Our cruise control just started acting up. It worked perfectly in the past. The green light comes on when we turn the cruise control on. But nothing happens when we press the "set" button. When pressing the "set" button, the van does not accelerate so we can designate a constant speed. Sometimes, if we fiddle with the "resume" button and the accelerator pedal, the cruise control kicks in. (possibly at a previously set speed?) But, even after doing the "resume" button/accelerator pedal fiddling, the speed doesn't remain constant; sometimes the van keeps accelerating without pressing the accelerator. The cruise always turns off, as it should, when the brake pedal is depressed.
Where do I start checking? Is the switch on the steering wheel bad? The cruise servo module? The cruise vacuum canister? The Dodge Service Manual says the cruise servo module and vacuum canister are located behind the passenger-side front fender extension, but I wanted to get some opinions before I started digging into anything.
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Class B Camper: 1989 Falcon 190 SLF, Dodge Ram B350 Chassis, 360 engine, 3K Onan, Monroe gas shocks
If he had a vacuum leak, I don't think it would work at all. There could be wires that are shorting out. Once my cruise was acting up. And I kept getting a check engine light. The plastic material that covers the metal wire had come off the 3 wires of my park/neutral safety switch wiring on top of my tranny. The wiring had not been protected. The 3 wires were touching each other causing a short. Cleaned it up and no more cruise control problems. GL
If he had a vacuum leak, I don't think it would work at all.
It would depend on the size of the leak. Obviously if there were a gapping hole in the vacuum line then you're correct, it wouldn't work at all. If however the vacuum line was brittle and cracked like so many end up, then enough vacuum could still be made in order for the modulator to work to a certain degree.
Also, you could have a sticking brake light switch...this disables the cruise. Pull your brake up by sliding your foot behind the brake pedal. I have to do this sometimes on my '04 Dodge 2500 Ram Truck