Emergency Brake Not Engaging but "Release Parking Brake" warning stays on 100% of the time

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by Jim Dunkerley, Dec 26, 2022.

  1. Jim Dunkerley

    Jim Dunkerley New Member

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    Buena Park, CA, USA
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    2017 Prius
    Model:
    Four
    Recently my 2017 Prius emergency/parking brake pedal would not click into place. It stays spongy like the regular brake panel, but the emergency light and warning stays on all the time while it keeps beeping all the time. I looked into disengaging the parking sensor because the brake fluid is at the correct level. I am at a loss for checking it myself but would like to at least turn off the parking brake sensor. I don't need to fix the brake itself right now. Any help would be greatly appreciated!!!!
     
    #1 Jim Dunkerley, Dec 26, 2022
  2. Pulse07

    Pulse07 Active Member

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    XLE AWD-e
    You wont like this answer, but bring it to the dealership or a independent shop. Something like this isn't worth the time to DIY
     
    #2 Pulse07, Dec 26, 2022
  3. Elektroingenieur

    Elektroingenieur Senior Member

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    Our state law (Cal. Veh. Code §§ 26451, 26453) says that you do.

    If you don’t want to take the car to a dealer or shop, as @Pulse07 kindly suggested, then start by checking the the No. 1 wire adjusting nut at the end of the parking brake cable. It’s shown in catalog Figure 46-01, Parking Brake & Cable, with part name code 46441, and in the Repair Manual (more info) topic Brake: Parking Brake: Parking Brake System: Adjustment, which gives the standard pedal travel, “8 to 11 notches [i.e., clicks] at 300 N (31 kgf, 67.4 lbf),” and states, “The brake warning light always illuminates at the first click.”

    It’s not in the Toyota manuals, but before you spend any time staring up into the underside of the instrument panel, I’d suggest to disconnect the negative (–) terminal of the auxiliary (12-volt) battery and wait for at least 90 seconds. Disconnecting the battery de-activates the supplemental restraint system, which reduces the risk of serious injury if the driver side knee airbag were somehow to fire while you’re down there.
     
    #3 Elektroingenieur, Dec 26, 2022
  4. Jim Dunkerley

    Jim Dunkerley New Member

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    Location:
    Buena Park, CA, USA
    Vehicle:
    2017 Prius
    Model:
    Four
    No worries, I'm actually taking it to a mechanic who specializes in Toyotas today. I did disconnect the battery last night for a few minutes, but to no avail. I did learn how to get my stuck hood open and found the brake fluid in the process, so that was a plus :)
     
    #4 Jim Dunkerley, Dec 27, 2022
    bisco likes this.
  5. Col. Thom

    Col. Thom New Member

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    2016 Prius
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    Two Eco
    This issue sounds a lot like one I'm currently experiencing. Out of curiosity, did you try lifting up on the pedal from underneath? I had intermittent issues with the ratchet not catching and then when several applications back and forth got it going again, the light/sensor stays on even when the parking brake is disengaged. If I lift up from the underside of the pedal, the light/sensor go away.
     
    #5 Col. Thom, Jan 9, 2023
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