Gear slips when hauling uphill

While in cruise control and hauling a light trailer uphill, my 2017 Tundra splits out of gear and sends the rpm's very high. After tapping the gas or break it goes back into gear. This has been happening ever since purchased new in 2017. Service station keeps telling me that nothing is wrong. No codes showing issues, etc. Anybody else experience this?

 

Are you sure it's not just downshifting?

 

Tow in S4 in Tow/Haul mode.

 

Does the rpm go high and you slow down? If it's actually slipping it'd rev up and you'd slow down, probably shoot to redline like if you were in neutral, and then if it re-engaged would lurch as the transmission goes from slipping to slamming power back through it. I would at a minimum change the fluid, and prepare for buying a new converter. A transmission slipping is really bad.

 

This........

 

NEVER TOW IN OD!!!!!!!

 

The Cruise Control is making every effort to try to maintain Set Speed and will down shift as many gears as it's able in that effort including applying full throttle. That's why the manual recommends NOT towing and using CC. This is normal for your Tundra.

 

I did not see that in the manual. My salesman said CC is fine. Maybe he doesn't know everything. I agree, its trying to downshift and can't find the right gear........... so, only way to stop the redlining is to shut off CC. Solved. Thanks!

 

Some salesmen know what they're talking about, some do not.

Here are a couple tidbits:

 

I will use cruise control on the flats towing. I have messed around with it a little bit, if I do hit a slight grade the truck will downshift from 5th to 4th, I will then manually put it in S4 So that it stops trying to upshift.

My personal preference is to tow in S mode. I’m always listening for the converter to be locked up, you can tell by the RPMs. I will tow in 5tg as long as the converter is locked up, once I hear the converter unlock I know that it is creating more heat inside the transmission. At that point I will shift to 4th. When that happens, I can hear and feel, along with observing the RPMs, that the converter locks back up and I can pretty much keep it there out on the interstate. Obviously winding mountain roads are different. I prefer to be in control of the up shifting in the transmission. I actually try to beat the transmission to the punch and give it a preemptive downshift at the base of the hill. It’s all about learning what your truck is going to do. Keep that converter locked up as much as possible, and you should be fine.

 

Probably feeling torque converter locking and unlocking