Exhaust brake

[DuncanJ]

I've got an 08 3500 4X4 and the exhaust brake has a mind of it's own.

When towing my fifth wheel in cruise and your speed exeeds 5 mph over the setting the brake cuts in exactly as it should but if I hit the cancel button sometimes it works and mostly it won't. Sometimes at 40 mph or so it lets the tach fall back to idle or 700 rpm. Took it to a dealer while I was on the road and they updated my software but said the "Jake" was normal. Has anyone else had a problem? I put 19,000 miles on my 07 and never had a problem.

 

[Drdorian]

The exhaust brake is RPM dependent not speed, so at 40 mph you need to be looking at your tach. It should cut off around 1100 rpm or so.

 

[DuncanJ]

I understand about the rpm but I also know that my 07 would still engage at low speeds, especially when in tow/haul mode. This truck is like freewheeling when it won't engage. Any help appreciated. I suspect a problem in the turbo after reading several threads relating to engine problems.

 

[jelag]

You don't say if you have a manual or stick... our new 08 5500 has the auto... it must be in tow/haul to have the brake function like it should... When its not in the tow/haul mode it's like the torque converter turns loose and it coasts.....

If you driven a stick on an earlier truck... with an exhaust brake... those that I've driven... (6. 7L) the brake functions as well as or better than some... on our 5500 we like the way the auto is programed to respond to the load, and road speed...

 

[Hoefler]

It is normal. If you manually drop it to a lower gear, it will work at lower speeds. I have found that the only gear it won't work in, is 1st. I can have it working down to about 15 mph. It also needs to be in Tow/Haul mode to do this.

 

[HBarlow]

The exhaust brake can't have a mind of it's own. It is controlled by the ECM. It opens or closes when told to.



Two features alter the computer programming and change shift points: The Tow/Haul mode and the Exhaust Brake on/off switch.



The ECM or PCM is programmed to activate the exhaust brake and even cause a downshift on a downgrade when road speed exceeds cruise control set speed. That is normal. If you select Tow/Haul mode before you start your steep descent the ECM will control your speed. It is usually a good idea to deactivate cruise control in the mountains, particularly if you don't want to be surprised by a downshift on a downgrade.

 

[DFeldman]

I have to say, I had my truck in for a P2000 code this week. After they cleaned everything and reflashed the ECM as per the TSB, the exhaust brake works very different than it did.



Now the Brake will pull down hard until about 1600 Rs and then I can feel it let up distinctly. The brake is still working but to a lesser level below 1600. It will also stay on now down to about 1000 instead of the 1100 before the flash.



I do not know which TSB or Flash as I assumed it would be printed out on the receipt like all the others. I checked it when I got how and I see it is not.