2003 GMC Sierra 1500 Pickup Owner's Manual - Page 348

0 Don't tow a trailer all during the first 500 miles at (800 km) your new vehicle is driven. Yourengine, axle or other parts could be damaged. Then, duringthe first 500 miles (800 km) thatyou tow 50 a trailer, don't drive over mph (80 km/h) and don't make starts at throttle. This helps your engine full and otherparts of your vehicle wear in at the heavier loads. If you havean automatic transmission,you can tow in DRIVE (D). You may want to shift transmission the to THIRD (3) or, if necessary, a lower gear selection if the transmission shifts too often (e.g., under heavy loads and/or hillyconditions). If you have amanual transmission and you are towing a trailer, it's better not to use the highest gear. See Tow/Hau/ Mode light on page 3-48. Tow/HauI Mode Tow/haul is a feature on automatic transmission equipped vehicles that assists when pulling a heavy trailer or a large or heavy load. The purpose of the tow/haul mode is to: 0 0 Reduce the frequency and improve the predictability of transmission shifts when pulling a heavy trailer or a large or heavy load. Provide the same solid shift feel when pulling a heavy trailer or a large or heavy load as when the vehicle is unloaded. Improve control of vehicle speed while requiring less throttle pedal activity when pulling a heavy trailer or a large or heavy load. 0 0 0 Three important considerations have to do with weight: the weight of the trailer, the weight of the trailer tongue 0 and the weight on your vehicle's tires. Automatic transmission equipped vehicles are provided with a button at the end of the shift lever which when pressed enables tow/haul. When the button is pressed, a light on the instrument panel will illuminate to indicate that tow/haul has been selected. Tow/haul may be turned off by pressing the button again, at which time the indicator light on the instrument panel will turn off. The vehicle will automatically turn off tow/haul every time it is started. 4-67