iaddiesel

Any one have this? When I have cruise on at about 67mph and go down a big hill at the bottom the rpms go up to around 2500 or so and then I quickly kick it off, before it revs higher, it is almost like it got between converter lock and unlock. The 2nd gen's used to do similar things when their TPS would act up, cruise or not. This won't do it if I just drive it that fast down the same hill cruise off. Any ideas? Not real concearned, I just wont keep cruise on down big hills, but I am curious.

rustyshakelford

mine will kinda downshift to maintain the set speed. is that kinda what your feeling?

brett

Erik

Does this happen when the cruise is set at approx 67mph?

I havent had this happen and use the cruise control alot, but I use mine at 75-85mph on the interstate. I'll try tonight at 67mph and see what happens.
Erik

timcasbolt

The cruise is doing whatever necessary to maintain the set speed. Perfectly normal.

DrDiesel

They also have set the RPM control for higher RPM`s to improve the exhaust brake function. The higher the RPM on a downhill the better the exhaust brake power. This is setup this way even if you have no exhaust brake installed. It`s part of the TCM function.

ASHNBAK

I've been told the same as timcasbolt posted. The truck will downshift to maintain speed when the cruise is engaged and your picking up speed. With my truck the maximum 3rd gear speed is about 68 or 69 mph. I don't think it will downshift past that point, but I don't know for sure.

dale29

Sounds normal to me. Probably depends on how much weight you're pulling. I usually kill the OD and the truck just crawls down pretty steep hills at 65 with the cruise on. 2500r's is nothing to fret, it will keep you from burning up your brakes on long downhills.

iaddiesel

I didn't know it would downshift to maintain the speed, I just thought it wold not give anymore fuel and basically drift and let the truck pick up speed. Maybe thats what its doing, if the hill was longer maybe I would see that, but it just so happens that it dose it right at the bottom right where it levels out. Thanks for the input.

djbikeman

I've had that happen on downhills less than a mile long. It is downshifting out of over drive into 3rd gear to maintain your selected speed. it is just trying to slow you down. Normal.

TonyB

This is only slightly related....but the factory exhaust brake works VERY well with the ECM to control downhill speed...loaded or unloaded. Usually within 1 mph of setpoint.

HTH

Tony

DrDiesel

That`s why the trans down shift`s like this. It`s for the purpose of an exhaust brake like I said. It`s setup to function this way even if the truck has no exhaust brake.