Hi,

Please do not panic. I want to give the community a 'heads up' on a problem found with an accelerator assembly that had a bent follower arm:

As you can see, the arm from the potentiometers is bent so the nylon bushing is angled into the slide mechanism. From another angle:

I noticed it because after cleaning the potentiometer, I still had an abnormal resistance slope on the lower one. I also noticed that a full deflection, the 'spring' was weaker because the nylon bushing was beginning to jam into the slide mechanism. In the worst case, the nylon bushing could jam leaving the accelerator in the full-on position. So I removed the potentiometer:



Once I straightened the arm so it made a 90 degree angle, the accelerator assembly worked smoothly and the resistance anomaly went away. I'm putting the repaired assembly in my Prius for field testing.

INSPECTION

I would recommend doing a quick inspection of your accelerator assembly. You will need someway to lay on your back and possibly a flashlight to see the assembly:


Lay down and shift yourself so you can see the accelerator assembly and the encoder shaft, the NHW11 uses dual potentiometers and the NHW20 uses a Hall effect device:

If the encoder arm looks like this, there is no problem. But if it looks to be at an angle, plan to take it into Toyota and ask that the problem be fixed. Alternatively, you can remove the accelerator assembly and try to fix the problem by bending the follower arm to be at a 90 degree angle.

I have no idea what a Toyota Service department will do since I am well beyond any Toyota warranty. However, I suspect after I send a note to Toyota America and a copy to the NHTSA this will be fixed.

If you have it, with the car powered off, press your accelerator to the floor and lift off. If the accelerator returns, do it several times, pushing hard each time, and if it always returns, you can probably drive the car safely to the dealer. If it sticks or 'feels funny,' I would not recommend driving the car if there is any chance you might have to stomp on the accelerator. For sure, get the accelerator assembly repaired.

Now what happens if Toyota gives you a 'ration of sh*t?' I would recommend having a copy of this note and ask to see the manager. Ask the manager his name and the owner of the dealership so if there is a run-away, the lawyers will know who refused to repair the defective part. Be polite but get their names and phone numbers. Make sure they have your contact information too, leave the note and ask their general manager to look at it and go home.

Now document the bent part with a photo and post your message to this thread with your mailing address contact information and that of the dealer. I suspect in a very short period of time, they will contact you and offer the repair for free. Be sure it includes them towing the car from your home to their shop and return or taxi fare for you to pick it up ... and for your time and effort, ask them to throw in having the transaxle oil changed and a sample of the old oil.

Did I mention, DONT PANIC. This is a potential problem and easily repaired once you know about it. But this would be a good time to 'do the right thing.'

Bob Wilson
625k Inc.

 

Yup. You are an engineer alright. Care to speculate on how this happened? My first thought is that possibly a floor mat got bunched up under there and tweaked the cam arm.

Does the Camry use the same design?

 

I suspect it might have been an assembly error. When I took out the pot to fix the arm, I found putting it back in took a little skill. If a robot were doing it or a worker under pressure to maintain production ...

Bob Wilson

 

Speculating, of course, but perhaps this was the cause of my '06's unexplained acceleration?

 

One of my co-workers has a 2008 Prius so she let me take a peek at her accelerator. Unlike the NHW11, the NHW20 unit is 'sealed' or at least blocked from casual inspection.

Did you get a new accelerator assembly after your incident? Do you have the old one?

Bob Wilson

 

If that were the cause, ("Oh look, our fault. It was this bent accelerator"), they never admitted it. They put it down to the carpet-over-the foot feed. They gave us the brakes which were burned out.