Tow/haul mode on Chevy 1/2 ton

[Ktimmons]

I'm looking for a simple, plain language explanation of what the tow/haul mode on a Chevy does. I'm assuming it changes the tranny shift points or something similar. Also, should I use this all the time when pulling our TT or is mainly a benefit for hard pulls ( mountains, high speed highways ), and does it have any braking benefits like the Allison tranny in a Chevy.

PS. I know I could search web and probably find a lot of info on this but I'm being lazy and thought some of you might be able to help and give info from your experiences. Thx

[JIMNLIN]

Hmmm, much depends on the tranny in your 1500 truck. What year model is your tranny/truck ?

The wifes '06 1500 chevy with the 4L60E has a tow haul mode. All it does is raise shift points to 2450 rpm min throttle, in 1st to 2nd shift and 2nd to 3rd (D). The problem is it also unlocks the TC clutch with little to none engine braking under that rpm.
The T/H mode in the new 6L80E may work different. However none works like the Allison.

[Randy the sly old fox]

The six speed in the 2500 works just like the Allison. It has what is called tow/haul II. My truck has grade braking that downshifts the tranny with every brake tap to help maintain speed on downhills. It also changes the shift points to closer to the 2000 RPM point. It does allow the transmission to use all gears - including 5 and 6 which are overdrives.

Earlier 4 speed transmissions with Tow/haul I simply change the shift points and the torque converter lock up.

[Hipshot]

I towed a 2010 Rockwood with a 2008 Silverado 1500 4X4 5.3 and 3.73 rear. The truck weighed 6200 lbs loaded for camping and the TT weighed 6300 lbs loaded. I drove this rig 8000 miles before I traded for the Bounder. I did not tow in any real big mountains. I found the best towing, less shifting, best power and best milage was in third gear with Tow/Haul on running 87 octane. While this rig did run good I would not have wanted to pull anything heavier.
Hope this helps, good luck.

[Cat320]

You might want to check your manual. My last Chevy said to use the T/H when the actual GCW was 75% or greater than the GCWR.

[Ktimmons]

Thx to everyone. Good info from all!