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Discussion Starter #1
I haven't had much opportunity to drive our new RAV4 as it's primarily the Mrs' ride. The only two issues she's reported to me were very easily resolved, i.e. sliding the visor mirror closed to turn off the light and informing her that the interior lights are supposed to come on when you shut off the engine and stay on for approx 30 secs afterwards. Other than that she absolutely loves her little SUV. I like it too and would like to know more about it.

Two things that I've had to adj to in the few times I've driven it is the steering and brakeing. I'd like to touch on the steering at this point.

In checking out the steering and in reading alittle about it, I'd like to know more about this electrically assisted power steering. I'm from the old school that taught me that you had to have an engine mounted hydraulic pump/resovoir and high pressure lines from it to the modified gear box and this consituted your power steering. It worked fine but it did rob the engine of some power to work and it took up precious space. Later technology introduced this new fangled McPherson Strut power steering pkg and it too had an engine mounted pump but it cut down in the steering components, hense weight & size of the steering pkg.
Now we this even newer fangled Toyota electrically assisted power steering pkg and this is an entirely new beast to me!
In checking it out I've discovered that the tiny, and I do mean tiny electrical motor/assist assembly is so compact that it fits right in under the dash. Right behind the instument cluster. And instead of being out in the sometimes harsh elements of the engine compartment, it resides in the conditioned operators compartment. No engine mounted pump and no high prssure lines snakeing around in the engine compartment. Matter of fact, theres not much of anything hanging out in the engine compartment related to the steering assembly that isn't enclosed in some sort of protective cover. Gotta say that I'm somewhat impressed with both the simplicity and cleanness of this concept.
I don't know how long it's been around nor what other models utilize this technology but it's a 1st for me.
The steering is effortless and even though it seems I don't feel or sense the road through the linkages as I'm used to with older autos, I don't necessarily consider this a bad thing. Just different.
It seems just as responsive as the traditional steering pkgs.

I used to be against loading the electrical system down powering subsystems that were traditionally powered mechanically by the engine and I've now come to realize that inorder to squeeze as much MPG out of each gallon of fuel, that moving such things as cooling fans, the myriad of vaccum assisted controllers and now the power steering to being electrical components is just another step forward in the evolution of automobiles. And when I think about it alittle deeper, the union of electrics and mechanics has been an ongoing and positive marriage of differing technologies in our auto's for decades now and the reliability of both seems to have surpassed the older technologies that many of us have grown up with. In other words, motor + electrics = GOOD! :D

So, with all that said, anyone know who originated this new approach to power steering and what other manuf's / models utilize it?

Volfandt
 

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Discussion Starter #3
Power steering...

I do believe you're right :shock: :D

I'm surprised that I haven't run across electrically assisted power steering before.
Course I may have but don't recall.
Looks like TRW is a big player in this auto technology.

In reading the attached TRW link, the TRW version (are there others?) can draw a max of 70 amps @ 13.5volts. Hummmm, now I'm going to have to research the charging system to see how this puppy is set up to keep all these electrical wonders supplied with power......

Volfandt

http://www.trw.com/images/cha_steering_suspension_english.pdf#search='electrically%20assisted%20power%20steering'
 

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trw huh? very good company. This is the supplier to ours??

Some charging systems stuf on the Rav.

Its a 'smart' charging system. Upon acceleration and idling the alternator cuts all the way back and charges very little (to help with gas mileage) and upon deceleration it charges its maxium amount. This helps slow the truck down and the full field charge of the alternator does not effect gas mileage. How cool is that?
 

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Discussion Starter #5
Chargeing

Yep, thats neat. But it opens up a whole 'nother can of worms :shock: :D

It appears that the patent for the electrically assisted steering come from a German or European source in 1998 and and I've seen where Honda is useing it, I don't know the models but I'd suspect the CRV. It's projected to be in about 90% of all new vehicles by 2010.

Now lets talk about this chargeing system. With the kind of smarts it has, that surely means that theres more than just an alternator, rectifier and regulator involved.
Wonder what other modules/assemby's are involved in controlling the chargeing system?

Volfandt
 

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:) Hows this??


