Emergency brake/parking brake not engaging

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Joey40202, Jan 28, 2019.

  1. Joey40202

    Joey40202 Junior Member

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    I have a 07' Prius, live in south Florida where it is flat and I hardly use the parking break. I may have used it 10 times in 10 years. I had the vehicle towed the other day and we went to apply the park brake for transport and the brake would not set. The parking brake pedal will depress all the way through the typical motion but the sound of it catching each "cog - the clicking sound" is very faint and distant sounding compared to how I remember it. I tried gently fully depressing the brake 4-5 times repeatedly and it caught one time out of 5 on attempt number 3 but then I was not able to get it set again after that. What is the cause and procedure for fixing it? Thank you in advance for any guidance.
     
    #1 Joey40202, Jan 28, 2019
    Last edited: Jan 29, 2019
  2. bisco

    bisco cookie crumbler

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    probably a disconnected/broken cable. are you the handy type?
     
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  3. Raytheeagle

    Raytheeagle Senior Member

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    When is the last brake inspection?

    How much brake pad is left on the rears?
     
  4. exstudent

    exstudent Senior Member

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    Proper maintenance on the brakes has been lacking. Someone has neglected the rear brakes. This entails cleaning, lubricating the contact points, checking remaining material thickness, and ADJUSTING the brakes, so the they are the correct distance from the drum which will allow the parking brake to engage properly.
     
  5. ChapmanF

    ChapmanF Senior Member

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    If the behavior you are describing is that the pedal does not stay down when you press it, but makes no clicks on the way down and then follows your foot right back up again, then the responses about broken cables or brake adjustment are not on point. What you have is a ratchet at the pedal itself that is not clicking into place and holding the pedal down.

    Mine gets very close to doing that in very cold weather, when the grease on the ratchet pawl thickens up and then the pawl doesn't spring quickly into place. Sometimes it will if you just press the pedal down, and hold it there a bit longer, so the thickened-greasy-ratchet-pawl can sloooowly settle into place.

    What temperatures are you seeing?

    If it's not super cold, it's also possible the ratchet there broke somehow, or the grease has just turned gummy altogether.
     
  6. Joey40202

    Joey40202 Junior Member

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    Yes, Pretty handy. I have update my original description as well.
     
  7. Joey40202

    Joey40202 Junior Member

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    Brakes were checked at last service by Toyota a few months back during oil change. Also, about two years ago I specifically had the brakes looked at by Toyota because I thought I need new pads and the dealer told me I was still good on brakes and that was about 10,000 miles/2 years ago. How do I inspect the rear pads for the amount of pad remaining? I also updated the original problem description.
     
    #7 Joey40202, Jan 29, 2019
    Last edited: Jan 29, 2019
  8. Joey40202

    Joey40202 Junior Member

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    Ok, so this sound similar to what I am experiencing. The last week since the first attempt to apply the parking brake the temp has been in the 50's. Its usually 70-90's degrees here in South Florida. The parking brake pedal will depress all the way through the typical motion but the sound of it catching each "cog - the clicking sound" is very faint and distant sounding compared to how I remember it. I tried gently and fully depressing the brake 4-5 times repeatedly and it caught one time out of 5, on attempt number 3 but then I was not able to get it set again after that. Temperature this morning is 46 degrees.
     
  9. ChapmanF

    ChapmanF Senior Member

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    Hmm, mine doesn't act that way unless it's a lot colder than that. But maybe you also have hotter summer temps there and the grease gets baked faster.

    I would try to get access to that ratchet mechanism on the pedal and clean off whatever original grease is there and apply new. I'm not sure how easy the pedal access is without some trim panel and/or dash disassembly ... the repair manual will give some insight.
     
  10. Joey40202

    Joey40202 Junior Member

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    UPDATE: Based on the explanation of the issue you provided I went back out to the car and tried the brake again. Again, the temp is around 49 degrees. I applied the parking brake but this time I held my foot in position on the brake for a few seconds and this time it locked into place and held. I repeated the process 3 more times, all at different parking brake positions, and waited about 3 seconds before lift my foot off the brake. All 3 times the parking brake engaged and locked into place. In order to release the brake I had to depress it further and it released as designed. The "clicking" sound when depressing the parking brake is still very muted compared to what I recollect. If my memory serve correct it is a loud and distinct "click" "click" "Click"... sound until the brake is set at desired location? So the question is if this a grease/cold related issue what the fix? Or, is the fix warmer weather?
     
