How do you use the jake brake on a truck with an automatic transmission?

I have Freightliner Dt-12 transmission. Lots or people try and Drive it like they did a manual and they say they don't have control or it shift gear for no reason.

First you leave the engine brake on all the way down the the hill. You need to know how stage 1 and 2 generally keep the engine RPMs between 1,200-1,750 RPMs all the time. Stage 3 will always keep 1,750-2,200 RPMs. The transmission will keep trying to slow the truck down until you turn off the engine brake. It will keep dropping gears as the trucks slow down all the way to like 15 MPH and it will never give up trying to slow the truck.

Say your going down hill in stage 3 the truck will drop gear raise engine to 1750-2200 RPM. As the truck slows down when the RPMs get to 1,800 you switch to stage 2 and let the truck roll back up to 2,200 RPM. Then at 2,200 or 2,100 switch back to stage 3 to slow the truck down. If you let the RPMs drop to 1750 or 1700 the transmission will drop a gear and keep trying to slow you down.

If your run stage 2 and the engine brake is slowing you down to much at about 1,200 RPMs switch to stage 1. This will keep truck in gear and let the RPMs climb back to 1,700 or 2,200 and then switch stage 2 back on to slow the truck and to keep the RPMs from going over 2,300.

Just remembered stage 1 and 2 are 1200-1750 RPMs and stage 3 is 1750-2200. You control or stop the down shift by keeping the RPM in the range for the difference stage of engine brake. If your really heavy you can roll down hill in stage 3. If the RPMs hit 2250 apply a little brake pressure to slow down. Don't turn off the engine brake because then it will go into neutral. If it's to much engine brake and truck is slowing down to 1,800 RPMs. Switch to stage 2 and let it roll back up to 2,200 then turn stage 3 back on. It will stay in gear all the way down the hill.

 

It took me a while to get comfortable with the way the dt12 deals with the engine brake on high.

I'm still not comfortable with it actually and usually put it in manual when down shifting or descending a grade. Especially in the winter! Hill descent is nice but you want more control if it's slippery out.

Best thing I can say is rtm. Do you know how to turn off hill start aid? Creep mode? E Coast? It's hard to believe that a driver that's been in this truck for a year doesn't even know if it has manual mode or not. Come on driver, if you're not learning all the time...

 

If you're at slower speeds, only use the jakes in the lowest setting or off entirely if the transmission is in auto mode. If you're in manual mode, use the jakes wherever you feel comfortable with them. The higher the jake setting, the more your tranny will downshift in auto mode.

 

Step One: read the operators manual.

 

That’s just how they have your truck set in the computer. Turning your cruse off every time you want to use the engine brake would get old.

 

I should clarify. The engine brake on my tractor does work when the cruise is on or off. When the cruise switch is in the "on" position while in manual mode, the engine brake does not engage unless you tap the brake pedal. With the cruise in the "off position", and the trans in manual mode, it operates as if you are driving a manual transmission.

 

Thank you couldn't of said it better

 

Are tee eff em.

 

I understood. That last auto truck I had the jake would work not mater what the transmission was set to. As long as the cruse was not active, let off the throttle and the engine brake came on.
There is a million different setting that can be change with the right software. Most of those choices are made by people that have never been in a truck.