Hi Everyone,

I am new to the forum, well i say that I am new I have used this forum for many years to get technical advice just from reading the post but I have never been a reqistered user. Here is my problem, I just bought a used 2004 ram 2500 with 60000 miles on it. This truck is cherry except for the fact that the curise control disengages at 50mph right on the money. You can turn the cruise control on and the light on the dash will light up and you can set your cruise but if you use the accelerate button and push the truck up over 50 the light on the dash will shut off. Now if you apply your brakes and slow down below 46-48mph you can press the on/off button and the light on the dash will come back on. The only mods that have been done to the truck are K&N CAI and flowmasters, and a set of 285/70/17 micky thompson tires. When i hook my data logger up to the truck I am not showing any DTC and the Vehicle speed sensors are showing the speed that is on the speedo and have been varified with gps.

any help would be great
thanks in advance

 

datalogging....You have a tune/r installed in the truck?

 

I have this problem with my diablo right at 70 mph, ive tried resetting the pcm and everything else ive been told but nothings worked.

 

I dont have a tuner all I have is a Snap on Solus Pro Scanner. I am thinking about getting a tuner but I havnt decided between SC or Diablo any suggestions?

 

Are you gas or diesel, manual or auto?

2500; 5.7L and diesel w/manual trans is fully eltn controlled by the PCM. More $$ to repair.
You have a servo-less system, w/o vacuum, servos of anyway.

If you have the diesel w/auto, start checking vaccum hoses for cracking and work up to the
bigger item $$ stuff. It just sounds as if there is a crack releasing at that point of pressure.

I have not heard if a PCM re-flash would/can do a fix.

 

The truck is a 2500 with a 5.7 w/auto. When i got home form work i set down with the scan tool and got into the 4 wheel abs and reset the tire size and pinion factor to stock and to what it should be with the larger tires. When I check all 3 vehicle speed sensors all of them are right on the money. Now here is where it gets crazy. When you are running down the road and turn the cruise control on and then set the cruise at say 45 the pcm sees the vehicle running down the road at about 24 mph. The pcm also stores the set point of the cruise control at 56 mph. Regardless of what the tire size and pinion factor are set to these are the values that you get. I am beginning to think that someone tried to update the pcm and it did not update correctly or the pcm is corrupt.

 

I have the same problem with my 5.9/Auto. Happened after I installed my Flashpaq. Like you say, no codes show for this problem. The only difference with mine is that it shuts off randomly. Sometimes it takes about 10 miles, other times, 1/2 mile. Dealer couldn't help.

 

I have the same problem. My cruise always worked until one day i had the scanner hooked up and I accidently changed the pinion factor and I had to change it back to what it was. Now the cruise shuts down at 60 mph. i also noticed the engine controller is way low on the actual speed of the vehicle. Has anyone figured this out yet ? Now that I have more info i will play with some stuff and report if I find something. Thanks.