Prius Brake Problem

[Opifex]

I’ve noticed an odd feeling to the brakes on my Gen 3 that I’ve not been aware of before. I had been parked for about 15 minutes and found that when I started to move backwards using the brake to control the speed, each time I increased the pressure on the brake pedal the brakes grabbed and it was impossible to move the car smoothly. I then had to move forward to negotiate my way out of the parking bay and after that the brakes behaved normally. Didn’t notice anything during the day but found the same problem again as I was reversing into the garage.

Both times the problem has happened just after I have switched on and the car is reversing on Battery without the engine starting. Both times it went away after I had gone forwards and stopped.

Has anyone else noticed this effect or is it something I should be worried about?

[Grumpy Cabbie]

Is the car in Ready mode and in Drive or Reverse or are you moving the vehicle on a slope using gravity in Neutral?

I move my car on and off the drive in EV mode and haven't had any brake issues.

[Opifex]

The story in a nutshell:-

Switched on in "normal" mode but the engine didn't start presumably because it was still warm and the Battery was charged -

Moved to Reverse - brakes grabbing

Moved to Drive - brakes OK

Moved to Reverse - brakes back to normal.

[Jan&tone]

Many years ago my Capri did that, it was the automatic adjustment - worked when you put the brakes on in reverse...

Probably not that but.....

[ashpole]

I've noticed an odd feeling to the brakes on my Gen 3 that I've not been aware of before. I had been parked for about 15 minutes and found that when I started to move backwards using the brake to control the speed, each time I increased the pressure on the brake pedal the brakes grabbed and it was impossible to move the car smoothly. I then had to move forward to negotiate my way out of the parking bay and after that the brakes behaved normally. Didn't notice anything during the day but found the same problem again as I was reversing into the garage.

Both times the problem has happened just after I have switched on and the car is reversing on battery without the engine starting. Both times it went away after I had gone forwards and stopped.

Has anyone else noticed this effect or is it something I should be worried about?

I've had that three of times (once in EV going forward, others EV in reverse) since I got my Auris HSD seven months ago. It's never affected normal driving and felt like premature brake assist kicking in. When it happened the peddle was at the top of its range.

[DrCez]

The story in a nutshell:-

Switched on in "normal" mode but the engine didn't start presumably because it was still warm and the battery was charged -

Moved to Reverse - brakes grabbing

Moved to Drive - brakes OK

Moved to Reverse - brakes back to normal.

I recalled reading about something like this with the Gen 3 so looked back and found this thread where SilverT4 reports a similar problem and also gives a link to a discussion on PriusChat about the same issue:

http://www.toyotaownersclub.com/forums/index.php?showtopic=103265

I haven't experienced it myself but clearly it is not a one-off. IIRC there was some suggestion that it could happen when setting off before the car has gone through all its "boot-up" routines, and I think it also seems to happen when the car is still warm. Others have also reported your remedy: change the drive selector (swap D to R or back to P) before trying again, so I wouldn't be too worried about it.

My last car, a Megane with a push button start, also had a quirk if I tried to start it when the engine had cooled slightly (say for about an hour or so): the engine would turn over but just wouldn't fire up. The remedy seemed to be to wait for the engine to cool even more - far more annoying than grabbing brakes!

[Ancient Nerd]

I've also had this a few times in the first few months. Always when manoeuvering from cold. It was highly embarassing because it made the car almost uncontrollable, and visibly so. The slightest touch of the brakes slammed them on. It looked very much like the brake assist function coming on when it shouldn't.

I think the fix was to switch the power off and then on again.

Having said that, it hasn't recurred since the brake recall that Toyota handled so well!

[Opifex]

Thanks for that reply, DrCez.

I see the link to Prius chat that was enclosed in your link has 30 pages of discussion about the problem. Either it's a lot more common over there or the Yanks are a chatty lot.

Anyway, it does seem that the problem is quite common and, although embarrassing when it happens, does not indicate anything serious. Yesterday I did try to create exactly the same circumstances as Monday but the car behaved perfectly. I had wondered whether it was something to do with the startup procedure because the brake pedal travel seemed to be reducing each time I pressed it as though pressure was building up in the system. I thought perhaps releasing the pedal for a couple of seconds between pressing the start button and moving into reverse may help.

Thanks again for the info - I'll stop worrying about that one now.

EDIT - just seen your post, AN. My car was registered May 2010 so I assume the brake mod was already done. How can I tell?

[johalareewi]

Thanks for that reply, DrCez.

I see the link to Prius chat that was enclosed in your link has 30 pages of discussion about the problem. Either it's a lot more common over there or the Yanks are a chatty lot.

They have a lot more gen3 prii than we do and have had them for longer so they find things before we do.

[Ancient Nerd]

EDIT - just seen your post, AN. My car was registered May 2010 so I assume the brake mod was already done. How can I tell?

I'm ot 100% convinced it was the brake mod that fixed it. I think, but can't remember for sure, that it happened once afterwards. There are certainly US reports of it happening post-fix.

With a mid-2010 car, it should have been done. Your dealer can check that.

The one thing you must do is tell the dealer at the next service, or before if it is convenient. Even if they can't fix it, there is a record of the problem. Repeat at every subsequent service. That way it remains a warranty issue, even if the warranty has otherwise expired (AFAIK).

[Opifex]

The one thing you must do is tell the dealer at the next service, or before if it is convenient. Even if they can't fix it, there is a record of the problem. Repeat at every subsequent service. That way it remains a warranty issue, even if the warranty has otherwise expired (AFAIK).

Good point - thanks.