Strange Shift Using Tow/Haul

daviddsims1 · November 4, 2017

I have a 2014 new to me Sierra 5.3 Z71 that I purchased last May. I recently towed a small aluminum trailer with two atv's and noticed some weird shifting while going down hills and letting off the gas. The truck would shift down and rev up to almost 5k RPM's and just act really strange. I took it off tow/haul and it seemed to do better but I got out of the hills about that time. Has anyone seen or heard of this?

Wxman · November 4, 2017

Were you using cruise control? It could have been the grade braking (engine braking) that the truck uses to attempt to maintain speed, not go too fast, on the down hills. It doesn't do this, or at least not to the same extent, when not in tow/haul. It will just let the truck go over the set speed.

Sierra706 · November 4, 2017

The grade braking feature engages much sooner with tow haul on to help slow your truck and trailer down using engine braking. Tow haul mode is optimized for a certain weight of trailer, I believe 5000lb but don’t quote me on that figure. Cruise control doesn’t have to be engaged.

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BringTheRain403 · November 4, 2017

Try turning off grade braking next time you are in tow/haul mode. To turn it off once you are in tow/haul mode press the button again but this time hold it in for about 5 seconds before you let it out. You should get a notice on your DIC that grade braking is off.

I have basically the same truck. I've had it since 2013 and to answer your question yes the weird shifting is "normal." The shifts even without tow/haul mode are terrible (especially getting it to downshift). I've complained to the dealership about it since it was new. The transmission is the worst part of these trucks and I'm almost certain it's the tuning. Once my power train warranty is out I'm probably going to get it tuned.

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newdude · November 4, 2017

10 hours ago, daviddsims1 said:

I have a 2014 new to me Sierra 5.3 Z71 that I purchased last May. I recently towed a small aluminum trailer with two atv's and noticed some weird shifting while going down hills and letting off the gas. The truck would shift down and rev up to almost 5k RPM's and just act really strange. I took it off tow/haul and it seemed to do better but I got out of the hills about that time. Has anyone seen or heard of this?

Normal. Its supposed to do that. That is the Tow/Haul grade braking feature, designed to help slow the vehicle via the drivetrain to take some of the stress off of the braking system.

Donstar · November 4, 2017

This feature is normal and found it useful when puling my box trailer in hilly terrain with my '09. These transmissions are solid workers and don't be swayed by the complaints on this forum. I find the GM 6 spd autos very responsive, predictable and smooth. I appreciate the differences in various makes and models of vehicles and sometimes my input has to differ to meet my needs.

tim leineke · July 16, 2023

My 2018 chevy silverado has twice had shifting issues with the tow haul on. It would not go into 3rd geer. Luckily both times i stope removed the battery cables amd the truck shifted properly with tow haul on after that. But the secomd time it happened i was going down the highway. It was acting strange, reving up, not reacting when id push the gas, speed up suddenly then lose power until it wouldnt shift into 3rd. I had to ride on the side of the road, rpms 4 to 5000 until i got off. I decided to pull battery cable , and reattach after about 5 min, everything went back to normal. Im thinking bcm issue, or electrical issue. All cables were tight, no corrosion. Maybe, a corroded ground could be an issue? Im not sure, but it shouldnt happen!

Edited July 16, 2023 by tim leineke
Misspelled words