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Brake light switch plunger length

Discussion in 'Gen 2 Prius Main Forum' started by Tynyyn, Jul 22, 2023.

  1. Tynyyn

    Tynyyn Member

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    2004 Prius
    Model:
    II
    Does anyone know how much of the brake light switch plunger should be sticking out from the bracket holding the switch? I've replace my brake light switch and am not sure if I measured the new switch's length to the old switch. So, now maybe I'm a few threads longer or shorter than OEM. Or does it matter how many threads are sticking through the back of the hold down bracket? Is the only relevent concern having the plunger sticking out from the bracket any length, just as long as it can fully retract into its houseing?

    I've put a new clock spring in it, a new cruise control stalk, and a new brake light switch and my CC still blinks on the dash. The only thing that I'm thinking could cause this condition is the aforementioned brake switch plunger length. Does anyone have a shop manual showing the correct length?

    I'm wondering if one thread would work or if ten threads would work? I figure as long as the plunger is fully sticking out when the brake pedal is depressed then the number of threads should be irrelevant. But does the brake pedal play some role in the amount of pressure exerted on the plunger and thus it should be only depressing the plunger a certain distance into the houseing?

    Thanks.
     
    #1 Tynyyn, Jul 22, 2023
  2. mr_guy_mann

    mr_guy_mann Senior Member

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    Use the search feature in the Gen2 forums- there's mention of a couple places on the web where you can download pdf versions of the factory service manual.

    You can also get a short term subscription to Toyota TIS which gives access to all factory service information.

    As far as your cruise control, you can throw more parts at your problem if you want, or you can consider doing some diagnosing.

    I would suggest getting a capable scantool and checking the system for codes, as well as viewing data for inputs such as control switches.

    Here's a thread that reviews several scantool apps and devices, some of which are capable of scanning all systems.
    https://priuschat.com/index.php?posts/3290690

    Posted via the PriusChat mobile app.
     
    #2 mr_guy_mann, Jul 22, 2023
    Last edited: Jul 22, 2023
    donbright likes this.
  3. mr_guy_mann

    mr_guy_mann Senior Member

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    FYI, the procedure for adjusting the brake switch mentions having 0.5 to 2.4mm of the plunger visible when the pedal is not pressed (ie, that much gap between the switch body and the part of the pedal that the plunger hits). Screenshot_20230722-123130.jpeg

    Posted via the PriusChat mobile app.
     
    #3 mr_guy_mann, Jul 22, 2023
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  4. ChapmanF

    ChapmanF Senior Member

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    2010 Prius
    Model:
    IV
    The switch adjustment matters, because you don't want it protruding so much that it stops the pedal coming up when released and holds the brakes partly applied, and you don't want it backed out so far that the stop lights are on or the car thinks you are pressing the pedal when you are not.

    The instructions in BRAKE PEDAL ➡ ADJUSTMENT in the repair manual would have you first back the switch way out and confirm that the pedal stops at the right height when released (138 to 148 mm measured perpendicular to the floor, from the middle top of the pedal to the asphalt silencer sheet beneath the carpet). That's adjusted with the master cylinder pushrod clevis if it needs adjustment (which it shouldn't, unless that stuff's been replaced). Then the switch gets threaded back in until the plunger protrudes 0.5 to 2.4 mm beyond the threaded neck, when the pedal is released.

    If the pedal height adjustment at the clevis had to be changed, the stroke sensor might also need adjustment. There are diagrams for all this in the manual to make it clearer.

    Toyota Service Information and Where To Find It | PriusChat

    oop, mr_guy_mann beat me to it.
     
    #4 ChapmanF, Jul 22, 2023
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