GM to recall nearly 300,000 Chevrolet Cruze cars

[Pardus]

http://money.cnn.com/2013/08/16/autos/chevrolet-cruze-recall/?hpt=hp_t2

August 16, 2013: 3:14 PM ET
NEW YORK (CNNMoney)
General Motors has announced plans to recall nearly 300,000 Chevrolet Cruze cars from model years 2011 and 2012 due to a problem with their brake assist systems.

GM (GM, Fortune 500) spokesman Alan Adler said that in Cruzes with six-speed automatic transmissions and 1.4 liter turbo engines, there is the potential for "intermittent loss of brake assist," forcing drivers to apply extra pressure on their brake pedals to stop their vehicles.

"GM is aware of 27 alleged low-speed crashes but no injuries related to brake performance, which could include this issue," Adler said in an email.

Related: Chevrolet Corvette, finally a legit Porsche killer from Detroit

Affected drivers can take their cars to their dealerships, which will replace a microswitch to address the problem.

GM announced the recall of nearly 194,000 SUVs in June due to a fire risk.

 

[LTC8K6]

In my Jeep, Brake Assist does nothing at all unless it detects you trying to make a panic stop. Then it applies max braking for you.

It's the same for the Cruze, so I'm confused as to how anyone would even know it wasn't helping unless they make a panic stop. Also confused as to how it can cause a low speed crash.

Brake Assist
This vehicle has a brake assist
feature designed to assist the driver
in stopping or decreasing vehicle
speed in emergency driving
conditions. This feature uses the
stability system hydraulic brake
control module to supplement the
power brake system under
conditions where the driver has
quickly and forcefully applied the
brake pedal in an attempt to quickly
stop or slow down the vehicle. The
stability system hydraulic brake
control module increases brake
pressure at each corner of the
vehicle until the ABS activates.
Minor brake pedal pulsation or
pedal movement during this time is
normal and the driver should
continue to apply the brake pedal as
the driving situation dictates. The
brake assist feature will
automatically disengage when the
brake pedal is released or brake
pedal pressure is quickly
decreased.

 

[EagleKeeper]

Any different than an anti brake system?
Pulses when brakes are locking up to retain some traction.

 

[LTC8K6]

Any different than an anti brake system?
Pulses when brakes are locking up to retain some traction.

ABS doesn't apply the brakes for you. It just keeps the wheels from locking when you use the brakes.

Brake Assist applies the brakes for you if it detects a panic stop.

If brake assist determines that you are trying to stop the vehicle quickly, it increases brake pressure to the maximum, until ABS is triggered.

It kicks in if the driver has not, or can not, press the brake pedal hard enough to achieve max braking.

 

[thedarkwolf]

Sounds to me like they are just saying they loose the POWER assist for the brakes. In other words they have a stiff brake pedal.

 

[LTC8K6]

My guess is that these drivers have triggered Brake Assist, and it felt funny to them.

 

[jagec]

ABS doesn't apply the brakes for you. It just keeps the wheels from locking when you use the brakes.

Brake Assist applies the brakes for you if it detects a panic stop.

If brake assist determines that you are trying to stop the vehicle quickly, it increases brake pressure to the maximum, until ABS is triggered.

It kicks in if the driver has not, or can not, press the brake pedal hard enough to achieve max braking.

If a driver CANNOT press the brake pedal hard enough to achieve max braking in a modern car with power brakes and ABS, then they have absolutely no business behind the wheel. If they HAVE not, in an emergency situation that would call for such a measure...well, they still have no business behind the wheel.

I really don't understand the need for this feature. It seems like one more thing to fail and provide conflicting feedback to the driver on how hard they are actually braking...which is, in fact, exactly what is happening here.

 

[LTC8K6]

From my Jeep manual.

BAS (Brake Assist System)
The BAS is designed to optimize the vehicle’s braking
capability during emergency braking maneuvers. The
system detects an emergency braking situation by sensing
the rate and amount of brake application and then
applies optimum pressure to the brakes. This can help
reduce braking distances. The BAS complements the
anti-lock brake system (ABS). Applying the brakes very
quickly results in the best BAS assistance. To receive the
benefit of the system, you must apply continuous braking
pressure during the stopping sequence (do not
“pump” the brakes). Do not reduce brake pedal pressure
unless braking is no longer desired. Once the brake pedal
is released, the BAS is deactivated.

I have never felt anything odd about my brakes.

