2010 Prius II Question Brake Test

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Johnrdl, Nov 22, 2019.

  1. Johnrdl

    Johnrdl Junior Member

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    Hello. This is probably a silly question but I would like any assistance that anyone might provide. Okay, so this is regarding the brake pressure test. What I am referring to is that if you have a vehicle off/not running, you press down on the brake pedal and release. Then you press down again and release again. Each subsequent time it should be a bit more difficult to press down on the brake pedal. I believe the pressure tells that the brake line is good. Once you start the car, you can press down on the brake pedal no problem like normal. Back to my question, I was trying to do that on my 2010 Toyota Prius the other day and I did not get that resistance when I pressed down on the brake pedal several times when the car is off as well as when the key fob is nowhere near the car. Is this normal for the Prius or does it mean that there is an issue with something? I would greatly appreciate any assistance. I haven't had any major service other than the usual oil changes, tire rotations, new tires, 12V battery replacement. I plan on getting the other major fluid changes soon, probably within the next 6 months or so. Again, I want to know if this is something that I need to be concerned about. I have done the other brake test of putting the emergency brakes on and moving the car into Drive, in which the car doesn't move. However, if I step on the gas pedal the car does move a bit. Thanks.
     
  2. bisco

    bisco cookie crumbler

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    how many miles on her?

    is this a prius service manual test, or just a generic brake test? the reason i ask is that prius brakes are a bit different than normal.
     
  3. ChapmanF

    ChapmanF Senior Member

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    Conventional cars with power brakes get their power assist from a big old chamber with the air sucked out, and you can usually use up that assist within two or three pedal strokes, the "pedal getting harder" effect you're thinking of.

    Prius doesn't do it that way, but with a gas-filled canister kept pumped up with brake fluid to a very high pressure. You can use that up too, it just takes more like twenty to forty pedal strokes, not two or three.

    You're not really going to feel a gradual increase in pedal effort; you'll get your twenty or thirty strokes that feel about the same, and the next one's like you stomped on a rock.

    That's all if you prevent the pump from just coming on and replacing the pressure you're using up. If you hear the pump start (a little buzzy noise under the hood), you might not reach the pressure-depleted point as soon as you expect. :)

    You can stroke the pedal fast enough to beat the pump at its own game, and so still eventually use up the assist even with the pump running. You will get brake warning lights on the dash and a high-pitched alarm if you do this.

    I'm not sure how much interesting information you really get from a test like this.
     
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  4. Johnrdl

    Johnrdl Junior Member

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    I currently have 23,650 miles. This is just a generic brake test. It makes sense if Prius brakes are different than others. I have a 2007 Toyota Camry and 2009 Toyota Venza, both of which are not hydrids. Again, the dealership service was telling me that I needed to change the brake fluid due to age and I opened up the reservoir just to take a look. I initially thought there was something else wrong because the generic brake test, of pumping the brake pedal several times and having that pressure build up and the following pump more difficult to push down, wasn't coming up. I don't remember ever doing/checking that before, so I was just curious. Thanks for helping to clarify things up.
     
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  5. Johnrdl

    Johnrdl Junior Member

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    Thanks for the help. I don't want the brake warning lights on the dash to come up nor hearing a high-pitched alarm. I was just mainly more curious because I recently took my car into the dealership for service. They informed me that the brake fluid needed to be changed due to age. I went home and opened/removed the cap on the reservoir just to take a look. I made sure to cap it back but when I thought about checking with the generic brake test, there wasn't a gradual "pedal getting harder" effect so I thought something else might be wrong. I am just so use to that when driving other cars like the 2007 Toyota Camry or 2009 Toyota Venza, both of which are not hydrids. Anyway, I appreciate the information and good to know that the Prius is not meant to do that, thus calming my nerves of thinking that there might be something else wrong with my car. Thanks again.
     
  6. bisco

    bisco cookie crumbler

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    i would change the fluid based on your maintenance schedule. go by years or miles, whichever comes first.

    also not the rough duty service, or whatever terminology they use. the intervals are shorter if your driving in severe conditions.
     
  7. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    Toyota USA has not recommendation for brake fluid change. Toyota Canada recommends tri-yearly or 48K kms (30K miles approx), whichever comes first.

    I think it's a good idea to change it periodically regardless which side of the 49th parallel you're on. I wouldn't bother with testing, just pick an interval and do it.

    I've had the dealership do it once, and did it myself a couple of times now. If you're interested in DIY'ing it, watch @NutzAboutBolts video on the subject: there's a thread pinned in third gen maintenance forum (at the top). Also, I've attached some Repair Manual info, the method without Techstream (Toyota proprietary software).

    If the dealership's offering to do it, and that's your preference, I would go for it. How much are they asking? It should only be around $100; if it's much more than that I would shop around, to other dealerships. There is a very specific method to doing, so I'd be careful about lietting other shops just hop in.

    In particular, the car needs to be in "invalid mode". This not hard to do, but if the shop doesn't know about it, you can end up with problems.

    FWIW, I did this a few weeks back, takes about an hour, and my wife helped, pushing the brake pedal. I used very rudimentary tools, nothing fancy.
     
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  8. Grit

    Grit Senior Member

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    Try pumping the brakes more than ten times, it will build up and check your brake reservoir level right afterwards.
     
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