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05-30-2016, **(Subject: ISX 600 Engine brake )**

I have a 08 T800 we just bought. 270k miles, Has 600 ISX, 18sp trans 4.33 gears,
My biggest complaint so far is the jake brake. Why when i let off throttle the engine brake is delayed 2-3sec? No the cruise control switch is not on! Cant use cruise in Ct! Im use to the Cat motors, jake comes on right away. This Cummings u can not jake shift it cause its so delayed. Is this just normal on this yr truck with this engine combo? No one likes this truck cause of this and the ultra sensitive throttle pedal.

Billdozer2 · 05-30-2016, **(Subject: ISX 600 Engine brake )**

It's a setting in the ecu. You need insite to change it.

Waterloo · 05-30-2016, **(Subject: ISX 600 Engine brake )**

Pop the top on the motor, odds are the Jake control sensors, and or its wire harness is shot. Replace that and you should be golden.

05-30-2016, **(Subject: ISX 600 Engine brake )**

(05-30-2016 )Waterloo Wrote: Pop the top on the motor, odds are the Jake control sensors, and or its wire harness is shot. Replace that and you should be golden.

Should this be working as soon as u let off throttle? Or that delay is not normal. Ive asked a few other guys but they had 485s and it was a Pete, but they say there is no delay.
I will check the things u mentioned. Thank you!

05-30-2016, **(Subject: ISX 600 Engine brake )**

(05-30-2016 )mHolc Wrote:
(05-30-2016 )Waterloo Wrote: Pop the top on the motor, odds are the Jake control sensors, and or its wire harness is shot. Replace that and you should be golden.
Should this be working as soon as u let off throttle? Or that delay is not normal. Ive asked a few other guys but they had 485s and it was a Pete, but they say there is no delay.
I will check the things u mentioned. Thank you!

Would a bad sensor make it delayed like it is, or make it seem like there is no difference in engine brake performance from #2 or #3 setting? Because setting 2 and 3 seem to be working the same. I feel no difference when i switch between them. On the Cats its a noticeable difference. Was thinking it was just that way on this motor. No codes stored for anything engine brake problems.

Waterloo · 05-30-2016, **(Subject: ISX 600 Engine brake )**

(05-30-2016 )mHolc Wrote:
(05-30-2016 )Waterloo Wrote: Pop the top on the motor, odds are the Jake control sensors, and or its wire harness is shot. Replace that and you should be golden.
Should this be working as soon as u let off throttle? Or that delay is not normal. Ive asked a few other guys but they had 485s and it was a Pete, but they say there is no delay.
I will check the things u mentioned. Thank you!

Wow! You got me there! Mine DID delay on my 2008 ProStar, 600 hp ISX... I just did the in frame and when we popped the top the wire harness was shot, along with one of the sensors, it was toast. And I hate to say, I tried the Jake once, do not recall if it still had the delay or not. I rarely if ever use my Jake, I just know it works. But, I would still inspect the harness and the two sensors. I will bet you a dollar that one of the harness sensors or connections is shot, if not the harness cable itself. Mine was ugly, and I was surprised the Jake even functioned when I saw what was left of the harness.

05-30-2016, **(Subject: ISX 600 Engine brake )**

(05-30-2016 )Waterloo Wrote:
(05-30-2016 )mHolc Wrote:
(05-30-2016 )Waterloo Wrote: Pop the top on the motor, odds are the Jake control sensors, and or its wire harness is shot. Replace that and you should be golden.
Should this be working as soon as u let off throttle? Or that delay is not normal. Ive asked a few other guys but they had 485s and it was a Pete, but they say there is no delay.
I will check the things u mentioned. Thank you!

Wow! You got me there! Mine DID delay on my 2008 ProStar, 600 hp ISX... I just did the in frame and when we popped the top the wire harness was shot, along with one of the sensors, it was toast. And I hate to say, I tried the Jake once, do not recall if it still had the delay or not. I rarely if ever use my Jake, I just know it works. But, I would still inspect the harness and the two sensors. I will bet you a dollar that one of the harness sensors or connections is shot, if not the harness cable itself. Mine was ugly, and I was surprised the Jake even functioned when I saw what was left of the harness.

Alright cool, thanks. Ill have to have it checked out. They did check the setting like mentioned above by other guy, when i first got it. But they said it was set where its supposed to be. I forget the 2 terms they called it.
I use the jake a lot cause its in a dumptruck and alot of areas we work are back roads. So it really bothers me and the other guys that drive it and its not there right away when u let off. Ive personally never drove another truck that was delayed like this.

Waterloo · 05-30-2016, **(Subject: ISX 600 Engine brake )**

(05-30-2016 )mHolc Wrote:
(05-30-2016 )Waterloo Wrote:
(05-30-2016 )mHolc Wrote:
(05-30-2016 )Waterloo Wrote: Pop the top on the motor, odds are the Jake control sensors, and or its wire harness is shot. Replace that and you should be golden.
Should this be working as soon as u let off throttle? Or that delay is not normal. Ive asked a few other guys but they had 485s and it was a Pete, but they say there is no delay.
I will check the things u mentioned. Thank you!

Wow! You got me there! Mine DID delay on my 2008 ProStar, 600 hp ISX... I just did the in frame and when we popped the top the wire harness was shot, along with one of the sensors, it was toast. And I hate to say, I tried the Jake once, do not recall if it still had the delay or not. I rarely if ever use my Jake, I just know it works. But, I would still inspect the harness and the two sensors. I will bet you a dollar that one of the harness sensors or connections is shot, if not the harness cable itself. Mine was ugly, and I was surprised the Jake even functioned when I saw what was left of the harness.
Alright cool, thanks. Ill have to have it checked out. They did check the setting like mentioned above by other guy, when i first got it. But they said it was set where its supposed to be. I forget the 2 terms they called it.
I use the jake a lot cause its in a dumptruck and alot of areas we work are back roads. So it really bothers me and the other guys that drive it and its not there right away when u let off. Ive personally never drove another truck that was delayed like this.

It is pretty easy to check, just pop the valve cover. The wire harness runs in from the drivers side and sits right on top of the head. Should not take more than twenty minutes to do the inspection and get it all back together.

05-30-2016, **(Subject: ISX 600 Engine brake )**

there is a setting in the ecm for jake delay - if it is set to zero they should come on immediately.

under the cover there are 2 solenoids and a harness, they are very forgot about pieces. If the solenoids are wore (fairly certain they are) they have a delay to them. if the jake rockers themselves are wore, the jake can do funny things. if the harness is kinda bad, it can cause jake delay. all these need to be checked by someone who has experience in these. this is fairly common - the jakes should be instant without delay if the delay is set at 0. How much boost does it build under full jake? that explains alot also.

one last thing to check is the oil and sludge buildup in the rocker drillings themselves. if they are plugged up or the wrong oil is used jakes will be delayed aswell - just food for though