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Warning Lights - Rear Brakes?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by hk phooey, Apr 3, 2017.

  1. hk phooey

    hk phooey Junior Member

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    Hi All

    Had some lights come up this last weekend (see attached) and at the same time brakes became stiff but still worked. This has happened recently in December, except for the OSD light, where the codes went away after restarting the car. time I did The car was able to drive fine after this occurred. In the incident this weekend I restarted the car but the lights did not go away initially.

    Later, the breakdown repair guy connected a handheld computer to check the code from the ECU but told me nothing was coming back. As he was doing this the warning lights went away on their own and the car is driving fine. He then checked the brakes visually and said one of my rear brakes was very worn down. I presume he mean the rotors. His feeling is that this somehow tripped a sensor which tripped the lights. Apparently the ECU would not report in this scenario, which I find hard to understand.

    The car has 107k of suburban driving on the clock and all the pads / rotors on my car are original. The toyota dealer said my rear pads were at 80% wear in 2015 when it had 99k on the clock. Thinking of just doing the pads tomorrow and see if this reoccurs. I suspect the service station (Halfords autocentre) will try to tell me the rotors need replacing but with regen braking I understand the Prius rotors hardly ever need replacing.

    Thought i may get toyota to see what error codes came up but was informed all the codes get flushed after 3 trips which I have already done.

    Cheers
    Hiro

    PS: Would be good if my phone could talk to my phone via an app and tell me what issues are happening in user friendly terms when they happen. Not sure if the latest Prius has that
     

    Attached Files:

    #1 hk phooey, Apr 3, 2017
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    Probably takes Techstream to determine what's going on.

    Who said that, not sure that's the case. Were you on the phone to dealership service department? I strongly suspect there would still be codes stored.

    I don't think so: the lights went away, but codes should still be stored.

    That sounds familiar. In our case it was "communications problem", never completely resolved. The brakes felt funny, like they were in some sort of fail-safe mode. Dealership concurred: when there is a problem it'll revert to a default mode: brakes still work, but somewhat less responsive. In our case the latest "smoking gun" was that I had scangauge constantly hooked up, that it was weighing on the obd port, causing an intermittent disconnect. I took it off about 18 months back, and problem has not reoccurred.
     
    #2 Mendel Leisk, Apr 3, 2017
  3. dolj

    dolj Senior Member

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    It is possible they need replacing, but usually not because of wear, but because they rust up due to a lack of use. In England, even in the "warmer" south, rusting discs (rotors) is a problem. The only way to keep on top of this, is to periodically force the hydraulic brakes on to clean the discs. The easiest way to do this is to find a nice quiet straight stretch of road where you can get up to 40 MPH, then slip the car into N and apply the brakes fairly strongly to bring the car to a stop. Repeat a couple of times.

    As for whether they need replacing, you can inspect them yourself and decide.
     
    #3 dolj, Apr 3, 2017
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Rear disc brakes can be reassembled wrong, creating uneven application and constant drag. That'd wear out pads and rotors.
     
    #4 Mendel Leisk, Apr 3, 2017
  5. 05PreeUs

    05PreeUs Senior Member

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    There are like a DOZEN computers on these cars, the ECM is the one that most software can read, but the brakes require software that is more specific - basically you will not likely get BRAKE codes to show in the ENGINE computer, which seems like what was checked.

    As Mendel suggested, Techstream is the software needed to get all codes from these cars.
     
    #5 05PreeUs, Apr 8, 2017
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