Exhaust Brake Unavailable

[SnoKing]

Isn't the same at all. Hardly any braking without tow/haul mode enabled. Night and day. Unless your truck has an issue. I can only get good breaking on tow/haul. Too weak to bother without tow/haul.

Earl

Running bobtail I always had the exhaust brake on without TH except I would push it on for freeway off ramps. In normal freeway traffic it worked fine to show down a bit, when traffic slowed. Down side is the guy behind you does not see your brake lights. Around tow I found that have TH on caused un-needed increased RPMs. It is all a mute point now for us.

 

[EZeis]

Running bobtail I always had the exhaust brake on without TH except I would push it on for freeway off ramps. In normal freeway traffic it work fine to show down a bit, when traffic slowed. Down side is the guy behind you does not see your brake lights. Around tow I found that have TH on caused un-needed increased RPMs. It is all a mute point now for us.

Love tow/haul on the interstates in heavy traffic when bobtailing. Used the hell out of EB with TH today on my drive down 81 to 70 to 270 to 495 to 95 to 64. Horrible traffic. Lots of stop and go and the classic 75 to zero stuff.

If someone needs brake lights to tell you're slowing down, they have issues, big issues, really really big issues.

Earl

 

[AH64ID]

Isn't the same at all. Hardly any braking without tow/haul mode enabled. Night and day. Unless your truck has an issue. I can only get good breaking on tow/haul. Too weak to bother without tow/haul.

Earl

The brake itself isn’t capable of anymore retarding power in TH, but the aggressive downshifting of TH makes the brake more usable as the tq converter is locked more.

There is still plenty of braking when not using TH. Went for a mountain drive today, never used TH but the EB works fantastic. If yours doesn’t then you may have an issue.

 

[Cummins12V98]

Problem solved...operator error. What I thought was Exhaust Brake actually is Hill Descent which won't work without the Exhaust Brake engaged. Duh!!!

Hill Descent???

 

[Cummins12V98]

Isn't the same at all. Hardly any braking without tow/haul mode enabled. Night and day. Unless your truck has an issue. I can only get good breaking on tow/haul. Too weak to bother without tow/haul.

Earl

I have had a few butt clench times when the TH was turned off and rapidly accelerating down a 6% grade at 35k combined.

 

[Cummins12V98]

The brake itself isn’t capable of anymore retarding power in TH, but the aggressive downshifting of TH makes the brake more usable as the tq converter is locked more.

There is still plenty of braking when not using TH. Went for a mountain drive today, never used TH but the EB works fantastic. If yours doesn’t then you may have an issue.

Please try it on 6% grade towing 35k combined or the max weight you can and report back.

 

[SnoKing]

I never liked the auto mode of the exhaust. The over speed of 4-5 mph was not in my wheelhouse. I ran manual mode and controlled speed with throttle pedal and manual gear selection.

 

[Ozymandias]

Please try it on 6% grade towing 35k combined or the max weight you can and report back.

Have you ever driven your truck without the fifth wheel?

I did and TH&EB on an empty 2019 truck is way to aggressive. Just feathering the service brake makes it downshift and head bangs to the steering wheel.

 

[AH64ID]

Please try it on 6% grade towing 35k combined or the max weight you can and report back.

Still doesn’t change what the brake is capable of. TH is a transmission setting, the exhaust brake itself doesn’t know or care that you’re using TH...at any GCW.

I never liked the auto mode of the exhaust. The over speed of 4-5 mph was not in my wheelhouse. I ran manual mode and controlled speed with throttle pedal and manual gear selection.

It also does that on full. It’s a cruise control feature that allows the overspend, not the EB. In auto mode and not in CC there is no over speed since the EB engages as you get above the speed you got off the throttle at.

 

[EZeis]

The brake itself isn’t capable of anymore retarding power in TH, but the aggressive downshifting of TH makes the brake more usable as the tq converter is locked more.

There is still plenty of braking when not using TH. Went for a mountain drive today, never used TH but the EB works fantastic. If yours doesn’t then you may have an issue.

Definitely an issue with your truck. Have you checked for codes? EB full on and in tow/haul mode, it should brake night and day difference. Very aggressive compared to hardly anything. To the point where it's not worth it to run without tow/haul enabled. Gotta keep the rpms up and the converter locked for good braking. Mine doesn't do that with the tow/haul off. Mine doesn't progressive downshift down with the tow/haul off. So no high rpms. Try running tow/haul and report back. It should be holy crap that's some serious progressive braking. If not, you have something going on. Which I believe you do from your statements. You're welcome to drive my truck to compare.

Note, my 07 manual trans had a pacbrake prxb and that thing could brake. Better than my 18. I was so use to that brake that no way could I run without tow/haul. Just too weak. It drops out too soon as well, instead of all the way down to 18ish with tow/haul enabled.

Earl

 

[AH64ID]

Definitely an issue with your truck. Have you checked for codes? EB full on and in tow/haul mode, it should brake night and day difference. Very aggressive compared to hardly anything. To the point where it's not worth it to run without tow/haul enabled. Gotta keep the rpms up and the converter locked for good braking. Mine doesn't do that with the tow/haul off. Mine doesn't progressive downshift down with the tow/haul off. So no high rpms. Try running tow/haul and report back. It should be holy crap that's some serious progressive braking. If not, you have something going on. Which I believe you do from your statements. You're welcome to drive my truck to compare.

Note, my 07 manual trans had a pacbrake prxb and that thing could brake. Better than my 18. I was so use to that brake that no way could I run without tow/haul. Just too weak. It drops out too soon as well, instead of all the way down to 18ish with tow/haul enabled.

