Cruise control automatic cutoff? (1 Viewer)

[e rock]

Something happened today that I've never experienced before. In a bit of spirited driving on my way home from a fishing trip, I was pulling a few mountain passes at ~80mph. For the most part, no problems with o/d locked out.


But at one point, on the final approach to the pass, the grade steepened just before the crest, and before I could cancel the cruise control, it felt like the transmission was about to shift into 2nd (which obviously would have have the motor spinning pretty fast at 75mph). But just as I was about to turn off the cruise control, it cut off on its own.

The transmission did not shift, the motor didn't rev up. I can only guess that the CC self-cancelled so that the motor didn't redline?

Is this a feature of the ECU? I don't think I've seen it mentioned before.

Thanks,
Eric

 

[-Spike-]

Yep, all the CC's that I've had will let off if the car can't maintain within ~10 MPH of the set speed. The one in our 4Runner used to blink the CC dash light when that happened, and the CC couldn't be set again until you turned it off, then back on. Oddly (I haven't had the 4Runner for at least 2 years) I can't remember what the 80 does. It probably blinks the dash indicator too. I probably can't remember 'cause the 80 holds speed a lot easier than the 4Runner did.

-Spike

 

[e rock]

Yep, all the CC's that I've had will let off if the car can't maintain within ~10 MPH of the set speed. The one in our 4Runner used to blink the CC dash light when that happened, and the CC couldn't be set again until you turned it off, then back on. Oddly (I haven't had the 4Runner for at least 2 years) I can't remember what the 80 does. It probably blinks the dash indicator too. I probably can't remember 'cause the 80 holds speed a lot easier than the 4Runner did.

-Spike

It was within 5mph, and holding there, but wasn't able to accelerate to the set speed without downshifting. AFAIK, nothing blinked and other than me doing a quick freakout checking all the gauges to make sure there wasn't anything major wrong, the only thing that actually happened was the CC cancelling. I didn't have to turn it off to reset it. By the time I figured out that nothing exploded, we were over the pass and I was able to reset the CC with no other apparent anomalies.

Now, it's possible that the cancelling had nothing to do with the possible downshift and had everything to do with not being able to maintain speed, but it was within 5mph. It was probably like that for 30 seconds, so maybe that's what triggered it?

 

[Red Beard]

Mine only works if I'm driving on a highway... If it cuts off it blinks for 5 seconds then doesn't work again till you turn off the cruiser.

 

[CJF]

Mine only works if I'm driving on a highway... If it cuts off it blinks for 5 seconds then doesn't work again till you turn off the cruiser.

That's not normal.

It's blinking to tell you there's a fault and that there are codes you can pull; the CC system has it's own diagnostics, analogous to the CEL.

Curtis

 

[cruiserdan]

A set cruise can kick-out under three conditions (4 in a 91-94).

#1: decrease in speed pulling a hill, greater than ~8-9 mph)

#2: application of brake pedal (or a brake swith that closes by it's self because it's bad)

#3: a low fluid level in the brake master cylinder

#4: pulling up the e-brake lever (1991-94 models only)



If you are certain that your speed was within the range of the set speed my first guess is that the fluid level in the master cylinder is at minimum and the angle may have tripped the cutoff.

 

[e rock]

If you are certain that your speed was within the range of the set speed my first guess is that the fluid level in the master cylinder is at minimum and the angle may have tripped the cutoff.

Well, I thought I was sure, but it's more likely that the speed dipped more than I thought than a low fluid level. But I'll check the fluid level just to be sure.


Thanks for the definitive facts.

 

[Grolar]

Just to chime in: had the same experience with a loaded 94 in Cajon Pass, trying to keep pace with Escalades @ 70 MPH on their way to Vegas :whoops:. Setting the CC to 65 fixed it.
OTOH, my Matrix, even empty, can't hold that speed there.

 

[blackisback]

This happens to me often on big hills in my neighborhood. The cruise control cant accelerate as much as your right foot can and cancels it self because it has reached its limit and dropped 8-9(thanks c-dan) mph below set speed.

Is there a way to lower the minumum speed needed to activate cruise?? I'll go search...

