First, be gentle with me, for the first time since 1984, I own a non GM vehicle, so everything I reference will be in relation to my GM knowledge. I just bought a beautiful 97 Ext cab 4X4 Laramie SLT Cummins, and man, I should have done this 10 years ago! In any instance, it has just over 100K on it, and everything, including the cruise control functions, with the exception of the heater control seems to be stuck on Defrost. Now, from my research, it appears as if the Cruise servo operates with vacuum, so obviously I have vacuum somewhere. The dealer that I bought it from had his mechanics install a new module ( no word on why his mechanics changed it and not found it still didnt work ) This dealer acknowledges his mechanics arent the swiftest, and he wants me to bring it in to be fixed ( for free ), but to tell you the truth, I dont really want them just pulling my baby apart and poking without some idea of what they are doing! Any ideas on what it might be? I hear no movement at all, as if perhaps a lever were broken, etc........

Thanks for any help, and for the million questions I will probably ask, but NOTHINGS TOO GOOD FOR MY BABY!!!!!!!!!!!!!!!!

Bet you cant tell I love this thing already.

 

Check the vacuum line that controls the door to switch positions. I've seen many trucks where this line becomes disconnected or broken. Without vacuum, the air will all be ducted to the defrost vents. Even had one truck where the line laid against the exhaust housing on the turbo and melted in two.

 

pop the dash bezel off and remove the heater control panel. check to be sure all vacuum lines are connected to the back of the vent control?

there should be a main vacuum tube that comes in (not sure of color) that supplies the vacuum to the control (when then sends it to the proper door actuator). you are not getting vacuum to the switch. start there and trace back to the firewall...you will find the leak/break

 

Dad's truck did the exact same thing, the tube fell down onto the turbo and melted apart. Everything stopped working that was related to vaccum, i would check the vaccum hoses under the hood first , it is easier than pulling the dash apart.

The cruise could be dependant on vaccum also , but it might not be too , does the light on the steering wheel come on when you press the on/off button?

 

JKM, The cruise is working fine, that is what confuses me about the system.
Though, if the line did happen to melt on the exhaust manifold, it might just have sealed itself off and retain enough vacuum to run the cruise servo. It already has a posi-lock for the 4WD actuate, so if I read things right, the only thing that requires vacuum for this truck should be Cruise and the HVAC system.

Sound about right?

Though now that I say that, is it normal for Dodge cruise controls to lose 2 or 3 MPH before coming back to speed? Mine works good, without hunting, but when you engage it, it is "dead" for a second or two and the truck will coast down say2 or 3 MPH before correcting itself and holding very close to set speed.

Im going outside to look right now!

Thanks for the quick help, lets hope it is that simple!

 

This probably isn't it but pull the **** and check it . Just had a problem with mine , the function **** ( top ) would turn but had no resistance . Couldn't get the heater off defrost . Pulled the **** and found the sleeve cracked so it just spun on the control shaft . ******* wanted 9 bucks for the **** , not , a dab of super glue and all is good . Good luck

 

Good call ticki.
I've run into this several times, found that super glue doesn't last long.
What I do now is slip short piece of 3/8" copper tubing over the part of the **** that cracks to reinforce it.

 

Sorry , my bad , i thought i read that your cruise control STILL doesn't work, check the Vaccum lines for the heater controls in the engine bay , it should be the only vaccum line going to the passenger side , it may be melted , or just pulled apart somewhere, or as other have said , maybe the switch is the problem.

 

Ok, I checked the tube all the way into the firewall, and I verified Vacuum at the firewall, so I think it is time to lose my cherry behind a Dodge dash. When they had it apart at the Dealership, I "think" all they did was pull the black surround on the outside of the main dash plastic, and then unscrew the module. I did a cursory examination, and it doesnt appear to want to come off. How do I get into this thing?

As always, thanks a million for any and all advise!

 

Remove the two screws that hold on the ash tray and the two that hold on the cup holder, remove them, then pull the dash front off. It's just snapped in. You may have to tilt the steering wheel low and shift out of park. Cig lighter wires will have to be disconnected to remove all the way.
While you're in there might as well do this simple mod
http://dodgeram.org/tech/repair/HVAC/Defrost_AC.htm

 

The actuator that controls the defrost/vent/floor action of the air is located just above the go fast pedal and to the center of the truck. Mine went bad and I replaced it with a junk yard find. You should be able to see or at least feel the arm on the actuator move if you can get yourself down in there and have someone turn the ****.

T-Bone

 

Ok, thanks for all the info.

I went back to my dealer to see if I could read up on the system from their FSM ( Im still searching for a good price on one ) and the owner red faced told me he was getting ready to call me and let me know that the module had not in fact been changed.... Lets just say he wasnt too happy with his service manager at that point.

So, for the present, I am going to wait until they change out the module and see where I am at.

Thanks for the info guys, so far it appears as if these trucks arent really that much different to work on than what I am used to!