For a number of years, Toyota Motors, as well as almost every other car manufacturer, has been using advanced electronics in its throttle systems and braking systems. There is nothing new in this technology. Many operators of newer cars are probably unaware that they are not applying pressure to a conventional gas pedal. In other words, there is no mechanical connection between the gas pedal and the actual throttle. What we are really doing is applying pressure to an electrical device that informs the power-train computer of our desired throttle angle (vehicle speed). The power-train computer will then command an actuator on the vehicles engine to allow more air and fuel to enter the engine.

In the case of the Toyota gas pedal recall, the vehicle’s floor mats are interfering with the gas pedal returning to the closed throttle (idle) position. Toyota uses two different manufacturers for the in-car electronic gas pedal. Both Nippondenso and CTS Corporation supply electronic pedals to Toyota. The CTS-manufactured pedals are the only pedals experiencing the floor mat interference problem. Toyota has advised all owners of vehicles affected not to add additional floor mats to the vehicles and to use only Toyota supplied mats. The Toyota original equipment floor mats come with hold-down clips that prevent the floor mats from working their way into an interference situation with the electronic gas pedal.

Further, Toyota has sent to each of its dealers a shim kit which will slightly alter the position of the CTS-manufactured pedal assemblies, allowing for more floor mat clearance. In addition to modifying the CTS-manufactured pedal position, Toyota Motors is reprogramming the onboard computer so it will be able too distinguish between an actual acceleration request from the operator and/or a braking request. In the future, operators of Toyota vehicles with these electronic gas pedals will not be able to “fool” the onboard computer into an acceleration event if the brake pedal is applied.

Many Toyotas and domestic manufacturers also use an electronic-controlled steering system. These systems have been around for quite some time. Electronic steering systems utilize an electric motor to supply hydraulic pressure to the steering gear assembly instead of a traditional mechanical pump. When we turn our steering wheels, the

onboard computer senses many vehicle operating parameters and then determines the exact amount of pressure necessary for any given vehicle speed or operating condition. In the event of an electrical steering system failure, the vehicle will still have a mechanical back-up steering system available to us. Steering our cars under these conditions would be like steering a car without power steering.

Both the systems mentioned above are a part of the new “drive-by-wire” electronic systems in today’s vehicles. Every manufacturer is using this technology. They are very similar to the way modern aircraft operate. Although most of us are unaware of these drive-by-wire systems operating on our cars, they have actually been in use for a long time. They break down less then the mechanical systems they replaced. These systems are lighter and smaller in size. They help manufacturers decrease the overall weight and size of a vehicle and, therefore, improve our fuel mileage.

Prius brake recall

The 2010 Toyota Prius hybrid is experiencing another type of problem altogether. The Prius hybrid uses two different types of braking systems. One of these systems slows the vehicle down while recharging the Prius’s

on-board battery. This is referred to as regenerative braking. The other braking system is a traditional hydraulic assisted braking system used for years on cars and trucks.

There is no problem with either of these braking systems. Both the regenerative braking system and the conventional braking systems on the Prius perform as engineered. A problem occurs during the transition from the regenerative braking feature to the conventional braking function. Toyota has reprogrammed the braking computer to shorten the transition time between the two braking systems.

During certain operating conditions, an unwanted or unscheduled transition would occur. This most often happened when the Prius went over a bump such as a pothole or railroad tracks with the brakes applied. Toyota indicates that no actual loss of brakes will occur. However, the sensation of loss of brakes occur because of the vehicle entering an unscheduled transition phase.

Understanding how our vehicles perform is essential for their safe operation. Driving one of these new breed of high-tech cars can be quite different then driving an “old-school” car or truck. The level of technology onboard today is really amazing. These new-age electronic vehicles incorporate vast amounts of sensors and actuators to accomplish a given task. Overall, they are much more dependable then the mechanical systems they replaced.

Any time a recall happens, our confidence in these vehicles and companies will be tested.

As consumers, we can only sit back and see how Toyota resolves these issues.

Once these problems are fixed, there should be no reason to not have confidence in Toyota again.

Nick Shultz is an instructor of Automotive Technologies at Owens Community College. He is an arbitrator for the Better Business Bureau who specializes in cases involving the Ohio and Michigan Lemon laws. He is a certified master automotive technician by ASE, General Motors Corp. and Ford Motor Co. E-mail your auto questions to news@toledofreepress.com.

Tags: Prius recalls, Toyota

This entry was posted on Thursday, February 11th, 2010 at 9:39 pm and is filed under Auto Sense, Wheels.
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