Faulty Cruise Control

[Jake B]

In my 2001 2500 6 speed, my cruise control turns on and off randomly with out me pushin the button. Also sometimes it turns on and sets itself to cruise at 50. Ever heard of this happening?? Any ideas to fix it?

 

MBRP 4 inch exhuast

Quadzilla Iquad

[Mopar1973Man]

Bad clock spring?

 

 

[Haggar]

Not exactly that problem, but a 2001 manual transmission cummins, the cruise is all software based. Most people find wiring issues.

 

the random on and off sounds like wiring issues in the steering column and wiring.  but funny signals from your vehicle speed could cause it too.  Here are the FSM pages that discuss the operation of the cruise.

 

GL HTH

 

Hag

2001 FSM Ram 8P-1 8P-3.pdf 2001 FSM Ram 8P-12 8P-13.pdf

[Mopar1973Man]

Cruise control is controlled by voltage. The buttons on the steering wheel create a different voltage for each function. If the PCM happens to get the right voltage for turn on, set, accelerate, etc. then the PCM would just continue to roll with the settings. 

[dripley]

We had someone on here a little while back that had an 01 manual with a vacuum servo on it. I dont think we ever determined wherther the tranny had been changed.

 

@Jake B do you have a vacuum servo under the drivers battery?

[Jake B]

I don't think I have that vacuum servo because I couldn't find any vac lines going anywhere under the battery tray. Also all the buttons work on the steering wheel. When the truck sets itself at 50, I can press the cruise button to turn it off or I can press the cancel button. One time I was driving and I had cruise set to 40, then the truck decided to set itself at 50 and I could fight the truck by pressing the coast button. 

[dripley]

No servo would equal fly by wire.

[trucktire01]

I have the same thing is happening to my 2001 2500 with a 5 speed, unplugged the clock spring and it was still doing it.  I was cruising along at 45 mph and it set itself to 85 mph

[Mopar1973Man]

PCM fault, Central Timer fault, wiring issues, etc.

[trucktire01]

So  an update on my issue, my oil pressure sender had gone bad, replaced it and everything works like it should

[Dieselfuture]

. So that would mean it's part of 5v loop system, anyone?

[dripley]

He has an 01 so it should be. I know it changed in 02 to the switch like I have, one wire to it and not 3. I dont know whether that means some late model 01's might have seen the change or some early model 02's have the 3 wire sensor. Bought my 02 in October of 01 and it has the one wire switch.

 

I seem to remeber a few discussions on here a while back involving a bad oil pressure sensor causing other issues. Thats about all I remember though.

[Mopar1973Man]

Fly by wire has no mechanical parts. PCM reads the road speed and pass fueling message on to the ECM by wire. This is true for manuals in the later years. 

 

Now all Automatics have a vacuum motor being the 46RE, 47RE and 48RE need mechanical movement for the throttle valve in the transmission. 

[AH64ID]

On 1/21/2020 at 7:50 AM, Mopar1973Man said:

Now all Automatics have a vacuum motor being the 46RE, 47RE and 48RE need mechanical movement for the throttle valve in the transmission. 

 

The later 48RE's had electrical TV's, so no cables. I think that 05 was the first year of not having a TV cable. 

[Evan]

Stupid question what is running the throttle when cruise is on vacumn?

 

Mines an 02

[Doubletrouble]

 The cruise in my manual '01 isn't setting itself but when I set it there seems to be a long delay before it takes over. I set it and usually it won't kick in until I let off the pedal and loose 5-10mph then it kicks in. 

[Haggar]

Evan,

 

For an automatic,  The vacuum goes to a servo (providing the force) a cable comes from the servo to the throttle linkage at the APPS.