1999 GMC Sierra 1500 Pickup Owner's Manual - Page 259

Engine Fan Noise This vehiclehasa clutched enginecoolingfan.Whentheclutch is engaged, thefanspinsfaster to provide more air to cool the engine. In mosteveryday drivingconditionstheclutchisnotengaged.Thisimprovesfueleconomyand reducesfannoise.Underheavyvehicleloading,trailertowing andlor high So outsidetemperatures,thefanspeedincreaseswhentheclutchengages. youmayhear anincrease in fan noise.This is normalandshouldnotbe mistakenas the transmissionslippingormakingextrashifts.It is merelythe slow downwhenadditional coolingsystemfunctioningproperly.Thefanwill cooling is notrequiredandtheclutchdisengages. Youmay alsohearthisfan noise whenyoustarttheengine. asthefan clutch disengages. It willgoaway If a Tire Goes Fiat It'sunusualforatire to "blow out" whileyou'redriving,especially if you maintainyourtiresproperly.Ifairgoesout of atire,it'smuchmorelikely to are a few tips leakoutslowly.But if youshouldeverhavea"blowout,"here aboutwhattoexpectandwhat to do: Ifa front tire fails, the flat tire will create a drag that pulls the vehicle toward thatside.Takeyourfootofftheacceleratorpedalandgripthesteeringwheel firmly.Steer to maintainlaneposition,thengentlybrake to astopwellout the traffic lane. of A rearblowout,particularlyonacurve,actsmuchlikea skid andmay requirethesamecorrectionyou'duse in askid. In anyrear blowout,remove yourfootfromtheacceleratorpedal.Get the'vehicle undercontrol by steering the wayyouwant thevehicle to go.It maybeverybumpyandnoisy,but youcanstillsteer.Gentlybrake to astop,welloff the road if possible. If your tire goes flat, the next part shows how to changeaflattiresafely. to use your jacking equipment Changing a Flat Tire If a tire goes flat, avoid further tire and wheel damage by driving slowly levelplace.Turnonyourhazardwarningflashers. to a 5-1 7