ok is the towhaul button supposed to dissengage o/d in the finally drive gear?
i never paid attention before but i just noticed after about 55 mph the tow/haul button doesnt do anything but when im in a lower gear doin around 30 or so it will dissengage. is this normal or is there a problem

 

ur post got me thinking so i went out 4 a test run and my towhaul never dissengaged. not from 55mph or under 30mph

 

tow/haul is supposed to keep you in gear longer... thats the most noticable effect at least

 

yeah i just found somethin that explains it all it doesnt change gears just shift patterns
this expains fully what tow/haul does
Tow/Haul Mode
Applies to the following models:

• 2000-2004 C/K Utility Models

• 1999-2004 Chevrolet and GMC C/K Pickup Models (Silverado and Sierra)

• 1999-2002 GMC S/T Utility Models (Jimmy and Envoy-Old Style)


PURPOSE


• Reduce the frequency and improve the predictability of transmission shifts when pulling a heavy trailer or a large or heavy load. This is most apparent in city traffic. Without tow/haul, the transmission may upshift on a closed throttle decel. With tow/haul, the transmission will hold the current gear on a closed throttle decel. This reduces upshifts and downshifts.

• 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.


ACTIVATION


• Tow/Haul is selected or de-selected via a switch on the end of the transmission shift lever for all models except the GMC Jimmy and Envoy, their switch is mounted on the shift console. A light on the instrument panel will illuminate to indicate that tow/haul has been selected.

• Tow/Haul must be reselected every time the vehicle is started (if desired).


FUNCTION


• 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).

• Operation of tow/haul in a lightly loaded or non-loaded vehicle will not cause damage. However, there is no benefit to the selection of tow/haul when the vehicle is unloaded, this situation will cause a firm shift. The tow/haul switch is not a performance switch.

• Selection of tow/haul when unloaded may result in unpleasant engine and transmission driving characteristics and reduced fuel economy. Tow/haul is recommend only when pulling a heavy trailer or a large or heavy load.

• Examples of altered shift speeds when in tow/haul:

- Minimum 1-2 shifts pushed out approximately 13 km/h (8 mph)

- Minimum 2-3 shifts pushed out approximately 24 km/h (15 mph)

- Minimum 3-4 shifts pushed out approximately 48 km/h (30 mph)

- Tow/haul only affects shift points below 88 km/h (55 mph).

Refer to vehicle Owner's Manual for further information regarding tow/haul mode.

 

great post !!