I have tried posting this message 3 times. The administrator says he does not know why it will not post. He said to resend it. I am retyping everything to see if I included some unsupported characters.I am on the road. I have a 2008 Monaco Dynasty 425hp Cummins with a Allison 3000 MH 6-Speed World Transmission and Electronic Shifter. Normally on steep downhill grades I can flip the Jake Brake on and it will hold the speed I want, normally 50mph. Now it will not only not hold the speed but the switch feels like it is not connected. I can flip it back and forth and nothing happens. There is a second Jake Brake, HiLo switch, and it works fine, next to the Jake Brake that I use for speed retention and to slow down when I approach a town speed post. I generally only use the second Jake Brake when I am below 40mph and it takes me down to 15mph and then turns me loose.My question is has anyone else experienced this and is it something I can fix? I appreciate your input. Maybe all of a sudden I am not operating them correctly.

Don't know anything about Jake Brakes except what they are, but you post shows up fine.

There are connections at the switch and solenoids under the valve cover.I don't know how you would trouble shoot everything.If it was a fuse, I would think nothing would work.May, need a expert mechanic for this one.Hopefully, someone will jump in with a better answer than mine.Pat

When you try and use the Jake does 2nd show up in the tranny shift pad? If not the switch may not be working... check with a ohm meter and if defective replace with a on/off switch with the same number of contacts. If 2nd shows up then it could be the two wires that connect to the head on your engine... not likely.iThere is a fuse in the front run box labeled Jake Brake... check it before the switch.

I'm assuming your 425hp Cummins is an ILS which has an "engine" brake (commonly referred to as a Jake brake) as opposed to an "exhaust" brake (which can also be referred to as a Jake brake). Engine brake has two positions (Hi and Lo as you indicated) whereas an exhaust brake only has one position (on or off) and is commonly found in the Cummins ISB and ISC engines.It sounds like you have a separate on/off switch and then a secondary switch to determine which position. Does the position switch have a "neutral" position??? If yes, then turning on the first switch will not cause the engine brake to activate....only if the position switch is in the Hi or Lo position.As mentioned above, when you turn on the engine brake and have the position switch in either Hi or Lo, the transmission gear indicator should go from 6th to 2nd and will cause the transmission to down shift at certain rpms until it gets to 2nd gear. Once in 2nd gear and the coach continues to slow, at a certain rpm, the engine brake will disengage and allow the coach to coast.Not sure if this answers your question or not, but it should help you understand the function and operation of the engine brake.Ron

becker wrote:I have tried posting this message 3 times. The administrator says he does not know why it will not post. He said to resend it. I am retyping everything to see if I included some unsupported characters.I am on the road. I have a 2008 Monaco Dynasty 425hp Cummins with a Allison 3000 MH 6-Speed World Transmission and Electronic Shifter. Normally on steep downhill grades I can flip the Jake Brake on and it will hold the speed I want, normally 50mph. Now it will not only not hold the speed but the switch feels like it is not connected. I can flip it back and forth and nothing happens. There is a second Jake Brake, HiLo switch, and it works fine, next to the Jake Brake that I use for speed retention and to slow down when I approach a town speed post. I generally only use the second Jake Brake when I am below 40mph and it takes me down to 15mph and then turns me loose.My question is has anyone else experienced this and is it something I can fix? I appreciate your input. Maybe all of a sudden I am not operating them correctly.You're being somewhat confusing in referring to a brand name for describing a retarding system of braking, but with what you're saying, it sounds like this Jacobs brand, you speak of is actually two different systems. One is an engine brake and the other is a two stage exhaust brake. Also sounds like the exhaust brake is working and the engine brake is not. Either that or it's only an engine brake and the one sw. works in conjunction with the other.I only have a single stage exhaust brake, made by Pac and leave it on all the time. Not only does it serve me better by doing so, I'm hopeful that it won't freeze up with constant use and save my wheel brake linings, as well. I do smear some lube on the movable parts, once in a while and that should help it some, also.As for your problem, someone should be able to chime in with some words of wit here, once it's figured out. I'd probably begin with said switch and to see if there was power available on one side and if the switch itself, was indeed working. Then go from there, back to the engine.

Jake Brake | Good Sam Community

cbshoestring
Explorer II
Feb 25, 2017
tropical36 wrote:

You might add that some (engine brakes) are extremely noisy (by comparison to exhaust brakes) and why you see so many near village signs prohibiting this cool sound.

I use "4" most of the time, "6" when loaded heavy and on step hills. "OFF" is NEVER an option (except when road conditions demand it). No tickets, lucky I guess.

As for the above nicknames, they describe products that are virtually the same, whereas an engine brake, differs dramatically from a compression brake.

They perform the same function...they slow you down. Is that NOT what most people think? Function---not form.

Personally....me thinks exhaust brakes STINK. They are not as effective as an engine brake.

As for people caring, they care plenty, when pricing the difference of having the two installed.

Many TRUCKING COMPANIES have gone to the cheaper exhaust brake. I am sure Cost has a lot to do with it. Although (my opinion AGAIN), I also think that newer drivers get into trouble with the added stopping ability (read as JACK KNIFE), and companies have gone to the least aggressive of the two.
tropical36
Explorer
Feb 25, 2017
cbshoestring wrote:
Canadian Rainbirds wrote:
And to add to the confusion our 2002 Itasca Horizon with the 5.9 Cummins ISB, the switch is labeled "Engine Brake" but is in fact an Exhaust brake.

Because most people do NOT know, or care to know, the difference between the two.

