Question For Downhill Driving With An Automatic?

When the engine brake is activated in some trucks the brake lights come on and stay on

I'm with Old School on this one. I'm not certain, but I am going to say not so. I have followed many trucks on downgrades. The trucks in front of me that are holding their speed like I am, do not have their brake lights on. An occasional short burst from time to time. I drive with my headlights on day and night. You may be following a truck that does the same, and are actually seeing the tail lights illuminated. Brake lights are normally much brighter than the tail lights.

Hey Phoenix, when you get the chance take a look at the info here. There's some really great information plus some helpful videos that will help you understand just what the "engine brake" is and how it works. Understanding it will help you know how to properly use it.

What Is The Jake Brake And How Does It Work?

OS and TM, thank you for responding... I do realize the engine brake requires higher rpms...I should have clarified that. Normally, 15-1700 is how high they go, at 18-1900 I start slowing it back down. However, occasionally it'll be humming along at about 1500rpms, then all of a sudden jump to 18+. Owners manual says they should never go beyond 2100 or engine damage may occur. This makes me worry that 1900 or 2000rpms is too high.

And what about starting up? Am I doing something wrong there?

As for the brake lights staying on, it was back in the old days.. like three years ago, lol, when I first began this career, that I recall wondering why some brake lights never went off down hills and were they riding their brakes? It was my trainer that told me some stayed on. I think it was freightliner that did it but I don't remember. I certainly could have been misinformed, in which case those drivers were in fact riding their brakes dangerously lol.

Our Cascadias at Prime will regularly, and automatically, reach RPMs of 2200-2300 during some engine braking. This is regulated by the on-board computer, which determines engine braking by weight of load, grade at present, pre-loaded terrain maps, etc. In our case, 2300 RPMs are safe and very effective in slowing the truck without damage to the engine. We're taught only to not let RPMs go in excess of 2500.

This may be company specific, based on optional features. It's best to ask your company what they prefer.

OS and TM, thank you for responding... I do realize the engine brake requires higher rpms...I should have clarified that. Normally, 15-1700 is how high they go, at 18-1900 I start slowing it back down. However, occasionally it'll be humming along at about 1500rpms, then all of a sudden jump to 18+. Owners manual says they should never go beyond 2100 or engine damage may occur. This makes me worry that 1900 or 2000rpms is too high.

And what about starting up? Am I doing something wrong there?

As for the brake lights staying on, it was back in the old days.. like three years ago, lol, when I first began this career, that I recall wondering why some brake lights never went off down hills and were they riding their brakes? It was my trainer that told me some stayed on. I think it was freightliner that did it but I don't remember. I certainly could have been misinformed, in which case those drivers were in fact riding their brakes dangerously lol.

I've noticed this too sometimes. I always assumed that the truck's computer is making automatic adjustments based on the steepness of the grade and how much momentum it senses you are building. As though it is applying more engine brake to compensate. If the RPMs start getting too high I just apply the brake.

When the engine brake is activated in some trucks the brake lights come on and stay on.

I'm not sure about that. I'm not saying you're wrong Phoenix, I have just never known that was the case. Can anyone verify this?

there's something I have trouble with on the hills when my engine brake is engaged... my engine shoots up to 1800-2000rpms while I'm going down a hill. Why does it do this? it's very frustrating. I switch to manual and go up a gear and then need to get my speed down cuz now I'm going faster than my safe speed.

Phoenix, your engine brake needs the higher RPMs to be effective - that's actually how it works. If you shift up a gear, it loses the RPMs and becomes less effective. Therefore your speed will increase. Higher RPMs are needed to maintain the lower speed. I know that sounds backwards, but that's how the Jake brakes work.

My truck is like this, when the engine break is on break lights are on for truck and trailer. 2017 10 speed pete.

The Millis t680's also light the brake lights when engine brakes engage.

My truck is like this, when the engine break is on break lights are on for truck and trailer. 2017 10 speed pete.

Thanks for the clarification on that. They may very we activate on my 2019 Cascadia too. I may need to jump out when going down hill and run behind and check!!

Don't you have a spotter for that, Tractor Man?

The break lights on the OD Kenworths come on with the engine break.