HI all. I am new to posting here but am an avid reader as I own a 99 dodge ram 1500 4wheel drive.

Lately while driving down the road I have noticed that my RPM's surge as if my transmission is jumping out of gear. Also, I am assuming as a result of this, my cruise control just shuts off as well as diminishes over time. If i set it at 70 mph for example, after some time of driving, I will notice that it has diminished. The above-mentioned issues happen while driving on flat highway and while there is no load on the truck. Any suggestions would be greatly appreciated. NOTE 155000 miles.

Thanks

 

Hey, a engine size would do better than mileage. Your TPS (Throttle Position Sensor) is likely going bad (happened to me). I cleaned mine and it worked good as new, but if you dont want to worry about it ever again, I would just replace it.
Here is a link to cleaning your TPS (read the posts after it, too):
https://dodgeforum.com/m_1059605/mpa...tm.htm#1059605

 

Thanks, I will read the posts you suggested. Engine is 5.9 360.

 

Yup, TPS. It is very common. If you are losing cruise speed you have a vacuume leak somewhere or the cruise unit under your battery is bad. Not sure of the tech name.

 

I have the same trans problem with my 98 1500 4x4 5.9. I replaced my TPS and it did nothing to fix the problem. I have since heard that this symptom generally means the locking tork converter is wearing out so I gave up and I just live with it.

 

The cruise control servo is directly under the battery so it is possible that some acid ate up the servo or the vacuum line connected to it. That would explain the cruise issue.

The TPS is the most common cause for an rpm surge while in overdrive but it could also be your spark plug wires. If one or two of your wires are cracked (or melted like mine were) then you can get cross talk between them and you might notice an rpm surge while in overdrive.

Re-route your spark plug wires according to this TSB http://dodgeram.info/tsb/1998/18-48-98/18-48-98-v8.htm and inspect them while you're doing it.

This is assuming that by surge you mean the rpms jump anywhere from 50 to 200 rpms while in overdrive.

 

Do you absolutely have to re rout the wires according to that? I know I've never done it before and my truck runs great.

 

You don't have to re-route the wires if you have high quality 8mm wires. If you just have middle of the road quality 7mm wires then it's a good idea to re-route them. Then again if you don't have the rpm surge and don't have any misfires then I wouldn't worry about it.

 

I do have surges when cruise control is on and when I hit pot holes in the road it will surge sometimes but no misfires.

 

Then the re-route wouldn't hurt, just inspect your wires while you're doing it. My surge pretty much went away completely a while back when I replaced my wires but came back after a while, then when I did the re-route I noticed that one of my wires was melted so I replaced them and did the re-route and the surge was gone.