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From: Dan on 15 Jul 2010 02:05
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.
From: Bill on 15 Jul 2010 10:33
"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.

The best source of information would be a factory service manual set of
books (sometimes 4 books to the complete set) which you can order from a
dealer. These have "descriptions of operation" for each thing in the vehicle
and will many times be quite detailed.

As to sensors, the following link sells easy to program microcontrollers,
robots, and sensors of all types. Click on Sensors, then Tilt, then you can
read all about how these work...
http://www.parallax.com


From: jim beam on 15 Jul 2010 12:09
On 07/14/2010 11:05 PM, Dan wrote:
> 2006 Corolla, when it's downhill and I press the brake pedal above a
> certain braking power, it shifts down the transmission.

it's supposed to.


> I was trying
> to figure out if that's a feature of the transmission

yes it is. it helps reduce brake load, thus premature wear, and in
extreme cases, brake overheating.


> and how does it
> know that the car is travelling downhill.

brakes are on, throttle is closed and speed is maintained above a
certain level.


> 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.

rubbish. any load from engine braking is well within the capabilities
of both engine and transmission and lower than when the gas pedal is down.


> BTW, no down shifting when braking on a level road.


--
nomina rutrum rutrum
From: jim beam on 15 Jul 2010 12:13
On 07/15/2010 07:33 AM, 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.

doesn't need tilt sensor - it has the engine rpm's and speed. otherwise
referred to as "grade logic". just map and program transmission shift
points accordingly.


> 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.

true dat.


>
> The best source of information would be a factory service manual set of
> books (sometimes 4 books to the complete set) which you can order from a
> dealer. These have "descriptions of operation" for each thing in the vehicle
> and will many times be quite detailed.
>
> As to sensors, the following link sells easy to program microcontrollers,
> robots, and sensors of all types. Click on Sensors, then Tilt, then you can
> read all about how these work...
> http://www.parallax.com
>
>


--
nomina rutrum rutrum
From: chuckcar on 15 Jul 2010 12:26
Dan <drnwnr(a)hotmail.com> wrote in news:b2648f19-54f7-4d7e-b8e2-
af76934b592c(a)r27g2000yqb.googlegroups.com:

> 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.

Well if you slow down, the car will shift to a lower gear. You *do* realize
that don't you?

How many speeds in your automatic transmission? That certainly will have an
effect as well.

As for "straining" he transmission and engine, just how many RPM are you
getting up to when this happens?

--
(setq (chuck nil) car(chuck) )
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