I was driving across the country a few weeks ago in my 02 5.9 QC. I had the cruise countrol set at 70, but but when I would come to a hill, the computer wouldn't realize it. It was like the pedal was just stuck in the position it was in. So when climbing the hill, my speed would drop to around 60, then when I would go down the hill, my speed would increase to around 80. The computer wouldn't keep the speed constant at 70. I don't know if it had something to with the 50 mph headwind I was facing, but it has never happened since. What happened?

 

well, i think the headwind would have something to do with it..but it doesnt really make since.. if ur goin uphill..ull lose speed...if u go downhill, you shouldnt gain that much speed with a head wind...

my 2003 QC seems to lose some performance over 75mph (yea i have a lead foot [8D]) seems when i am goin up a gradual hill with the A/C running on low, i lose enough speed to where the cruise control has to rev up and gain back the 5mph it just lost...then it will shift again, lose 5mph, and rev up again (i think u get the point)...

 

The problem was that it wouldn't rev up to keep the speed constant going up the hill and it wouldn't back off when going down the hill. It was just stuck the same rpm.

 

My 03 QC 4x4 5.9L diesel when on cruz only fluxes 1 mph either way and thats it.
i have seen that happen before with another truck i owned but like yours i pulled over did a once over shut the truck off and when i restartd mine the problem was gone? like you not sure why? had the dealer check it and the tech told me they freak out sometimes and he has spent hours trying to solve it!
i would be hard pressed to replace the unit.
pray it goes away! lol

 

wrong forums,
these are 3rd gen 2003-present


no i don't think it has anything to do with the headwind (because of it's inablility to coast down the hill and pedal was stuck in position. instead it went to 80mph from 60.) if it hasnt happened again then don't worry about it. i dont really know what went on but something was screwed up. sometimes i hear of cruise control thingys going out on people. don't know what causes it.

 

b3nzyme, actually this is the correct forum. 3rd generation rams are 02-present. 3rd gen. rams are the trucks with the new body style and they have an IFS rather than solid front axle (only on 1500's). So don't be fooled into thinking that just because my truck doesn't say "hemi" on it, that it's a 2nd gen. ram. But it's ok, you're new here.
Byrdman, I actually did pull over and disconnect the battery to reset the system, but it kept on doing it that entire day, but the next day it was fine. Anyways, thanks everyone for the input, if it happens again, I'll take a trip to the dealer and let ya'll know what it is.

 

Might be your speed control computer, I had the 5.9 in my 97 and it acted up and I found a hairline crack in the very small tube that goes to the speed control computer.
Hope it helps.