  11. John321

    John321 Active Member

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    You have had some good replies. It does seem temperature related. Some greases thicken as temperature decreases. If there are no mechanical issues that are causing this problem then cleaning off the old grease and using a lighter weight grease could help.

    My 2008 Prius emergency brake works fine and today it was 12 degrees this morning with plenty of moisture/ precip. I wonder if there isn't something else mechanical going on with your ratcheting mechanism or cable? These emergency brake cables will also sometimes have lubricant applied to them that can stiffen with colder temps.
     
  12. Joey40202

    Joey40202 Junior Member

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    John321: "I wonder if there isn't something else mechanical going on with your ratcheting mechanism or cable? " — I haven't ruled that out as a possibility. I very rarely ever use the parking brake an up until this week I have never used in in "cooler" temperatures. I have always used it at 80-95 degrees. The last question I have is - it appears to me that the parking brake is complete independent of the break actuator for the driving brakes. Do you know or can anyone else confirm. Thanks again for the help!
     
  13. John321

    John321 Active Member

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    Typically the parking brake is actuated mechanically by the parking brake pedal and cable system. This can be applied with the car completely off or with the car on.

    Your assumption that it is independent of the brake actuator system is correct. Emergency/parking brake is a completely mechanical system that does not use the brake actuator.

    One quick suggestion is to disconnect the cable from the parking brake pedal /actuator assembly then push the parking brake pedal and see how it responds, this may help you isolate the problem without having to go underneath the car or open up the rear brakes
     
    #13 John321, Jan 29, 2019
    Last edited: Jan 29, 2019
  14. Joey40202

    Joey40202 Junior Member

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    Perfect thank you. Based on the symptoms and all the contributors info on this thread I believe it is a "gummy/hardened grease" issue either at the gear causing it to release slowly or possible grease on/in the cabe itself that has hardened. I feel like its not cold enough at 61 degrees to cause "grease stiffness" unless that is in combination with grease that is already "hardened or gummy" and the cold is only amplifying the issue causing the systems. I am going to take a look and also wait a few days for the temperatures to get back up our normal and I will report back.
     
  15. Skibob

    Skibob Senior Member

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    You really should use your parking brake on a regular basis, at least once a week. The rear drums have a self adjuster that basically turns the screw on the bottom of the brake shoes to make them be as close to the drums as possible. When you don’t use the parking brake this never gets adjusted as the parking brake is how the adjuster works.
     
  16. Joey40202

    Joey40202 Junior Member

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    Yep I agree. Before I started on here I had no idea about the self adjustment however as a result of this forum I am a bit wiser to the matter. Do you know if through repeated usage of the parking brake it will self regulate and correct?
     
  17. ChapmanF

    ChapmanF Senior Member

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    The story you're telling here is exactly the story of a sluggishly-moving ratchet pawl right up in the pedal mechanism.

    There are other things that can go wrong with brakes (sticky cables, etc.), but they would give you different stories, which are not the one you're telling here. (If you had a story about the pedal being hard to press down, or staying stuck down after you release it, or rising back up only part way, that would be a sticking-cable story, for example.)

    It will, but you can't hurry it by just stomping the parking brake a bunch of times.

    Each time you apply the parking brake, if there is more than the correct clearance between the shoes and the drum, a lever in each rear brake will be lifted up over a starwheel tooth and click down behind the next tooth.

    The next time you stop using the regular brake, the shoes being expanded by the regular brake will take the return-spring pressure briefly off that starwheel adjuster, allowing the adjust lever to turn it by that one notch, and adjusting 0.03 mm out of the brake clearance.

    That will keep happening, 0.03 mm at a time, until the clearances are within tolerance.

    If they are badly out of adjustment, there's a rubber plug in the backing plate that can be removed so a screwdriver can be poked in to turn the starwheel by hand a few teeth at a time. Don't overdo it or the brakes will drag.
     
  18. Joey40202

    Joey40202 Junior Member

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    So, the weather has warmed back up and the paw in the ratchet is functiong normal. No delay which leads me to presume its a combo of aged grease and the cold cause the delayed setting of the brake catching. Now that the temp is back in the 70’s I can push the parking break and it instantly sets. Should I do anything or let it ride since everthing appears to be functioning as designed. Also, thank you to everyone has contributed.
     
  19. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I think you should use the parking brake daily instead of annually.
     
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