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Am I crazy or did I just break something?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Bill Lumbergh, Sep 17, 2006.

  1. Bill Lumbergh

    Bill Lumbergh USAF Aircraft Maintainer

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    I found out this evening my dimmer switch stopped working. The speedometer display and MFD are on full bright and I'm sure I've been able to turn them down before. I tried making the adjustment with the headlights on and off and it never mattered.

    I also recall seeing somewhere on the MFD that I could set it to full bright, but I never even saw that button on any of the screens. Perhaps because it's already detecting full current from the adjustment knob?

    The switch itself feels normal, has good feel and the detent for full bright is noticable. If I had a multimeter handy I could shoot the resistance through the variable resistor, but I don't, nor do I feel like popping it out of the dash.

    I guess I have to go back to the dealer now..... :angry:

    Any ideas?
     
    #1 Bill Lumbergh, Sep 17, 2006
  2. Michgal007

    Michgal007 Senior Member

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    <div class='quotetop'>QUOTE(Boxster...WRX...Prius? @ Sep 17 2006, 02:14 AM) [snapback]320754[/snapback]</div>
    No idea :(
     
    #2 Michgal007, Sep 17, 2006
  3. thomasbe

    thomasbe New Member

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    I had the same problem - took it to the Toyota Dealership and they found the wire on the back of the dimmer switch had fallen off. I also lost all light behind the radio controls (seek/scan etc as well as the transmission shifter). They removed the silver vent from the dash to the left oof the steering wheel (it just pulled out - no fasteners) and found the wire loose - not connected to the control. As soon as they plugged it back in everything was fine. Good Luck.
     
    #3 thomasbe, Sep 17, 2006
  4. efusco

    efusco Moderator Emeritus
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    same thought crossed my mind...worth checking anyway, worst case is that the switch went bad. If you're still under warranty and this is a covered item let them do it. If not just order the part and install yourself...look in the articles section for how to install the OEM EV button and it'll tell you how to access that part of the dash.
     
    #4 efusco, Sep 17, 2006
  5. Bill Lumbergh

    Bill Lumbergh USAF Aircraft Maintainer

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    Way to go Toyotaman! I did exactly what the dealership did to your Prius and I found I had the same problem. After reconnecting the switch, everything works as normal. Total time to perform the repair: less than one minute.

    Thanks!
     
    #5 Bill Lumbergh, Sep 17, 2006
  6. hobbit

    hobbit Senior Member

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    It's actually not a rheostat, it's a little low-side PWM unit:
    .
    [​IMG]
    .
    Click the pic for a big detailed one. The chip is a timer of some
    sort, which drives the power transistor in a duty cycle varied by
    the dashboard pot. It runs at about 200 Hz, so you don't see any
    flicker. The pot is the small round thing in the middle of where
    the knob mounts; the extra metallic tracks around it are just sliding
    contacts that let the wipers "fall off" the end to signal the MFD
    and meters to go full-bright, etc.
    .
    _H*
     
    #6 hobbit, Sep 18, 2006
  7. thepawn

    thepawn New Member

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    Wow, thanks guys, I had this exact problem come up the other day! My cable fell out as well.

    That left panel piece wasn't quite a "slide out" on my 2005...it had 4 yellow clips that made it quite a bear to pull out, though it does just pull straight out.
     
    #7 thepawn, Nov 27, 2006
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