1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Brake Booster ECU Woes: How do I Reset the ECU?

Discussion in 'Prius c Care, Maintenance and Troubleshooting' started by Bob Smith, May 26, 2015.

  1. Bob Smith

    Bob Smith New Member

    Joined:
    May 26, 2015
    6
    1
    0
    Location:
    Japan
    Vehicle:
    2015 Prius c
    Model:
    N/A
    I accepted delivery of a new 2015 Aqua (Prius-C outside Japan) recently. Using a DENSO "DST-i" OBD Scan Tool (with the newest firmware as of March 2015 firmware) and of course with Ignition ON, I sent a "Stop Brake Control" command to the vehicle, which communicates with the Brake Booster Assembly. I later exited from that "Stop Brake Control" mode, and then I performed the required 120-second "Brake System Initialization." After that I exited out from the DENSO Scan Tool, I noticed that 3 or 4 dash check lights were lit. Normally the brake system "Initialize" command via the DST-i should address and clear error flags (check lights), but in this case it did not. I used the DST-i again to Reset, the pertinent flags were not clear as evidenced by the fact the check lights remained lit.

    Not knowing what to do, I returned to the Toyota dealer with the car and consulted about solutions. They changed the brake fluid to see if that would help, resulting in 1 of the check lamps no longer glowing (that flag was somehow cleared). But brake fluid replacement procedure unfortunately did not clear the remaining check lights.

    Since the DST-i is an official DENSO scan tool used in the proper manner, this kind of problem should not have happened. But since the dealer changed the brake fluid thinking that would solve the problem, and since it did not solve the problem, the dealer had no further explanation, so they simply said it would cost approximately $2000 (equivalent) to replace the entire Brake Booster ECU. And since that part is not normally stocked, it will take time to order and receive it.

    A DENSO scan tool is technically not a Toyota problem, but DENSO is inseparably tied to Toyota insofar as Toyota uses DENSO scan tools. To even change the brake fluid the dealer must use the DENSO scan tool to issue the "Stop Brake Control" command. But of course, since it was me who sent the command with my own DENSO tool instead of the dealer doing it, the dealer will of course not take responsibility to investigate the matter too extensively, opting instead to say that a complete replacement of the Brake Boost ECU is the only recourse.

    Clearly, there is some kind of design problem in the Aqua / Prius-C Brake Booster ECU to even allow this kind of problem to occur. Nevertheless, I wish to keep the focus of this post on what can be done to solve the problem.

    Simply put, I am sharing this experience in part to warn others about issuing DST-i commands to the Brake Booster on the Aqua / Prius-C but also in part to ask your advice and help. Do any of you know of the Brake Booster ECU stores flags in its own flash memory? Surely there must be a way (other than just replacing the ECU unit outright) to clear flags in the Brake Booster ECU. The vehicle drives fine and the brakes work as usual. The only "problem" is that the ERROR FLAGS remain perpetually lit.

    How could I possibly clear the Brake Booster ECU, other than simply removing battery power?
    (Removing battery power won't help of flags are stored in flash memory.)

    Thank you.
     
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    109,998
    49,981
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    have you tried disconnecting the 12 volt battery for a few minutes?
     
  3. Bob Smith

    Bob Smith New Member

    Joined:
    May 26, 2015
    6
    1
    0
    Location:
    Japan
    Vehicle:
    2015 Prius c
    Model:
    N/A
    Thank you for your reply.

    I disconnected the battery for more than 15 minutes. Upon reconnect I confirmed the check lights are still lit. So as I expected, there is flash memory in the ECU which saves these flags. Flash memory will not be cleared by removing power.

    Here are photos of the dash Check Lamps I mentioned in my opening post. Sorry, but because I am new to this forum, I am technically not allowed to post URLs, so you need to manually enter them in your browser:

    http://bit.ly/1EwpUvF

    http://bit.ly/1PLWt4M

    http://bit.ly/1etwvlV

    Further thoughts and advice would be greatly appreciated.

    Thank you.
     
    #3 Bob Smith, May 26, 2015
    Last edited: May 31, 2015
  4. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    109,998
    49,981
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    you might need toyota tech steam software to reset it.
     
  5. Bob Smith

    Bob Smith New Member

    Joined:
    May 26, 2015
    6
    1
    0
    Location:
    Japan
    Vehicle:
    2015 Prius c
    Model:
    N/A
    Thank you again for your reply.

    The DST-i scan tool (& TaSCAN) and the Global Techstream (GTS) software are basically the same, except that the GTS is the software edition running on a PC while the DST-i is a standalone unit with built-in screen. HOWEVER...

