2012 Prius V intermittent brake issue.

Discussion in 'Prius v Care, Maintenance and Troubleshooting' started by Lance DiBitetto, Apr 10, 2020.

  1. Lance DiBitetto

    Lance DiBitetto Junior Member

    Joined:
    Feb 14, 2016
    23
    7
    0
    Location:
    ocala, Fl
    Vehicle:
    2004 Prius
    Model:
    N/A
    (I checked other threads and none were specific to what I am experiencing, so I decided to start a new thread.)

    Hello, I have been having an issue with the brakes in my '12 They work fine when I am driving around town on the weekends but, when I am working with the car (I'm a Courier) with a lot of stop and go driving, the regen braking stops working and the pedal gets slightly harder to press but still brakes fine. It will display the standard 4 dummy lights when this happens, The thing is, it is not throwing any codes...none. Even Toyota tech stream found no errors with anything....even the cached codes from previous events don't relate to any issues with the brakes. If the car sits for a little while the lights disappear and the car will drive normally with nary an issue. This only happens when I am working (The reason why I bought the car) It almost feels related to temperature, like the hotter the brakes system gets is when the issue appears. I am really hoping that it is not the dreaded brake issue I have read about plaguing the third gen models.
     
    #1 Lance DiBitetto, Apr 10, 2020
    Last edited: Apr 10, 2020
  2. Mendel Leisk

    Mendel Leisk Sand Pounder

    Joined:
    Oct 17, 2010
    45,456
    32,446
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Do you have anything plugged constantly into the OBD port?
     
    Lance DiBitetto likes this.
  3. royrose

    royrose Senior Member

    Joined:
    Mar 21, 2009
    1,290
    862
    4
    Location:
    Foot of Pikes Peak
    Vehicle:
    2010 Prius
    Model:
    IV
    Good question. I have both a scanguage and an OBDII adapter. I had one of them plugged in loosely (I don't remember which) and had exactly the same symptoms. I pushed it in firmly and restarted and the problem went away.
     
    Lance DiBitetto likes this.
  4. Lance DiBitetto

    Lance DiBitetto Junior Member

    Joined:
    Feb 14, 2016
    23
    7
    0
    Location:
    ocala, Fl
    Vehicle:
    2004 Prius
    Model:
    N/A
    I have had a cheap chinese BT micro ELM 327 in the port....will it do that? I had an 04 Prius that I replaced with this car that I left it in with no issues, I never even thought that it would cause any problems, if that could be the issue it may very well save me from driving this car off a cliff. (well, more like a sink hole, I live in FL) :p
     
  5. royrose

    royrose Senior Member

    Joined:
    Mar 21, 2009
    1,290
    862
    4
    Location:
    Foot of Pikes Peak
    Vehicle:
    2010 Prius
    Model:
    IV
    It may be making poor contact. See my post above. Try removing it, restarting and checking the brakes. Then try putting it back in firmly and try again.
     
    Lance DiBitetto likes this.
  6. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    14,570
    10,255
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    It is possible for the quality and condition of the connector pins when something is plugged in there to lead to communication errors of varying severity between the computers that run the car.

    If that variable is eliminated and the behavior persists, I might start to think that the braking system is able to maintain pressure during normal driving but not when you are doing the more frequent braking of your work trips. But that would have definite trouble codes to go with it.
     
    Lance DiBitetto likes this.
  7. Lance DiBitetto

    Lance DiBitetto Junior Member

    Joined:
    Feb 14, 2016
    23
    7
    0
    Location:
    ocala, Fl
    Vehicle:
    2004 Prius
    Model:
    N/A
    To be honest, it is not terribly important to have the dongle in the port anyway, I only did it with my old Prius because I was monitoring the systems in the car because It crested 400k and I wanted to quickly diagnose issues if they occurred while I was working.
     
  8. Lance DiBitetto

    Lance DiBitetto Junior Member

    Joined:
    Feb 14, 2016
    23
    7
    0
    Location:
    ocala, Fl
    Vehicle:
    2004 Prius
    Model:
    N/A
    Understandable, That was going to be my play, remove the dongle and see if it continues, not throwing any codes concerning this issue gives me hope. The quality of the dongle is in question as well, I know very well that computers can be fickle (some more than others) so it is pretty darn plausible that the cheap Chinese ($7.00) BT dongle could be riddled with poor workmanship thus, making the Prius systems see ghosts. :unsure:
     
  9. Mendel Leisk

    Mendel Leisk Sand Pounder

    Joined:
    Oct 17, 2010
    45,456
    32,446
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Yeah I would try that.

