Truck downshifting while going down hill

[garner]

Tonight I was driving down the road at between 60 and 65 mph(1500ish rpm) but while going downhill my truck downshifted and rpms jumped to around 2100

After that I put it into manual mode in 6th then back into drive and the rpms dropped back to normal. Popped it back into manual mode and the 2100ish rpm corresponds with 4th on the gauge cluster. Went down the hill 2 more times and it did the same thing but shifted itself back to the normal gear. Tranny temps were in the low to mid 130s

Was it just the truck "engine braking"? Or something else?

 

[ZCR]

Yep, just engine braking so speed doesn't get crazy. When this happens the engine isn't using any more fuel; since the throttle is closed and the driveline is keeping the engine spinning, fuel scheduling is essentially set to zero no matter the RPM.

 

[garner]

Gotcha. Thanks. Guess I've just never noticed it before

 

[WilCon76]

Does your truck have the tow package? I would also guess that because of the trailer brake controller and sway control etc this would be more pronounced on a tow equipped vehicle with these features than one without?

 

[garner]

Yupp I have all of that. But that stuff only goes into effect when a trailer is connected

However I think the engine braking is a low speed thing, I went down the same hill at a higher speed and I didn't feel it engine brake

 

[LB3711]

did you have tow/haul switch on?

 

[garner]

Nope. Truck in drive with cruise control set both days(first post, then post #5)

 

[Ona4day]

I've only notice mine do that when cruise is set. Think its trying to keep set speed.

 

[emjohn4]

I've only notice mine do that when cruise is set. Think its trying to keep set speed.

Same here.

It'll only downshift to "hold" speed if you have the cruise set.

I personally find it annoying, but that's me. Doubly so since I live and drive in some hilly areas and love cruise control.

No workaround is available, so you just get to deal with it.

 

[garner]

Idk. On post 5 I had cruise set just like post 1 but at a higher speed and I didn't feel it engine brake. So either it's not noticeable with rpm over 2,000 or it doesn't do it at all at higher speeds. Who knows lol

 

[emjohn4]

Idk. On post 5 I had cruise set just like post 1 but at a higher speed and I didn't feel it engine brake. So either it's not noticeable with rpm over 2,000 or it doesn't do it at all at higher speeds. Who knows lol

It's done it on my truck as low as 35 mph, and as high as 80mph.

It's certainly noticeable when it downshifts at 80mph to hold speed!