How does your Cruise Control work?

Did you release the stalk when you cancelled it? You have to pull it back, release it, then set it again by pushing it down. If you hold it back, that won't do it.

 

Sounds like you're doing it right. Holding cancel and then going to set won't work, but pulling to cancel and then releasing and then resetting will.

 

First off, it is easy to turn off the cruise control 'setting' most often by manually braking. The cruise control remains technically "ON" but "in-active" at the last speed setting.

In "ON" but "in-active", I typically wait until the car is going 28 mph or faster. Then I "pat-up" the stalk which seems to resume the last setting. I then adjust the speed by holding the stalk UP or DOWN to set my target speed.

In traffic, I use the stalk UP and DOWN functions to adjust the set speed. The only way I know to set the speed is upon first POWER-ON, using the end button:

• Quick push on the end button to "POWER-OFF"
• Quick push to "POWER-ON", now armed for setting the initial speed
• Stalk down to set the speed

This is typically done fairly quickly, 1-2 seconds. But practice helps.

Bob Wilson

 

Is there a reason why DRCC works different than regular cruise when it comes to setting cruise speed? Since this is about setting speed not distance, which is a separate button. Unless I am missing something. I realize that when following someone your current speed may be slower than what you are currently set, but in the OP's second scenario he has used the throttle to accelerate higher than his current set speed, so I don't see why you can't set the new higher speed with a single down click like you do on other cruise controls.

 

It is super simple, just tap on the brake and cancel it, or press the Enable button to cancel it. Press the button again real fast and push down to set current speed. It is pretty simple and easy in my mind. I don't even bother with the cancel function. Sounds like it is slower than pressing the button fast twice. I never tried and not going to bother doing it that way.

 

I think it should be pretty simple for the computer to figure out, if the driver presses SET/- then it's permanent, if they don't press SET/- then it's temporary, in that case when they let off the throttle it will know to drop back to the set speed. Like standard cruise control works.

Agree that RES/+ is a different situation, but the computer knows whether or not you are following another car so there shouldn't be any risk, if the driver presses RES/+ while the system is actively following another car the computer should simply ignore RES/+ and not change the set speed. Only after the car ahead speeds up or moves out of the way will pressing RES/+ do anything.

Back to SET/- that also shouldn't be too hard for the computer to know what to do. If travelling at or below the set speed then tapping SET/- will lower the set speed. If you are travelling above the set speed then tapping SET/- will set the new higher speed. Similar to how standard cruise controls work.

I agree reading the manual is always important but there is also an advantage to making things work the way people expect, if it can be done safely. Maybe the engineers had good intentions but wound up adding unnecessary steps. I remember years ago when cruise control worked quite differently depending on the manufacturer. For example not all cruise controls had a cancel feature. Then in the past decade or so they really seemed to standardize which is nice. If it starts diverging again that's disappointing unless there is a good reason for it.

 

Tapping the brakes causes your brake lights to flash and the driver behind you to think that you are hitting your brakes, causing them to slow down or even hit their brakes. As a courtesy to other drivers I never use the brake pedal just to cancel the cruise. That's what the cancel function is for. I guess if I'm in the middle of nowhere and no one is behind me it wouldn't matter, but pulling the stalk to cancel is just as easy as pressing the brake pedal so I just make that my habit.

 

Bob slowly raises his hand.

 

At least on the Gen 4, that would only be true in PWR mode. In ECO mode, the acceleration would definitely not be rapid. I am currently driving in Normal mode which is between those extremes.

I assume the Prime behaves similar to the Gen 4. If not, feel free to ignore the above information.

 

I am trying to think of arguments against my opinion about how RES/+ and SET/- should work. I have come up with one possible argument although I'm not sure it sways me.

First I don't know if there is terminology for when DRCC is "locked onto" a car in front of you which is within range of DRCC and going at or below your set speed. For now I am referring to that as "Actively following".

In this example, cruise is set at 55, which is the speed limit, and you are actively following a car that is also going 55mph or close to it. Then the speed limit changes to 65mph. The car in front doesn't react immediately, but you would like to proactively increase your set speed to 65mph so that when the car in front does start speeding up your speed will increase also. Well I can see that apparently the current method allows this, which I suppose is nice. Whereas using my proposed method pressing RES/+ will do nothing, you will have to wait for the car in front to start speeding up before you can use RES/+ to set a higher speed. Maybe that would be annoying to some people, but I think it would be safer, otherwise an untrained driver might start clicking RES/+ repeatedly, or holding it, but not paying attention to the display and thus not realize that they have just set it for 90mph, which they won't find out until the car in front changes lanes. Don't know how often that would actually happen but that's why I think for safety reasons probably RES/+ should not be operational during active following. RES/+ should only work when pressing it will provide immediate acceleration, that way the driver gets instant feedback on what is happening even if they aren't looking at the display. SET/- would not need this restriction since pressing SET/- repeatedly or holding it will always have immediate results.

 

Having driven 1,200 miles, I found it best to set the cruise control speed to speed limit + 10 mph. I then pull behind a vehicle running relatively constant speed like a semi-trailer truck or pick-up towing.

Setting the speed to the initial vehicle speed does not work as any hill or grade will change the speed and the lead vehicle can pull beyond the detection range and lose Prime speed control. Then any subsequent slow down of the lead vehicle will cause the rapidly moving Prime to come into range with a considerable speed difference. This can lead to unnecessary braking.

If you've ever tried to tow a vehicle with a rope, any slack can result in a snapping action. Having the cruise control set too close to the lead vehicle speed is the electronic version of towing with a rope.

Now I drive in ECO mode and there is no risk of the Prius 'taking off like a rocket.' If others choose NORMAL or POWER, good luck. I prefer a sedate and efficient Prius driving experience.

Bob Wilson

 

On the Gen 4, it seems DRCC seems to use engine braking instead of regenerative braking to slow on downhill stretches. Does the Prime do the same thing?

I ECO mode with many uphill/downhill stretches, I found the speed variation too much, Normal or PWR mode seem to mitigate this issue. Non-RADAR cruise control seems unaffected by driving mode setting.

 

Not that I can tell. The Prius Prime has ~6.3 kWh of extra battery capacity and excellent regeneration.

Bob Wilson

 

I find the engine revving quite noticeable. It would be difficult to miss.

 

Oh, don't know that. So the car follows the ECO mode during DRCC? That is neat.