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Old 01-30-2010, 09:02 AM   #99
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Originally Posted by Denis4x4 View Post
So, is drive by wire really progress and what does it really do to make cars/trucks better?
Through out history folks have questioned up to date technology but in the end it seems to work better than the old ways.

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Old 01-30-2010, 05:33 PM   #100
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Here is a link to some mug shots of the suspect part along with a video:

Exclusive Video: Up Close With Toyota's Recalled Accelerator Pedal

I've got lousy WiFi and haven't been able to play the video yet.
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Old 01-30-2010, 06:33 PM   #101
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Thnxs for the link Al. Assuming the info is correct it looks like a bind in the pedal pivot, shaft/bushing, is the root problem. Makes sense.
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Old 01-30-2010, 06:35 PM   #102
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Boy I would love to see an effected throttle. I would want to see the actual position of the magnet after the problem has happened.

It is hard to envision that the bearing if used on a regular bases could become so defective that it could not overcome the spring tension of the return spring. Look at the difference in the 2 moment arms. The mechanical advantage favors the spring. I can see the magnet or the sencor, which ever is the upper part falling free and thus feeding a false signal to the CPU.
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Old 01-30-2010, 06:44 PM   #103
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Boy I would love to see an effected throttle. I would want to see the actual position of the magnet after the problem has happened.

It is hard to envision that the bearing if used on a regular bases could become so defective that it could not overcome the spring tension of the return spring. Look at the difference in the 2 moment arms. The mechanical advantage favors the spring. I can see the magnet or the sencor, which ever is the upper part falling free and thus feeding a false signal to the CPU.
YouTube - Toyota Recall - a look inside the Gas Pedal and all its parts - a YouTube first
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Old 01-30-2010, 08:10 PM   #104
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Well we are getting somewhere now.

They have clearly discounted the floor mat, corrosion, and the return spring.

A floor mat Behind the pedal, as suggested by Toyota, would tend to hold the pedal off the higher throttle settings. Corrosion would be clearly evident upon inspection of any of the failed systems. The return spring, as demonstrated in the video, has significant pressure to overcome all but a clear mechanical jam, again that would be evident on any of the failed systems.

It also appears unlikely that the sensor, that is connected to the wiring could dislodge and fall out of position. Any disconnect of the sensor would cut off the signal to the CPU.

Since there are several wires leading to the sensor we can assume there an electric circuit in the sensor that detects changes in the magnet field induced by the magnet position with respect to the sensor. Could that circuit be failing and feeding a false signal to the CPU?

The fact that the cases reported to date all seam to be sudden and significant in reaction and showing no evidence of mechanical failure put one back to thinking electrical.

Unfortunately all too many electrical circuits of this nature are POTTED in had plastic so investigation of the individual components, when the circuit is opened, is almost impossible. External bench testing would determine if the sensor does or does not work. A yes or no game and replacement of the defective part without a good explanation.

At least when the GM windshield wipers failed, assuming it did not set the car on fire, you could get inside and see the broken foil on the board and fix them
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Old 01-30-2010, 08:22 PM   #105
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this was briefly mentioned earlier by anther poster, but passed over.

with drive by WIRE systems, depressing the brake pedal should CUT the accelerator input...correct???

in daze of old one could HOLD down the brake pedal and REV the engine on automatics...

on my drive by wire car (with an AT) that's not possible, the accelerator input cuts out while the brake is held down...

IF the toyota system doesn't operate that way, the issue would seem to go beyond sticky mechanical parts.

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Old 01-30-2010, 10:14 PM   #106
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Originally Posted by HowieE View Post

Since there are several wires leading to the sensor we can assume there an electric circuit in the sensor that detects changes in the magnet field induced by the magnet position with respect to the sensor. Could that circuit be failing and feeding a false signal to the CPU?

