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Brake actuator replacement in pictures

Discussion in 'Gen II Prius Care, Maintenance and Troubleshooting' started by galaxee, Feb 13, 2009.

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  1. galaxee

    galaxee mostly benevolent

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    ADVANCE NOTE: THIS IS NOT A DO IT YOURSELF JOB. THESE ARE NOT INSTRUCTIONS. REPLACING THE ABS ACTUATOR IS A JOB FOR A QUALIFIED TECHNICIAN WITH PROPER EQUIPMENT.
    I REPEAT: YOU CANNOT DO THIS AT HOME.


    Our 05 Prius with just under 60k miles started doing the brake “bark†sound on me not too long ago. There is a TSB out for the issue, but the job is only covered under the 3/36 warranty. Since we got the extended warranty here at PC, we figured this was an opportune time to use it.

    Part: 1769.07
    Labor (5.5 hours): 407.00
    Supplies (fluids): 25.30
    Total: 2322.49
    Our cost: 0
    Extended warranty just paid for itself a couple of times over…

    DH took it to the only other tech who is allowed to touch our car. And being DH, he also ended up insisting on doing most of the work. (which is a no-no, but he’s kind of an exception since he used to be a ‘yota hybrid tech himself and knows the right people.)

    Ok, first things first. The resistor pack gets replaced first, because it’s under the dash and that type of interior work is best done with clean hands. The resistor pack is replaced along with the inverter because they are made and serviced as matched sets. If they’re replaced separately, they get less quiet.

    [​IMG]

    [​IMG]

    [​IMG]

    Next, some digging around under the hood. The inverter has to come out. So the whole wiper cowling setup has to come out. Next, clamping of coolant hoses and removal of various plugs inside and outside the inverter case to be able to pull it out.

    [​IMG]

    Like the inverter crash sensor
    [​IMG]

    Battery connections [yes, the safety plug is removed and the 12v is also disconnected.]
    [​IMG]

    MG connectors
    [​IMG]

    Other internal connectors
    [​IMG]

    Even more MG connectors
    [​IMG]
    disconnected
    [​IMG]

    Even more connectors
    [​IMG]

    And a shot of the whole thing minus cover
    [​IMG]

    And out goes the inverter! First look at the actuator- it’s got the sticker with the big B on it.
    [​IMG]

    Engine electric water pump (big black thing in the center)
    [​IMG]

    Brake fluid line non-pressure hose disconnected in preparation for removal of the actuator
    [​IMG]

    Actuator now out, with bracket
    [​IMG]

    A better profile shot- you can see the solid iron vibration dampener that it bolts to as well
    [​IMG]

    Old actuator part- note that the accumulator tank end is rounded.
    [​IMG]

    New actuator part- here the accumulator tank end is flat. The early actuator replacements were with the same part. This one is now different.
    [​IMG]

    Lots of fun to put everything back together. Then the brake bleed and inverter bleed via the Toyota scantool- allow me to reiterate the only possible way to bleed the brakes on this car is with the Toyota scantool. DH always bleeds the inverter first because an inverter without coolant is bad news, and you might as well do it right when you add the coolant back. Then brakes- by this time, the car is angry and throwing codes left and right because there is air in the brake lines.

    So far no more brakes barking! It hasn’t been very cold since the job was done, though, and the sound was associated with cold weather. The accumulator pump seems a little quieter, too.
    1 person likes this.
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Hi Galaxee,

    Thanks for providing the photos and the steps behind that job. Truly fascinating.

    Yesterday, having the cowl off my 2004 to do some routine maintenance, I was nosing around that area. I took a couple of photos on the passenger side of the cowl focusing on brake parts, and wanted to ask for your (or your DH's) comments.

    The first photo is of the brake stroke simulator, I believe. Can you confirm?

    The second photo seems to be some kind of horn but I can't find it in the repair manual. That is located below the brake stroke simulator. Is that the horn that provides warning when the brake system has a serious problem?

    Thanks!