    I am pleased to report that the problem is now fixed. An engineer friend has access to Toyota's TECHINFO website which provided the solution:

    1) CLEAR CODES: With Ignition (IG) OFF, connect OBD pin-13 (TC - Timing Check) to pin-4 (pin-4 is GROUND) — manually short them together and leave them shorted together. (I used an OBD connector with wires exiting the back to accomplish this.) Then switch on IG and press the foot brake more than 8 times within 5 seconds. Now disconnect pins 13 & 4.

    2) CLEAR CALIBRATION DATA: With IG OFF, steering wheel centered, gear in P (park), foot brake not pressed, and Parking Brake not set, switch IG ON. Connect OBD pin-13 (TC - Timing Check) to pin-4 (pin-4 is GROUND) briefly and repeatedly four times (or more) within 8 seconds.

    3) INITIALIZE & CALIBRATE: With IG OFF, steering wheel centered, gear in P (park), foot brake not pressed, and Parking Brake not set, connect Pin-12 (TS) to Pin-4 (GND) — manually short them together and leave them shorted together. Turn IG ON. Wait until the initialization sequence is done (you will hear solenoid noises and see dash warning lights flash), which takes about 2 minutes. Turn IG OFF. Disconnect pins 12 & 4. I then used the DST-i scan tool to verify all was well.

    So there appears to be a bug at work. Performing a software CLEAR & INIT using the DST-i did not work properly (the dash check/warning lights never were cleared). But doing the same thing via the car's built-in RESET and INIT/CAL works perfectly.

    I hope this information helps others.
     
  6. Motov8r

    Motov8r Member

    Joined:
    May 25, 2014
    102
    41
    0
    Vehicle:
    2013 Prius c
    Model:
    Two
    Odd that a dealer could not figure this out.


    iPhone ?
     
    Bob Smith likes this.
  7. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    109,998
    49,981
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    congrats!(y)
     
    Bob Smith likes this.
  8. Bob Smith

    Bob Smith New Member

    Joined:
    May 26, 2015
    6
    1
    0
    Location:
    Japan
    Vehicle:
    2015 Prius c
    Model:
    N/A
    Perhaps they did know the solution but preferred to avoid mentioning that so as to profit off a Brake Booster sale. Dealers do make most of their money selling us "options."
     
    bisco likes this.
  9. ewaboy

    ewaboy Active Member

    Joined:
    Feb 18, 2012
    693
    205
    0
    Location:
    Hawaii
    Vehicle:
    2012 Prius c
    Model:
    Two
    Glad you got your problem solved. Good info. Thanks.
     
    Bob Smith likes this.
  10. orenji

    orenji Senior Member

    Joined:
    Aug 17, 2013
    5,884
    3,486
    0
    Vehicle:
    2010 Prius
    Model:
    Three
    Thanks for the info. Maybe the dealer did not know all the steps involved to just clear some codes, they are not engineers ;). It does seem ridicules how many steps are needed to reset some warning lights!
     
    Bob Smith likes this.
  11. Bob Smith

    Bob Smith New Member

    Joined:
    May 26, 2015
    6
    1
    0
    Location:
    Japan
    Vehicle:
    2015 Prius c
    Model:
    N/A
    The warning lights pertain to the braking system, so that explains why they make you jump through hoops to clear them.

    Toyota is nuts about liability. Here in Japan they build in TV capability to all navigation systems they sell, but the TV features (any video features, actually) are disabled until you stop the vehicle, put it in Park and set the parking brake! Most people here avoid the factory navi option for that reason, going to their local AutoBacs and putting in a 3rd party navi unit instead which lets you show as much video as you want while blazing down the highway. It's silly you cannot show video while you drive seeing that the person most likely wanting to watch it is your passenger. I can't imagine ever wanting to watch video myself as a driver. Then again, I cannot comprehend the mentality of people who text while they drive. When I drive, I DRIVE. That's it.

    Anyway, I hope the info in this thread can help some of you.
     
  12. Matt H

    Matt H Active Member

    Joined:
    Nov 23, 2012
    164
    104
    0
    Location:
    Okinawa Japan
    Vehicle:
    2012 Aqua
    Model:
    N/A
    Hello Bob,
    The Denso DST tools are not factory tools. The ones available to the aftermarket are watered down versions of the factory tools, and I've found lots of things they can't do compared to the factory gear (programming for one). The software is pretty incomplete. T

    As a note, Techstream from the US won't work on a lot of JDM Toyota's, so I'd be careful using it. JDM cars are very specific, car to car. I've used it on a few hybrids for diagnostics only, as it has really good graphing, and will communicate with JDM hybrids.

