Exhaust Brake Unavailable

[SnoKing]

I think you totally misread what I said. I did not discuss a scenario of NOT using the EB.

Simplified points of my post....
EB works better in lower gears, whether you manually shift down, or use T/H and it automatically shifts down.
EB works better in lower gears primarily from the gear reduction itself, not just engine RPM.

EBs work because of brake horse power, which is created by RPMs when the EB is active. I believe the brake horse power is more in play than the gear ratios. If what you are saying was more true I would have seen the truck on the off ramp increase in it's hold back significantly as it slowed and down shifted which did not occur without the EB on. That was at 8K+, try that at 24,500 as see how your theory works.

Lets say the drive train create 5 or 10 HP of braking/hold back it at throttle off on a level road in 6th at highway speed, which is a lot less then the wind resistance. In second gear that might be 25 to 50 HP or not very much is comparison to 150-200 HP the exhaust brake creates, now multiply that exhaust brake HP by gear reductions and see what is really in effect.

 

[kthaxton]

Again, you misunderstand. I am not speaking of ANY scenario that does not include using the EB. In order for my example to be legitimate, the engine must be able to have influence on the load in a descending, deceleration situation. With a Diesel, that will happen only with the EB, with a gasser, only with the throttle closed.

In either situation, the engine will be better able to slow a load when it is in a lower gear....because of gear multiplication, but again, this IS WITH EB on!

I think the guys with lower rear end ratios will tell you that the EB in their trucks work better than those with higher rear end ratios. But again, find any kind of geared contraption with shiftable gears and see how much harder it is to turn the output when in a low gear, vs. a high gear, even without the load of engine compression on it you can feel it. Heck, I can make a Lego transmission and feel the difference.

 

[Cummins12V98]

My EB works better on current 15 with 4.10's compared to 11 with 3.42's. I am betting gear ratio and possible different braking mechanics on turbo???

 

[bcbender]

So now that we have thoroughly discussed the theory of gear multiplication, mech advantage, computer logic, and thermal fluid dynamics.... I am with kthaxton in that I don't think the OP's question was answered. I had a note today on startup (never seen before) that said "Exhaust Brake Off" after the startup splash screen. But did anyone figure out why his said "Exhaust Brake Unavailable"? Id be in the camp that the actuator stuck or there was some fault, Also I thought Hill Decent was only available on the Power Wagon which is not a CTD.

 

[brucejohnson]

Also I thought Hill Decent was only available on the Power Wagon which is not a CTD.

It's also part of the Off Road package. I have it on my 2020 2500 Laramie CTD...a pushbutton on the electronic transfer case selector panel. Haven't used it, but it has some engagement limitations like speed, transmission gear, transfer case mode, etc..

