From the 2000 Owner's Manual, Page 4.57 ..............
"Tow/Haul Mode (If Equipped)
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:
- 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.
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.
Tow/haul is designed to be most effective when the vehicle and trailer combined weight is at least 75% of the vehicle’s Gross Combined Weight Rating (GCWR).
Tow/haul is most useful under the following driving conditions:
- When pulling a heavy trailer or a large or heavy load through rolling terrain.
- When pulling a heavy trailer or a large or heavy load in stop and go traffic.
- When pulling a heavy trailer or a large or heavy load in busy parking lots where improved low speed control of the vehicle is desired.
Operating the vehicle in tow/haul when lightly loaded or with no trailer at all will not cause damage. However, there is no benefit to the selection of tow/haul when the vehicle is unloaded. Such a selection when unloaded may result in unpleasant engine and transmission driving characteristics and reduced fuel economy.
Tow/haul is recommended only when pulling a heavy trailer or a large or heavy load."
This manual does not differentiate between 1500, 2500 or 3500 trucks. IIRC there was no downshift/engine braking feature of Tow/Haul in 2000.
