Car moves with brake ON and put then into drive

wow, can this have anything to do with the hill assist?

 

it is very odd, i wonder if it's an adjustment in the pedal or tranny interlock? sorry, i'm just guessing here.

 

This can't have anything to do with the transmission or parking pawl. Since the service brakes are applied, no normal amount of creep could possibly make the Prius move. Assuming the OP's description is correct, this means that the service brakes are not applying hydraulic pressure to the brake cylinders. Pumping the brakes restores pressure. This sounds like a brake ECU issue, or something wrong with the brake master unit, whatever it is called.

Tom

 

Are there any warning lights/sounds?

 

How hard are you pressing the pedal? At least 112 pounds?

This pedal force (actually 500 newtons) is a magic number for some federal regulations. It should override all the drive-by-wire stuff, bypassing any electronics faults and applying direct mechanical / hydraulic force to the brakes. It should even bypass any single mechanical / hydraulic brake circuit failure by putting sufficient holding force on the other brake circuit. If that much pedal force won't hold the car still, and the shop can't find anything wrong or the car shows no warning indicators, then it is time to file a defect report with NHTSA.

While the great majority of alleged Toyota brake failures are operator error, that doesn't mean absolutely all of them are so. I'd hate to see a real but rare car problem ignored under the flood of driver errors.

 

Because you reported this to the dealer during the warranty period, they will most likely repair this under warranty. It sounds to me like something you should take care of.

 

I wonder if any of the ECUs put a stored code that isn't causing any warning lights to go on. If you were on the opposite coast, I'd try to hook it up with the cable to TechStream and see if there were any stored codes.

Has the dealer even hooked it up to see if there's any stored codes? How frequently would you say this happens?

 

Have the brakes on this ever been serviced?

I don't know what was done at the recall --- but at the very least this car should have a complete fluid change ... not just a bleed. I had a car that must have had some air in the ABS unit that did what you describe -- mostly in the morning when the engine would be running faster and the operator would use normal pedal force ....... it was totally random.

 

OP - These sorts of intermittent problems can be a bear to deal with for both you and the dealer. The issue for them is that without being able to pull a code or reproduce the issue they are at a loss. Before mechanics used to have to actually diagnose issues, these days that is a lost art and most just read codes and fix what the computer says is broken.

Hopefully this was documented at the dealer prior to your warranty running out - if so it should be in Toyota's system - if so perhaps another dealer would be more accommodating with a loaner.

 

You could actually get a car cheaper than that if you priceline it. The competition in your area should allow it to be pretty good. I had a full size rental on Oahu for roughly that, and prices are higher on the islands.

 

My 2004 does this. I step on the brake, shift in to D or R and then it moves a few feet. Scary when your parked at a marina or the kids are around the car. Was there ever any resolution to this issue. BTW, my scan guage shows no codes. Also, my electronic brakes recently failed with the VSC/ABS/Brake light on, but this issue predates that and is still happening. so now im just using mechanical brakes and it still happens. kinda dangerous. wish someone could shed some light onto this.

 

What does this mean? How do you chose between electronic brakes and mechanical brakes?

 

I had a very similar experience recently in my 2008 Prius that was fixed by changing the auxillary battery ~$340 at the dealer with Toyota battery, $150 if you do it yourself with 3rd party battery. The car would turn on with the brake depressed, but the instrument panel would stay alit. Shifting to reverse/drive the car would start moving EVEN WITH THE BRAKE STILL DOWN! This was very scary in parking lots and on hills.

The workaround for me was to release the brake after starting the car, and usually the instrument panel lights would go off and it would go to ready status.

I think what must have happened was that there must have been a low voltage on the Aux battery. Releasing the brake must have allowed the engine to run, normalizing voltage, and the rest of everything works once voltage is normal.

 

the 12v does some odd things, but many newbies fail to understand.

 

My 2010 does exactly this, sometimes starts moving with brake depressed after power on, the only way to correct it is to let off and reapply. It will be interesting to see if it stops happening after I eventually replace the original 12V, although I've measured the 12V a few times and it's still reasonable.

 

If I were the only one driving the car, I might not have got it fixed since I learned the workaround. But my wife drives the car too and I worried that she would forget and potentially hit someone in a crowded parking lot.