Prius Rolled Backwards (and crashed)

("Parking Brake on and Emergency Brake fully engaged"? Presumably that means "shifted to Park and parking brake set"? There is only one parking brake. There is no separate "emergency" brake.)

I vote operator error. Evidently the transmission was not in Park, which can happen if one carelessly stabs at the Park button, and the parking brake slipped. If you had shut the car OFF it would have automatically shifted itself to Park and would not have gone anywhere. The alternative is that both the parking pawl and the parking brake failed, which is much less credible.

Leaving the car ON is also the easiest theft scenario. A thief needs only to break in and drive away with it. Say, there's a thought: if you didn't lock the car perhaps some rascally scalawag got into it, backed it across the street, and there shifted it into Park and set the parking brake just to f!!ck with you.

 

Note that "putting on the parking brake" does not mean it will be on enough to stop the car from rolling. You have to really press it down hard to get it to lock well. Especially for reverse. Drum parking brakes are "leading shoe" or "trailing shoe". They work well in one direction only. Prius rear parking brakes work well in the forward direction and are weak in reverse.

Did the dash indicator read "P"? If so, the parking mechanism may be damaged. You can test it by putting it in "P" and trying to push the car (on level ground!). If it's damaged it's not the end of the world. It can be replaced without disassembling the whole HSD. It's an external module on the HSD.

 

take it to the shop... apparently your parking paw is broken.

as others have mentioned, the parking brake is very weak.. you really have to lay into it for it to work.. even then, the car will still slowly roll... with a screeching sound.

car off, or car on.. either way, the parking mechanisms failed. i've never had a problem in many cases as you've described.. no point lecturing the OP about turning the car off or just "jabbing" the park button when any of those SHOULD have stopped the car.

 

It's a strange one but it does seem like your park mechansim is broken. Can you try the test David suggested about pushing it (transmission in park but park brake off) on level ground.

 

The parking brake on our Prius is extremely poor. For instance in drive with it fully engaged it will roll down our driveway too. The Lexus on the other hand will not move without significant throttle when the parking brake is engaged. Its been that way since new, I've had it looked and and have always been told it was normal.

I also think you probably failed to put it into park.

 

Note that if you confuse the car by jabbing the "P" position, it will usually go into "N". It won't do any of that on its' own. If you left it in "N" it wouldn't go into "P" on its' own. If you left it in "P" it wouldn't go into "N" then back into "P". So it looks like the park mechanism may be faulty. BTW, while most here call it a "pawl" it isn't. It's a gear. Like a hypoid oil pump. The rotor connects to the drive and the stator is bolted to the HSD housing. The rotor is electrically driven into the stator when engaged.

 

A general FYI: There were a few times when I was ready to drive forward or back out of the garage I had forgotten to release the parking brake and the car just won't move at all. I do push my parking brake in firmly when I use it.

 

Sorry to hear about your incident. I think it's unfortunate that other members have chosen to blame you as a primary cause for your accident as a first response. I hope you get your car sorted out soon.

 

Nobody is "blaming" him. Its an easy thing to do jumping out of the car real quick as if to run into the house. Note the police said the car was running and the parking brake was engaged...no mention of it being in park. The Prius' parking brake is pretty terrible and I know for a fact it won't hold the car on its own on an incline.

People make mistakes but pretending that it couldn't at all be driver's error doesn't make any sense.

Whatever the simplest solution is usually the truth...

 

Sounds like Paranormal Activity to me. Coat your Prius in Powder and look for mysterious unseen hand prints...

 

Here is my guess / take on it:

You pressed the "P" button before coming to a complete stop (0 MPH). The car protected itself and put it in "N". This happens at highway speed so I am not sure the minimum speed for it to occur.

You pressed the parking brake but very lightly. The car then roll backward slowly on it's own.

If this happened in your case (not in "P"), as soon as you opened the driver door, the car will give a long beep. Do you recall hearing unusual beep?

 

Quick question on topic: If I turn the power off and exit the car, does it go into park automatically? I don't use the parking brake and am wondering if I should.

 

Yes, if you successfully make the car IG-OFF then the gear selector will automatically shift into P before powering down. (However if for some reason the car is not IG-OFF, then the gear selector will remain in D or whatever other gear it had been in.)

Yes, you should always apply the parking brake as well, as an additional safety measure. You have to press hard on the parking brake pedal to engage it.

 

No. P only lights if the car is in Park. A failure in the parking pawl mechanism could lead to a situation where P is lit, but the pawl is not engaged, but in normal operation this will never happen.

Tom