Gas Pedal or Floor Mat - what is it?

Not sure yet, I've heard conflicting stories. The carpet thing, and now, a possible linkeage problem as the components age and wear.

When did you get your recall notice? I haven't seen one yet.

 

On the Prius it's the floor mat. The fix they will eventually call you in for involves ensuring the mats are secured (replacing the Toyota all-weather mats with ones that use the clips and ensuring the carpeted mats are secured with the clips). Then they will cut part of the accelerator pedal off, making it shorter and harder to trap on the floor.

Certain other Toyotas have faulty accelerator pedal assemblies. The electronic part, not the mechanical pedal. It appears we (Canadians) are at fault here. The faulty parts may have been made in Canada. Prius never got the faulty parts. They use Japanese parts that appear to be reliable.

I said "they will -eventually- call you in for" because it appears they have drained the swamp and are a little busy with the alligators (faulty accelerator assemblies) on other models right now.

But I'm sure you will be notified. They are very worried about their reputation!

 

Here's my personal list (#3 is not acknowledged as a problem, by Toyota):

Problem and solution

1. All-weather Floor Mats interfere with accelerator pedal. New front floor mats will be provided to Prius owners who currently own the Toyota all-weather black rubber floor mats. Unclear when these will become available.

2. Accelerator Pedal interferes with floor mats. The dealer tech will cut off a portion of the bottom of the existing pedal. As new pedals become available, they will be offered to owners.

3. HV ECU logic glitch causes vehicle to ignore driver brake pedal input. No resolution.

 

Yes. I received my notice to ensure the mats are secured and that they will be calling me in to have the pedal shortened. I'll be passing on that. I don't believe it's necessary. There was no time line in the notification. As I said above, they are probably busy with the more serious problem on other models.

 

Patrick,

You mean when you are slowing down and all of a sudden it feels like the car ISN'T slowing down anymore?

 

No, that behavior is classified as an undocumented feature...

What I mean is that #1 and #2 don't account for the few Prius incidences where the owners have experienced unintended vehicle acceleration, they've depressed the brake pedal, skid marks are left by the tires, and/or brake damage occurs.

 

I think there is an issue with the pedal itself - but NOT with the Prius. The Prius was not in the list of Toyota 'stop-ship' vehicles.

I'd opine that as long as you have the floor hooks for your floor mats, it is unlikely that you will have any problems with the throttle.

 

Just remember (and instruct others who drive your car as well):
If the car won't stop shift to "N" OR press and hold the start/stop button for more than 3 seconds.
Shifting to "N" won't cause the engine to rev.
Pressing the start/stop button -may- cause a bit of steering power loss and eventually brake power loss but not so much you would loose control.

 

Neither.

The gas pedal recall has nothing to do with the Prius.

The floor mat recall is bogus and only applicable if the owner is absolutely deficient in common sense and has a wish to live life and death on the edge.

USE the OEM carpetted mats, SECURE them to the anchors, DRIVE 250,000 miles, EXPERIENCE no issues.

 

He was right. If you have a recall notice though then they must do the modifications if you instruct them to do it. However I've told my service department not to do anything or touch anything on my 2005.

 

I agree with DeadPhish....... Floormat recall was a bunch of crap and the gas pedal has nothing to do with ANY of the hybrids. I have 2.... A Hybrid Camry and a Prius. All AOK

 

The hydraulic pressure sensors, which measure the pressure generated in the master cylinder when you press the brake pedal, are connected to the Skid Control ECU, not the HV ECU. The accelerator pedal connects to the HV ECU, which decides how much power and torque it wants from the engine, and requests that from the Engine ECU. The Engine ECU controls the throttle blade.

When pressing the brake, the Skid Control ECU asks the HV ECU to provide braking force through regeneration, and the HV ECU replies with the amount of force it has provided. If the HV ECU does not reply, the Skid Control ECU logs DTC U0293 (Lost Communication With HV ECU) and assumes full friction braking. A warning light comes on.

There should be no way that a failure in the HV ECU can prevent the brakes from working, but could possibly still cause the engine and motors to be producing maximum power. The friction brakes are sized for emergency braking from high speeds (that's why we have huge dual-ventilated front discs - the problem for braking is not the area of the pad that grips the disc, it's dissipating the heat generated so that the pad material doesn't degrade) but they may have trouble if you draw out the braking process. If the throttle appears to be stuck you need to brake hard, without letting up, to a complete stop.