Here is what matters....OFF: vehicle will coast, no cool sound.
ON: Vehicle is "held"..cool GRRRRRRRR sound.

kleenex, zerox, crock pot, jet ski, Jacuzzi, etc....

If it goes GRRRRRRRRRRRRRRRRRRRRR it has a JAKE BRAKE.

You might add that some (engine brakes) are extremely noisy (by comparison to exhaust brakes) and why you see so many near village signs prohibiting this cool sound.
As for the above nicknames, they describe products that are virtually the same, whereas an engine brake, differs dramatically from a compression brake. As for people caring, they care plenty, when pricing the difference of having the two installed.
cbshoestring
Explorer II
Feb 25, 2017
Canadian Rainbirds wrote:
And to add to the confusion our 2002 Itasca Horizon with the 5.9 Cummins ISB, the switch is labeled "Engine Brake" but is in fact an Exhaust brake.

Because most people do NOT know, or care to know, the difference between the two.

Here is what matters:

OFF: vehicle will coast, no cool sound.
ON: Vehicle is "held"..cool GRRRRRRRR sound.

kleenex, zerox, crock pot, jet ski, Jacuzzi, etc... (see where I am going with this)...

If it goes GRRRRRRRRRRRRRRRRRRRRR it has a JAKE BRAKE.
tropical36
Explorer
Feb 25, 2017
mowermech wrote:
I suspect the OP has a compression brake, since I have never heard of nor seen a 2-stage exhaust brake. Whether it is actually a real Jake Brake or merely a jake-brake type system I don't know.

This quote...."Two stage pressure control increase in the back pressure with the help of a butterfly valve can also be achieved by operating in two stages i.e. two valves can be used. This also ensures the efficient working of valve and long its long life by avoiding valve failure. Such type of arrangement is found to be very useful in case of heavy duty trucks. Because to create sufficient back pressure to slow down the engine speed, it requires large force from the valve which is possible by two valves arrangement.".......was...Taken From Here
with a pic included for a variable exhaust brake.
mowermech
Explorer
Feb 25, 2017
Long ago and far away, I went to the Jacobs website to investigate whether a Jacobs Rambrake on a 5.9 Cummins could reasonably be called a "Jake Brake".
On that Jacobs website homepage, JACOBS identified the Rambrake exhaust brake as installed on the 5.9 Cummins in a Dodge pickup as a "JAKE BRAKE".
IMO, if it is good enough for the manufacturer, it is good enough for me.
The Jacobs Rambrake that was on my old 1994 Dodge 3500 CTD actually was a Jake Brake.
The Jacobs company said so!
I suspect the OP has a compression brake, since I have never heard of nor seen a 2-stage exhaust brake. Whether it is actually a real Jake Brake or merely a jake-brake type system I don't know.
lanerd
Explorer II
Feb 25, 2017
It was obvious when he said he had a 425hp engine. However, he said what he said and what he said was that he had a second" jake brake. When only dealing with a written communication, you have to take the person at their written word....you can 2nd guess them, but you are still left with what they actually wrote and have to surmise that is what they believe. You and I both know that he doesn't have two Jake brakes, but maybe he doesn't. Anyway, it's a moot point as I'm sure he is fully aware of his error just from the replies he was given.

Ron
Ivylog
Explorer III
Feb 25, 2017
The OP said "There is a second Jake Brake, HiLo switch, and it works fine,". Just because he then said "I generally only use the second Jake Brake when I am below 40mph" did not imply he thought he had two Jake Brakes. Granted he could have said the second Jake Brake position... low or only three cylinders.

It was obvious he had a true Jake Brake because of the HI/low switch as a exhaust brake is either on or off... no hi/low.
lanerd
Explorer II
Feb 25, 2017
Bill.Satellite wrote:
I clicked there and there. Despite the Jacobs name, an exhaust brake is not a Jake Brake. A Jake brake is an engine compression unit and an exhaust brake works by increasing back pressure on the exhaust system.

I don't disagree with you. Just saying that I've heard exhaust brakes being called a Jake brake and theoretically, since it's made by Jacobs, it would be called that. A person with little or no prior knowledge wouldn't know the difference....such as the OP thinking he has two Jake brakes.

Ron
wolfe10
Explorer
Feb 24, 2017
Ivylog wrote:
Big Katuna wrote:
It doesn't rely on compression, it prevents it.

You might want to rethink this statement as it is totally wrong.

OK, how an engine compression brake (AKA Jake brake) works:

It take a LOT of energy as the piston comes up on the compression stroke to do the 15:1 or more compression.

If the engine brake is not on, once past TDC most of that work is returned, pushing the piston back down. Yes, there is a little friction loss.

What the engine compression brake does, is as the piston reaches TDC, it OPENS the exhaust valve. That allows all that work stored in the compressed air in the cylinder to escape out the exhaust. So that amount of work is lost. Most are two stage-- with 3 or 6 cylinders doing this.

And, the wiring is connected to the Allison ECM so the transmission also downshifts toward the pre-select gear. This part the same for engine compression brakes and exhaust brakes.
tropical36
Explorer
Feb 24, 2017
I think I have this figured out...
Now, since I have an exhaust brake, made by Pac, I'm going to call it a Pac brake and if I should get an engine brake, made by Pac, I'm going to call it a Jake brake, so as to eliminate confusion... :S
Only problem I can is if, I should call Jacobs for parts... :?
As for the Jake's operation (engine brake) vs the said Pac brake which is more like stuffing a potato in the exhaust outlet,... CLICK HERE

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