    We had brake issues with increasing frequency (on our 2010), about 6~7 years back. Warning lights would come one, and the brakes would feel "weird": they worked but at first it felt like they were gone. Then you'd realize they were still functional, but the felt decidedly different, took more effort, seemed to be "working to rule".

    I brought it in to dealership 3 times, and the first two times I disconnected the ScanGuage I had on the OBD port (constantly connected). After second time they said: if it happens again bring straight here without turning the car off. About a week later that happened, and the mechanic came straight out to the car with Techstream laptop, disconnected the SG and did some checks, dismissed codes.

    Then he pointed out he could shake the Techstream cable a bit and get intermittent connection. He theorized the constant weight of SG cable on the OBD port might be causing problems.

    I've not used SG since, apart from a few around-the-block tests of specific problems, and had no further brake problems.
     
    Lance DiBitetto likes this.
  10. rjparker

    rjparker Senior Member

    Joined:
    Jun 6, 2008
    4,020
    2,101
    2
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    1. How do you know the regen braking stops working?
    2. What are the "standard 4 dummy lights"?
    3. When do the "dummy lights" go away?
     
    Mendel Leisk likes this.
  11. Lance DiBitetto

    Lance DiBitetto Junior Member

    Joined:
    Feb 14, 2016
    23
    7
    0
    Location:
    ocala, Fl
    Vehicle:
    2004 Prius
    Model:
    N/A
    I knew someone was going to ask "what lights?" they are off now but (1)ABS (2) VSC, (3)the one that looks like drum brakes with the exclamation point and the one that says (4)"brakes".
    It turns off after the car has been powered off for longer than a few min. it will either return or not. it triggers absolutely no codes, either with a basic OBDII dongle or the Toyota TechStream diagnostics.
    How I know regen braking stops working, first the brakes feel markedly different, harder to press but no much, at the same time the dash lights go on as well as the regen dash indicator and the one on the radio/mfd that shows transfer of power from the wheels to the battery displays no activity during braking. (I know, that may not indicate anything but, the other symptoms combined made me come to that conclusion)
     
    #11 Lance DiBitetto, Apr 10, 2020
    Last edited: Apr 10, 2020
    Mendel Leisk likes this.
  12. Mendel Leisk

    Mendel Leisk Sand Pounder

    Joined:
    Oct 17, 2010
    45,456
    32,446
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Maybe have dealership verify what codes are present, and what it might be.
     
  13. Lance DiBitetto

    Lance DiBitetto Junior Member

    Joined:
    Feb 14, 2016
    23
    7
    0
    Location:
    ocala, Fl
    Vehicle:
    2004 Prius
    Model:
    N/A
    I'm dreading going to my Local dealership, They are probably the worst dealership I have ever encountered, the owner is arrogant presumptuous and it filters down into the rest of the dealership. I worked for Toyota for a number of years back when I was a much younger and I have seen what a good dealerships service department is willing to do to soak the customer. I couldn't imagine what a bad dealership would do.
     
  14. rjparker

    rjparker Senior Member

    Joined:
    Jun 6, 2008
    4,020
    2,101
    2
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    Classic brake accumulator and actuator problem. Most of the time a weak accumulator will run excessively trying to maintain its reservoir of hydraulic pressure, but if it does not run for five minutes continuously it won’t throw a code. The actuator (master cylinder) is integral to regen as its ecu helps determine how much of the accumulator’s hydraulic force to use.

    The brakes are entirely brake by wire except under totally failure of the accumulator when no hydraulic pressure is available OR under failure of the actuator/abs/ecu. In those worse case failure modes two normally open solenoids fail to their open position allowing your pedal pressure to directly create hydraulic force to the brakes. Most never feel this hard brake which can greatly extend stopping distances.

    Gen 3s are so bad in this area that most everyone except the v is eligible for free replacements. My dealer was going to charge $2250 which was discounted but I had used put in for $1200 parts and labor by an independent prius mechanic. Most have done hundreds on gen2 and gen3.

    Gen3s are more difficult due to access and the bleed procedure requires techstream once air or nitrogen has gotten in.

    Caution - standard prius actuators won’t work because of different ecus. Many resellers don’t know this and list standard and v’s as interchangeable. You want part 47070-12020.

