Intermitent Cruise Control

[JMLambert]

The cruise control lights up when turned on. When hitting the set button it may or may not engage. If it does engage it may stay on for a short time or it may hold for miles. I have checked the vacuum lines and could not find a problem. Any help would be appreciated, thanks in advance.

 

[Ozymandias]

Worn out brake light switch?

 

[JMLambert]

Thank you.

 

[mothertrucker]

Same thing happened to mine & it was the brake light switch.

 

[Joe Mc]

The cruise control lights up when turned on. When hitting the set button it may or may not engage. If it does engage it may stay on for a short time or it may hold for miles. I have checked the vacuum lines and could not find a problem. Any help would be appreciated, thanks in advance.

That's how mine started acting, back around 2005 and finally the light would stay on but cruise would not engage at all. Hope it's something as simple as the brake light switch for you (note: don't play with the new one = read the instructions to set it up first).
Here's what solved the issue on mine. Turns out the left battery (OEM) leaked down on the cruise servo and the acid ate thru the rubber diaphragm. Was like $70 at the dealer back then, surprised to see this many years later its only $83+change!
https://www.moparpartsgiant.com/par...tml?Filter=(E=ETC;T=DGP;M=Quad+Cab+4WD)&PNC=1

 

[gtwitch]

jml look at the vaccum line tee just above the fuel filter , I have had that vac line/tee come off a couple of times and that also affects the heater/defrost control door and the 4wd shift in and out diaphram.
gtwitch in wyoming

 

[JMLambert]

Thanks for the responses. I checked the vacuum lines and all appear good. I will change out the brake light switch next.

 

[DavidC]

Thanks for the responses. I checked the vacuum lines and all appear good. I will change out the brake light switch next.

Maybe disconnect it and take a drive on a lonely road ?.

 

[Joe Mc]

Get a hand held vacuum pump, like a brake bleeding tool, connect to the hose going to the servo and see if it (diaphragm) holds vacuum.

 

[Joe Mc]

Any update???

 

[JMLambert]

I tested all vacuum lines (all held pressure) with a hand held pump. Since then I am getting an Air Bag warning light almost continually. It used to come on about once every six months to a year and then go off. My next step will be replacing the clock spring first as it is the most annoying issue at the present time. Thanks for all the help and information.

 

[Joe Mc]

Hey thanks for the update. I hear you on the clock spring - I've replaced about 3 with married successes that eventually end up in the same place. 1st was from Dodge (when they used to be available), then from the aftermarket (forget where) and the last was from iCardi (I'm pretty sure). I think the first aftermarket one worked (my issue is the radio control buttons don't work) while sitting in the driveway with the key switched to accessory, then "as soon" as I started the truck they no longer worked, oh yea not very happy at all. I feel your pain.

Back to the cruise... You say you tested "all lines", have you tested the components attached to those lines to see if they work/hold vacuum? See post #5.

 

[JMLambert]

I replaced the clock spring. While I had it apart I checked all the electrical connector from the cruise control switches through the steering column to the brake pedal switch. The Air Bag warning light is off and the cruise control is functioning properly. Thanks for all the input and help.

 

[Joe Mc]

Glad its working. What do you think did the trick? Where'd you get the clockspring?

 

[JMLambert]

My guess would be one of the electrical plugs vibrated loose over the years and miles and was making contact every once in a while. I got the clock spring from NAPA.

 

[Joe Mc]

Would have never thought of NAPA to source a clock spring. Hope it lasts a long time for you. I'm on 4th one... orig, 2nd from dealer (when still available), 3rd & this one aftermarket. Every one of the replacement units worked fine for a little while. Then the radio controls would be intermittent then totally fail, then the cruise would work intermittently then just fail. Most recent one, the radio controls worked fine "until I started the truck". I've given up on the radio controls and settling on having to hold the cruise button while turning the steering wheel back and forth a few times to get cruise light to come on, then cruise function is normal?

 

[JMLambert]

Several months after this was posted I again started having problem with the cruise control. I changed the brake light switch as directed by several other members. Since then and having put 1000 miles on the truck it has cured the issue. It has also stopped the auto transmission from doing its hunting and jumping rpm.

 

[Joe Mc]

Good for you. I replaced the brake switch some time back as well when cruise wouldn't work = light would come on but cruise wouldn't hold. Ended up being cruise module the rubber diaphragm rotted.

 

[Bill Lins]

I've replaced about 3 with married successes

Were you referring to wives? ;-)

 

[Joe Mc]

Bill, pretty good, thanks for the laugh. Definitly needed it.
Nope, there was only one for me, she passed a week shy of our 31st anniversary. We had a good life. One is all I'll ever need.