Hi Everybody! Im brand new here. I own a 2004 Dodge Ram 1500 SLT 5.7L HEMI 4X4. Last year I had to replace the PCM. Ever since then my Cruise control works great until I hit 65MPH then it just turns off. I actually work at a large Dodge Dealership here in UTother then sim and have had our shop look at it quite a few times and they cant figure out what's going on. So far we have replaced the PCM 3 times thinking that was the problem since all this started once we replaced it the first time. No change. We have replaced the speed sensor in the rear diff, transmission and front wheel hub. No change. we have replaced the brake switch. No change. I even went out with our shop foreman who had his scan tool plugged in as we drove down the freeway. He said all speed sensors were reading the same speed but as soon as we hit 65mph the computer said I pressed the cancel button the the steering wheel ( which I hadn't) We even replace the cruise control buttons on the steering wheel. If I run the engine codes it shows P0585 "Speed control switch 1/2 Correlation". What does that mean? What part do I need to replace? Can this be whats causing my cruise control issues?


Thanks for the help!

 

Did you replace the clockspring as well?? Sounds like maybe an intermittent short.

 

we have not replaced the clock spring yet. That might be something to look into for sure. It's strange that it turn off 100% of the time right at 65mph

 

Entirely possible that that is programming.... but, 65 seems a bit low for 'max speed'..... also, I really don't think the clock spring would be that consistent....... I will grant you, that IS an odd one.

Oh, Welcome to DF!

 

Thank you ! I've been chasing this issue for over a year now! I personally believe it has to be a programming problem. The cruise control worked great until we replaced the PCM. We did have a coil pack melt down which took out the PCM. We did have to run a jumper wire from the coil pack directly to the pcm as the factory wire had melted. I wonder if its possible it damaged another wire that has something to do with the cruise control. But then again. I cant see it causing it to shut off right at 65mph. I would think it just wouldn't work all together. Its a strange one for sure.

 

Question becomes, if it is programming, why is it consistent across multiple PCM's??? Unless there is some other module that deals with cruise? (I don't know..... one of the techs at the dealership should though.)

Maybe you could try and flash the existing PCM, with whatever is supposedly correct for your truck? See if that changes anything? Maybe 65 is the default value.... and it has to be specifically told different??

 

85 mph is the normal 1500 default highest cruise in the 3G PCI bus trucks. PCM to TB is all that deals with it on the hemi except for the switches to activate it. The DTC you are getting means the fault is somewhere between the switches, clockspring and PCM.