How Toyota Brake Override Works

In an attempt to put to rest increasing concerns that the fix to be implemented in the millions of vehicle recalled due to unintended acceleration, Japanese carmaker Toyota decided to detail how its other extra-safety measure, the brake override, works.

As you know, the brake override system is not the same thing with the fix found for the accelerator problem. To fix unintended acceleration, Toyota designed a "precision-cut steel reinforcement bar" which will be installed into the accelerator assembly to reduce "the surface tension between the friction shoe and the adjoining surface". This in turn, Toyota says, eliminates the cause of the stuck accelerator problem.

The brake override system on the other hand, soon to be installed in all Toyota vehicles, is built to help the driver override acceleration by applying the brakes. Built to be unobtrusive in normal driving conditions, the override kicks in as soon as, at speeds greater than five miles per hour, the brakes are applied firmly for longer than one-half second.

If this occurs, the override reduces engine output to the idle position, allowing greater braking performance. If when the brake is no longer applied the engine speed does not return to normal operation, Toyota... advises owners to stop the car, shut off the engine and than call a dealer.

Below are excerpts from Toyota's release, showcasing how the system works in normal driving conditions.

"The feature has sophisticated control logic intended to eliminate undesirable or inappropriate activation and is designed to be imperceptible.  In certain driving conditions, unnecessary activation of brake override would create an inconvenient or even unsafe situation."

"For example, the brake override feature does not operate if the brake pedal is depressed before the accelerator pedal.  This logic allows for vehicles starting on a steep a hill to safely accelerate without rolling backwards, otherwise known as a hill start."

"Toyota engineers have carefully calibrated the system control logic to prevent the system from interfering with efforts to free a vehicle by rocking it to gain traction in snow or mud. Since some drivers prefer to brake with the left foot, the system also recognizes this as an intentional action by the driver and will allow the accelerator to function normally."
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About the author: Daniel Patrascu
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Daniel loves writing (or so he claims), and he uses this skill to offer readers a "behind the scenes" look at the automotive industry. He also enjoys talking about space exploration and robots, because in his view the only way forward for humanity is away from this planet, in metal bodies.
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