Hello, first of all I have an 03 5.9 D. The problem I've been trying to figure out for months is with the cruise control and so far had no luck. Basically it will turn the cruise light on and off as many times as you want with the on/off button when the key is on but the engine is off, so far so good, but when you have the engine running, pressing the cruise on button will light up the cruise light fine but the set button does nothing, now if you turn off the cruise and turn it back on, the cruise light will light up for a second then go out and you cannot turn it back on untill you turn the key off and back on again, then the same thing happens all over again. I'm not getting any MIL codes any part of the cruise system which I believe are in the high P0500's.

Just wondering if this is a symptom that points to a specific fault or if it not turning on anymore is because something trips one of the many fail-safes in the cruise system.

So far I already tested the resistance values on the switches of all the buttons and everything checks out good there. I think all what's left in the system is connections from the PCM, brake switch, and cruise servo. I hope the ABS isn't invovled or that could make things very complicated but it shouldn't if the ABS is only working when the brake is pressed and/or when the car in moving, and my symptoms occur even when the car is in park and the engine is running, it will only turn the cruise on once then nothing.

Anyone have any ideas where to start?

 

I was thinking along the lines of the clockspring but, you say your getting the proper values when you test so, maybe the switches them self are bad or going bad?

just a guess

 

When I tested the switches, I disconnected them and just probed the actual switches themselves. But I am getting 4.86v at 1 wire of the switches and a good ground at the other (this is at the switch connectors after the clockspring), if that helps any. I could test the entire circuit from the PCM to the switches but I don't have a service manual for this vehicle so I have no idea where to begin tracing wires.

 

there is a link in the FAQ to a series of Durango PDFs, one of the files in that folder should be the 1998 service manual (most of it anyway) have yourself a look.

 

Ah found it, the service manuals are missing most of the wiring sections, but it did remind me that I still have the factory service manual for my old 98, for the most part everything is the same on the 03s, at least all the wire colors stayed the same.

I started pulling everything apart, tested resistance on all the wiring, all checked out good and no shorts to ground. Probed PCM pins and everything is good, the only thing that might be off is the 5v reference line for the switches was 4.86 volts, don't know if that's an issue or not. All grounds are checked and good. And finally the brake switch is making a solid connection on the contacts.

So I put it all back together and now what happens is with the key on and engine not running the on/off switch when pressed will turn the cruise light on but as soon as you let go of it the cruise light on the dash goes out, it will only stay on as long as you're holding the button down. Then after about a minute of the key being on the light will stop lighting up and nothing will happen. Whenever the engine is running the on/off button won't even turn the light on anymore.

I want to say at this point it it could just be a fried PCM. Unless a bad speed control servo would cause the cruise to turn off right away. I'm trying to avoid the dealer at all costs because they will do exactly what I did, take twice as long and probably say oh you need a new $800 computer. They want $150 just for the switches. So I was just wondering if anyone here has any advice/experience with this.
Thanks

 

Could be a bad clock spring or a bad brake switch. I have seen people simply replace the brake light switch above the brake peddel and it fixes everything. It also could be a bad TPS which would also cause the PCM to shut it down.

 

I checked all the wiring for 2 wires that pass through the clockspring while turning it lock to lock a few times and everything was solid, also took the brake switch out and apart and checked the 2 pins that contact each other when the brake is off and was getting a perfect reading.
I talked to a local mechanic and he said the PCM probably sends out some pulses to the speed control servo when the cruise is turned on to make sure it's all working and it's expecting some kind of certain feedback from it or the whole cruise system just shuts off. So I'll replace the servo with 1 from a pick and pull shouldn't be more than $10, just starting off the the cheap stuff so i can rule that out. If the light still goes out after that I think I'm looking at a bad PCM.

 

if you have a 2003 you should be looking at the 2002 factory service manual, it should match up 95% or better, 98-00 has quite a bit that is different from the 01-03 trucks.

 

Well it sounds like you know exactly how to fix it, please update when you finally figure out what the issue is.

 

Well I got it fixed...for about 2 minutes it was working great, then by the time I got home all the same problems listed in the first post came back. I was at the junkyard trying to find a speed control servo, found a few that looked exactly the same and has the same wiring color on a few 96-02 RAMs they had there and there was a 5.2L 99 durango there too but I wanted to be sure, so anyone know if those would swap out? Seems there is a hairpin clip holding the throttle cable on so it can connect to various different engines or be mounted in different places.

So I saw the 2 steering wheel cruise switchs in an 02 RAM and took those since they were only $5 a piece so why not, just 1 more part to check off the list. Installed them in the parking lot and for the first time you could switch on and off the cruise while the engine was running, so far so good. Got on the highway and set the speed and it held for a few minutes then all of a sudden the cruise light went out and nothing, had to turn the key off and back on to get the cruise light to light up but now it only comes on once when the engine is running and when you turn it off and back on again it lights few a second then goes out and then nothing untill you cycle the keys again.

So at this point I am completely lost, I'll get the speed servo tomorrow from the same 02 RAM just to see if it will do anything, i didn't expect the switches to do anything but they fixed it for a short time so who knows.