11. Charging Control
General
This system lowers the generated voltage when the vehicle is idling or is being driven at a constant speed,
and raises the generated voltage when the vehicle is decelerating. This reduces the load on the engine as
a result of the electric generation of the generator, thus contributing to the fuel economy of the engine.
During acceleration, this system regulates the generated voltage in order to place the amperage estimation
value close to the target value.
 This control consists of the ECM, battery current sensor with a built-in battery temperature sensor,
generator, and various sensors and switches.
 The ECM detects driving condition based on signals from various sensors and switches, and detects
charging condition based on signals from the generator, battery current sensor and battery temperature
sensor. Then the ECM outputs signals to the IC regulator to control the genetated voltage of the generator.
The ECM stops the charging control and the generator switches to normal power generation mode under
the following conditions:
 Low battery capacity
 Low or high battery temparature
 Wipers operating or blower motor operating with tail lamp relay ON
 System Diagram 
ENGINE - 2AZ-FE ENGINE
281EG86 258AS61
Output
Voltage
5 (V)
0
- 100 Current +100 (A)
Characteristic of Current Sensor
288EG61C
60 (C)
Battery Temperature
0
Resistance
(kW)
6
EG-66
Battery Current Sensor
Installed on the negative terminal of the battery, this sensor detects the amount of charging and discharging
amperage of the battery and sends signal to the ECM. Based on this signal, the ECM calculates the battery
capacity. A Hall IC is used for detecting the amount of charging and discharging amperage. The changes
that occur in the magnetic flux density in the core as a result of the charging and amperage of the battery
are converted and output as voltage.
Batter Temperature Sensor
 The battery temperature sensor is built into the battery current sensor.
 The battery characteristic (battery internal resistance) of taking in current for charging varies according
to battery electrolyte temperature. If the electrolyte temperature is too low or too high, the battery internal
resistance will increase, resulting in early deterioration. To prevent this, the battery temperature sensor
changes its resistance as shown below to detect the temperature.
ENGINE - 2AZ-FE ENGINE
Service Tip
To clear the DTC that is stored in the ECM, use a hand-held tester or disconnect the battery terminal
or remove the EFI fuse for 1 minute or longer.
EG-67
Fail-safe
Due to a failure in the battery current sensor or battery temperature sensor, the ECM may determine the
necessity of performing a fail-safe operation. Then, the ECM stops the charging control and the generator
switches to the normal power generation mode.
When the ECM detects a malfunction in a sensor, the ECM memorizes the DTC (Diagnostic Trouble Code).
The MIL (Malfunction Indicator Lamp) does not illuminate.
 DTC Chart 
DTC No. Detection Item DTC No. Detection Item
P0516
Battery Temperature Sensor
Circuit Low
P1551
Battery Current Sensor
Circuit Low
P0517
Battery Temperature Sensor
Circuit High
P1552
Battery Current Sensor
Circuit High
P0560 System Voltage P1602 Detection of Battery
P1550
Battery Current Sensor
Circuit
12. Diagnosis
 When the ECM detects a malfunction, the ECM makes a diagnosis and memorizes the failed section.
Furthermore, the MIL in the combination meter illuminates or blinks to inform the driver.
 The ECM will also store the DTCs of the malfunctions. The DTCs can be accessed by the use of the
hand-held tester.
 For details, refer to the 2006 RAV4 Repair Manual (Pub. No. RM01M1U).
13. Fail-safe
When a malfunction is detected at any of the sensors, there is a possibility of an engine or other malfunction
occurring if the ECM were to continue to control the engine control system in the normal way. To prevent
such a problem, the fail-safe function of the ECM either relies on the data stored in memory to allow the
engine control system to continue operating, or stops the engine if a hazard is anticipated. For details, refer
to the 2006 RAV4 Repair Manual (Pub. No. RM01M1U).
 

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So how does this electric power steering work? Is there a position indicator that inputs into the electric motor and the motor turns the rack and pinion thru a gear box?????
 

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Discussion Starter #8
Flyingn, sorry didn't address your question. I don't know if it's TRW that makes the steering assembly, I'd almost suspect it would be Denso as they make quite a few of the electromechanical assemby's for Toyota. Theres several plants around my area.

When I looked up under the dash to see this marvel for myself, it appears very similar to the TRW pic in the webpage I linked.

Now that info on the charging system is what I'm looking for. Does someone have a shop manual on one of these new RAV4's :wink: :D Sounds like theres some serious engineering going on with making these auto's more fuel efficient.

Gman, the way I read it, the electrical motor assists the std steering column and only draws power when the wheel is turned. I'd guess that there is some sort of position control sensor located on the part of the steering column that goes through the electrical assist assembly. According to TRW's website, the assembly has programmable features built in.

The whole assembly is very easy to see, just look up under the dash on the drivers side.

I noticed some folks w/the V6's complaining about some sort of noise that comes out from behind the dash at times, this assembly may be something they should check. Especially if it only happens when the wheels are turning. In the few times I've driven my wifes I4 I haven't noticed any creaks or sounds anywhere. Course it's only got around 650 miles on i and I've not seen much of her or the RAV4 since we brought it home. Hummmm, that almost seems to be a good thing :shock: :shock: :D :D

Volfandt
 

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The G Man said:
So how does this electric power steering work? Is there a position indicator that inputs into the electric motor and the motor turns the rack and pinion thru a gear box?????
Email me . I will email you a PDF on how it works..

[email protected]
 

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Discussion Starter #10
RAV4

Well I got to haul 4 adults in the RAV the other evening and that I4 didn't have any problems at all with move'n on in both bumper to bumper and interstate environs. It definitely knew it had more load but it didn't phase it, it just grunted alittle louder :D
We all said that the RAV wasn't to shabby at all for a 4 banger :D Course the Mrs said "slow it down, your burning MY gas" :shock: :D

The brakes have an all together different feel than what I'm used to. This is my 1st 4 wheel disc brake setup but I don't think that is what gives it the different feel.
I believe it has something to do with the stability control.
The thing that I notice is that even though I am not applying any more pedal pressure as I'm trying to do a slow stop, the brakes system seems to sense my foot pressure and attempt to stop it alittle sooner than I expect. The Mrs hasn't noticed this and I'm not saying that it's a bad thing, it's just a different thing :D
With all the smarts built into both the steering and charging systems ( and we've not even touched on the engine or tranny yet) I'd like to know alittle more about the braking system on the 2wd and 4wd RAV's.

Volfandt
 
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