Community Forums

LeeB · 04-26-2018, 08:28 PM

I have a 2017 Silverado Z71 4x4 5.3 with 6 speed trans.

I know I turn on Tow/Haul when towing my trailer and it changes the shift points to assist towing. Couple questions.

1st can I shift in and out AND back in as I am driving?

If while in Tow/Haul and descending a grade will it automatically down shift?
I had occasion I was descending a grade and I double pumped the brake peddle and it seemed to downshift all by it's self. Did that really happen or was it was my imagination? LoL

Thanks LeeB

Ray,IN · 04-26-2018, 09:00 PM

Yes you may shift in/out as you desire.
Your experience is exactly the way T/H is designed to operate. Tow/Haul has a grade retard feature to assist in controlling down-hill speed. It also locks out 6th gear(2nd overdrive) comparing tach RPM will confirm; this also locks out the GM EFM= Electronic Fuel Management system, which-when out of T/H mode, disables 4 cylinders-2 on each bank, to supposedly improve fuel mileage approx. 5%. Look up Chevrolet EFM or DoD(old term) to read the complete facts.

Old-Biscuit · 04-26-2018, 10:49 PM

YES and YES

Aint Tow/Haul a neat feature

I use it even when NOT towing
Stop/Go traffic.....limits all the shifting

Gigattime · 04-28-2018, 09:33 AM

Not sure about GM, but my 2011 F350 downshifts automatically when you tap the break going down a decent in tow haul. Designed to do that in place of a j-break.

travelerbill · 04-30-2018, 05:04 AM

I use the tow/haul mode all the time when towing. Anything I can do to extend the life of my transmission is a good idea. As previous posters have said, yes you can go in and out of it any time.

runamuck · 05-15-2018, 06:20 AM

Quote:

Originally Posted by Ray,IN

Yes you may shift in/out as you desire.
Your experience is exactly the way T/H is designed to operate. Tow/Haul has a grade retard feature to assist in controlling down-hill speed. It also locks out 6th gear(2nd overdrive) comparing tach RPM will confirm; this also locks out the GM EFM= Electronic Fuel Management system, which-when out of T/H mode, disables 4 cylinders-2 on each bank, to supposedly improve fuel mileage approx. 5%. Look up Chevrolet EFM or DoD(old term) to read the complete facts.

I have a 2017 sierra 1500 4x4 slt 5.3 also and I have seen V4 or what ever the indicator is when in 4 cylinder mode many times when towing in tow/haul mode..mostly when coasting on flat or on slightly down hill roads. I too thought afm would be turned off when in tow/haul mode. just last week towing from big bend to ft. worth for example..not sure if it is a good thing or not.

kcmusa · 05-15-2018, 06:26 AM

The T/H mode changes the shift points, when breaking it is more aggressive then normal mode.

**Spdracr39** · 05-22-2018, 08:51 AM

I generally take it out of tow haul when climbing hills and use the manual shifters. It keeps the rpms too high for too long sometimes when it isn't necessary. Other than that it works well.

JohnBoyToo · 05-22-2018, 09:29 AM

I rarely used the t/h mode when I had TT's and 5'ers...
as long as I had enough truck to properly handle the load, the engine did fine without it... as long as it was not hunting for the right gear (indicating too much rv for the truck imho)

And I liked using all the gears for best mpg and quiet comfort!
Now, I have been known to punch t/h whenever I needed extra braking to slow down (even when not towing), which may be why I never had to change brakes on any of my tow vehicles

AND... the drive train / tranny had a long warranty whereas the brakes had none !

01tundra · 05-23-2018, 06:10 AM

I always use it, even though according to the owner's manual I should not use it due to the weight of our TT.

To me it shifts a lot better in the mountains, plus the only way that I can see the trailer brake output screen is in T/H mode and the engine brake seems more aggressive.

I've towed both in T/H and out of it and don't really see a difference in overall fuel mileage.

runamuck · 05-24-2018, 08:02 AM

I use it when towing. my trailer is a pretty big load for my truck and I like the way it shifts when towing in tow/haul mode. I dont use it when towing my 12' utility trailer as it is a lot lighter. I often use it the mountains when not towing and I use a lot of 3rd gear when descending

glwinger · 11-16-2018, 05:49 PM

I sue it all the time when my toy hauler is connected. It scared the Sh$& out of the the first time is downshifted on a hill. I was not expecting it to be so aggressive.

Wait until you see the engine go into 4 cylinder mode while cruising!!!

Mine's a 2015 with the same specs.

engine103 · 11-16-2018, 06:57 PM

I have a 2004 2500HD with tow mode. Although I don't have a TT I do have a large tractor I move around a lot to different properties. I use tow mode until I get to cruising speed then shift to regular 6 speed mode. The more weight you have pushing you down hill, the more aggressive the down shift will be. The 2004 does not have the ability to deactivate cylinders so the gas mileage decreases while in tow mode because you are never in overdrive. Jim E. OKC