Bleeding 05 Prius brakes the old fashion way

FXG,
If you go onto the "My Toyota web site" it gives you the Toyota fixed prices for services and some other items including discs and pads so yes your dealer is ripping you off. If you log in you can see your cars service history, but unlike the US you cannot add work you do yourself.

The Techstream software does "guide" you through the brake bleeding procedure for which you need two people.

More often than not it is the slide pins that cause trouble with uneven brake ware, and not the actual pistons/calipers. The slide pins can be replaced if worn.

You will probably find the rear pads only 25% worn at your millage, but unless you are in the habit of using the brakes in neutral the rear discs go very rusty. If you need replacement discs let me know and I will see if I can dig out the address and phone number of my supplier. As I said before I got the rears for £16 the pair.

Beware if ordering discs make sure they are the five stud versions as a lot of suppliers are sending out the four stud versions for the 2003 and before Prius. The same goes for the rear pads, they are not the type with two pins going through the pads to hold them in place.

If your rear pads have plenty of life left in them you can rub them flat on some sand or emery paper and re use.

When you have done the work make sure you bed the brakes in by getting the car up to 50 mph going into neutral and brake. Do this until the brakes feel good. If you do not do this you will get a nasty surprise if you have to brake in an emergency and the regen braking is bypassed.

Finally do not forget to disconnect the 12 volt battery before starting work. If the hydraulic pump starts while you are working, it will push out the pistons!!!

John (Britprius)

 

Even after disconnecting the 12V there are still the emergency brake capacitors that need to be discharged. See hobbit's web page for details.

 

That's what I thought, brilliant link ... arf ... so much help ... thanks guys.
BritPrius you're my savior. will be in touch soon.

 

Back a few decades I basically did protracted bleeding of the brakes on a few cars. Intentionally bleeding say a cup's worth at each corner, to flush the brake fluid. But my technique maybe wasn't that good; I'd notice the brakes if anything were a bit mushy after. I found it easier and less stress to let the dealerships do it from then on, for under $100. They have the expertise, and apparently some machine that semi-automates the process.

I've next to never needed to have a disk replaced, on any of our cars. Just one, that had a crack. I think the brakes were not releasing properly on that car, the wheels always felt warm/hot after a drive, and it ate brake pads. I believe the discs on that car were flirting with min. thickness. (A micrometer or caliper is handy to have.)

Testimony to our dealership's level of competence:

We were driving, and every time I touched the brakes it sounded sick, like the car had a broken back or something, LOL.

Got home, pulled off the wheel on the front left corner, where the sound seemed to be coming from. I looked with a good light, and found a radial crack. Could snag it with a finger nail.

Called the dealership, brought it in, walked home (close by). About an hour later, got a call, (paraphrasing): "Your car's ready, and you're in luck, there's no problem with the brakes".

Well..., for about one second I actually believed him, then reality kicked in, and I told him they better take another look. Hung up, went into a slow burn, emailed the Service Manager.

From past experience, he was a really good guy, very diligent/thorough, always explained everything to you and so on. Anyway, he phoned back about another hour on, said he had the disk on his desk, appologized, and so on.

I've never touched the brakes on our Prius. My impression: the likelyhood of trigger codes goes from low to high in the order of the following list:

1. Just opening up the caliper, say by removing the lower bolt and rotating it up. Pulling out the pads and cleaning pad backs, shims, caliper contact points. Lubing all faying surfaces with a thin application of something like anti-sieze molybdenum and re-assembling.

2. Per above, but replacing pads with new, pushing the pistons back to clear the new pads.

3. Per above, but also bleeding the brakes lines, and/or replacing fluid.


There's also the possibility that the car will try to "pressurize" the brakes (I think that's the whirring sound you often hear when opening the driver's door). If that happens when you've got a caliper opened up I'm not sure what happens. Maybe disconnecting the 12 volt battery negative cable, and/or making sure to never open the driver's door, and/or pulling a fuse would prevent that?

 

The Toyota instructions say remove the two light blue relays in the fuse box under the bonnet/hood, and disconnect the 12 volt battery, waiting two mins before starting work.

Having replaced discs and pads on my own car I found that the new front pads could be pushed back against the discs after fitting by pushing the brake pedal in the normal way.

This did not work for the rears "no movement of the pads no matter how much pressure was put on the pedal.

However when the relays were replaced and the battery reconnected there was a noticeable metallic clang as the pads were powered by the hydraulic pressure reservoir back against the discs with no other action from myself.