    Antilock Brake Part Actuator Pump Assy 47070-12020 Fits 12-17 Toyota Prius V OEM | eBay
    A
    nd
    2010-2015 TOYOTA PRIUS ANTI-LOCK BRAKE ABS ACTUATOR PUMP ASSEMBLY 11 12 13 14 15 | eBay
     
    #14 rjparker, Apr 10, 2020
    Last edited: Apr 10, 2020
  15. Lance DiBitetto

    Lance DiBitetto Junior Member

    Joined:
    Feb 14, 2016
    23
    7
    0
    Location:
    ocala, Fl
    Vehicle:
    2004 Prius
    Model:
    N/A
    I really appreciate the input from everybody, I sure hope that it is not the "brake accumulator and actuator", I have only owned this car for less than 6 months and have poured more money into it than I really should have. my second gen '04 gave me over 360k of trouble free operation. I guess I was asking too much to get at least half that reliability from the gen 3 models...:unsure:

    The real shame of it is I really love the car......
     
  16. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    14,570
    10,255
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Some way of solving the mystery of the unretrieved codes would make the diagnosis easier. I can read the "absolutely no codes" in the above posts, but by the same token, there are warning lights coming on, which means there are codes.
     
    Mendel Leisk likes this.
  17. rjparker

    rjparker Senior Member

    Joined:
    Jun 6, 2008
    4,020
    2,101
    2
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    I agree, there must be codes but they may be clearing before you can read them or they require special abs modes. I will say this, my car never threw codes or the light but the two brake items were still bad. Other than those items, there is very little else in the braking system other than the standard stuff at the wheels.

    On my car, I knew there was an issue because of excessive accumulator runtimes and the frequency of its runtime. Other owners have had all the codes (one of which is necessary for the free replacement on the standard prii) but the codes and lights did not make the car stop.

    If it were me, I would take it in for a diagnostic. Assuming they come back with accumulator and actuator, ask them to check for a Toyota extended warranty (service campaign) replacement. In the end your safety and those around you on the road make the cost issue less important. Don't overpay, $2250 was my dealer's price, or find an independent that has done it many times and is willing to warranty work.

    Its possible that a pending complaint to the NTSB will result in the v's being covered. A similar thing happened with the v's inverters and Toyota then retroactively reimbursed as long as the work was done by an authorized shop.
     
    Mollyisadog and Lance DiBitetto like this.
  18. Lance DiBitetto

    Lance DiBitetto Junior Member

    Joined:
    Feb 14, 2016
    23
    7
    0
    Location:
    ocala, Fl
    Vehicle:
    2004 Prius
    Model:
    N/A
    Hey, I know that this thread is a little old now but, I was able to completely verify that it was the ELM327 Bluetooth OBDII dongle causing the issue. First off there are none of the symptoms that come with a bad brake accumulator (the weird cycling sound every 10 or so seconds or so hard braking etc...) I removed the OBDII dongle and the issue never came back...for months. just today, though. I was checking codes with the Dongle and had to run to the store and forgot to take it out, I had no issues going to the store but, when I was on my way back, the lights on the dash indicating a brake problem popped on and the regen braking stopped working, I pulled over turned off the car and pulled the dongle. started the car back up and everything was gone, as if it never happened. haven't had the problem again, and it never threw any codes. Matter of fact I upgraded to a different OBDII dongle that uses Toyota Techstream software and there are no codes with that as well.
    I thank everyone for their input, without it, I may have made a terrible, very expensive mistake. download.png
     
    Mollyisadog, Air_Boss and royrose like this.
  19. Betsy R

    Betsy R New Member

    Joined:
    Nov 10, 2020
    4
    0
    0
    Location:
    DFW
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    $2250 Sounds more reasonable than my quote by a Toyota dealership in the DFW (TX) for $3,500( parts and labor). Do you mind sharing what dealership and how long along you had your repair done? My service advisor said unfortunately I am missing a specific code for Toyota to cover the actuator issue. My Prius V 12’ (112k miles) went into the dealership with no lights on but a lot of clicking when breaking at stop lights and they fixed clicking and then they returned with diagnosis that it was an actuator issue now not allowing them to reset breaking system so now i have all breaking system lights on my dashboard on.
     
  20. rjparker

    rjparker Senior Member

    Joined:
    Jun 6, 2008
    4,020
    2,101
    2
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    Try another dealer for your "braking" lights under the customer support problem. Obviously if the brakes do not stop normally tow it in. If you have all the lights now you probably have the codes. Do not disconnect the 12v battery as that will likely clear codes and it can take time for them to reappear. Do not let anyone but the dealer read the codes as a third party may clear the codes.
     
Loading...