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Gen II Prius DTC C1343 and C1344 - Hydraulic Failures

Discussion in 'Gen 2 Prius Technical Discussion' started by Chris 2007 Prius, Jan 21, 2024.

  1. Chris 2007 Prius

    Chris 2007 Prius New Member

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    Austin, TX
    Vehicle:
    2007 Prius
    Model:
    II
    My 16yo son has a 2017 Prius with 115k miles, new HV battery, new 12V AGM battery, and new combination meter.

    Yesterday he drove about 12 miles with the emergency brake engaged traveling up to 55mph. The car had new brakes installed 500 miles ago.

    Today, the brake light, VSC light, the (!) light, and ABS light are illuminated and I am getting codes C1343 (RR RH HYDRAULIC) and C1344 (RR LH HYDRAULIC). I pulled the rear drum brakes to do a visual inspection and ensure the brakes were not seized up. Lots of brake dust, but nothing unusual/seized.

    In my initial research, I assumed he damaged the ABS actuator, but C1342 nor C1341 (the two front brake hydraulic codes) are NOT popping up and there are no other DTCs. I assume if he toasted the ABS actuator that additional codes affecting the entire system/front brakes would appear?

    It does appear that there is a slight leak (smaller that dime sized after 24 hours) of fluid (assuming brake fluid) under the engine bay. So that leads me to believe that he may have done damage to a connection or portion of the hydraulic system that only affects the rear brakes. This car has never had any other leaks.

    Does anyone have any thoughts? I see a lot of posts for a single C1343 or C1344, but no one is reporting them as receiving both DTCs together.
     
    #1 Chris 2007 Prius, Jan 21, 2024
  2. mr_guy_mann

    mr_guy_mann Senior Member

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    If the parking brake was applied and he drove the car at highway speeds, the fluid in the rear wheel cylinders might have boiled, due to the heat of brake shoe friction.

    That would have caused pressure problems in both rear brake circuits.

    I would suggest checking the wheel cylinders for seeps inside the boots. Then clear the codes and bleed - flush the brake fluid. Also readjust the rear brakes.

    Posted via the PriusChat mobile app.
     
    #2 mr_guy_mann, Jan 22, 2024
    Chris 2007 Prius likes this.
  3. Chris 2007 Prius

    Chris 2007 Prius New Member

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    II
    Thank you, sir. I will check it out!
     
    #3 Chris 2007 Prius, Jan 22, 2024
  4. stanley kim

    stanley kim New Member

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    maricopa ca
    Vehicle:
    2006 Prius
    Model:
    Four Touring
    2nd Time C1344 error was on 2006 prius, my technician replaced ABS actuator big module, but Error appeared again. He drained one tire brake side's brake fluid100mL , then C1344 disappeared, problem was solved eventually. Problem was not the expensive ABS actuator big module. One year ago I and technician had solved the first time trouble C1344 for same car by changing ABS actuator big module, that is expensive repair job( module $300+ replace labor $400). Try draining(removing) one tire brake side's brake fluid100mL before replacing expensive ABS actuator big module, That saves big money !!
     
    #4 stanley kim, Nov 23, 2024 at 5:18 PM
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