This action shows that if the pads had not been in place or the caliper not fitted with the 12 volt supply intact the pistons in the calipers would have been ejected.

John (Britprius)

 

The pressurising is a reservoir like the vacuum booster of your old car held a spring back with atmospheric pressure. The prius does it with pressurised brake fluid. The brakes have their own battery as a backup, disconnecting the 12 volt battery wont disable them.

 

The Prius has a capacitor bank as a backup "the black plastic box next to the battery" this is why Toyota say to remove the two relays and wait 2 mins for the capacitor bank to discharge.

John (Britprius)

 

Here's something from Raybestos. No date though, or mention of generation number:

http://www.raybestos.com/wps/wcm/connect/4c56d4804ee82f6f9c26bd8b8d93e121/BPI+09-10.pdf?MOD=AJPERES

 

Nice find, it does say all Prius models but basically confirms my post (45).

John (Britprius)

 

Looking at the circuit diagram for the brake system the capacitor bank is not there to power the hydraulic pump, but to supply the ecu and control solenoids for the brakes in case of total loss of the 12 volt bus. Enabling the system to work normally with whatever pressure is available in the pressure reservoir. That in normal circumstances is kept automatically near full pressure.

John (Britprius)

 

3rd gen fuse box looks quite a bit different. There's 3 light blue relays. Maybe the 2 together?

 

Yes quite possible, unfortunately I do not have access to the gen3 information so I cannot confirm.

John (Britprius)

 

Let the car sit a good while, pull those two light blue relays that are together, then open drivers door and see what happens? Hopefully does not throw a code... Not sure I'd want to chance it myself

 

Alloosh, Most brake fluids are hydroscopic. You should try to replace brake fluid once every year or so to prevent the moisture content from getting too high. This will decrease your braking capability and even corrode the metal in the system over time.
If you just changed the pads, now is a good time to flush the fluid. If you wait until you change the pads next time it could be years based on how long pads last on a Prius. Using a silicone/DOT5 fluid will prolong the life of the fluid as it is hydrophobic.

 

^ I'd be careful with fluid choice, (3rd gen) repair manual spec's:

SAE J1703 or FMVSS No. 116 DOT3

Mixing different types can be bad, I think.

Also, once a year replacement seems excessive.

 

Just starting to get some of the tools I need to take a good look at what's going on. First thing I can confirm is that cheepo ebay VCI seems to manage brakes bleeding. Will open a new thread to report any significant work on the brakes that'll come up if any.

 

Yup. Mixing can be quite bad. The fluid can form a gel if even a trace of one type is mixed with the other.

Goes to show, be careful taking advice from random strangers on the Internet.

Only time one would want to change fluid often is if he is doing lots of heavy braking: pulling a trailer or driving on a track.

 

i got car back yesterday from shop, i took it to an electrical specialist cause my relay change and resetting of light wouldnt work.

turns out the abs pump module was out, got a used one for $110 delivered compared to $1800 new
almost every relay and resistor was bad on brakes, 1 blue and green relay, the long clear microchiped relay on left side of fuse box,
the resistor under dash was burned bad enough to take off the paint. got at junkyard for $10 compared to 250 and almost 2 week wait

since the car had been sitting block 5 of the hv battery is showing bad, though that block is reading about 14.4v or somewhere around there, the rest of the blocks are reading closer to 16v. i will change block 5 battery soon

 

Hi dmphilli,
I'd like a little clarification regarding bleeding the brakes on my Gen II.
My brakes are currently working and I have no warning lights on but I have 210k miles on the car and it's time to bleed the system. Brake pads have already been changed at 185k so I'm not doing that. I have no air in the brake system.
Your jumpering of the OBD terminal was just to turn off the warning lights, right?
Bleeding procedure:
Don't pull any relays or fuses.
Suck out old fluid from the reservoir, no valves are open so no air enters the system. Refill with clean fluid.
With the engine off, (and the driver's door kept closed to prevent the pump from running... I hear) an assistant depresses the brake pedal for less than 5 seconds during which I open the bleed valve. Open bleeder valve every other time the pedal gets depressed (when pump runs).
Keep an eye on brake fluid level and go from RR, LR,RF to LF.
You said that you did this for 30 min. Did you keep going around the vehicle or did you spend a lot of time on the first valve to renew the fluid then move on?
Please let me know if I'm correct. Thanks!!

 

I think it's just terminology, just checking:

Bleeding is the term usually applied to just getting air out of the system. Your intention is to change the brake fluid? Through protracted bleeding? (Geesh I hate the expression "protracted bleeding", LOL)