Tow-Haul Mode Engine Braking: How does it work?
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Elder User
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From: Baltimore
Tow-Haul Mode Engine Braking: How does it work?
Diesel engines typically don't have the engine braking that a gas motor does. A 6.0L coupled with the Torque-shift transmission can almost bring the truck to a halt without the brakes. How is the engine braking generated?
Last edited by whalerron; Sep 27, 2005 at 11:55 PM.
Former Vendor
Joined: Mar 2004
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From: Hendersonville, NC
When the computer determines by means of the vehicle speed sensor and a set of calculations that engine braking is neccessary, the transmission torque converter, coast clutch, and present gear ratio clutch are locked.
After locking the gear that it needs, the computer will command extra exhaust backpressure (just like an aftermarket exhaust brake valve) and correspondingly shut the VGT turbo vanes to build backpressure. This backpressure is what builds retarding horsepower, and by locking the transmission it puts the retarding horsepower to the ground, thereby slowing the truck.
After locking the gear that it needs, the computer will command extra exhaust backpressure (just like an aftermarket exhaust brake valve) and correspondingly shut the VGT turbo vanes to build backpressure. This backpressure is what builds retarding horsepower, and by locking the transmission it puts the retarding horsepower to the ground, thereby slowing the truck.
Got Diesel?
Joined: Jan 2004
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Originally Posted by PSD 60L Fx4
When the computer determines by means of the vehicle speed sensor and a set of calculations that engine braking is neccessary, the transmission torque converter, coast clutch, and present gear ratio clutch are locked.
After locking the gear that it needs, the computer will command extra exhaust backpressure (just like an aftermarket exhaust brake valve) and correspondingly shut the VGT turbo vanes to build backpressure. This backpressure is what builds retarding horsepower, and by locking the transmission it puts the retarding horsepower to the ground, thereby slowing the truck.
After locking the gear that it needs, the computer will command extra exhaust backpressure (just like an aftermarket exhaust brake valve) and correspondingly shut the VGT turbo vanes to build backpressure. This backpressure is what builds retarding horsepower, and by locking the transmission it puts the retarding horsepower to the ground, thereby slowing the truck.
I may not know how it works... but it does... and I thought there were little mice in there that put their feet out on the ground and generated extra friction on the road like Fred Flintstone... darn... wrong again!!!
With my 12/03 flash on my 2003 Excursion, I still have a working tow-haul mode feature that works (less than when new, but it works)!!!
Thanks Matt for your answer above... I will go to the library and research what you said (ha, ha), take care.
Senior User
Joined: Jul 2005
Posts: 111
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From: Fairbanks, AK
While Pulling a 17,000# 38' boat from Valdez to Fairbanks, AK through 2 mountain ranges earlier this month boy did the 6.0 and tranny shine. It was set the cruise control at 45 and forget about it. It would do 45 up the hills and 45 down the hills.
We were a little nervous after the first pit stop at 60 miles when we found that the trailer brake module on the trailer had failed, but the tow/haul mode pretty much eliminated most brake use anyway, it was as if the truck had a mind of it's own...in a very, very intelligent way.
Great truck!
We were a little nervous after the first pit stop at 60 miles when we found that the trailer brake module on the trailer had failed, but the tow/haul mode pretty much eliminated most brake use anyway, it was as if the truck had a mind of it's own...in a very, very intelligent way.
Great truck!
New User
Joined: Jul 2005
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Is there any way to put a manual override switch on the brakes? Some times mine dont kick on as fast as I would like them to come on.
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Cargo Master
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From: Carlsbad, California
And here I thought all along that a tiny set of feet dropped out the bottom and started doing a Fred Flintstone. Gosh, the things you learn here . . . 
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Junior User
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From: Eagle River Alaska
All I can say is the tow haul mode on my 2005 6.0L F350 does a better job then I ever was able to with 4 speed stick transmission carrying 3300# of camper. It sure impress the heck out of me.
The instruction manual has some words of wisdom. Do not use the tow haul mode with an empty truck in snow. It changes the portioning of brake pressure between front and rear axles, or you may have rear end getting ahead of you!
The instruction manual has some words of wisdom. Do not use the tow haul mode with an empty truck in snow. It changes the portioning of brake pressure between front and rear axles, or you may have rear end getting ahead of you!
Junior User
Joined: Oct 2004
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does any one know why sometimes when im using tow haul the truck will down shift and hold back to the point where using the brakes is almost unnessary but other times it will hardly down shift and you have to use all brakes. also i like to use tow haul mode on back roads when i am not towing and in a hurry it helps keep the tranny from gear hunting and helps limit the use of brakes
Post Fiend
Joined: Jul 2005
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From: 21791
Originally Posted by tn mac
diesel engines most certainly do have engine brakes, that is what a jake brake is and that is what is used on cummins engines, and big rigs just not on the 6.0 or durajunks.
Elder User
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An engine brake is a device...engine braking describes how an engine, such as a gas motor with a butterfly type air inlet control (carburator), can act as a braking system by closing off the air coming into (or out of) itself.
Diesels do not have an air inlet control short of the turbo changing boost. The combustion chamber is open to the outside air source, and more or less fuel is delivered to the combustion chamber to vary it's speed.
This is also why diesels cannot make a vacuum.
Diesels do not have an air inlet control short of the turbo changing boost. The combustion chamber is open to the outside air source, and more or less fuel is delivered to the combustion chamber to vary it's speed.
This is also why diesels cannot make a vacuum.
Posting Guru
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strokin correct me if I am wrong but I believe the cummins does have a jake brake for the pickups, and I believe they are marketed as engine brakes. I know the 6.0 is not a engine brake,it sure is to bad ford took away the orginal trans brake it was sweet.
Postmaster
Joined: Jan 2005
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From: BC Canada
If you want the TS to downshift an extra gear apply the brakes and release, if their is rev room it will grab a gear and hold better. If you aply and release again it will shift down again until its holding better. It just wont shift down enough to over rev. It is a little less aggressive than the old programs but on a slippery road with no weight, be careful or it will slide the rear around.
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