I don't know what's going on with the Cruze. I only guessed that it felt funny to drivers. It may actually be malfunctioning.

After all, we now have vehicles that stop for you even if you don't use the brake pedal...

It's hard to be bothered by BAS in my Jeep, when it has all this other electronic gimcrackery. :biggrin:

ELECTRONIC BRAKE CONTROL SYSTEM
Your vehicle is equipped with an advanced electronic
brake control system that includes ABS (Anti-Lock Brake
System), TCS (Traction Control System), BAS (Brake
Assist System), ERM (Electronic Roll Mitigation), and
ESP (Electronic Stability Program). All five of these
systems work together to enhance vehicle stability and
control in various driving conditions.
Also, your vehicle is equipped with TSC (Trailer Sway
Control) and, if it has 4WD with the NV245 two-speed
transfer case, HSA (Hill Start Assist) and HDC (Hill
Descent Control).

The HDC is fucking magic, btw. 😀

 

[soccerballtux]

Any different than an anti brake system?
Pulses when brakes are locking up to retain some traction.

btw pretty sure this interferes with stopping distance on my car. It pushes the pedal back against me. I only just figured out if I put my whole foot into it, I can get it to brake better.

 

[ThatsABigOne]

If a driver CANNOT press the brake pedal hard enough to achieve max braking in a modern car with power brakes and ABS, then they have absolutely no business behind the wheel. If they HAVE not, in an emergency situation that would call for such a measure...well, they still have no business behind the wheel.

I really don't understand the need for this feature. It seems like one more thing to fail and provide conflicting feedback to the driver on how hard they are actually braking...which is, in fact, exactly what is happening here.

Truth.

 

[LTC8K6]

I would guess that studies showed that people were not braking as hard as their cars could brake in a panic stop.

 

[LTC8K6]

Here is a study from the 1970s. Concerning the standard brake force number used in FMVSS. Those numbers appear to be the same today. The study recommended reducing the force required because a large % of adult females tested could not apply enough force to the brake pedal.

http://archive.org/download/brakepedalforcec557radl/brakepedalforcec557radl.pdf

http://www.gpo.gov/fdsys/pkg/CFR-2012-title49-vol6/xml/CFR-2012-title49-vol6-sec571-105.xml

Full brake force 150 pounds in .3 seconds
Spike brake force 200 pounds in .08 seconds

Apparently a lot of adult females couldn't do those numbers when sitting in a car seat in that early study.

 

[DaTT]

As stated above, it sounds like power assist is failing...not this bizarre "press the brake pedal for you" gimmick.

 

[iamwiz82]

As stated above, it sounds like power assist if failing...not this bizarre "press the brake pedal for you" gimmick.

Especially since I don't believe the Cruze has automatic crash avoidance as an option :biggrin:

...spokesman Alan Adler said that in Cruzes with six-speed automatic transmissions and 1.4 liter turbo engines, there is the potential for "intermittent loss of brake assist," forcing drivers to apply extra pressure on their brake pedals to stop their vehicles.

Loss of power assisted brakes.

 

[Jimzz]

Yep sounds like people just got use to the power assist and then don't push hard enough when they need to.

Just like the other day I saw a idiot back into a yellow round poll. It was large and easy to see but since its narrow his backup sensors did not beep so he just kept coming and wamm.

All these things that makes cars safer just make people more dumb and leave common sense at home.

 

[Zap]

My guess is that these drivers have triggered Brake Assist, and it felt funny to them.

Let's see what the magic 8 ball says?

I would guess that studies showed that people were not braking as hard as their cars could brake in a panic stop.

I remember reading something like that. I think it may have been some car magazine test where the writers brought in their mothers to do some performance driving. These older women just would not press hard on the brake pedal. I don't think it was a matter of not being able to, but rather they were timid. I think one of them even said that they didn't press harder on the brake pedal because they didn't want to break it... even as they plowed into cones.

All these things that makes cars safer just make people more dumb and leave common sense at home.

😡

 

[ultimatebob]

Holy crap... I had this problem happen in my Cruze! For some reason, I had to slam on the brakes to get the sucker stopped in traffic just a few weeks ago. I just thought that it was a one time fluke... Guess not.

 

[HeXen]

I have driven old work trucks with over 300k miles and no maintenance so I'm pretty used to improper brakes.
Other things I do to aid stopping. Downshift, gently apply Ebrake, spin a 180 and hammer the gass....Had to do that on Ice before to prevent hitting the guy in front of me, worked out quite well.

