Cruise Control Not Deactivated By Braking

[eglmainz]

I have been trying to recreate a situation which concerns me in regards to the Cruise Control. I have a 2010 V, with Nav (not Advanced Tech), and I am a able to regularly, while in CC mode, set to a given speed, to reduce the car speed with the brakes, and when I let go, the car lurches back to my set speed. I noticed this a few times in the first 15,000 miles, but now I seem to feel it a lot more.

The way to see if your car does this, it to set the car to a given speed. I have tried this at 25, 35, 55, and 70mph, all with very similar results. Once you have your speed set, very gently place your foot on the brake pedal. Then, using only slight pressure (like you may be covering the brakes in anticipation of slowing down), you will see the HSI indicator move from the right side (let's say the 1/2 way mark), into the regen braking area as I press my foot slowly. The SET light remains lit. This will slow the car a few miles per hour, but you will feel the car trying to get up to the set speed.

If you then let go of the brakes, you will see the HSI zoom back to at least the 1/2 mark, or more to get you back up to speed. I am not sure what is happening here, as I do not have an easy way to confirm if the brake lights are being triggered.

My suspicion is that it is because the brake pedal electrical switch (which must activate the brakelights) has a different sensor, which is set to a different sensitivity, and does not trigger at the same time as the brakelights. Or, it is possible that the physical braking begins slightly before the brake switch is triggered, causing the vehicle to not sense electrically that I am pressing the brakes.

As I do this test, if I press with any 'real' pressure on the brake pedal, the SET light will turn off, and the CC is deactivated, as it SHOULD. What worries me is that I am able to slow down by five or more miles per hour, without deactivating CC, and it will lurch back up to that speed if you let go of the pedal. ON a highway, I almost nudged into someone due to this, as I slowed, then relaxed my foot off the brakes.

Has this happened to others?

[jburns]

Originally Posted by eglmainz

I have been trying to recreate a situation which concerns me in regards to the Cruise Control. I have a 2010 V, with Nav (not Advanced Tech), and I am a able to regularly, while in CC mode, set to a given speed, to reduce the car speed with the brakes, and when I let go, the car lurches back to my set speed. I noticed this a few times in the first 15,000 miles, but now I seem to feel it a lot more.

The way to see if your car does this, it to set the car to a given speed. I have tried this at 25, 35, 55, and 70mph, all with very similar results. Once you have your speed set, very gently place your foot on the brake pedal. Then, using only slight pressure (like you may be covering the brakes in anticipation of slowing down), you will see the HSI indicator move from the right side (let's say the 1/2 way mark), into the regen braking area as I press my foot slowly. The SET light remains lit. This will slow the car a few miles per hour, but you will feel the car trying to get up to the set speed.

If you then let go of the brakes, you will see the HSI zoom back to at least the 1/2 mark, or more to get you back up to speed. I am not sure what is happening here, as I do not have an easy way to confirm if the brake lights are being triggered.

My suspicion is that it is because the brake pedal electrical switch (which must activate the brakelights) has a different sensor, which is set to a different sensitivity, and does not trigger at the same time as the brakelights. Or, it is possible that the physical braking begins slightly before the brake switch is triggered, causing the vehicle to not sense electrically that I am pressing the brakes.

As I do this test, if I press with any 'real' pressure on the brake pedal, the SET light will turn off, and the CC is deactivated, as it SHOULD. What worries me is that I am able to slow down by five or more miles per hour, without deactivating CC, and it will lurch back up to that speed if you let go of the pedal. ON a highway, I almost nudged into someone due to this, as I slowed, then relaxed my foot off the brakes.

Has this happened to others?

It takes more brake pressure to release cruise control than any car I've ever had. I've learned to tap the pedal firmly to release rather than just pushing down slightly. That releases it before the brakes have a chance to apply and keeps the passengers heads from lolling about.

[KCPrius]

I have noticed that the cruise control requires a pretty significant amount of pressure on the brake pedal to deactivate. I haven't noticed that I slow down and speed back up...just the it doesn't disengage with a slight tap on the brake.

[claridiva]

I have never had the CC reactivate itself after pressing the brakes, which I only use to control the speed of the car when using CC if I need to stop quickly. Otherwise, I find that using the CC stick to control speed avoids the jerkiness experienced when having to apply pressure with the brakes. I use the stick much more often to control CC than the brakes.

It sounds like what the OP is describing may be a problem with the car that needs to be seen about? I, too, am curious whether others have experienced the above issue. The brakes should disengage the CC until resumed or reset by the driver using the CC stick. Personally, I have not encountered this issue.