The fact that the cases reported to date all seam to be sudden and significant in reaction and showing no evidence of mechanical failure put one back to thinking electrical.
ETCS-I system

1) Electronic Feedback loop controls are not present. Whenever the brake pedals are depressed, the ECU must monitor the engine speed and vehicle speed. If the speeds have not been reduced, the ECU must cut out the following:
i) ignition to the coils.
ii) fuel cuts to the injectors
iii) combination of ignition and fuel cuts.
Toyota ECU fails to include i,ii, and iii. The domestic American cars have these safety feedback control systems built in.



YouTube - 1998 Supra Electronic Throttle Control System
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Old 01-31-2010, 09:10 AM   #107
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If I heard right that ,1998 system, was Throttle Cable Controlled with the ECU reading and interpreting the cable position and in turn setting the throttle plate. It make no mention of controlling the fuel injection timing ot duration, the second have of power application.

At the end of the video he mentions a FAIL SAFE override that I believe is nothing more than a LIMP MODE mechanical override.

The current system is a fly by wire system.

Something that has not been discussed enough is the comparison of brake horse power compared to engine horse power. Think about it. It takes close to a 1/4 mile or more for the average car to accelerate to 60 mph. It takes far less to stop that car from 60 mph when applying the brakes. Another consideration is the stall test. Stand on the brakes and apply full throttle. In each case the brakes will win. Toyota's suggestion to Stand on the brakes should stop the car and avert disaster allowing one time to have the problem corrected.
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Old 01-31-2010, 09:26 AM   #108
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If I heard right that ,1998 system, was Throttle Cable Controlled with the ECU reading and interpreting the cable position and in turn setting the throttle plate. It make no mention of controlling the fuel injection timing ot duration, the second have of power application.

At the end of the video he mentions a FAIL SAFE override that I believe is nothing more than a LIMP MODE mechanical override.

The current system is a fly by wire system.

Something that has not been discussed enough is the comparison of brake horse power compared to engine horse power. Think about it. It takes close to a 1/4 mile or more for the average car to accelerate to 60 mph. It takes far less to stop that car from 60 mph when applying the brakes. Another consideration is the stall test. Stand on the brakes and apply full throttle. In each case the brakes will win. Toyota's suggestion to Stand on the brakes should stop the car and avert disaster allowing one time to have the problem corrected.
More detailed info........

http://www.ncttora.com/fsm/2003/4run...-fe_etcs-i.pdf
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Old 01-31-2010, 09:40 AM   #109
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WOW, how comforting...they use a DC motor to control the throttle, and we all know how reliable they are, long term.

I for one would be much happier with a cable attached to a throttle pedal/lever.
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Old 01-31-2010, 10:01 AM   #110
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WOW, how comforting...they use a DC motor to control the throttle, and we all know how reliable they are, long term.

I for one would be much happier with a cable attached to a throttle pedal/lever.
That is the Toyota Drive By Wire system. Toyota has several different options on them. This particular one has the traction control. When the ECM seen that the gearbox speed sensor acceleration/speed does not conform to to wheel speed sensor(s) output, it can reduced the throttle valve opening through the throttle servo motor. Toyota does not have a brake software to override the throttle in the event the servo motor sticks, if condensation builts up in the dual sensors of the gas pedal (which would produce the wrong return voltage), or EMI (Electro Magnetic Interference) prevention (the ignition coils, injectors and other electronic/electrical units produce EMI).
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Old 01-31-2010, 12:54 PM   #111
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Hans, the Toe Vehicle has a drive by wire system. Actually it is a drive by cable system.
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Old 01-31-2010, 07:00 PM   #112
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Originally Posted by 2airishuman View Post
...

with drive by WIRE systems, depressing the brake pedal should CUT the accelerator input...correct???

in daze of old one could HOLD down the brake pedal and REV the engine on automatics...

on my drive by wire car (with an AT) that's not possible, the accelerator input cuts out while the brake is held down...

IF the toyota system doesn't operate that way, the issue would seem to go beyond sticky mechanical parts.

cheers
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