Tahoe Towing Tow Mode or Range Selection Mode?

wintersun wrote:
With trucks the Range mode shuts off the downhill grade control completely which is not good when towing. The tow haul mode is designed to protect the transmission when towing a very heavy load. With trucks that is 75% of the maximum tow load per GM's recommendations. On steep 8% grades I use tow haul with any load as it makes for an easier descent with very little use of the brakes needed.

Range mode puts your vehicle back 20 years in towing performance. The only time it is advantageous is when starting out on soft ground where you can shift it into 2 gear and the vehicle will apply less torque to the rear wheels to minimize loss of traction.

Well I completely disagree. Use tow haul mode for any high walled RV. Towing an RV is the hardest type of trialer to tow. 4000 pounds or 10,000 pounds same (poor) aero drag and 8-10mpg. Thus, use tow/haul mode for the higher shift points and more torque converter lock time. No other types of trailer owners (boats, race cars, landscaping. etc use as much fuel as we RVers do. We work the truck the hardest, so use the tow/haul mode.

Manual/range mode when combined with tow haul does still use first gear in it's normal tow/haul mode shift pattern.

wintersun wrote:
Range mode puts your vehicle back 20 years in towing performance.

Well, that may be kinda true, but there are circumstances where t/h just wont get it done. For example, t/h can't see that 20 mph corner coming up that you need to slow way down for. T/h also won't shift down into 1st gear, and up in the mountains on 2-lane roads, there are plenty of grades that require shifting clear down to 1st in order to get the needed engine braking.

The grade braking in my vehicles has worked very well, but there are just some scenarios where I've needed to override it and control the shifting myself.

With trucks the Range mode shuts off the downhill grade control completely which is not good when towing. The tow haul mode is designed to protect the transmission when towing a very heavy load. With trucks that is 75% of the maximum tow load per GM's recommendations. On steep 8% grades I use tow haul with any load as it makes for an easier descent with very little use of the brakes needed.

Range mode puts your vehicle back 20 years in towing performance. The only time it is advantageous is when starting out on soft ground where you can shift it into 2 gear and the vehicle will apply less torque to the rear wheels to minimize loss of traction.

pappcam wrote:
I can't believe how many questions get asked about tow/haul mode.

I don't get it. If you are towing a trailer put it in tow/haul mode. Period.

I'm not sure why it would be questioned.

Sorry I asked...........NOT

Thanks everyone for posting their experiences in the Tow/Haul and the tranny hunting.

Here is some documentation for the 2014 GM half tons, but it is very similar if not the same algorirthims for 2009-2013 GM transmissions.

With Tow/Haul mode engaged, Sierra’s Trailer Grade Braking is activated when the driver lightly applies the brakes. This feature initiates downshifts to assist with braking on long downgrades. In addition to slowing the vehicle more efficiently, Auto Grade Braking can reduce brake rotor temperatures by 100 degrees Celsius during a braking event.

For drivers who prefer full control over their truck’s shifting, improved TapShift controls on the shift lever are backed by a patent-pending shift algorithm that improves shift response time by up to 60 percent compared to previous systems. When the TapShift controls are in use, Sierra’s Trailer Grade Braking is deactivated because the driver is manually controlling gearshifts.

Source.

I am aware of the grade braking function and that it is disabled in M mode. I prefer to control the gears myself in that situation.

Land28BH wrote:
Slight deviation from OP topic. Can someone comment on the effectiveness or usefulness of the grade braking feature on this transmission? Familiar with engine braking on a diesel but not sure how this really works. Haven't had any experience yet with my new van.

It just downshifts into lower gear ranges to help slow you down. Usually, a tap of the brake pedal will indicate the speed you want it to keep, and it will downshift to try to keep that speed. Another press of the pedal will initiate a downshift, and so on. It isn't 100% reliable, of course (sometimes I'm expecting a downshift and don't get one), but it works pretty good. My experience is that it works very better on the freeway or at higher speeds. On pretty much every Interstate grade that I can recall towing down, I haven't had to take over and manually shift. On steeper and slower roads, I usually have to take over, as it isn't great at shifting down into 2nd (which I often need to do).

Good luck!

We have a 2010 Suburban that is probably pretty similar to your Tahoe. I use t/h every time the trailer is hooked up. I leave the truck in D most of the time, unless the transmission starts 'hunting,' which means it is shifting up and down too often. My truck almost never gets into 6th gear when towing -- it is in 4 or 5th most of the time. However, it is pretty good at avoiding hunting too much. Perhaps ironically, I get more hunting on apparent flat surfaces than I do in the mountains. Out in the flats (most land out here is not truly flat, of course), a gust of wind or an overpass is always enough to kick it out of 6th, and maybe down to 4th. When going up hills, it seems to do a very good job of holding the gear.

Note that when it is shifted out of D, the grade braking feature does not work, and you'll have to downshift manually to slow.

I can't believe how many questions get asked about tow/haul mode.

I don't get it. If you are towing a trailer put it in tow/haul mode. Period.

I'm not sure why it would be questioned.

Slight deviation from OP topic. Can someone comment on the effectiveness or usefulness of the grade braking feature on this transmission? Familiar with engine braking on a diesel but not sure how this really works. Haven't had any experience yet with my new van.

I use tow haul whenever I tow my TT. The engine speeds are higher providing more power. The transmission torque converter stays locked up more often. I think my manual says it is only recommended at 80% of GCWR, but the huge frontal area of a travel trailer has more impact than weight for RVers.

I also use M5 for highway cruising. The trans does attempt to hold 6th gear with my combo at 65mph but cannot maintain speed. 5th gear 65mpg is about 2200rpm, not very high given peak torque is over 4000rpm and hp 5500rpm.

For the 5.3L/6-spd/3.42, you may want to limit gear to 4th or 5th. Frequent shifts generate extra heat in the trans. 4th gear should still be under 3000rpm with good throttle response and fuel economy is likely the same as 5th gear it your truck can hold it. Do some experimenting.