    Attached Files:

  3. galaxee

    galaxee mostly benevolent

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    Patrick-
    why are we not surprised you're the first reply? :)

    your first picture looks very much like the stroke simulator. if it was on the passenger side, that is likely it. the second is probably the anti-theft horn. it's buried way in the engine compartment so it's not easy to just clip off during a theft attempt. the brake problem buzzer is in the interior of the vehicle, he spent some time listening to that yesterday.
  4. jayman

    jayman Senior Member

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    Hmmm only slightly less complicated than building your own nuclear bomb. I'm sure he had fun with that job
  5. hobbit

    hobbit Senior Member

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    Wow, great stuff! I have some additional pix of the actuator
    and its relationship to the inverter in my maint50k page
    and managed to avoid dropping the inverter too heavily onto the brake
    lines during all that, but have never actually cracked any of the
    coolant lines for that process or cleaning the throttle body. Never
    had the inverter completely out of my car, obviously.
    .
    What's with the "resistor pack", what does it do? I think I've seen
    it up under the dash [left side next to the sidewall, right?] but
    never really knew what subsystem it was for. You didn't change the
    brake ECU during this, correct?
    .
    How many hands/fingers at once did it take to perform the initial
    bleeding? The manual implies that it takes at least two people to
    start the process and get the rest of the lines hooked up, before
    the scantool stuff even begins.
    .
    The brake beeper is definitely inside, mounted right on the ECU,
    visible in this pic from the wheel-speed-diff page next to all the
    metal spikes that form the brake-ECU heatsink. [Why heatsinked?
    Because all the solenoid drivers for the actuator are in the ECU.]
    Pulling the two pump relays and playing with the pedal is a good
    way to make it start howling, if anyone's curious to mess with it.
    .
    _H*
  6. galaxee

    galaxee mostly benevolent

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    he enjoyed getting back under the hood. and yeah, only a little less complicated.
  7. galaxee

    galaxee mostly benevolent

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    that is indeed its location. the resistor pack is for the pump motor. he's not sure why its actual purpose is, and why it couldn't be built into the unit itself. but... there it is.

    no change of brake ecu.



    the r&r and bleed initiation can be done by one person. the brake bleeding procedure is a little less difficult than the manual has led you to believe- but just a little. one person can do most of a bleed, but it takes about twice as long as two people. there is one point where you do need two people, but it's brief.
  8. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I looked in the repair manual, and this says: "Be sure to replace the actuator and the resistor together. If they are not replaced together, motor noise may be increased."


    However the 2004 wiring diagram manual, Brake Control System section, does not show the resistor assembly so it is very strange.

    Also, to remove that resistor it looks like the instrument panel has to be disassembled to the point where the passenger airbag can be removed, so it seems that part of the repair is not a minor effort.
  9. galaxee

    galaxee mostly benevolent

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    you have to pull the MFD to pull the dash panel high enough to reach it, but not the entire dash.
  10. Mike Dimmick

    Mike Dimmick Active Member

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    Psst, 2006 manual here. Keep it quiet. (Despite the EU URL, this is the North America manual.) Either there wasn't a resistor there on the 2004-2006 car, or they didn't think it was going to need replacement and didn't mention it. It could be that the resistor has to be a specific value to perform whatever task is necessary (motor speed control?) and the motors are actually varied enough in winding resistance that they can't use the same resistance on all cars.

    I wouldn't be surprised if the complaint that the motor was too noisy was 'fixed' by adding resistance to reduce the voltage across the motor, making it spin slower.



    I'd guess that the resistor is in that odd place so it's in the cabin air flow. It looks like it dissipates quite a lot of power.
  11. galaxee

    galaxee mostly benevolent

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    i found mention of and instructions for replacing the resistor in 2004-2006 repair manuals.

    here is a screenshot of the 2006 ewd- they made it interactive in 06. (see attachment)

    Attached Files:

  12. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Hi Galaxee,

    I've attached two pages from the 2004 EWD that seem to correspond to the fuzzy screenshot in your post #11. Note that in the 2004 diagram, a 30A ABS fuse (F17 fuse holder) is shown instead of the resistor. Does that fuse appear somewhere else in the 2006 wiring diagram?

    The green wire receives switched power from the ABS MTR relay, which receives 12V power via the 30A ABS-1 fuse. It is very strange that there are two 30A fuses inline in that circuit.

    If all that the resistor does is reduce current flow to the motor, then it seems strange that it is necessary to match a particular resistor value to a given brake actuator.

    Perhaps that resistor was added as an engineering change just prior to production start, so the 2004 repair manual was updated but the wiring diagram was left alone.

