vehicle. 2-22Mirrors . 2-55Object Detection Systems . 2-63OnStar System. 2-65Universal Home Remote System. 2-68Storage Areas. 2-74Sunroof. 2-79Instrument Panel . 3-1Instrument Panel Overview . 3-4Climate Controls. 3-25Warning Lights, Gages, and Indicators. 3-34Driver Information Center (DIC). 3-54Audio System(s) . 3-80MDriving Your Vehicle . 4-1Your Driving, the Road, and Your Vehicle. 4-2Towing. 4-50Service and Appearance Care . 5-1Service . 5-4Fuel . 5-6Checking Things Under the Hood. 5-12Rear Axle. 5-51Four-Wheel Drive. 5-52Front Axle. 5-54Noise Control System. 5-56Headlamp Aiming . 5-56Bulb Replacement. 5-59Windshield Wiper Blade Replacement. 5-65Tires. 5-66Appearance Care. 5-112Vehicle Identification. 5-121Electrical System. 5-122Capacities and Specifications. 5-130Maintenance Schedule . 6-1Maintenance Schedule . 6-2Customer Assistance Information . 7-1Customer Assistance and Information. 7-2Reporting Safety Defects . 7-14Vehicle Data Recording and Privacy. 7-16Index . 1

Canadian OwnersA French language copy of this manual can be obtainedfrom your dealer/retailer or from:Helm, IncorporatedP.O. Box 07130Detroit, MI 48207GENERAL MOTORS, GM, the GM Emblem, GMC, theGMC Truck Emblem, and the name SIERRA areregistered trademarks of General Motors Corporation.This manual includes the latest information at the time itwas printed. We reserve the right to make changesafter that time without further notice. For vehicles firstsold in Canada, substitute the name “General Motors ofCanada Limited” for GMC whenever it appears in ires CanadiensOn peut obtenir un exemplaire de ce guide en françaisauprès de concessionnaire ou à l’adresse suivante:Helm IncorporatedP.O. Box 07130Detroit, MI 482071-800-551-4123www.helminc.comThis manual describes features that may be available inthis model, but your vehicle may not have all of them.For example, more than one entertainment system maybe offered or your vehicle may have been orderedwithout a front passenger or rear seats.Keep this manual in the vehicle for quick reference.Litho in U.S.A.Part No. 15854802 A First Printingii 2007 General Motors Corporation. All Rights Reserved.

Using this ManualMany people read the owner manual from beginning toend when they first receive their new vehicle. If thisis done, it can help you learn about the featuresand controls for the vehicle. Pictures and words worktogether in the owner manual to explain things.If your vehicle has the DURAMAX Diesel engine, referto the DURAMAX Diesel supplement for additionaland specific information on this engine.IndexA good place to quickly locate information about thevehicle is the Index in the back of the manual. It is analphabetical list of what is in the manual and thepage number where it can be found.{CAUTION:These mean there is something that could hurtyou or other people.We tell you what the hazard is and what to do to helpavoid or reduce the hazard. Please read these cautions.If you do not, you or others could be hurt.A circle with a slashthrough it is a safetysymbol which means “DoNot,” “Do Not do this”or “Do Not let this happen.”Safety Warnings and SymbolsThere are a number of safety cautions in this book. Abox with the word CAUTION is used to tell about thingsthat could hurt you or others if you were to ignore thewarning.iii

Vehicle Damage WarningsVehicle SymbolsYou will also find notices in this manual.The vehicle has components and labels that usesymbols instead of text. Symbols are shown along withthe text describing the operation or informationrelating to a specific component, control, message,gage, or indicator.Notice: These mean there is something that coulddamage your vehicle.A notice tells about something that can damage thevehicle. Many times, this damage would not be coveredby your vehicle’s warranty, and it could be costly.The notice tells what to do to help avoid the damage.When you read other manuals, you might seeCAUTION and NOTICE warnings in different colorsor in different words.There are also warning labels on the vehicle which usethe same words, CAUTION or NOTICE.iv

Section 1Seats and Restraint SystemsFront Seats .1-3Manual Seats .1-3Power Seats .1-4Manual Lumbar .1-5Power Lumbar .1-5Heated Seats .1-6Memory Seat, Mirrors, and Pedals .1-6Reclining Seatbacks .1-8Head Restraints .1-10Seatback Latches .1-11Center Seat .1-12Rear Seats .1-12Rear Seat Operation (Full Bench) .1-12Rear Seat Operation (Split Bench) .1-13Safety Belts .1-14Safety Belts: They Are for Everyone .1-14How to Wear Safety Belts Properly .1-19Lap-Shoulder Belt .1-28Safety Belt Use During Pregnancy .1-33Lap Belt (Crew and Extended Cab) .1-34Safety Belt Extender .1-35Child Restraints .1-35Older Children .1-35Infants and Young Children .1-38Child Restraint Systems .1-42Where to Put the Restraint .1-44Lower Anchors and Tethers for Children(LATCH) .1-45Securing a Child Restraint in a Rear SeatPosition .1-55Securing a Child Restraint in the Center FrontSeat Position .1-57Securing a Child Restraint in the Right FrontSeat Position (With Airbag Off Switch) .1-58Securing a Child Restraint in the Right FrontSeat Position (With Passenger SensingSystem) .1-62Securing a Child Restraint in the RightFront Seat Position (Heavy Duty CrewCab Only) .1-661-1

