How to bleed brake on 2005 Prius?

Ohboy. Yes, bleeding the Prius brake system is inordinately complex,
because your foot doesn't push fluid around in the traditional way.
The "special tool" is the handheld tester, aka Mastertech scantool,
which allows actuation of certain solenoids to open fluid paths in
ways that make sense for bleeding but not during regular operation.
.
In the interest of saving time and headache, you might want to just
take it to the stealer this time and then read up on the whole system
and process for dealing with it before going after it again...
.
_H*

 

the normal braking on a prius feels very different from a regular car.

and bleeding the system is a far different job on a prius than on a regular car- in fact it's kind of a PITA even for an experienced tech. the system is touchy. and you do need the toyota scantool to do the job, so this has to go to the dealer.

the beeping sound means you don't want to drive it until you've got this taken care of... please don't drive it in this condition. that is dangerous and nobody wants you to get hurt.

good luck

 

<div class='quotetop'>QUOTE(hsujohn @ Nov 22 2006, 10:31 PM) [snapback]353401[/snapback]</div>

There is no mechanical connection between the brake pedal and the brake master cylinder in the Prius. When traveling at a speed over eight miles per hour, the braking is accomplished by regenerating electricity, not by conventional friction brakes. It is a complex drive, or rather brake, by wire system. The feeling you experienced had nothing to do with air in the brake lines. That is how the pedal normally feels. I am afraid that the current symptoms that you are describing are the result of insufficient amount of hydraulic fluid in the brake system.

 

So, are you saying that if you are driving down the road and the engine quits running and you have not electrical power, a dead or low main battery, then you have no brakes? If I roll my Prius forward in the driveway with the system off I have no brakes?

I wonder if you can blead the rear brakes by having the system on and just opening the bleader screws and let the brake fluid run out. The brake assist feature will come on when the static pressure drops and start putting pressure on the system which will force it out the bleader screw. It works that way on my 03 4Runner. If so then there is only the front brakes to figure out.

 

<div class='quotetop'>QUOTE(LongRun @ Nov 23 2006, 12:48 PM) [snapback]353517[/snapback]</div>

well... there's the "engine off" and the "system off" and they are two entirely different things. the brakes are in no way interconnected with the engine running. if you have a dead main battery, well, the car won't start so brakes won't exactly be a concern. however, should some massive failure occur there is a backup power supply which will allow you to get off the road and stop.

the prius' brake system is NOTHING LIKE the 4runner or any other conventional vehicle! this is exactly the problem here. people are assuming the brake system is like the one in a conventional car and this is NOT the case. if you open the rear bleeder screws without a scantool you're going to suck more air into the system than the brake fluid you'd drain.

 

eh, john, hate to tell you but this is a dealer only (for the most part- some indy shops may spring the cash) tool that costs multiple thousands of dollars

my husband works at one of the top 2 busiest prius shops in the country, so he and all his guys have plenty of experience and can do this more quickly than someone with zero experience. find a toyota shop with high prius volume, they're more likely to be talked into charging you a little less than someone who's never done it before. on the west coast, longo is the only shop that compares to where DH works over here.

if you want to call around to local shops and try your luck there, ask them if they have the toyota scantool. any other scantool will not access the hybrid specific functions. keep in mind that someone who has not done this before could have quite a bit of trouble doing so, at a dealer or indy shop.

happy thanksgiving (and sorry for the unhappy news), and let us know how things work out.

 

Okay, to lay this to rest quickly, you should read this PDF.
I am hoping that some of the independent scantool makers [notably
AutoEnginuity, who seem to be closest to getting the Toyota enhanced
stuff in proper order] will have this functionality in their own
products soon, for an order of magnitude less $$ than Mastertech.
.
I had to put a Prius through the "linear valve zero offset calibration"
dance recently. The instructions aren't too detailed; you invoke the
function from the scantool and wait. But under the covers I heard
an *elaborate* dance going on with firing various solenoids and
pressurizing various wheel brakes individually and letting them
back off again and running the accumulator, and finally the ABS
light changed its blink rate and it was done. Weird stuff.
.
Oh, this pic of the brake system might help, too.
.
_H*

 

<div class='quotetop'>QUOTE(LongRun @ Nov 23 2006, 09:48 AM) [snapback]353517[/snapback]</div>

If I remember correctly, you will still have the hydraulic brakes, what you wll lose is control over the ABS function of the antilock brakes and the regeneration feature, but the car will still stop.