 

[natto fire]

Seems like a stupid feature, IMO. I have never owned a car that I had problems with the regular vac booster/hydraulic system being able to overcome the tires. Starting with full on lock up (I started driving in the '90s and have always had older cars) and then ABS events. They always required efforts that did not seem very high to me, but I am not exactly in the worst shape I guess.

Just seems like it is more dangerous for the people behind you if you are using this system that automatically panic stops for you, even if you have an enormous amount of room in front of you. It's that tired old argument of having to over-engineer the vehicle to compensate for the bad driver.

 

[Zenmervolt]

Yep sounds like people just got use to the power assist and then don't push hard enough when they need to.

Much like with power assisted steering, power assisted brakes generally require more force if power assist is absent than non-assisted brakes did on their own.

Power assisted braking systems typically use a larger bore master cylinder because this keeps the vacuum assist from allowing the driver to press too hard on the pedal and build too much pressure in the system (a larger master cylinder bore means a harder pedal for a given system pressure, but the vacuum assist negates that). A non-assisted system would use a smaller-bore master cylinder to reduce the pedal pressure necessary to generate the appropriate system pressures.

When the vacuum assist on brakes fails, they become harder to press than a system designed to be naturally unassisted would be.

ZV

 

[LTC8K6]

http://www.arabnews.com/news/461691

Quoting CNN, Saudi Press Agency Sunday said, “GM has admitted that Cruzes with six-speed automatic transmissions and 1.4 liter turbo engines could experience 'intermittent loss of brake assist,' requiring drivers to hit brakes a bit harder to stop the vehicles.
“GM is aware of 27 alleged low-speed crashes but no injuries related to the brake performance, which could include this issue,” it said. The auto giant has said that owners of affected vehicles can get replacement microswitches free of charge at GM dealerships.
"Dealers will replace a switch in the power brake vacuum pipe assembly for free," it said.

 

[boomerang]

My Regal has brake assist. It also has the smallest booster I think I've ever seen along with a switch in the vacuum line to it. My guess is that the booster is small for weight reduction. Brake assist then becomes a necessity because in a panic stop situation, the small booster is not up to the task.

It's important to remember that many of the systems we see in modern cars are dictated by mileage requirements by our government. We'd still be driving around with carburetors, points and condensors, drum brakes and monster V-8's made out of cast iron otherwise. Increases in complexity mean increased costs for both the manufacturer and the consumer.

Hmm, should have looked before I posted...

http://auto.howstuffworks.com/car-driving-safety/safety-regulatory-devices/brake-assist.htm

 

[DaTT]

Much like with power assisted steering, power assisted brakes generally require more force if power assist is absent than non-assisted brakes did on their own.

Power assisted braking systems typically use a larger bore master cylinder because this keeps the vacuum assist from allowing the driver to press too hard on the pedal and build too much pressure in the system (a larger master cylinder bore means a harder pedal for a given system pressure, but the vacuum assist negates that). A non-assisted system would use a smaller-bore master cylinder to reduce the pedal pressure necessary to generate the appropriate system pressures.

When the vacuum assist on brakes fails, they become harder to press than a system designed to be naturally unassisted would be.

ZV

Exactly. Go out and press your brake pedal while the car is off, there is your unassited-power-assist brakes.

I had a Thunderbird SC that had a Teves II brake system...great when it worked but prone to failure. It was not vacuum assist, it was hydraulic assist, it failed on me quite a few times before I fixed it.

 

[LTC8K6]

My Regal has brake assist. It also has the smallest booster I think I've ever seen along with a switch in the vacuum line to it. My guess is that the booster is small for weight reduction. Brake assist then becomes a necessity because in a panic stop situation, the small booster is not up to the task.

It's important to remember that many of the systems we see in modern cars are dictated by mileage requirements by our government. We'd still be driving around with carburetors, points and condensors, drum brakes and monster V-8's made out of cast iron otherwise. Increases in complexity mean increased costs for both the manufacturer and the consumer.

Hmm, should have looked before I posted...

http://auto.howstuffworks.com/car-driving-safety/safety-regulatory-devices/brake-assist.htm

The booster in my Jeep is still large.

 

[Zenmervolt]

1.4 liter turbo engines could experience 'intermittent loss of brake assist,'

I'm betting it's a faulty check valve that works OK in the NA cars but doesn't fully stand up to the positive manifold pressure in the turbo engines. That would explain why it's only the turbo models affected.

ZV