Hill Descent Control (HDC) — If Equipped Hill Descent Control (HDC) is intended for low speed off road driving while in 4L Range. HDC maintains vehicle speed while descending hills during various driving situations. HDC controls vehicle speed by actively controlling the brakes. HDC Has Three States: 1. Off (feature is not enabled and will not activate) 2. Enabled (feature is enabled and ready but activation conditions are not met, or driver is actively overriding with brake or throttle application) 3. Active (feature is enabled and actively controlling vehicle speed) Enabling HDC HDC is enabled by pushing the HDC switch, but the following conditions must also be met to enable HDC:  Driveline is in 4L Range  Vehicle speed is below 5 mph (8 km/h)  Parking brake is released  Driver door is closed
Activating HDC Once HDC is enabled it will activate automatically if driven down a grade of sufficient magnitude. The set speed for HDC is selectable by the driver, and can be adjusted by using the gear shift +/-. The following summarizes the HDC set speeds: HDC Target Set Speeds  P = No set speed. HDC may be enabled but will not activate.  R = 0.6 mph (1 km/h)  N = 1.2 mph (2 km/h
D = 0.6 mph (1 km/h)  1st = 0.6 mph (1 km/h)  2nd = 1.2 mph (2 km/h)  3rd = 1.8 mph (3 km/h)  4th = 2.5 mph (4 km/h)  5th = 3.1 mph (5 km/h)  6th = 3.7 mph (6 km/h)  7th = 4.3 mph (7 km/h)  8th = 5.0 mph (8 km/h)  9th = 5.6 mph (9 km/h) – If Equipped NOTE: During HDC the +/- shifter input is used for HDC target speed selection, but will not affect the gear chosen by the transmission. When actively controlling HDC the transmission will shift appropriately for the driver-selected set speed and corresponding driving conditions. Driver Override The driver may override HDC activation with throttle or brake application at any time. Deactivating HDC HDC will be deactivated but remain available if any of the following conditions occur:  Driver overrides HDC set speed with throttle or brake application.  Vehicle speed exceeds 20 mph (32 km/h) but remains below 40 mph (64 km/h).  Vehicle is on a downhill grade of insufficient magnitude, is on level ground, or is on an uphill grade.  Vehicle is shifted to PARK. Disabling HDC HDC will be deactivated and disabled if any of the following conditions occur:  The driver pushes the HDC switch.  The driveline is shifted out of 4L Range.  The parking brake is applied.  The driver door opens.  The vehicle is driven greater than 20 mph (32 km/h) for greater than 70 seconds.  The vehicle is driven greater than 40 mph (64 km/h) (HDC exits immediately).  HDC detects excessive brake temperature
Disabling HDC HDC will be deactivated and disabled if any of the following conditions occur:  The driver pushes the HDC switch.  The driveline is shifted out of 4L Range.  The parking brake is applied.  The driver door opens.  The vehicle is driven greater than 20 mph (32 km/h) for greater than 70 seconds.  The vehicle is driven greater than 40 mph (64 km/h) (HDC exits immediately).  HDC detects excessive brake temperature. Feedback To The Driver The instrument cluster has an HDC icon and the HDC switch has an LED icon, which offers feedback to the driver about the state HDC is in.  The cluster icon and switch lamp will illuminate and remain on solid when HDC is enabled or activated. This is the normal operating condition for HDC.  The cluster icon and switch lamp will flash for several seconds then extinguish when the driver pushes the HDC switch but enable conditions are not met.  The cluster icon and switch lamp will flash for several seconds then extinguish when HDC disables due to excess speed.  The cluster icon and switch lamp will flash when HDC deactivates due to overheated brakes. The flashing will stop and HDC will activate again once the brakes have cooled sufficiently.​

 

[MarkEagleUSA]

I am with kthaxton in that I don't think the OP's question was answered.

He answered his own question.

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

 

[bcbender]

learned something new today.. I was unaware that like the HO / AISIN combination, that particular package was model specific.

 

[SnoKing]

learned something new today.. I was unaware that like the HO / AISIN combination, that particular package was model specific.

Yes offered in the 3500 SRW and DRW only. Not available in the 2500. During shortages of Aisin trannies in the past then only DRWs.

 

[CCCRAM]

He answered his own question.

At the risk of continuing the circular discussion... I want to ask a question that could help a lot of us CTD users who haul a 5th wheel. What is the best way to use TH and EB in combination to safely descend significant grades?

I am embarrassed, yes EMBARRASSED, to admit I haven't used TH or EB at all. I use the truck's service brakes and trailer brakes to stop. Always allowed plenty of room between me and the vehicles ahead and kept a sharp lookout for trouble ahead, and I've never had a problem I know this is probably against some trucker code or something.... however, I want to admit I'd rather have a higher level of safety.

So what I'd like to challenge you to do is to SIMPLY explain how an experienced 5th wheel hauler should use TH and EB separately or in combination to best take advantage of what the CTD offers. Please don't be condescending in comments, but educational.

What I Picked Up

• From what gather, everyone recommends always running TH whenever hauling something more than 2500 lbs.
• Some think you should run TH whenever they're in the truck, some with EB on (seems overkill to me)
• Some believe only manual EB is the way to run the truck, I guess in combination with ESR
• Others believe using the auto EB is best
• And others think TH and EB are best used together

From the outside in looking at your discussion it is very confusing!

KISS, where art thou?

Tracy

 

[Wiredawg]

I run Full EB all the time, loaded/towing and unloaded. I like it to engage everytime I take my foot off the accelerator.
I use TH when unloaded around town and loaded/towing. I correlate TH with performance mode.

