Cruise control hunting

[RBeard]

Engaged the cruise today and after about a minute the truck started losing about 5-10 mph, then surged to set speed. It did this intermittently until it scared me into turning it off. Any ideas where to start looking, it has electronic type APPS, fuel pressure is good.

 

[petersonj]

it has electronic type APPS,

Only automatic transmission trucks use the signal from the APPS and a vacuum controlled cruise control. The manual transmission truck's cruise control is controlled completely by the ECM - no APPS signal nor vacuum controls.

It would be worth checking the wiring conditions under the tilt wheel. Some wires can break internally (insulation still intact) and cause cruise control problems. I have had to repair mine twice. I didn't have your symptoms, but I certainly could have. Getting access is easy - just two screws (I think) and the cover comes right off for easy inspection. These wires can break just from repeated operation of the tilt wheel over the years.

- John

 

[GAmes]

Check your factory service maual. The '97 one has a procedure for fixing cruise control hunting. It involves "unlearning" the PCM.

 

[hcole]

Engaged the cruise today and after about a minute the truck started losing about 5-10 mph, then surged to set speed. It did this intermittently until it scared me into turning it off. Any ideas where to start looking, it has electronic type APPS, fuel pressure is good.

Engaged the cruise today and after about a minute the truck started losing about 5-10 mph, then surged to set speed. It did this intermittently until it scared me into turning it off. Any ideas where to start looking, it has electronic type APPS, fuel pressure is good.

Beard, check this out. https://www.turbodieselregister.com/threads/mild-surging.258960/#post-2514225

 

[petersonj]

@hcole offers good advice. Since the manual transmission cruise control is operated solely by the ECM, electrical connections must be in excellent condition. Check vehicle grounds as well.

- John

 

[Seabee]

Interesting. Many times when I first set mine, it will accelerate 5-10MPH over set speed. Sometimes it will keep accelerating! I have to hit the brakes, slow down, reset and see what happens. Sometimes it takes around 8-10 resets before it settles down. Lately it has been working well, so I hope I didn't just jinx myself!

 

[GAmes]

I know for a fact that it is addressed in the '97 FSM. You can fix cruise control "hunting" and learn what causes it. I was once pulled over because I was doing what you did. Accelerate, hit the brakes, reset the cruise, accelerate, repeat. The trooper was checking to see if I was drunk.

 

[Seabee]

I know for a fact that it is addressed in the '97 FSM. You can fix cruise control "hunting" and learn what causes it. I was once pulled over because I was doing what you did. Accelerate, hit the brakes, reset the cruise, accelerate, repeat. The trooper was checking to see if I was drunk.

Good thing I don't drink anymore Gary! I know the ritual to clear it, but it seems to "re-learn" it's bad habits. Especially after it has sat for several weeks, as it often does................

 

[GAmes]

But do you know the ritual to keep it from starting again? Don't activate the set button until you are at the desired speed. Hold that speed manually for at least 10 seconds. If you kick off the cruise control then do the same when you reset. Mine sits idle more and more too. Weaning myself of whiteline fever so it only moves when I hook up my camper.

 

[Shelby Griggs]

Engaged the cruise today and after about a minute the truck started losing about 5-10 mph, then surged to set speed. It did this intermittently until it scared me into turning it off. Any ideas where to start looking, it has electronic type APPS, fuel pressure is good.

I don't know if you followed my CC thread, possible similar symptoms also with 2001.5 manual truck. I replaced the ABS sensor and the brake light switch first with no change. Followed that with reseating the main engine harness in the PDC (fuse box) under the hood and removing and cleaning all four battery cables. I did both under hood items without testing in between each. In any event CC now appears to be cured. It could have been the act of pulling all power too, but a couple months now and no more issues. I really suspect it was the battery cables or the engine harness connection, occasionally a good bump in the road would cause mine to stutter, that indicates an intermittent wiring connection. My CC was intermittent too, sometimes worked, sometimes didn't sometimes surged. At first, I thought it was ambient temperature related (due to working in morning most days and then failing later in day) and if it was, I won't know that until next year when we get above 80F again.