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From: Hachiroku ハチロク on 15 Jul 2010 18:16
On Thu, 15 Jul 2010 07:33:03 -0700, Bill wrote:

> "Dan" wrote in message
>> 2006 Corolla, when it's downhill and I press the brake pedal above a
>> certain braking power, it shifts down the transmission. I was trying to
>> figure out if that's a feature of the transmission and how does it know
>> that the car is travelling downhill. It's probably intended for adding
>> engine braking but sometimes it's just annoying since revs go up and it
>> strains the engine and transmission.
>> BTW, no down shifting when braking on a level road.
>>
>>
> That could be done fairly easily with a tilt sensor as well as input from
> the brake pedal and speed sensors. You might find information on this in
> your owner's manual? Don't ask a salesman because they don't understand
> technical things and you will likely get misinformation.

And this is a shame. Toyota salesmaen (most of them) used to really know
the product and could answer the questions. Now, they're *just* salesman
and would be selling Fuller brushes if they weren't selling Toyotas...


From: Hachiroku ハチロク on 15 Jul 2010 20:02
On Wed, 14 Jul 2010 23:05:02 -0700, Dan wrote:

> 2006 Corolla, when it's downhill and I press the brake pedal above a
> certain braking power, it shifts down the transmission. I was trying to
> figure out if that's a feature of the transmission and how does it know
> that the car is travelling downhill. It's probably intended for adding
> engine braking but sometimes it's just annoying since revs go up and it
> strains the engine and transmission.
> BTW, no down shifting when braking on a level road.

It should be freewheeling. The only time it should downshift is when the
rpms and the speed gets below a certain level, and I'm not sure what that
would be for your car. It seems you should be going fairly slow before the
trans downshifts.

I would have the operation of the trans ECU checked.


From: Paul on 15 Jul 2010 23:24
Dan wrote:
> 2006 Corolla, when it's downhill and I press the brake pedal above a
> certain braking power, it shifts down the transmission. I was trying
> to figure out if that's a feature of the transmission and how does it
> know that the car is travelling downhill.
> It's probably intended for adding engine braking but sometimes it's
> just annoying since revs go up and it strains the engine and
> transmission.
> BTW, no down shifting when braking on a level road.

I have never heard of any normal car doing that.
There are no level sensors that I have ever heard of.
Most cars down shift according to rpm and speed.
But it is at slow speeds. Like under 20 mph.
Is your trans fluid level normal?
Screen clean?
From: Bill on 16 Jul 2010 00:01
> There are no level sensors that I have ever heard of.
>

Vehicles are now more sophisticated than the first rockets to go into outer
space...

Bosch Automotive Sensors...

Drivetrain Safety Convenience features
Radar distance sensor
(Headlamp aiming system)
(Vehicle dynamics control)
(ACC, precrash)
Tilt sensor
Acceleration sensor (Airbag)
Tilt sensor (Vehicle security sensor)
Torque sensor (Power steering)
(Roll over sensing)
Angular rate sensor
Rotional speed sensor
Yaw rate sensor
Seat occupancy sensor (Airbag)
Manifold absolute pressure sensor
(Electronic diesel control, motronic)
Angular rate sensor (Navigation)
Air quality sensor (Air conditioning control)
Humidity / temperature sensor
(Heating and air conditioning control)
Pressure sensor
(Central locking system)
Rain sensor
(Wash/wipe control)
Pressure sensor (Electronic
transmission control, motronic)
Mass air flow sensor (Motronic)
Knock sensor (Motronic)
Atmospheric pressure sensor
(Motronic)
Oxygen sensor
Angular position sensor
(Motronic)
Tank pressure sensor
(On board diagnostics)
Rotational speed sensor (Electronic
transmission control, motronic)
High pressure sensor
(Vehicle dynamics control)
Steering wheel angle sensor
Acceleration sensor
High pressure sensor
(Fuel injection system, common rail)
(Antilock braking system)
(Antilock braking system)
(Vehicle dynamics control)
Ultrasonic distance sensor
(Rear proximity warning system)

Above from...
(See page 2 - take awhile to load after downloading)
http://robotics.eecs.berkeley.edu/~pister/etc/Bosch.pdf


From: jim beam on 16 Jul 2010 01:16
On 07/15/2010 09:01 PM, Bill wrote:
>> There are no level sensors that I have ever heard of.
>>
>
> Vehicles are now more sophisticated than the first rockets to go into outer
> space...

"electronic" != "sophisticated". there was a /lot/ of technology that
went into space. and a lot of it was bleeding edge. the stuff that
finds its way into consumer cars is /way/ down the food chain. it has
to be to be cheap.


>
> Bosch Automotive Sensors...
>
> Drivetrain Safety Convenience features
> Radar distance sensor
> (Headlamp aiming system)
> (Vehicle dynamics control)
> (ACC, precrash)
> Tilt sensor

that tilt sensor is for lateral stuff - like ditching.


> Acceleration sensor (Airbag)
> Tilt sensor (Vehicle security sensor)

and that one is as advertised.


> Torque sensor (Power steering)
> (Roll over sensing)
> Angular rate sensor
> Rotional speed sensor
> Yaw rate sensor
> Seat occupancy sensor (Airbag)
> Manifold absolute pressure sensor
> (Electronic diesel control, motronic)
> Angular rate sensor (Navigation)
> Air quality sensor (Air conditioning control)
> Humidity / temperature sensor
> (Heating and air conditioning control)
> Pressure sensor
> (Central locking system)
> Rain sensor
> (Wash/wipe control)
> Pressure sensor (Electronic
> transmission control, motronic)
> Mass air flow sensor (Motronic)
> Knock sensor (Motronic)
> Atmospheric pressure sensor
> (Motronic)
> Oxygen sensor
> Angular position sensor
> (Motronic)
> Tank pressure sensor
> (On board diagnostics)
> Rotational speed sensor (Electronic
> transmission control, motronic)
> High pressure sensor
> (Vehicle dynamics control)
> Steering wheel angle sensor
> Acceleration sensor
> High pressure sensor
> (Fuel injection system, common rail)
> (Antilock braking system)
> (Antilock braking system)
> (Vehicle dynamics control)
> Ultrasonic distance sensor
> (Rear proximity warning system)
>
> Above from...
> (See page 2 - take awhile to load after downloading)
> http://robotics.eecs.berkeley.edu/~pister/etc/Bosch.pdf
>
>

not all of those are used on all vehicles. the high end, especially
4wd's use all the tilt/stability stuff to help with poor handling
dynamics fundamentals. "real" cars don't need it to anywhere near the
same extent.




--
nomina rutrum rutrum
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