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3rd abs module, 3rd brake failure... wrong repair?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by rooshio, Oct 24, 2022.

  1. rooshio

    rooshio Junior Member

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    My 2008 worked fine yesterday, but as soon as I opened my door this morning, the brake alarm beeped incessantly. Sure enough, I got the vsc, abs, and (!) lights on the dash, along with no brake power except to the rear drums. I hear the ABS module clicking when I depress the pedal (as well as the pump whirling), and when I do, the pedal forcibly pushes back toward me.

    Shorting OBD pins 4 & 5 and starting the car with 8 pedal pumps to reset the ABS didn't help. And when I do that, the traction light blinks out codes 21, 22, and 24. (I have not done blink code diagnostics before).

    I DIY replaced my abs module for the 3rd time about 2 months ago (used ebay unit). I didn't use techstream to bleed the brakes for either replacement, just a buddy pressing the brake pedal while popping open each wheel's bleeder valve until no more bubbles. Doing this along with shorting OBD pins 4&5 seemed to restore the car to working order until it suddenly didn't work at all.

    Aside from hearing the abs accumulator pump working frequently at stops, the brakes showed no signs of performance slippage before suddenly failing. The failure a few months ago happened after my car had been sitting in a parking lot on an unusually hot day. And today's failure happened right after our first cold & rainy day in months... Neither failure happened while driving, only after the vehicle had been off for several hours.

    I'm beginning to wonder if my issue isn't the ABS accumulator assembly itself, but something else. (Maybe lingering air bubbles in the brake lines responding to temperature changes?)

    Any advice? I love my Prius but I'm at my wits end with this recurring issue.
     
  2. bisco

    bisco cookie crumbler

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    idk, but could these ebay products be a problem?
     
  3. rooshio

    rooshio Junior Member

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    Definitely possible, but I think it's a low chance that 2 would go bad within 5k miles of owning them.
     
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  4. TMR-JWAP

    TMR-JWAP Senior Member

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    If the pump was cycling frequently as you mentioned, it was already failing. Once the pump runs and pressurizes the accumulator tank, it shouldn't have to run again until you use the brakes at least three separate times (individual pumps of the pedal).

    Aside from hearing the abs accumulator pump working frequently at stops,
     
  5. ChapmanF

    ChapmanF Senior Member

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    Are you sure that was the traction light (the car on squiggly road)? I do not see those in the repair manual among any of the codes that light can blink.

    Any chance it could have been the ECB light, that looks like ((!)) ? That one does have 21 (C1352), 22 (C1356), and 24 (C1357) codes it can blink.

    Those all have to do with electrical circuit malfunctions involving valves inside the actuator: C1352 is about the SLAFR valve, C1356 is about SLRFR, and C1357 is about SLRFL. Each of those codes has four different INF codes to pin down whether is overcurrent, short, open when on, or open when off. But to get the INF codes, you'd need a better scan tool.

    That's no substitute for actually bleeding the system when the actuator has been replaced. From the codes you have, it looks like the electrical issues with those valves are the first things to look at, but eventually, you should also bleed the system properly.
     
  6. rooshio

    rooshio Junior Member

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    No, the ECB light blinks steadily in tandem with the VSC and ABS lights. Could the traction control be sending the same codes or is it part of a different system/convention?
     
  7. ChapmanF

    ChapmanF Senior Member

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    Any chance you could post video?