    Hands down, the best tool for JDM cars that's available to the aftermarket in Japan is the Gscan. It breaks it down to International or JDM Toyota, and then Model, VIN, Year, Engine, etc. With other tools, even some functions that are listed won't complete. If you have that problem with the Gscan, you log the attempt to file, and send it to Gscan. They usually come back with a patch for the problem in under 24 hours. Not a cheap tool, though.


    That said, what your friend did was essentially a zero-point reset. It's usually found under special functions in the TCCS or ABC/VSC menu. The ABS/VSC has nine items under the special functions menu. There are relearn and reset functions throughout. The Gscan can do everything the dealer can do with the exception of programming, as that info is not available to anyone outside of the dealer in Japan... :-( Can even reset the immobilizer system, program keys, and on and on.

    I have Denso DST-i, Denso DST-2, Snap On MTG-1000, Snap On MTG-3000, Verus Pro, and a few others that just sit on the shelf since I got the Gscan. I've had a frustrating time with the Denso tools.

    Cheers.




    20150604_184241.jpg
    20150604_184034.jpg
     
  13. Matt H

    Matt H Active Member

    Joined:
    Nov 23, 2012
    164
    104
    0
    Location:
    Okinawa Japan
    Vehicle:
    2012 Aqua
    Model:
    N/A

    All you have to do is ask the dealer to turn it on. The TV can be viewed on the fly, it's just a simple programming mod. They won't tell you that they can do it, but if you ask, they'll do it. My Aqua, and Lexus NX300h have the factory navi, and have been switched to work on the fly ;-)
     
  14. Bob Smith

    Bob Smith New Member

    Joined:
    May 26, 2015
    6
    1
    0
    Location:
    Japan
    Vehicle:
    2015 Prius c
    Model:
    N/A
    Thank you for sharing your experience, Matt. I appreciate hearing your thoughts and recommendations.

    I am aware of G-scan, which is represented here in Japan by this company:


    株式会社 インターサポート


    But I am curious about your comments regarding DENSO scan tools. DENSO is a separate company from Toyota, but here in Japan the two firms are so tightly intertwined they appear as if they were the same company. As far as I know, DENSO tools are the factory-grade tools insofar as Toyota dealers in Japan use them. I would guess that one would not need them at the assembly "factory," but I lack information on that.

    Although I have found a couple "bugs" in DENSO scan tools (such as triggering of Warning lights mentioned in this thread, and accidental triggering of high-current draw on Noah, Voxy and Esquire vehicles even after you disconnect the scan tool), it's still difficult for me to imagine that a third-party aftermarket scan tool maker would best DENSO in its understanding of Toyota vehicles. G-SCAN is much snappier to use than DENSO scan tools, that's for sure. DENSO scan tools are dog slow. But is "compatibility" really "better" across the full spectrum of Toyota cars manufactured and sold here in Japan? Again, I have my doubts. But I would agree that after-sale SUPPORT would be better with anyone than DENSO. With DENSO, you buy the tool and that's it. Go ahead and report a problem, but you're stuck until they get around fixing it. In that regard, you may be right about G-SCAN being better.

    As to Navi systems here in Japan, Japanese dealers will not "flip it on" even if you ask. Boy, I wish they would. But they are so hard-headedly stubborn and serious about liability they would never even in their wildest dreams consider it. That's why most Toyota buyers here ditch the dealer option of Navi so they can trek down to AutoBacs and install an unlocked 3rd party NAVI system. It's also cheaper that way too.
     
  15. Matt H

    Matt H Active Member

    Joined:
    Nov 23, 2012
    164
    104
    0
    Location:
    Okinawa Japan
    Vehicle:
    2012 Aqua
    Model:
    N/A
    Bob, don't get me wrong, the Denso tools are great, and ahead of the curve compared to the other aftermarket tools available in Japan, with the exception of the Gscan. In the US, the manufacturers have to make available to the public, the same tooling and SI that's available to the dealer. Here in Japan, they have it locked down, as I'm sure you know. Can't even get service info from them anymore, so I've had to subscribe to a newer Japanese info site called Fines. Sort of like Alldata or Mitchel, but only available to "ninsho" or "shitei" sebikoujou... It's freaking ridiculous, as the dealer doesn't want to work on stuff after the second shaken at the five year mark...right when the warranty is up. Sigh...