Just to clarify, as people often don't understand this - there are many completely independent computers in the car, each controlling one aspect of the car's behaviour, though they do work co-operatively to an extent (more so on the Prius than on other conventional cars). Even any one ECU may have multiple processors in it performing different tasks - it appears that the HV ECU has one master processor that determines the speed and torque required from the engine and motors, then the job of actually generating the right waveforms to achieve that is given to a separate processor for each motor. Each ECU generally has one processor to perform its required function and a separate processor to communicate on the CAN bus.

I'm a software engineer. I have a bachelor's degree in computing science. I took the course on Embedded Systems, and while I don't work in that area, I know a little about it. I also took courses on formal program proofs, mathematically determining that the program's execution will be correct. It is possible to determine, without exhaustively testing every possible input, that the program will always function correctly given valid inputs, and given perfectly-functioning hardware. Embedded systems developers normally use these techniques to ensure that their programs are correct, particularly where the software is safety-critical.

The problem for mainstream software development is that these techniques don't scale well with the size of a program - a program twice the size generally costs a lot more than twice as much time (hence money) to validate, meaning that only the smallest programs, and the most important, get validated.

In addition, to generate the proof, you need a detailed, complete specification of what the software has to do.

Do not compare the reliability of desktop computer software with embedded software - desktop software is developed under completely different constraints: normally the race to add as many new features as possible in as little time as possible at the lowest cost. Often it doesn't even have a specification.

Computer hardware can and does fail in peculiar ways, sometimes causing a program to crash in a way that appears, from inspection of the processor's state and of the program, to be impossible. It usually turns out that a stored data bit has got stuck at the wrong value and changed the meaning of an instruction, or a piece of data. It's not bad software design nor bad hardware design, just the limits of how reliable we can make our technology. (The ECU does contain some self-checking software and will log a DTC and illuminate the warning lights if a problem is found.)

The probabilities of such a failure are very low indeed, so it's not surprising that they don't happen very often and frequently cannot be detected after the event, nor prevented. One approach to resolve this is 'voting', where multiple independent ECUs (usually three) evaluate the same inputs and, where there is a difference in outputs, the value calculated by the majority of the ECUs is used. It's very expensive, though, requiring three times as much hardware and ideally independent programmers, maybe using different types of processor, and would likely make the cost of the car unacceptably high.

I think it's much more likely, if there is a runaway and that the pedal is not hindered by the floor mat, that a sensor has failed in a way that causes the car to open the throttle further than the driver is requesting. This could be any of: the accelerator pedal sensors floating above the actual position; throttle position sensor reporting consistently less than actual position; throttle blade sticking and becoming disconnected from the axle, so position sensor reports where the axle is but the blade is fully open. The Engine ECU does cross-check the mass air-flow meter response with what it's expected to be based on the throttle position (DTC P0101), though it doesn't seem to have a fail-safe response to this. For other mass air-flow problems (stuck low, or stuck high - well above the expected maximum value) the car calculates fuel input based only on engine speed and throttle position.

The TPS appears to work in the same way as the Gen 1 accelerator pedal - a variable resistor (potentiometer) that changes value as the throttle blade moves - so I suppose it could also suffer from a 'big hand' problem: reporting consistent, but incorrectly low, values.

 

This is the Toyota problem that is floating around in the world of dealers, not the gas pedal.

 

I have 129,000 miles on my '05 Prius and have never had any kind of problems with the gas pedal or floor mats.

Regardless, I did do the "stuck gas pedal drill", where I put the car in neutral while driving on the freeway to make sure it worked as I assumed it would and went into neutral. No problem.

 

This has been handled by so poorly by Toyota!! I haven't received a single letter or confirmatiom by my dealer to take out the mat. The only reason I took my rubber floormat out of my Prius was the good people of priuschat, so thanks priuschat for saving my life everyday because it doesn't seem like Toyota gives a crap. One day, I would like to put my floormat back in my car.

 

Well, first the letter won't come from your dealer, it will come from Toyota USA.

Second, do you have the floormat clips? They clip the carpeted floormat to the carpet. You'd know if you had them. It's difficult to remove or install the carpeted floormat with the clips in there. If you don't have the clips, go to the dealer with your floormats and ask them to install the clips and the floormats (and clip them in). They should immediately give you or install the clips at no charge! If they are busy they should make an appointment for you for a no charge install.

If they don't, call Toyota USA (the number is in your owners documentation). Dealers who don't take care of this are one of the main reasons we have the floormat recall.

 

I just recently bought the clip in mats, but I like using my rubber mats for when it snows and on really wet muddy days. Oh well. Thanks for the infomation, so Toyota USA is the folks I'll call.