Engine/Transmission (1998.5 - 2002) High Idle After Cruise Control Use

[Diesel Gunner]

Whenever I use the cruise control for more than 5 minutes and exit the highway the engine will idle anywhere from 825 to about 1000 RPM. All that I need to do to get the idle back to normal is turn it off while at a full stop for about 5-10 seconds an the idle will again be normal. The real problem here is that I have an exahust brake and it will not operate whenever the idle is above normal. The ebrake is wired to the ECM and is switched at the shifter. Has anyoine else run into this problem? And, what did you do to remedy?



Thanks

 

[Sticks]

Tagged for reference.

Another member here is having idle issues as well. Went away when he borrowed a buddies ECM. Still trying to verify source of problem.

Is your cruise vacuum controlled or electronic? I can't remember which year/model they went all electronic.

 

[HBarlow]

Whenever I use the cruise control for more than 5 minutes and exit the highway the engine will idle anywhere from 825 to about 1000 RPM. All that I need to do to get the idle back to normal is turn it off while at a full stop for about 5-10 seconds an the idle will again be normal. The real problem here is that I have an exahust brake and it will not operate whenever the idle is above normal. The ebrake is wired to the ECM and is switched at the shifter. Has anyoine else run into this problem? And, what did you do to remedy?

Thanks

Ten or eleven years ago when my '01 HO/six speed was relatively new and still in warranty I had that problem. My truck had a Jacobs exhaust brake also installed by the dealer before I took delivery. My selling dealer was stumped and couldn't find the cause.

After using the cruise control my exhaust brake would not engage because the ECM was seeing an engine speed above idle. In order for the ECM to activate the exhaust brake the ECM has to sense a "closed throttle signal. "

I exchanged messages with Carlton Bale, a Jacobs Exhaust Brake engineer who had been deeply involved in the engineering and testing of Jacobs brakes on the Cummins engines in the Ram platform. He took an interest in the issue and contacted my selling dealer and STAR, which was the warranty parts replacement manager, and arranged for the dealer to install a replacement APPS under warranty. The problem was corrected.

I think a replacement APPS will cure your problem.

EDIT:

I reviewed my old PM files and found my memory was close but not completely correct. The problem was caused by the APPS but Carlton was not able to get the APPS replaced under warranty because he learned that the APPS was a Dodge electronic part covered only under the 3/36 warranty not the Cummins engine warranty which was 5/100.

Here is the final pm received from Carlton ten years ago:

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Re: APPS Assistance

Harvey,

Grounding the light green wire that goes from the solenoid to pin 42 of the ECM will activate the exhaust brake. Let me know if you need anything else.

-Carlton
HBarlow wrote on 05-10-2003 04:05 PM:
Carlton:

I appreciate your attempts to help me even if it was ultimately not successful. You did your best.

I've found a dealer who will sell the APPS at a deep discount from retail but I'm not sure I'm going to buy one. I may just bypass the APPS and ECM.

Does the exhaust brake receive switched 12v power to operate or does it have 12v dc applied all the time and a ground is applied to operate?

Harvey

Carlton Bale
Cummins Product Engineering
Cummins Exhaust Brake Official Web Page
Installation and Operators Manuals for Cummins/Jacobs Exhaust Brakes

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Ultimately I decided to replace the APPS out of pocket.



​

 

[Sticks]

The APPS crossed my mind, and if this is the cause this would be the second ever (that I have encountered) that gave that symptom.

It irritates me to no end that after all these years, Dodge has not found a viable solution to both the APPS and transfer pumps. They made this series of truck for 4 years then forgot all about us.

 

[HBarlow]

Sticks,

Manufacturers don't provide lifetime warranties. Why should they feel obligated to do anything more than replace failed parts under warranty?

The problems experienced with fuel transfer pumps have been enormously exaggerated here on TDR. My experience with an '01 was the APPS was the weakest part on the entire truck but even the APPS, although I replaced many of them, always lasted in excess of the warranty period.

 

[Bob4x4]

The apps affects the idle speed on the manual trans trucks only. You may have found your issue

 

[ABarrey]

I had the same issue and just changed my APPS with a Timbo APPS from: http://www.dodgecumminsapps.com/index.html.
It was so easy to change , and not only did it fix the problem you describe but also a fixed my surging, rough acceleration at around 2000 RPM which I thought was related to bigger injectors I installed. -should have done it long ago.