    Toyota licenses and allows Denso to sell the tool, but with exceptions in the software for the aftermarket. There are quite a few functions that are only available on the OEM tool, and updates for newer cars are slow coming. Probably because no one but the dealer touches cars under five years old, anyway. My oldest son works as a tech for Kanagawa Toyota, and I've compared them side by side. As you know, we have no programming capability in the aftermarket, as none of the OEM's make that info available. Module failure is exceptionally rare, but it's frustrating to have to take a customers car to the dealer to do something... Ditto being able to do things with the factory navi systems. When I bought my NX300h F-Sport, my wife brought up the BS about the TV not being able to be seen by passengers, so they turned it on for us. I asked them to do the Aqua, and they did that, as well. Maybe the Toyota dealers won't do it, but when you drop 6.4 million on a Lexus... Well, let's just say that Lexus plays in a different league when it comes to customer service, and Toyota is no slouch!.

    My Japanese reading comprehension sucks in technical matters, so I bought the Gscan from the Oceana distributor through a friend in Australia (they can't ship direct). The difference is that it's in English. They're serious about region, and the Japan tool will only do Japanese. I was told the US version was really lacking on the JDM side, so I blew the $6000 for the full kit from Oz, which comes with all of the early JDM OBD adapters.

    On that note, what you experienced might just be that the software hasn't caught up yet? I haven't updated the Denso tools in a while, but for the Aqua, it wasn't listed for the Gscan until just the last update. Before that, I was just using the Toyota International hybrid 16p DLC generic settings. When the Aqua-specific software dropped, I was astounded by how many, and how in depth the functional tests, PIDS, and bi-directional controls were.

    I've found things the Gscan failed at, and the Denso tool did, but like I said, I just logged the attempt, and sent it to GIT. They have always come back with a patch for the bug, in about 24 hours. It's then included in the next update, which are quarterly. Full kit includes 3 years of updates, and it's about $500 per year after that. Graphing sucks. That's my only complaint, about it, and they tell me they're working on it.

    Good to talk to someone else in Japan with pro-level diagnostic capabilities!

    Cheers.
     
    Bob Smith likes this.
  16. 2004priusgal

    2004priusgal Junior Member

    Joined:
    Sep 6, 2017
    71
    8
    0
    Location:
    new jersey
    Vehicle:
    2004 Prius
    Model:
    Upgrade
    Would this apply to gen 2 as well?
    diy rear brakes... all.. without undoing 12v. got codes but cleared them and i worry the system is not set correctly, as pump seemed to work more often and longer, however , a month after dealer brake flush it appears normal. thx
     
  17. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    24,860
    16,182
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    A really weird thing about this thread is the way it went on for more than a dozen posts, including really technical questions and speculations ("Clearly, there is some kind of design problem", "stores flags in its own flash memory?", "must be a way (other than just replacing the ECU unit outright", and so on), being made by somebody who clearly had access to a scan tool, and not one of the posts has the OP ever mentioning what trouble codes the car was reporting, or any other poster even asking what the codes were, or anybody even asking how it possibly got that far without anybody asking what the codes were.

    That led kind of unsurprisingly to the "solution" that was described in #5, which can't be described any other way than some kind of blind frenzy to do all of the things that might or might not be needed depending on what trouble codes are present, without anybody checking what trouble codes are present. Followed, naturally, by comments like "It does seem ridicules how many steps are needed to reset some warning lights!".

    The way to have it seem less ridiculous is to get the trouble codes, and then follow the specific steps those trouble codes require you to follow. If you have the code saying the linear solenoid offset needs to be relearned, then you do the procedure for clearing and relearning that. If you have a C1451, you bleed the brakes. And so on with the other codes. It all seems much less baffling that way. And just like any other time when warning lights are on, it simply begins by finding out what the trouble codes are.

    In the OP's case, probably the original code was a C1451. That code is stored when entering "invalid mode" (or "stop brake control" mode) via the scan tool, and only a bleed sequence clears it. Since the OP then went to a dealer and they faffed around with it for a while, and they "changed the brake fluid to see if that would help" (which involves a bleed sequence), that would be when the C1451 went away, but something else in their faffing around clearly set one or more other codes, including the one for solenoid offset learning that ended up getting cleared by relearning that offset in post #5.

    The codes and procedures for Gen 2 are not identical, but the part that definitely does apply is: think how much more straightforward it would have been to read the codes, look them up in the manual, follow the indicated steps, and be done with it?