I have a very frustrating problem with my cruise control on my 98.5 2500. I bought the truck used a little over a year ago. Beginning last summer, it began having occasional instances where the cruise control wouldn't work, and it gradually became more and more frequent. It happens much of the time now, though it seems to occur much less often in cold weather. If it's below 35 degrees or so it works much more consistently, and in the coldest part of the winter it worked most of the time. If it gets up above 35 degrees, however, it stops working more and more often. Here are the symptoms:
1. Sometimes the "cruise" light illuminates on the instrument cluster but it simply will not engage.
2. Sometimes when it's working and I'm cruising along the highway it'll simply switch off, though the indicator is still lit on the instrument cluster. At that point you may as well not even try to use it again until next time you drive it, at which time it may or may not work.
3. Often I have to press the On/Off button 4 times before the light comes on. Usually on the 3rd press of the button the "cruise" light briefly blinks on and back off, and on the 4th press of the button it comes on. Occasionally it doesn't blink on the 3rd time. In either case, it never engages when this condition happens, even though the indicator light is on.
4. On just a few occasions, while driving at highway speed and NOT using the cruise, all of a sudden it has kicked on for no particular reason, like it's trying to drive the truck by itself. This is a bit disconcerting.

Last summer my ABS and brake lights started coming on quite a bit of the time. I replaced the sending unit that is mounted on the pumpkin and it solved an accompanying speedometer problem (common on these trucks), but it did not completely remedy the brake/abs lights. The condition of the lights being on or off are no guarantee of whether or not my cruise control will work, however.
Does anyone have any suggestions? This is driving me crazy! Sorry for the long post, but figured the more details the better.

Thanks in advance.

 

Check the clock spring, located in the steering column. They have had problems with them around that year and earlier years. It will cause the cruise to act sporadic at times and will engage and disengage at different times.

 

hi
check the brake light switch adjustment , a bump in the road may be causing it to think you have pressed the brake pedal therefore disingauging cruse !

 

Thank you for the suggestions, guys.
If it's indeed the clockspring, would this also cause me to have to press on the horn with all my strength for the horn to work? Or is the clockspring completely unrelated to the horn?
As for the brake switch, I have fiddled with the brake pedal to see if that would fix it but have been unsuccessful. I will admit, however, that on occasion when hitting a bump in the road it has caused my abs/brake lights to come on.

 

Hmm, just remembered....
There have been a couple times that my airbag light has come on, but that happens rarely. Sounds like more and more of a chance it's the clockspring?

 

I'd also say it's the clockspring. Everything on the steering wheel operates through the spring; cruise, horn, air bag. Never replaced one, but it does not look to be very difficult.

 

Actually you have to be extremely careful when replaceing the clockspring, or you can set off the airbag. There is a proper procedure for disconnecting the air bag and you need to wear a static strap while doing so.

 

Yes, that's what I understand, and thanks for the reminder. I will follow the procedures outlined for doing so, though it does make me a bit cautious.
BTW, is there ANY chance this could affect the reason my ABS and brake lights are coming on? Doesn't make sense to me, but it WOULD be nice...

 

My clockspring went up but my symptoms were a little different. Something had been rattling around in the steering wheel for a couple years but everything worked fine. Then all at once the air bag light came on and the cruise control stopped functioning. The horn still worked. I purchased a new clockspring from RockAuto for $35 plus freight. Installed it following the TSB recall instructions exactly (http://dodgeram.info/tsb/recalls/982.htm). Used a gear puller on the wheel. Took 1 hour, not including the Bud break. Problem solved, piece of cake.

 

Got the new clockspring from Auto Zone, now just need to find the time to put it in. Hopefully it'll solve my problems.
BTW, thanks for the link to the TSB...

 

There was a recall from the dealer to replace the clock spring for free... You may want to check if your truck is included, I had mine done in 2001.

 

I did check with the dealer and mine wasn't included in the recall.
RGBruce is right, the job is a piece of cake and doesn't take long at all. Unfortunately the horn is still difficult to blow, but the good news is that my airbag didn't blow during the process, and so far my cruise control works fine. Hope it keeps working. Thanks, everyone, for your help.