1999 GMC Sierra 1500 Pickup Owner's Manual - Page 225

As in anydrivingsituation,keeppacewithtrafficandallowadequate following distances. Hill and Mountain Roads I r AM470001 Drivingonsteep hills ormountains is different from driving in flat or rolling if you'replanning to visit terrain. If youdriveregularlyinsteepcountry,or there,herearesometipsthatcanmakeyourtripssaferandmoreenjoyable. (See "Off-Road" in theIndexforinformationaboutdrivingoff-road.) Keepyourvehicleingoodshape.Checkall fluid levelsandalsothe brakes,tires,coolingsystemandtransmission.Thesepartscanwork hard onmountainroads. Knowhow to godownhills.Themostimportant thing to know is this:let it yourenginedosome of theslowingdown.Don'tmakeyourbrakesdo all.Shift to alowergearwhenyougodownasteeporlonghill.That way, youwill slowdown withoutexcessiveuse ofyourbrakes. I I you don't shift down,' your brakes could get so hot that they f b wouldn't work well. You would then have poor braking or even none going down a hill. You could crash. .Shift down to let your engine assist your brakes on a steep downhill slope. I 4-47