    Attached Files:

  13. galaxee

    galaxee mostly benevolent

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    i see the forum software didn't like my wide picture. i wanted to provide enough context.

    that would be an error in the EWD, it happens. it was corrected in 2005.
  14. LYLUVLY

    LYLUVLY New Member

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    Our brake twerping sounds have been with us since 25K. It is now at 30k. We took our 07 in this week [2-2-2010]. The dealer said the squawking noise was due to air in the brake line. The dealer bled the brake lines and replaced with 4 pts of brake fluid. So far, the noise is gone. Are we going to be weary of an actual brake actuator failure in the future? That $2322 repair job is scary. Another advice we need: should we buy the xt-warranty for $----, with the possibility of the actuator failing or do you think it was just as the dealer stated: leak/air in the brake line, fixed! ?
  15. jdenenberg

    jdenenberg EE Professor

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    My 2004 "bark" was fixed by bleeding the right front brake in December 2007. No return of bark yet (about 60k miles since the bleed). Have faith.

    JeffD
  16. Eoin

    Eoin Active Member

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    Thanks for all this information and pictures. Amazing people at PC! My 2010 has the same barking problem. Bleeding was only a temporary fix. The actuator will probably be replaced tomorrow, if the Toyota rep agrees. Man it is a big job!
  17. connorwes

    connorwes Junior Member

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    galaxee & patrick wong,

    I posted at the begining of last year with my BRAKE, (!), VSC, & ABS lights illuminated. At that point (thanks to you investigative sluething by patrick) I managed to diasgnose the problem as a Relay issue.

    Unfortunately, these same warning lights came on, and after checking relays, I gave the 'ol prius to a shop to diagnose. As I dreaded, it turns out the brake acutator is not holding pressure -- indicating an internal leak.

    My question is threefold:

    1) Is there any special trick to de-pressure the braking system? I understand that brake lines are generally very high-pressure systems. I noted that you removed the "non-pressure hose" first, but do not make any mention of the rest of the hoses.
    2) There is no final agreement in this thread about whether or not the resistor pack MUST be replaced. Does any diligent home mechanic happen to have a part # to refer to? I was not able to find it at Toyota Parts - Genuine OEM Toyota Auto Parts and Accessories -- unless is called "DAMPER, BRAKE ACTUATOR" part # 44599-47010
    3) Lastly, I am looking at salvage parts and finding two differnt part #'s for the brake actuator. The parts all seem to list part # 44510-47050, but when i search that on toyotapartszone, I can only find part # 44500-47090. do all the 2004-2009 Prius use the same part? Or, does the 04-05 model differ from the 06-09?

    Answers to any of these questions would be wonderful! (most importantly my question about de-pressuring the brake system).

    Thank you,

    Connor
  18. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Hi Connor,

    Galaxee does not monitor PC as much as in the past so she may not respond to you.

    Regarding depressurizing the system, I suggest you disconnect the 12V battery negative cable where it bolts to the body, then depress the brake pedal a few times. That might work.

    The resistor pack does not have to be replaced if you can tolerate more noise produced by the system.

    You'll have to figure out the part numbering on your own, perhaps toyodiy.com might help.

    Please note her warning that this job is not for the home DIYer especially if you do not have access to Techstream. If you persist, then I strongly suggest you obtain repair manual info from techinfo.toyota.com so that you will have the full procedure and associated safety warnings available to you.
  19. Chris Ward

    Chris Ward New Member

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    Guys thanks for all the information. I've read several of the forums over the brake actuator. I understand that this shouldn't be attempted at home but KBB tells me the car isn't worth me getting the work done. I have found a salvage part, got the mini VCI, and will be buying the 48 hour on TIS. Before I take the plunge has anyone done this? And any last advise. I use this car for delivering newspapers and I'll run it into the ground. Plus I find this good experience because I want start school for automotive tech in the fall.
  20. Patrick Wong

    Patrick Wong DIY Enthusiast

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    There is nothing wrong with you doing the work at home if you obtain the factory repair manual info, have Mini VCI which emulates Toyota Techstream, and the correct tool to remove the brake lines from the actuator (a six point box wrench of the proper size with a slit to allow you to get past the brake line, onto the hex fitting) without causing damage to the brake line fittings.
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