'Jake brake' question

[shwilcomb]

My 2000 Magna has a three-position Jake brake. Hi, all six cylinders, Medium, four cylinders, and low, 2 cylinders. It is on most of the time on high. Works great! In previous coaches, there was just an exhaust brake, on or off. Not very good at slowing down the coach.

Steve

C-10 Cat

[Boomper]

I have never heard of the term "Cummins death rattle." Is that a term that you came up with?
The reason I ask is that I used to install Jacob Engine Brakes on Cummins and DD's and had never heard that expression. I know certain auto makes/models have earned that term.

[Windward]

No the "Death Rattle" was one I found on some other post when I was searching for how to troubleshoot my problem. It does describe the strange noise when it is on low and comes to stop. You would think it would do it on high with all 6 cylinders braking.

I have driven lots of trucks with Cats and they don't seem to do it regardless of how many cylinders are braking

[Boomper]

Does the low selection slow your coach? There could be one misadjusted Jake.

Did you drive CAT powered trucks years ago? Back in the days, many years ago, the CAT engines, which were excellent, had an extremely clattery intake/combustion rattle. We used to call them Rattapillers. Still a great motor, much heavier than Cummins at that time.

[Windward]

Yes on low it does slow the rig. My problem was an electrical connection between high and low somewhere in the chassis wiring. Regardless of which position the switch was in, I had high only. Replacing the switch did not fix it. It is impossible to trace the wires from the engine to the shift consul.

My work around, while not ideal, was to add a duplex cable from the high wire on the engine to the switch and interrupt that circuit. Low is enabled by the Cummins ECM, goes to the Allison ECM, to the switch and back to the Jake (as near as I can tell without a wiring diagram). High adds the second Jake.

My truck experience with Cats was 1990 to 2010 vintage.

[tinman 55]

I had the same issue on my ISL 400 that Windward experienced. Mine however, was an easy fix as the wire itself was broken at the 90 degree plug that he circled on his photo. I re-wired it, put a little shrink tubing over it and it works perfectly now.

[a250gpguy]

I'm glad that the OP asked this question as I also was curious as we were getting ready to take possession of a new to us '05 Magna.

Now that we have it FWIW here's my experience..

On the drivers panel there are 2 rocker switches. One that arms the system and has no detent whatsoever. On our Magna right nextdoor is a 3 position switch. Down is marked low, there is a middle detent that does nothing and the Forward detent is labelled high.

Both work as advertised and you can feel the action in the coach when driving. Also we have a green dash warning light that says "Engine Brake" that lights up on the dash when the Jake is active..

Ch

[a250gpguy]

Edit.....we have a 3 position switch ...
Low to the back
Med in the middle
High to the forward position

Cheers
Ch

[efstewart]

On my 2006 CC intrigue, I have a 3 position rocker for the Jake brake (High, Low, and off, in the middle). This is how I found out the difference between high and low. One day I was driving on I 70 WB in Colorado towing by 2006 Lexus 470. As I cleared the Eisenhower tunnel and about 11000 feet above sea level, I started the steep descent with the Low selection. I realized that wasn't doing a whole lot as I had to use my air brakes quite a bit. Then I switched it over to the High rocker position, and then I had some REAL assistance in slowing down, and only had to use my air brakes occasionally.

So its simple for me, High for more slowing and low for less slowing.

[Jackcjr]

Hello All,

I have the above coach. I do not have the manuals with me at my home, however I swear there was a Jake Brake" section.

Moving on, the brake worked one day and the next trip, no brake. I fee it is possible voltage related because there was absolutely zero symptoms of it going down.

I am a PE, however while I am intimately familiar with 120V, 240V and higher circuitry, the low voltage rat's nest located under the driver's armrest is a nightmare, so if you can provide detailed instructions, it would be extremely helpful. Also, I have to believe there is a buss fuse located somewhere and hoping it would be this simple.

I spoke to the service manager down the street from the coach in Ft. Myers FL "Kelley Cat" and he advised the corp. office has a rule in place "Mechanics can only go to the driver's seat and not beyond, due to Covid", so he did not want to have me bring it in only to find out they couldn't access the engine if required. Not sure who dreamed up this rule...Sounds like Fauchi is overseeing the operation!

I asked him about Cat and Jake Brakes and was informed that Jake Brake is now used generically as a term, however Cat manufactures their own Brake (similar to Jacob Brake).

Thanks in advance for any assistance you may be able to offer.

Jack C.
jackcassidyjr@gmail.com (if you have photos)

[Max Headroom]

I have a 97 Exec with the M11 and the two position Jake. Hi is all 6 cyl, Lo is 3 cyl. There is a distinct difference between the two, and you can't really mistake one setting for the other except at 'in the neighborhood' speeds.

[a250gpguy]

From my manual (C13)...Your Caterpillar engine is equipped with a real deal Jacobs brake..

As far as the application in your coach I have no idea. My brake is a 2 switch 3 position brake.

1 switch for on or off

1 three position switch Lo-Mid-High and there is a distinct difference between the 3 plus a green warning lamp that comes on the dash when it is active...

On these coaches I agree. An all of a sudden electrical failure is likely fuse related..

Sudden Mechanical failure however whole different story...

Ch

[TR4]

Originally Posted by Jackcjr

Not sure who dreamed up this rule...Sounds like Fauchi is overseeing the operation!

Not necessary to describe your problem

Bill