Earl

I know there is nothing wrong. You’re confusing the exhaust brake function with TH function. The brake itself is capable of the same retarding power as that is only a function of vane position and rpm, nothing else. TH will have a more aggressive downshift schedule and hold the torque converter locked longer, but that doesn’t mean the brake is making more retarding power it just means it’s more usable, which is great with a load and annoying (for me) when empty.

I will go on to say that if you think it’s pointless to run without TH then there is something wrong with your truck, as it’s very beneficial. It’s does feel different than in TH but it’s still very usable, especially in conjunction with CC for speed management downhill.

Dads 17 works identical to my 18, they work as advertised and designed. Nothing wrong, just you’re interpretation of what’s actually happening when you engage TH.

I’ve run TH lots and know the difference, as well as what creates the difference. The brake isn’t programmed different in TH, just the transmission. This is my point that you’re missing.

It would be nice if activating the EB would change the lockup schedule, but not the downshift schedule.

I ran both a Jacobs and a PRXB on my 05/NV5600. They both worked similar but a little different. The PRXB was much stronger below 2000 but the Jacobs was stronger above 2500, but that’s not a normal condition. The cam I had would run the back pressure up over 75 on the Jacobs where the PRXB stayed at 60. More pressure means more braking.

 

[Wiredawg]

Pretty much saying the same thing John is, my 2017 Ram 5500 holds EB longer, more related to my 4:88s keeping higher RPMs at lower speeds. Last week I took 5500 and dump trailer 7Klbs empty to get inspected and TH was too aggressive to operate with EB. When I say annoying, I mean pop the seatbelt annoying. Very excellent when towing a loaded trailer though.

So folks with 342s, 3:73s, 4:10s AND 4.44s will drop EB at higher speeds @1,100 RPMs than my 4:88s.

Since I've decided to keep my 5500, looking at putting 285/70R 19.5s on it when current tires wear out. 35s should be pretty cool and will act like 4.44s were on the truck. Not many tricked out C&Cs out there.

Anyhoo, these EB/TH threads always interesting.

Cheers, Ron

 

[kthaxton]

AD64ID is correct. It is the auto downshifting of the trans that makes the EB more effective with T/H on. You could leave T/H off and downshift manually and have a similar braking as with T/H.

I use EB all the time, always use T/H when towing, and sometimes in stop and go traffic. But in normal commuting, I don't bother with T/H.

I use full EB when towing, but while doing steep descents, more so if it is a twisty descent, I'll use Auto EB as I find that it behaves better.....not as much jerkyness and not as much on and off the throttle.

 

[Cummins12V98]

Have you ever driven your truck without the fifth wheel?

I did and TH&EB on an empty 2019 truck is way to aggressive. Just feathering the service brake makes it downshift and head bangs to the steering wheel.

I drive it a lot solo and always run EB/TH. Love it. Muscle memory has me letting off at the right time with slight application of brakes coming to a stop.

Yep it’s aggressive but I like it that way.

 

[Cummins12V98]

Simply put without TH engaged I would have used the runaway many times. You need to get the rpm’s up to make the EB do its job best.

 

[AH64ID]

Simply put without TH engaged I would have used the runaway many times. You need to get the rpm’s up to make the EB do its job best.

Yes it makes a difference, but I’m not sure I’d ever run at 35K GCW without using TH. Heck I run TH anytime I have about 4K extra, just not any lower.

 

[bcbender]

Heck I run TH anytime I have about 4K extra, just not any lower.

John, That is a question I have been longing to ask but not worth starting a thread.... I tow several "light" trailers and neither are over 2500# empty, I was curious about what is considered "TOW / HAUL" with the HO / AISIN combination (whether in the bed or behind). I towed my Alumaline dump trailer to Danville last weekend and it was perfectly happy in 6th on the backroads, seemed like I might've squeaked out a little better MPG, but TH mode doesn't shift into 6th until 65mph so basically not used on rural highways...... I had a NV5600 / HO before so everything was Tow/Haul on it

 

[AH64ID]

John, That is a question I have been longing to ask but not worth starting a thread.... I tow several "light" trailers and neither are over 2500# empty, I was curious about what is considered "TOW / HAUL" with the HO / AISIN combination (whether in the bed or behind). I towed my Alumaline dump trailer to Danville last weekend and it was perfectly happy in 6th on the backroads, seemed like I might've squeaked out a little better MPG, but TH mode doesn't shift into 6th until 65mph so basically not used on rural highways...... I had a NV5600 / HO before so everything was Tow/Haul on it

It a lot of personal preference. I feel that the truck runs too many rpms with light loads in TH and I don’t like the aggressive downshift schedule when light.

TH is just a different shift schedule. It delays up shifts, holds gears longer, and has a more aggressive decel downshift program. There are no added power or other engine related changes.

So I’d say play with it some. Some folks like TH empty, so there is no right or wrong answer.

 

[Cummins12V98]

Yes it makes a difference, but I’m not sure I’d ever run at 35K GCW without using TH. Heck I run TH anytime I have about 4K extra, just not any lower.

that was my point. I would never run without TH as SnoKing did as you never know when you need to stop fast.

 

[Cummins12V98]

It a lot of personal preference. I feel that the truck runs too many rpms with light loads in TH and I don’t like the aggressive downshift schedule when light.

TH is just a different shift schedule. It delays up shifts, holds gears longer, and has a more aggressive decel downshift program. There are no added power or other engine related changes.

So I’d say play with it some. Some folks like TH empty, so there is no right or wrong answer.

Agreed!!!