Difference in braking between Exhaust Brake and Tow/Haul Mode?

mekkerlc · 07-21-2016, 12:58 PM

We have been towing this year with the Tow/Haul button on, and the Exhaust Brake on.
For braking (slowing down) purposes, don't these two features basically do the same thing? Down-Shift to help slow the truck/camper?
All we hear in the truck is a high RPM, rev'd engine. Not much exhaust noise.

dbuster · 07-21-2016, 05:38 PM

My understanding is that the tow/haul mode is for going, while the exhaust brake is for stopping. The tow/haul mode, I think, adjusts the shift points so you're not trying to tow a heavy load in too high of a gear. You might also want to think about setting the +/- button on the shift lever so the transmission never goes higher than 5th gear, if you'll be encountering any nasty hills.

ChooChooMan74 · 07-21-2016, 05:41 PM

Some trucks have a seperate switch for engine braking. Others turn it on when the Tow/Haul button is pressed. Not sure which category your truck falls. Tow Haul mode also changes the shift points on most vehicles for towing.

bluewoo · 07-21-2016, 05:51 PM

Diesel do not have a throttle body as do gasoline engines to control RPM thus diesels by fault are unable to slow you down by de-excelleration as a gasoline engine can. Diesels have an jake brake or exhaust brake to restrict the air leaving the engine thus slowing you down.

https://en.wikipedia.org/wiki/Engine_braking

Big Red and 30WR · 07-21-2016, 07:00 PM

I use tow haul when starting off on a hill or when slowing down with the exhaust brake on. Tap the brake pedal and let the engine and tranny do the rest. Saves on brakes.

davel1971 · 07-21-2016, 07:31 PM

2 completely different things, and both are effective in aiding with braking/slowing. Use them both all the time when towing. No reason you would not want too have the best possible braking and have control of your speed on downgrades.

shorthorn · 07-22-2016, 05:05 AM

Dave nailed it. The reason you hear "high RPM" is because the transfer is in a lower gear to help slow the truck. Once the lower gear engages and locks the TC the exhaust brake will activate and further slow the truck. In all its a great system. I just gave my Ram a test last week in the Smokey Mountains of Tennessee and NC... it worked awesome!

spock123 · 07-22-2016, 06:07 AM

Quote:

Originally Posted by shorthorn

Dave nailed it. The reason you hear "high RPM" is because the transfer is in a lower gear to help slow the truck. Once the lower gear engages and locks the TC the exhaust brake will activate and further slow the truck. In all its a great system. I just gave my Ram a test last week in the Smokey Mountains of Tennessee and NC... it worked awesome!

Try this the next time you are going down a steep hill, set the truck in cruise at the speed you want to descend at, you will never touch the brakes. You don't have to have the camper hooked up, besides the truck doesn't know when the camper is behind you or not

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shorthorn · 07-22-2016, 01:18 PM

Yep... Spock, I did use the Auto mode as u describe... it worked wonderfully

PSU Turf · 07-22-2016, 01:43 PM

A Duramax exhaust brake is not designed to make noise like you hear on a Kenworth. The Duramax runs much more quiet than Cummins or Powerstroke and that carries over to the exhaust brake. I always engage tow / haul and exhaust brake when towing. The stopping power with this setup is incredible compared to any other pickup truck I have driven.

Handydc · 07-22-2016, 02:49 PM

Wait a minute. You turn on exhaust brake and leave it on when towing?? You don't just turn it on when you want to help you slowdown as in going down steep hills.

railroaderone · 07-22-2016, 02:55 PM

Also use the exhust brake some while not loaded so it doesn't freeze up over long periods of non use

guyster · 07-22-2016, 02:58 PM

First thing I do after starting the motor is reach over and turn exhaust brake on. Keeps the vains in the turbo clean.

PSU Turf · 07-22-2016, 04:08 PM

Handydc - You don't want to be reaching for a button on the dash when you need to hit the brakes, especially if it is a panic stop.

DreiHunde · 07-22-2016, 04:24 PM

Quote:

Originally Posted by Handydc

Wait a minute. You turn on exhaust brake and leave it on when towing?? You don't just turn it on when you want to help you slowdown as in going down steep hills.

Yep. Whenever I'm towing I turn on the tow/haul and the exhaust brake then let the truck do all the work while I supervise!

Handydc · 07-22-2016, 04:59 PM

Quote:

Originally Posted by DreiHunde

Yep. Whenever I'm towing I turn on the tow/haul and the exhaust brake then let the truck do all the work while I supervise!

Well you learn something new everyday.

friendofacatahoula · 07-22-2016, 05:03 PM

Some of you may want to have a quick look at this simple link

GMC Sierra HD Exhaust Brake Video | GM Authority

I read someone mentioned you should use it from time to time so it doesn't freeze up. Nothing is going to freeze up. Its the turbo vanes, they are in constant motion, opening and closing. Variable geometry or variable vane turbos allow the vanes to open and close. When the "Exhaust Brake" is active the vanes close and create what I will call "compression braking" essentially using additional back pressure to slow the motor rpm down.

You can leave the exhaust brake on all the time if you wish. I have not encountered any data that would suggest it is harmful in any way to do such. One thing to keep in mind is during slippery conditions the exhaust brake can cause the truck to break lose and slide. I leave mine engaged a lot even when driving around down. It helps keep the motor loaded when not towing, generates a little extra heat, but again, not harmful. In winter this is nice on the Cummins.

The newer Rams also have an "auto" mode which I am not sure is the same as the GM's, but it will only activate when the brake pedal is pressed vs any time the accelerator is released.

When towing moderate to heavy loads your tow/haul helps the transmission by holding shift points longer to also reduce gear hunting.

My Ram when hauling in the rocky mountains, exhaust brake "on" with tow/haul and cruise will maintain my set speed up and down mountain passes without touching the brakes. Heavier loads will require some braking pressure and assistance from the TT.

Filterman · 07-22-2016, 05:29 PM

Two completely different systems. I pull with gas so no option for an engine brake. The tow haul mode will keep you from running away on a hill by down shifting your transmission. We live on BC so pull long steep hills pretty much every place we go. In steep country I prefer to turn off tow haul and control the transmission manually because sometimes you can travel faster downhill than the mode will allow you without over revving. I would guess an engine brake in combination with tow haul is the best of all world's.

WolfWhistle · 07-22-2016, 05:39 PM

like guyster my exhaust brake is on all the time... a respected Ram diesel mechanic said do it that way ...Tow/Haul when towing the toy hauler and it does affect the exhaust brake. I dont use it for my small cargo trailer.
WW

spock123 · 07-22-2016, 07:51 PM

I had a 08 2500 diesel and no exhaust brake but you could set the cruise and put truck in tow/haul and truck would act like it had a exhaust brake. As a matter of fact you can do the same with a 2500 gas burner and I think with a 1500, Silverado of course

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