cruise control quits on hills

[JBain]

I'm helping a friend out with his 2004 2500 plus I'm trying to get him to sign up on TDR if I can fix his truck using TDR.



Problem:



Cruising at 70 in cruise control and come to a hill and the cruise control drops out. Any ideas out there?



John

 

[GaryOwen]

Possibly brake switch needs adjusting. Had this happen on my 95. Try lifting up the brake pedal with one foot when you come to a hill.



Any codes set?



Automatic or manual?

 

[sag2]

Depends what kind of hill your trying to climb. If the speed control has to open the throttle too far to maintain speed it will drop out. This is normal. What you need to do is compare the operation to a hill that it used to work properly on. Also keep in mind that if the fuel or air filter is plugged, or any other reason to limit the engines ability to make normal power will cause the throttle to open further than normal resulting in drop out.

 

[JBain]

Thanks, guys it is an automatic. don't know how to check codes don't you need a reader? I'll find out what type of hill and have him check the filters.



John

 

[PWitteveen]

I had an Olds Cutlas that would do the same thing if the engine came under any stress. Turned out to be a vacuum leak.

 

[Pawpaw]

If it's an early '04, a vacuum leak is a definite possiblity.

The '03 and early '04 automatics have a small electric vacuum pump mounted on the passenger fender, between the battery & firewall.

I think the vacuum line is a small black plastic tube that runs from there to the driver's side along the top edge of the firewall.

If you don't know whether it's an '04 or '04. 5, check out the label on the driver's side of the valve cover. An '04. 5 will say 325 hp. Anything less and it's an '04.

Bob

 

[JBain]

thanks again, i found out some more info



1. the truck has to be shut down to get the cruise to work again

2. the cruise indicates still in cruise when it hits the hill

3. very slight hill is all it takes to kick it out

4. no codes



My friend is going to check vacuum hoses tonight



your info on where the vacuum pump is helps alot thanks



john

 

[GaryOwen]

Codes can be checked by turning the key ON-OFF-ON-OFF-ON (not to START). Leave key in ON position and watch odometer for codes. It will sequence through stored codes and display "done" when complete.

 

[JBain]

My friend found the problem a vacuum hose had a worn spot on it causing it to leak. Fixed the hose and all works great. thanks all of you for your help.



john