This has occurred several times while reversing out of a parking space. Basically, I've been parked at a store for a short while (less than 15 minutes). However, when I back the 2007 Prius out, 1) the brakes don't catch initially and 2) the car stops so abruptly I'm certain that I've hit something (or someone). This entire sequence occurs within a few feet of starting the car and backing out. Today I backed out a parking spot, car stopped like I hit something; I then got out of the car because I expected that I had run over someone's body...neither person nor object were there though. What I do (and have always done/no issues) but now with unexpected results: 1. get in car and apply the brake with foot 2. start car and put in reverse 3. release the brake and reverse but the car now "rolls" without any tension from the brake being released 4. as soon as I realize I'm rolling, I panic and reapply the brake 5. car abruptly stops (to the point of shuddering stop) 6. then drive away is fine Checked the brake fluid and last time my tires were inspected about 3 months ago they told me my front brakes were still good/had life in them. Is this an indicator of the brake actuator going bad (car has 340,000 miles)? Thoughts?
And no lights or anything on the dash interesting I guess first I would bleed the brakes or just see what happens when I crack the screws or the fittings one at a time starting with the right rear do you have fluid dripping when you crack the fitting let it sit there and drip a minute does it ever stop or slow down yeah I know. Now see if the car still does it
UPDATE: I just noticed the lack of braking ability as I tried to stop going forward at a slow speed. Its like (similar to in reverse) the brakes too a few feet to "catch". gonna look at my brakes/lines over the weekend. might be as simple as the front pads going bad.
I get that on my gen3, occasionally. First time it happened I was backing up in prep to leave a parallel parking spot. I touched the brakes and the stop was so abrupt I thought I'd misjudged, backed into the car behind. No clue what causes it, always happens when just starting up, in reverse. And just every so often, not an everday thing.
If the OP's car does this consistently... Start the car. Wait 30 seconds (just a guess, 10 seconds might be enough) Pump the brakes a few times. Do the brakes now work normally the first time? It kind of sounds like brake fluid pressure is low initially (so the brakes work poorly) and then after a few seconds it returns to normal, but the brakes are next applied hard so the car slams to a stop. If the car is given some time to warm up, and the brakes pumped proactively, the "low fluid pressure" phase may go away. That said, the brakes shouldn't ever do that. It could be that the part of the ABS system which hold pressure has a leak, so after the car has sat for a while the expected stored pressure isn't there, it only comes back after the pump has run for a while.
I had that happen consistently for a while. My ABS lights came on as well later. I also had the intermittent whirring that sounded like something was winding or cranking. I ended up getting my ABS diagnosed as bad and replaced it with a new one.
Thanks all. Yeah. Its still doing it and I plan to look at the brake pads tomorrow. My guess is that they are fine and it is indeed something like the ABS or something. How much was the ABS replacement labor please (if you remember)? Did it end up being the final solution or did you experience this issue again? I have a junker 2007 sitting in my yard so i might try to pull the brake actuator out myself. Everything was working fine until it was in an accident.
Check the rear drums and shoes too. There's a "servo action" that helps apply the brakes in forward and rolls the self-adjusters when in reverse. There might be something going on there too.
Gen 1 and 2 Prius rear brakes use parking-brake adjusters, not reverse-travel adjusters. The adjustment is maintained by regular uses of the parking brake, with uses of the service brake in between.
The big pedal just to the left of the go pedal that is used for slowing or stopping the car in normal service/use. In a gen 1 or gen 2 Prius, each time you apply the parking brake, if there is more than 0.03 mm shoe clearance, a springy lever gets cocked up over a star wheel. When you release the parking brake, the lever is left cocked one tooth up on the wheel. The next time you apply the service brake after releasing the parking brake (or right away, if you have your foot on the service brake while releasing the parking brake), the shoes are spread apart by the service brake cylinder, taking pressure off the adjuster, and the springy lever comes back down and extends the adjuster by 0.03 mm. If it has been a long time since anyone used the parking brake, the shoes can be many times 0.03 mm out of adjustment.
OK. thank you. I was about to take the car apart...but can I just "parking brake" my way out of this problem by using it frequently henceforth to get it back to .03 mm?
If you're in a quiet enough place, you can kind of sit with the car off and push down on the parking pedal with the doors open and listen for a faint metallic click from the rears as the adjust levers click over the starwheel tooth, then let the parking pedal up and press the service brake, then let that up and repeat. You'll hear the click every time until the clearance is back within spec, and after that pushing the parking pedal will not make that click sound from the rears. Hard to hear if you're in noisier surroundings though. However, if it's been a long time since the adjusters even moved, it's probably worth taking the rear wheels and drums off and taking an actual look, making sure the star wheels turn freely, a tooth isn't worn smooth, and so on.
