Cruise control issue

I just bought a 04 CTD and I am having an issue with the cruise control. At slower speeds it works and functions fine. But when I try to use it at faster speeds it doesn't work. Has anybody seen this before, and if so, what was the fix?

 

I would use a drb to test this,with out seeing live data or inhibit reason it's just guess work

 

Same issue with mine. Vacuum servo chk'd w/no leaks so vacuum pump [pass. side] getting weak. I tapped into my [Banks] Exhaust Brake vacuum pump line & now plenty 'power' to pull in the vacuum servo for cruise cntl. at higher speeds.

 

Sounds like one of the simple things to check is the vacuum supply from the pump.

 

Does anyone have pictures of the vacuum pump and a diagram of the routing of the vacuum lines. I have done google and yahoo searches and looked in the Haynes manual and have not found anything.

 

Pretty sure 3rd gens do not have a vacuum any longer. All electronically controlled.

 

My 3rd Gen (2003) has vacuum line. Mine got terribly brittle and fell to pieces so I replaced it temporarily with some tubing I had out in the shed. It works again but I think the larger diameter tube allows the truck to vary the speed more than it used to. Anyway, at least some 3rd gens have vaccum line.

 

You are correct they removed the vacuum pump in 2005.

 

5-26-2017 Update: Now 3 months later, cruise is unreliable, typically OK at city speeds but 'falls out' above 50mph...can't handle the force of the diaphragm return spring I suppose. At least it worked for 1300 miles coming down to FL. aaargh.

Anyone have an electrical troubleshooting clue??

 

I don't know about ya'lls trucks, but mine does not have a vacuum pump. Its all electronic

 

dorman 204-214 mechanical vacuum

Cruise cntl up thru 2004...'05 went electric. Good luck mate.

 

The 2004-05 do in fact have a vacuum pump, unless you have a manual transmission. All of the auto equipped trucks have the pump (but no separate reservoir).

 

Have you looked at the throttle position sensor?

 

Unless you have one of the wierd hermaphrodites like mine that has it on the bell crank.

 

04.5 is under the battery tray on the drivers side. They are on national backorder through Dodge. I found a place in California that has them. http://www.alldodgetruckpartsncal.com/

 

I have not seen any of those. I know the auto's were on the front of the engine. I had several diesel shops that had never heard of any under the battery tray. I had cummins run the serial number on my engine and they said it was an 05, so I started looking into changing mine over to the 05 setup on the throttle pedal. Cummins thinks it can be done,Dodge said they didn't think so. I think it is possible, but have not had time to look into it.