 

[-Spike-]

Is there a way to lower the minumum speed needed to activate cruise?? I'll go search...

I can run my '95 at 25 MPH- how slow do you want to be able to cruise?

-Spike

 

[Ebag333]

I can run my '95 at 25 MPH- how slow do you want to be able to cruise?

-Spike

It'd be interesting if we could disable the lower limit. That'd be nice for long stretches of trail where you're crawling at 5-10 MPH, but there's not much to do.

(Or think of the 2008 'cruiser's "crawl" mode, where you can select for it to crawl at 1, 2, or 3 MPH. Potentially useful in a few spots.)

 

[blackisback]

mine seems to cut out around there as well 25-30 mph, but i am looking for super slow similar to what ebag said, no lower limit would be cool. My friend has a 4runner an dual t-cases with crazy low gearing, he can leave the truck in first gear, get out and guide the truck as it idles over absolutely anything. I think it would be cool to set cruise at 1 mph and do the same thing... I'm not sure whether or not this is the best driving technique but man it looks like fun.

 

[cruiserdan]

The minimum set speed is ~25 mph. (Very handy where I live because that is the posted speed limit in the village and the local constabulary likes to write tickets... )

 

[Beowulf]

#1: decrease in speed pulling a hill, greater than ~8-9 mph)

... or a Wyoming headwind. BTDT.

-B-

 

[rhyary]

Me too.
When I tow my ATV, it cancels itself few times going up moderate hill for few minutes. But I can reuse it.
Once in a while (not towing) it will cancel itself, the green Cruise light will blink and after that I have to shut off engine to reset.

 

[CJF]

Once in a while (not towing) it will cancel itself, the green Cruise light will blink and after that I have to shut off engine to reset.

See post #5.

 

[ToyotaDon]

It'd be interesting if we could disable the lower limit. That'd be nice for long stretches of trail where you're crawling at 5-10 MPH, but there's not much to do.

(Or think of the 2008 'cruiser's "crawl" mode, where you can select for it to crawl at 1, 2, or 3 MPH. Potentially useful in a few spots.)

There would be two ways I can see to do this electronically.
The first would involve relearning the Cruise Control ECU or Engine ECU, whichever is used based on year & model. Someone would have to basically rebuild/relearn the ECU to not have a lower limit, if this is even possible. It may be a programmed feature that cannot be erased.

The second way may hold some promise if the resources were available. This would be to add a module inline that would modify the signal from the VSS/Combination Meter. It's a frequency signal (hertz), so some sort of generator would have to be devised that would interpret 1 MPH as 25 MPH. There would need to be a bypass system so it could be turned off for normal operation. I think it could work for a wider range of vehicles, since most use the same sort of signal. If anybody wants to take this idea and run with it, I'd be happy with 5% of the profits.

Or, it may be best just to go with a hand throttle.

 

[cruiserruf]

does having the cruiser modified have any effect on the Cruise Control? Like weights: sliders, bumpers, tires, winch, etc and lift?

 

[Beowulf]

The second way may hold some promise if the resources were available. This would be to add a module inline that would modify the signal from the VSS/Combination Meter. It's a frequency signal (hertz), so some sort of generator would have to be devised that would interpret 1 MPH as 25 MPH. There would need to be a bypass system so it could be turned off for normal operation. I think it could work for a wider range of vehicles, since most use the same sort of signal.

The yellow box device already does this. All it needs is +12v and a VSS signal and it adds/subtracts a percentage based on the setting of some dip switches. So if your CC lower limit is currently 25mph, and you wanted it to be 5mph, you would need to reduce the signal by 70% (or whatever the math is). If Ebag333 is serious then check the YB web site to see if there is a max/min % that can be added/subtracted.

-B-

 

[Beowulf]

does having the cruiser modified have any effect on the Cruise Control? Like weights: sliders, bumpers, tires, winch, etc and lift?

Not most of those that you listed but gears and/or larger tyres would change the true vehicle speed and that would, of course, effect the CC since the vehicle would think it was traveling at 65mph when it is really traveling at 70mph (or vise versa)

-B-