Toyota Prius Controls  
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CONTROL


MYTH BANISHMENT #4
It takes special knowledge or training to drive a hybrid automobile.




Control Systems

There's nothing new to learn when driving a Toyota Prius that results from the fact that it's a gas-electric hybrid. There are some outstanding new features that make the car more enjoyable to operate, but these are the result of advancement rather than necessity.

The same controls that operate standard cars are used to control the major functions of the Prius as well. The hybrid system is most noticable when operating the accelerator or the brake pedal. I describe it as two stage operation for both pedals (I'm certain this is an oversimplification). When accelerating, the car's computer judges how much power is needed based on how quickly you push down. A relatively gentle press on the accelerator starts the car moving with the electric motor; at about ten miles per hour, the gas engine bumps quietly to a start and starts pulling.

When braking there's an analogous response. Braking lightly starts the regenerative braking, where the car's momentum is used to turn its generators and recharge the batteries. Hard braking brings in the car's normal braking system to stop the car more quickly. Since ABS is standard in the Prius, there's also another stage, but it's used much less often.

Another interesting feature of the cars control systems is that they're all electric powered. The power steering, power brakes, and even "engine braking" all have to work when the internal combustion engine (ICE) isn't running.

Control Layout


The control layout in the Toyota Prius does take a little getting used to. The controls are arranged more around the center of the vehicle than the driver's side. Most of the digital gauges such as the speedometer, the odometer and dual trip odometers, indicators and signals are at the top center of the dashboard.

The speedo numbers are large and visible. People have pointed out that someone in a nearby car can read how fast the car is going. It just means I have to be more careful. From what I've read, the down-the-middle organization makes it easier for Toyota to sell this car in the USA as well as Japan, where they have left side drive.

The controls that have to be near the driver's hands and feet are, of course. The cruise control is on the steering wheel, and the pedal layout is identical to that of standard US vehicles. The one control that seems out of place is the shift lever. As you can see from the picture above, it's on the dash, just to the right of the steering wheel.

Since I have used automatics with both center ridge and steering wheel mounted shift levers as well as standard transmission, it didn't take me long to adapt to this location. Toyota would have had a hard time putting it anywhere else. The two nitpicks I have are that it makes a couple of the dash controls hard to see, and its location made Toyota move the windshield wiper stalk to a higher, less intuitive location on the steering column.

That's my only complaint, though, and it's more than compensated for by the nerve center of the Prius dashboard - its graphical display.


Touch-Screen Display

Some of the useful features the touch screen display provides are

  • Energy monitor with battery charge level, current engine status, outside temperature
  • Bar graph of fuel efficiency for trip, current and accumulated MPG
  • Control of all audio equipment including FM/Text, cassette tape, and optional CD players
  • Maintenance schedules including on-screen reminders
  • "Secret" Diagnostic displays of scan codes and system status
  • Optional touch-screen controlled GPS Navigation System

I'm still amazed at how well the controls for this vehicle have been integrated with its touch-screen display. There are a handful of buttons and switches on the dashboard as well. These are controls that you'd expect to be in specific places, such as the electronic climate controls, defroster, hazard lights, and optional cruise controls. There's also a handful of buttons for less used features of the car's audio system.

Diagnostics

For those who are interested, I've taken some photos of the diagnostic screens that can be displayed on the Prius touchscreen if you use the "secret" screen taps to bring them up. To bring up the diagnostic menu, do the following.

  1. Park the car and engage the emergency brake.
  2. Bring up the energy monitor display (shown above) by tapping the "INFO" button on the dash and selecting the "Trip Information" icon.
  3. Bring up the Display "overlay" controls by touching the Display Button on the dashboard.
  4. If there's anything tricky about this, it's this step. The Display overlay forms an oval box around the large center portion of the touchscreen. The invisible control areas for bringing up the diagnostic menu are just inside this box at the left edge. Tap once in the upper left corner of this box, then once in the lower left corner. Repeat this twice for a total of six taps.
  5. At this point, you should be looking at the diagnostics menu. If the stereo was on, it will cut off automatically.
  6. In order to exit diagnostic mode, switch the key to off, then on again.

A Brief Tour of Diagnostic Screens

These two screens pertain to diagnostic codes. The one on the left shows all of the vehicle systems and will check for any codes that have been recorded in the computer's memory. The one on the right is a detail level view that can be displayed for any codes that have been reported.

This screen is the display diagnostic menu. It lists a variety of checks that can be performed to diagnose and calibrate the display system.

These color bars are an example display diagnostic mode.

The display menu also lists this selection, which is Vehicle Signal Check. Not sure why it's included in the display list. It shows a handful of sensor readouts including the 12V standard battery's voltage, vehicle speed, and parking brake status.

If you have the Navigation System option, there's a diagnostic menu with a number of selections for this feature.

The GPS Information display shows the GPS sattelites currently being read and their locations.

There's another vehicle signal display for GPS diagnostics. These sensors are used by the GPS system to determine the car's velocity and orientation.


For technical information on the Prius control systems and much else, check out the Yahoo online group Prius_Technical_Stuff. It requires obtaining a free membership, but this is a great source of information for Prius owners who want to dig deeper into the impressive technology that's been bundled into this little car.

Next: The Toyota Prius Navigation System