Section 1Seats and Restraint SystemsAirbag System .1-68Where Are the Airbags? .1-71When Should an Airbag Inflate? .1-73What Makes an Airbag Inflate? .1-74How Does an Airbag Restrain? .1-74What Will You See After an Airbag Inflates? .1-75Airbag Off Switch .1-761-2Passenger Sensing System .1-80Servicing Your Airbag-Equipped Vehicle .1-84Adding Equipment to Your Airbag-EquippedVehicle .1-85Restraint System Check .1-87Checking the Restraint Systems .1-87Replacing Restraint System Parts Aftera Crash .1-88

Front SeatsManual Seats{CAUTION:You can lose control of the vehicle if you try toadjust a manual driver’s seat while the vehicleis moving. The sudden movement could startleand confuse you, or make you push a pedalwhen you do not want to. Adjust the driver’sseat only when the vehicle is not moving.To move a manual seat forward or rearward:1. Lift the bar to unlockthe seat.2. Slide the seat to thedesired position andrelease the bar.Try to move the seat with your body to be sure the seatis locked in place.1-3

Power SeatsOn a vehicle with power seats, the controls used tooperate them are located on the outboard side of theseats. To adjust the seat, do any of the following: Move the seat forward or rearward by sliding thecontrol forward or rearward. Raise or lower the front part of the seat cushion bymoving the front of the control up or down. Raise or lower the rear part of the seat cushion bymoving the rear of the control up or down. Raise or lower the entire seat by moving the entirecontrol up or down.Driver’s Seat with Power Seat Control, PowerRecline, and Power Lumbar shown1-4On seats with power reclining seatbacks, the control islocated behind the power seat control on the outboardside of the seats. See “Power Reclining Seatbacks”under Reclining Seatbacks on page 1-8.A vehicle with a memory function allows seat settings tobe saved and recalled. See Memory Seat, Mirrors,and Pedals on page 1-6 for more information.

Manual LumbarPower LumbarOn vehicles with this feature, turn the knob forward orrearward to increase or decrease lumbar support.If the seats have power lumbar, the controls used tooperate this feature are located on the outboard side ofthe seats. To increase lumbar support, press and hold thefront of the control. To decrease lumbar support, press and hold therear of the control. To raise the height of the lumbar support, pressand hold the top of the control. To lower the height of the lumbar support, pressand hold the bottom of the control.1-5

Release the control when the lower seatback reachesthe desired level of lumbar support.Your vehicle may have a memory function which allowsseat settings to be saved and recalled. See MemorySeat, Mirrors, and Pedals on page 1-6 for moreinformation.Keep in mind that as your seating position changes, asit may during long trips, so should the position ofyour lumbar support. Adjust the seat as needed.Heated SeatsOn vehicles with heated front seats, the controls arelocated on the driver’s and passenger’s doors.I(Heated Seatback): Press to turn on the heatedseatback.The heated seats will be canceled ten seconds after theignition is turned off. To use the heated seat featureafter restarting your vehicle, press the heated seator seatback button again.Memory Seat, Mirrors, and PedalsYour vehicle may have the memory package.The controls for thisfeature are located on thedriver’s door panel, andare used to programand recall memory settingsfor the driver’s seat,outside mirrors, and theadjustable throttle andbrake pedal.J (Heated Seat and Seatback): Press to turn on theheated seat and seatback.The light on the button will come on to indicate that thefeature is working. Press the button to cycle throughthe temperature settings of high, medium, and low andto turn the heat to the seat off. Indicator lights willshow the level of heat selected: three for high, two formedium, and one for low.1-6To save your positions in memory, do the following:1. Adjust the driver’s seat, including the seatbackrecliner and lumbar, both outside mirrors, andthe throttle and brake pedals to a comfortableposition.

See Outside Power Mirrors on page 2-59 andAdjustable Throttle and Brake Pedal on page 2-26for more information.Not all mirrors will have the ability to save andrecall their positions.Not all adjustable throttles and brake pedals willhave the ability to save and recall their positions.2. Press and hold button 1 until two beeps are heardindicating that the position has been stored.A second seating, mirror, and throttle and brake pedalposition can be programmed by repeating the abovesteps and pressing button 2.To recall the memory positions, the vehicle must be inPARK (P). Press and release either button 1 or button 2corresponding to the desired driving position. Theseat, outside mirrors, and adjustable throttle and brakepedals will move to the position previously stored.You will hear a single beep.If you use the remote keyless entry transmitter to enteryour vehicle and the remote recall memory featureis on, automatic seat, adjustable mirror, and adjustablepedal movements will occur.

Canada Limited” for GMC whenever it appears in this manual. This manual describes features that may be available in this model, but your vehicle may not have all of them. For example, more than one entertainment system may be offered or your vehicle may have