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Old 04-26-2018, 08:28 PM   #1
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GM Tow/Haul Mode Use

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
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Old 04-26-2018, 09:00 PM   #2
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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.
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Old 04-26-2018, 10:49 PM   #3
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YES and YES

Aint Tow/Haul a neat feature

I use it even when NOT towing
Stop/Go traffic.....limits all the shifting
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Old 04-28-2018, 09:33 AM   #4
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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.
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Old 04-30-2018, 05:04 AM   #5
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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.
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Old 05-15-2018, 06:20 AM   #6
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Quote:
Originally Posted by Ray,IN View Post
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.
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Old 05-15-2018, 06:26 AM   #7
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The T/H mode changes the shift points, when breaking it is more aggressive then normal mode.
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Old 05-22-2018, 08:51 AM   #8
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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.
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Old 05-22-2018, 09:29 AM   #9
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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 !
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Old 05-23-2018, 06:10 AM   #10
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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.
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Old 05-24-2018, 08:02 AM   #11
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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
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