PDF file of the official CHP report on the Sikes affair

While there's a possibility the car was in a malfunction state and very difficult to duplicate, it's confirmed you needed to press the brake pedal at least 50% in order to kill the throttle. One can in theory apply an indefinite times of braking without triggering a single log of the throttle being killed as long as you stay under 50%.

Only Toyota knows what these log data really mean. The rest of us can only speculate based on limited information offered us.

 

I can't say for the 2010, but with my Gen II Prius, the ABS system does not "hammer" the brakes. The ABS system on my 2006 is virtually undetectable without the indicator light.

Tom

 

Yes, I noticed that the Prius has LINEAR manifold brake pressure porting for each wheel along with pressure sensors for each wheel but didn't realize they were also used for ABS.

I would vote that they restore the "hammering" effect so the driver gets a better "headsup" about ABS activation. Or at least "vibrate" the brake pedal.

 

"..at least 50%...

The factory documentation seems to indicate that when the brake light switch is triggered the system goes into braking mode, regen if possible/needed. That would mean a very light touch on the brakes would disable the forward "DRIVE" system.

 

No, that's a different issue. We're talking about brake override (as in killing the throttle), not just any braking. It won't disable the forward drive system if the throttle/accelerator is engaged when it's less than 50%. In fact, it forms the basis of Sikes allegedly "wearing out" the brakes while maintaining a constant high speed.

 

Sorry, I just can't buy into this 50% issue.

The factory documentation is very clear on this point, the brake light switch will ALWAYS result in the HSD drive train going into "simulated" neutral (the ICE RPM may or may not decay), or into regen mode if regen is needed and/or is possible.

And for just what logical reason would anyone specify such a design aspect...??

 

the phone call was 24 minutes

lets say he was pressing the brakes on and off for 20 minutes for a total of 254 times


thats 4.7 times a minute at roughly 12.7 seconds of braking.



would somebody do that in a panic situation?



i think not

 

This disagrees with the tested results. Hobbit reports measuring brake activation while applying full throttle. He also reports that the override is triggered by the pressure sensors on the hydraulic system, not the brake light switch, and kicks in somewhere near 50%.

This is also what I have experienced with my Gen II, although I lack the extra sensor wiring that hobbit has on his Prius.

Tom

 

Except we don't know exactly what the time course of the 250 data points is. This question has been brought up and nobody knows except Toyota.

 

I-8 and La Posta is about halfway between San Diego metro and Jacumba. If he was headed back from SD which seems likely, he had probably gone some 40 miles before the 911 call.

 

First they told use that both the brake pedal and gas pedal had been "cycled" ~250 times. Then they came back with a correction that said only the brake was cycled 254 times and the throttle remained fully open the entire time.

"Throttle" remained fully open the entire time....!!!

If there is anyone out there in internet land that would not have pumped the brakes numerous times in the feverant hope "the next time will work" then that person is an idiot of the 1st magnitude.

250 times I will willingly attribute to a computer flaw, maybe like the one Dr. Gilbert uncovered until proven otherwise.

 

Is this a serious question? Because 500 horsepower was being added to the car that had to be overcome by the brakes. It doesn't matter if the power is applied at the front or the rear wheels. Of course the front brakes have to overcome the engine driving force (at a ratio of 70 to 80%).

 

And that makes good logical sense to someone...??

 

Then you don't understand the purpose of ABS or how it works.

 

You are purely guessing and you would not make that mistake, if you understand how HSD works.

ICE is 76 hp and the generator (MG1) is less than 30 hp. If the HSD is "stuck" in accelerate, MG1 will be burned out. It was not and the car continues to drive normally.

 

It makes sense to me. Some people two-foot the pedals, or do heel-toe driving. I don't, and it seems a bit silly with a car like the Prius, but Toyota is trying to prevent one problem without creating more.

The only time you need brake override is when you are braking hard. In an emergency, you hit the brakes hard. If you are playing with them, then you must not need very much braking. This is why Toyota uses a 50% threshold.

Tom

 

Assuming the HSD control computer was stuck in the "set/accel" mode what makes you think that the ICE, MG1 and MG2 would not be properly coordinated, just as the would be in the "normal" set/accel mode.

 

I'll say it again....

 

Dr. Gilbert was already proven otherwise, lol.

 

Looked at CNN report on the Harrison case today. Toyota recorded the accelerator pedal was press 100%. But in Sike case. No mention on the position of the accelerator was given. Do Toyota show only what they want us to see (the truth but not the whole truth, may be 50%, 60%??).