I recently wanted to change the brake fluid myself and despite havinf been a mechanic in a previous life I was happy to pay the dealership to do something this critical for me.

 

Since the dealer may be the only place to get your brakes blead, how much do they charge? This sounds like a serious expense.

 

<div class='quotetop'>QUOTE(LongRun @ Nov 25 2006, 05:26 PM) [snapback]354069[/snapback]</div>

This is not a normal maintenance item. Normally the bleeding would be done only when other brake work requires it. The cost would be a part of the other work.

The abnormal is when a new owner is not familiar with Prius brakes and assumes they need bleeding so he does it himself and screws up the system.

 

<div class='quotetop'>QUOTE(seasalsa @ Nov 25 2006, 08:44 PM) [snapback]354074[/snapback]</div>

Brake bleeding/changing has always been a routine maintenance item for me... but now that I'd need a mega$ tool, I reckon it no longer is.

I've always changed my brake fluid every spring because it can get pretty nasty in there. I wish I could still do this little service item, but I reckon time has rolled onward and left me beside the road...with dirty brake fluid. (okay, maybe not yet; it's a 2006)

GeronimoPFudgemuffin

 

<div class='quotetop'>QUOTE(GeronimoPFudgemuffin @ Nov 25 2006, 06:51 PM) [snapback]354088[/snapback]</div>

do not know what you been driving that got your brake fluid so dirty? Must be a Fudgemuffin Thing.

I haven't bled or had my brakes bled on any car I have owned since the 1950's. New pads when needed but no bleeding and never have changed fluid.

IMO Brake bleeding is not a normal maintenance item.

 

how come on my 2005 prius when it was being towed for like 40 ft the brakes worked like a conventional car? ( no 12 v power ) there wasnt a tow bar either, it was towed with cargo straps

or maybe they make it mechanical to a certain point

 

I was really talking about exchanging the brake fluid, say every two or three years. I like the idea of keeping moisture out of the system and checking everything.

 

labor charges should be in the 2-3 hour range at standard labor rate (now about $80/hr, variable by region) plus shop supplies and brake fluid.

 

Changing brake fluid is a normal maintenance item. It may not be listed in the maintenance chart but should be done every two years. Brake fluid is glycol based and absorbs water from the air. The water is distributed throughout the fluid but concentrates at the calipers, where it corrodes parts. It also lowers the temp. at which the fluid boils, and when the fluid boils you loose braking. In modern brake systems with a "bladder" at the master cylinder there is very little air contact with the fluid, but it still seems to get water in it. Perhaps at the slave cylinders.

DOT 5 brake fluid is silicone based and doesn't absorb water. However, if any water gets in the system (and it will) it works its way down to the calipers. There it will quickly corrode the parts and will definitely boil at low temps (compared to the temp the brake fluid boils at). This again causes loss of braking. It's not recommended to use DOT 5 fluid on street cars. Those racers who use it in their cars change the fluid every week.

 

<div class='quotetop'>QUOTE(seasalsa @ Nov 25 2006, 10:53 PM) [snapback]354100[/snapback]</div>

IMO, yes it is, especially in a humid climate, or if you have a "project car" or other car that's not driven a lot. If you are planning on not keeping a car that long, then it may not matter, but as someone who usually keeps a car 10 or 12 years, then it's definitely worth the trouble, especially now that cars have ABS etc.

I flush the brakes every two years, using one of those handy dandy tools that's basically a brake fluid cap with an air line that hooks to a front wheel's air valve.

 

brake fluid does absorb water. it's hygroscopic. absorption can vary from area to area. places with very high humidity might see the need to change the fluid more often than dry places.

maybe at 150k or so you could change out the brake fluid... he's seen prius at 100k with very good looking fluid, looks like the ones with 5k. any other car, sure, change every few years. but the prius is different (as usual). it has a very tightly sealed system, plus the sheer volume of brake fluid that exists within the system is much higher. the reservoir itself contains about 1 qt of fluid. most other cars don't hold 1 qt of fluid in the entire brake system.

overall, don't worry about it. get it to 100k and check the color of the fluid. the color isn't the definitive indicator, but it's the quickest and easiest way to check.

if DH had to put an arbitrary number on it, he'd say 10 years/100k miles. if you want to change out more often, it's your prerogative, but it's not really all that necessary and pretty much needs to be done at a dealership.