cruise control and idle up

[dripley]

I originally was going to start this thread asking for help, but I seem to have fixed the issues inadvertently. Here is the issues.

 

My cruise control had been acting up of late. At first the cruise would act like it was backing off and then re accelerating. Very much like lightly lifting the throttle and easing it back on. Seemed to be doing it after about an hour of it being turned on. As time passed it got much worse and was actually cutting out in in harshly. So much so I just shut it off. Then out of the blue it would work just fine. The throttle itself worked fine thru all of this. Also during this time the idle up feature when releasing the clutch seemed to not function and I was choking the engine out like a freaking rookie first time stick driver. This to was kind off hit and miss as to when it would happen.

 One thing that I had noticed prior to these issues showing up was the negative cable end on the passenger battery was cracked on one side where the bolt passes thru. The connection was tight and I could not move it. I figured it was fine for a while until I could fix it.

 I went home last weekend and still had the issues, but figured it was at least time to fix the cable end. It was still tight and clean(used motor oil works great for that, thanks Mikey). So I took the cable off and sawed off the offending end. Replaced the clamp with a military style clamp and soldered new ends on the battery cable and the 2 ground wires that were also present at the cable end.

 I made my return trip last Sunday and no issues with the cruise and so far no issue with the idle up feature. I didn't have a wiring diagram to tell me what the grounds controlled, but so far that seems to have fixed the problem.

 

[Wild and Free]

Nice for the simple fix to work first, after reading the first sentene about the very faint surging of the cruise it remeinded me of the first symptoms of the dying VP44 on my 02 while it was still under warranty, that was the first symptom and then the vp failed a couple days later as I got the dead pedal and hard start when hot.

[dripley]

I was not thinking the VP since the throttle still worked just fine. But I did start thinking maybe the ECM. Neither one very budget friendly. 

[Ilikeoldfords]

I was actually just checking around for this same exact situation. We took a trip to Missoula, MT and back this weekend (yes, almost 2000 miles in 2 days) and I noticed about halfway there the cruise started to buck slightly. Not to much on flat ground but anytime we started up a hill or anything it seemed to put to much power on then back way off then come back on strong, etc. Its like it couldnt figure out how fast it was going or something.

 

I had cleaned all the cables and the two block grounds right before winter but maybe I need to check out some of the body grounds? Not sure where else I can check. I very much hope that the VP is ok. It should be though, only about 20k miles on a fresh VP and never had below 14 psi getting to it.

 

Guess I will start cleaning any and every ground I can find and see where that goes. We have another trip to Missoula coming up in a couple weeks.

[dripley]

Mine acted similar but not just pulling hills.Just did it when and where it wanted. The only body I touched was the one to the passenger inner fender. Have you noticed anything wrong with the idle up when launching? I think I have that term right.

[Ilikeoldfords]

I did not realize there was even such a feature in these trucks. Does that just keep the rpm constant while you are first taking off? My truck will drop in rpms a little on launch but I think it has always done that...

[dripley]

Thats one reason these manuals are so easy to launch. The ECM is trying to keep the engine at idle speed when it drops while launching. Even when I have the 5th wheel hooked up I dont have to give it any throttle to get moving. When it was not working it was embarrassing. Just was not used to that.

[Ilikeoldfords]

Well as far as I can tell, that is still working. I will see what rpm it drops down to when I go to work in the morning. Were you pulling the trailer when it stopped working? Or was it bad even with the truck being empty?

[dripley]

I was not pulling the trailer. It started a few weeks ago and was minor. Then started getting worse and worse, but like the last trip home it worked fine for that last 75 miles or so. It has worked fine since fixing the battery terminal. Hope thats not just a coincidence. The throttle/APPS worked fine the whole time. If the cruise started cutting out all I had to do was mash the pedal.

[Mopar1973Man]

Passenger side battery does have ground leads going back into the wiring. (But not confirmed 100% what it ties too).

 

http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/26-engine-systems/87-dodge-ram-turbo-cummins-24-valve-engine-wiring