[eglmainz]

Originally Posted by claridiva

I have never had the CC reactivate itself after pressing the brakes, which I only use to control the speed of the car when using CC if I need to stop quickly. Otherwise, I find that using the CC stick to control speed avoids the jerkiness experienced when having to apply pressure with the brakes. I use the stick much more often to control CC than the brakes.

It sounds like what the OP is describing may be a problem with the car that needs to be seen about? I, too, am curious whether others have experienced the above issue. The brakes should disengage the CC until resumed or reset by the driver using the CC stick. Personally, I have not encountered this issue.

Yes, I agree with you regarding never having a car with CC reactivate like this (except for an old car, where if I accelerated above the set speed, it would not allow me under that speed without braking or canceling.

In this case, I suspect that it is related to a sensor which triggers the brakes, and likely also tells the car to disengage the CC. If this is not triggered, and no brake lights are illuminated, there is not another way for the car to know that the brakes are pressed.

I would also imagine that the actual brakes are not being engaged, but the engine someone 'feels' this, as I can hear the noise differently from the ICE, as the HSI moves over to the Regen area.

I will ask my wife to follow me, and see if she sees the brake lights on as I do this. This could well explain it.

[Jabber]

Eric, I have my top prius tech looking into the wiring of the cruise for you. Specifically, what sensor needs to be triggered in order to actually cancel the cruise. I'll post up here once I get the answer.

[eglmainz]

Originally Posted by Jabber

Eric, I have my top prius tech looking into the wiring of the cruise for you. Specifically, what sensor needs to be triggered in order to actually cancel the cruise. I'll post up here once I get the answer.

Damn, Your quick, and on top of this. This is why I recommend Jeff to anyone in the Midwest looking for a Toyota to you. My friends on the west coast get Dianne's info.

I/m hoping to swing up there in the next week or two for the 15,000 mile oil change, as I just passed that. I'll talk to your before then.

[qbee42]

This is a duplicate of another thread. CC is disabled by a switch on the brake pedal arm. On the 2010, it takes a fair amount of pedal pressure to deactivate CC and likewise lite the brake lamps.

On the other hand, it is very easy to deactivate CC by pulling on the CC lever.

Tom

[Jabber]

Ok, got some info. And are you pressing the brake pedal with a feather??? The cruise is turned off via the brake lights, i.e. lights come on, cruise shuts off. That is what I expected. So I jumped into a prius to see how sensitive the brake pedal is. It is sensitive, but I can definitely see how it could happen. It seems that the regen braking is more sensitive then the actual brake light switch. Just to be sure, I hopped into a RAV, Sienna, and Avalon also. The Avalon required a harder push on the pedal to activate the rear taillights. The Rav required almost no pressure at all. Doesn't sound like it is a "problem", just a weird anomoly. Just to be sure, when you bring it up for the oil change, I'll have my guy take a look at it to be safe.

[eglmainz]

Originally Posted by Jabber

Ok, got some info. And are you pressing the brake pedal with a feather??? The cruise is turned off via the brake lights, i.e. lights come on, cruise shuts off. That is what I expected. So I jumped into a prius to see how sensitive the brake pedal is. It is sensitive, but I can definitely see how it could happen. It seems that the regen braking is more sensitive then the actual brake light switch. Just to be sure, I hopped into a RAV, Sienna, and Avalon also. The Avalon required a harder push on the pedal to activate the rear taillights. The Rav required almost no pressure at all. Doesn't sound like it is a "problem", just a weird anomoly. Just to be sure, when you bring it up for the oil change, I'll have my guy take a look at it to be safe.

It happened the first few times when I was just covering the brake pedal, and applying no real pressure. What did happen is that I slowed from about 55 to 49, just kind of coasting, but as I looked down at the HSI, I saw it was doing regeneration, about 1/3 of that bar lit. Then, a few seconds later, as I moved my foot away from the brake pedal, and was about to hit the gas, the car re-accelerated all by itself, going into the PWR zone to do so, and zoomed back to 55 miles per hour, where it was previously set. I noticed it, and had to brake hard enough to jolt me in the car, in order to not hit the car in front of me who was traveling at about 52-53 mph.

The first time it did it, I just assumed the CC was disabled, as I slowed the car 6 mph less than prior to touching my brake pedal.

Regardless of why, I would say that if the car is sensing regenerative braking, it should deactivate the CC, just as if the pedal were depressed.