One more tidbit: on very steep grades loaded/towing, I like manual downshift, Full EB/TH for maximum downhill speed management.

There are a lot of driving towing techniques that optimizes your driving style. After reading you may want to try combinations to see what works for you. You can't easily hurt it so give it a try.

 

[NIsaacs]

Please don't be condescending in comments,

What I Picked Up

• From what gather, everyone recommends always running TH whenever hauling something more than 2500 lbs.
• Some think you should run TH whenever they're in the truck, some with EB on (seems overkill to me)
• Some believe only manual EB is the way to run the truck, I guess in combination with ESR
• Others believe using the auto EB is best
• And others think TH and EB are best used together

Tracy

I recommend you practice/experiment with the list you have. It covers the subject pretty well.

 

[p-Bar]

When towing I use the T/H and full exhaust brake. I find that with Aisin trans grabs gears (down shifts) nicely by its self. I tow a 14k 5er. I use full exhaust brake when not towing.

 

[BigPapa]

Sometimes some ppl get so involved in the details they can't agree on something so simple.

...

 

[Robbie Antonosn]

CCCRAM
When I first read your post, I was taken aback. Why would any one buy a modern diesel truck and not use some of the best features, besides the power and Fuel economy. Especially towing.
I would agree that you need to go experiment with your truck. Some here have way more experience than I with the
Cummins engine in the Ram. The exhaust brake use to be an expensive add on, now it is standard. Help save wear and tear on all the brakes on your truck and trailer. I believe you will be amazed on how well you can control your trailer down big mountain passes(if you travel those routes). With out the use of the truck and or trailer brakes. I love using the EB all the time, I am not in a hurry, it helps slowing down in town, and on the Highway. I down shift with the Manual option, make the truck do the work, not the brakes. Save them for when you really need them.
I personally like the Full exhaust feature over the Auto.
Tow haul is a great tool as well. Shifts the RPM Band higher, to hold the TQ/HP a bit better.
Anyhow, not wanting to side track this thread. Good luck with the new found tools. It will make driving some much better. And, last but not least, use it the way you want. Take it all as recommendations. Play and learn, be safe.

 

[Ozymandias]

Very good write up!

 

[kthaxton]

I use EB 100% of the time. T/H and EB 100% of the time towing. I sometimes use T/H when not towing and going through slow, stop and go traffic where there are slower speeds involved.

As said, when I tow, I always use T/H and EB and almost always use "Full" EB, with one exception....I have found that using Auto EB on steep, winding descents to be a better experience, because honestly, the full EB works a bit too well in those situations. With Auto, there is less getting on and off the throttle (to control the EB which can be too much at times). I also get a warm fuzzy because this better allows for using the service brakes a little bit which splits braking forces to all 8 tires instead of just two.

 

[Cummins12V98]

Add cruise control to your descending!!! Use your gear selector to grab lower gears for more braking. Works GREAT. 34k down long 14% grade without brake application using TH, EB and cruise.

 

[bcbender]

Actually I've been using cruise control more these days (was not really an option towing with my 04 and NV5600). I use the Automatic EB in the rolling hills of NC to prevent it from coming on every time I go down a hill, works pretty good, I use full EB when descending grades and driving w/o cruise when I can modulate the throttle to prevent it from coming on when not needed... but alas this is just an effort to improve FE.

 

[kthaxton]

Add cruise control to your descending!!! Use your gear selector to grab lower gears for more braking. Works GREAT. 34k down long 14% grade without brake application using TH, EB and cruise.

Are you addressing my comment above yours? If so.....no thanks. "Winding" road being the key point here...the type you'd never use cruise control on.

 

[AH64ID]

Actually I've been using cruise control more these days (was not really an option towing with my 04 and NV5600).

Why wasn’t it an option on your 04?

I lived in CC with my 05/NV5600 combo, especially in the mountains.

l"Winding" road being the key point here...the type you'd never use cruise control on.

That’s the type of road I mostly tow on and I live in CC whenever possible. Not sure why you’d “never” use it.