2nd Gen Non-Engine/Transmission cruise control sensitive to temperature--why?

[DrJC]

The cruise control on my '96 Ram, 2500, 5-speed, Cummins holds the speed accurately only when the outside temperature is about 60 - 70F, or higher.



If it is set at outside temps lower than that, the speed of my truck will vary widely from that set. The lower the outside temp, the more the variation.



For example, if I set the cruise control at 50 mph at 40 degrees, the vehicle will accelerate as much as 15 or 20 mph over the set speed.



The variation is always higher than the speed set, and amount of variation is pretty much tied to the decrease in temp.



Now, if I turn the cruise control on in cold weather, but do not actually set it for a length of time, then the operation will be closer to normal--depending upon the length of time before it is set and the outdoor temp.



The result of this is that I don't use my cruise control in chilly/cold weather unless I want to experience a wild ride!



What is the diagnosis? And the correction?



Sure appreciate your help, fellows and ladies.



DrJC

Michigan

 

[AMink]

Thank God I'm not the only one! I thought I was going nuts on this. I've had this happen a lot in the past. Run all summer, no problem, then when it gets cold it accelerates. I did the check under the battery tray for bad wires, but it's ok. Still doesn't explain why only in the cold. Anyone?

 

[DrJC]

temp sensitive cruise control

AMink



Here's some additional info on the problem:



It has been occuring since the truck was about year old. I took it back to the dealer and they responded by saying it was caused by the driver. Somehow I had a "lazy foot". They gave me a bulletin from the corporation explaining how to correct the matter by holding a set speed with the accelerator, then repeatedly activating/disabling the cruise control setting.



I think their "cure" is a bunch of hooey. The real operational thing here is that while you are driving along holding a constant speed and setting/un-setting the cruise control repeatedly, the motor is heating up the engine compartment (and the cruise control electronics).



Perhaps this is a vehicle safety issue that ought to be brought to the attention of the Consumer Safety Commission?



Are there other Dodge owners out there who have experienced the same conditions?



It would sure be nice to find resolution to this vexing problem. And it sounds as though you will agree!



DrJC

 

[AMink]

I got the same "fix". Hold for 15 seconds or something, then turn it off, then do it again. Eventually, and I agree with you, the engine compartment warms up enough to make it work. I don't know that the on-off-on thing really did anything or not.

 

[Canadian Cummins]

Dont use mine in the COLD

Yep,

I have the same problem here especialy when it gets to -30, forget the control cruise.

Like you guys have, mine accelerates 10 to 15 past the set speed at least, most times I have to shut it off as it just keeps going.

I bet it is in the servo/vacume actuator as I cant see the PCM sending a faulse signal, unless the trany temp has anything to do with it. (Auto trany),

Do you 5 speed guys have the same problem?

CC

 

[ox1]

'99 5 speed here.



Been an issue for only 200K, but I would like to fix it if it's possible. ???

 

[WDaniels]

I am also glad that I'm not the only one. Except mine starts doing its accel thing at about 15 degrees and colder. Will speed up about 10 or 15 over the set speed, hold it for about 1-3 minutes and will finally fall back to the original set speed. It doesn't matter how long I turn on the cruise control for before I set it. It will take off. As far as activating and deactivating the cruise control for 10 times while maintaining a constant speed. That comes straight from the maintenance manual. I find that clearing the memory from the cruise control, disconnecting both batteries faster and eaiser.

WD

 

[Forrest Nearing]

the cruise on my '98 is downright dangerous... doesn't matter what speed you set it on, it will eventually creep up to 85 or 87 or whatever the max is. sometimes it accelerates up there rapidly, others it's just a steady creep up.



suffice it to say, I don't use the cruise on my '98. my previous '98 was the same way. oddly enough, the '98 I had before that worked perfect



the cruise on my '04 works awesome... I guess that's one benefit of drive-by-wire

 

[DrJC]

Wild Cruise Control

After reading the above posts to my original, I am convinced that the Corp. has been sitting on this problem for a long time. They have admonished the users to stop using a "lazy foot" as a cure to the problem. In reality, the problem is one of the company's making . . . and hiding . . . for all these years.



I am still amazed that this potentially dangerous condition has not been addressed by the federal agency concerned with safety.



Thanks for your responses.



Dr JC

 

[damar]

I had the same thing happen on my 1998. 5. Took it into the dealer and they did a reflash and it holds where it is set. Never had a repeat problem and have 168,000 miles on it. I don't know what they did as there seems to be no TSB to correct the problem. Was real early ISB assembled & released from the factory January 98.

 

[wcjp]

On my 96', problem was a vacuum leak at the transfer case.

 

[LHastings]

I have the same problem. In the winter with cool to cold temperature I fight with the cruise control until it settles down, and in the summer no problem. I had the servo replaced 3 time while under warranty. The problem would eventually come back. I decided to just live with it. The electronics they put in to those servo must not have very good temperature spec.

 

[paulsmith]

This thread is 5 years old, any answers???

Just bought a 1998 12 valve 4 door, and very disappointed. Bought the truck from down south, and up here in 6 degrees, it is out of wack!



So, after 5 years on TDR, has ANYONE figured out what causes this? I wont keep the truck with out cruise.



Also, truck has "Banks" kit. Dual horn intake, not sure about the turbo, but it is VERY cold natured (bogs) and Power steering/Brakes are stiff until it warms up.



Paul

 

[KYOUNG]

My 98 does it to! maybe its vaccum related??

 

[JVackiner]

My '99 has been doing it for the last 150K or so. Temperature does not matter. If I am on a long trip, I will mess with it (set, reset, reset, reset, etc. ) until it stays where it is supposed to. I looked for vacuum leaks and could not find any. I really hope someone would come up with the answer as it is a real PITA.

 

[LHastings]

I have the same problem. I had the cruise control replaced twice when it was under warranty and it fixed the problem only to return later. I now just live with it. I wait for the engine compartment to warm up before I try to set the cruise. After it warm up it take about 5 min. playing with the settings before it settles down. In the summer I don't have any problems. It is definitely a electronic temperature tolerance problem.

 

[Joe Mc]

Back in 02 my 99 started to "run away" when on cruise, or it would go beyond where it was set then return to set speed. If you hit the brake or coast, then hit resume it would go beyond and then return. I did the BS on-off-on-off thing and that worked until restarting. Then one day the cruise just stopped working, light still came on the dash but the cruise would not set. Replaced vacuum unit under left battery (about $75 at the time) and (knock on wood) its been fine ever since. Outside temps here don't seem to matter it always operates fine. But, the lowest we've seen here is like +10F.

 

[fstfish66]

ok my problem is back wards for all of you,,,it is currently winter here,,, the cruise control wiill power on and set when the motor is cold,,,once the motor/gauge comes up in temp,,the cruise will not power on. ,



the only thing ive done recently,,was remove the radiator,for degresing,,replace all the water hoses,t stat,,and water pump,,,i didnt nt have the battery trays out,,the batterys are 2 years old,,the orignals never leaked,,, the only engine bay plugs i had apart were for the windshield washer bottle pump,,,2002 98600 miles auto 4x4



any ideas???