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MFD in and out

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Gino Veltri, Jan 17, 2022.

  1. Gino Veltri

    Gino Veltri Member

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    So for years my MFD has played the "check air conditioning connection" game with me. Ive installed an AUX and 68 ohm resistor on both my pri. Usually a press of the screen or unplugg the 12 volt fixes it, but not anymore. The battery on the MFD shows empty, AC is stuck on with no way to turn it off, but the car runs more or less the way it always has.

    Recently, my other prius (also 2005) started doing this very rarely. I know there's a capicitor in the dash that causes the cluster to go out. Is this related?
     
    #1 Gino Veltri, Jan 17, 2022
  2. TMR-JWAP

    TMR-JWAP Senior Member

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    Have you thought about just replacing the MFD?
    It's not an uncommon problem.
     
    #2 TMR-JWAP, Jan 17, 2022
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  3. Tombukt2

    Tombukt2 Senior Member

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    I've it seen my MFD do anything during my dash unlit conditions ever.
     
    #3 Tombukt2, Jan 18, 2022
  4. ChapmanF

    ChapmanF Senior Member

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    The MFD does have some infotainment diagnostic screens for just such situations.

    Most of the time they get mentioned on PriusChat, when it isn't for checking the battery voltage, it will be somebody trying to read OBD-II diagnostic codes there, so most of my time on the subject is spent telling people "no, sorry, those aren't the codes you can pull up there."

    But when the thing you're trying to find out is whether the MFD is communicating with thing x, y, or z, well, those totally are the codes you can pull up there.

    I used those screens a lot while I was struggling with the evil iPod thingy.
     
    #4 ChapmanF, Jan 18, 2022
  5. Gino Veltri

    Gino Veltri Member

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    These are the “NCON” “OK” etc in the safety check mode screen? Or are you talking about the jumbled letter and number codes that no one can decipher?

    either way when the mfd goes out, these options don’t work , the screen lags really bad, and some (most) options don’t work on it. I now fix it by talking the mfd out n knocking some wires (to the mfd and all the wires behind it) around and start the car till it works again..so I can deduce it’s a wire back there but none look out of place and there are ALOT back there
     
    #5 Gino Veltri, Jan 23, 2022
  6. Gino Veltri

    Gino Veltri Member

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    My mfd will come on, slowly, show a completely empty battery, “check air conditioner connection “ error when you try to use anything on it…
    I can’t recall if the dash lights go out at the same time… (the check engine faintly glows I think but not fully lit)..if I’m recalling correctly.
     
    #6 Gino Veltri, Jan 23, 2022
  7. Tombukt2

    Tombukt2 Senior Member

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    But the check engine light is not part of the MFD in any sort of way The check engine light is on the roll of amber lights 4 in above the MFD on the speedometer display with the VSC the traction control ABS those orange lights That's why I was getting confused in the discussion how your MFD and check engine light are having anything to do with each other sounds like you have a low battery 12 volt but maybe not it showing you an empty battery that's not the 12 volt that's the HV battery I do believe and what is the car sitting so long that it's literally got no voltage in it or what's happening The car not driven
     
    #7 Tombukt2, Jan 24, 2022
  8. Gino Veltri

    Gino Veltri Member

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    Perhaps I’m wrong about them cooccuring, I know they’re separate but I think my cluster would go dim (only partially illuminated check engine , no actual code) at the same time my mfd would go “out”. It’s clearly a wire connection for the mfd where as I think the cluster going out is related to a single capacitor needing replacement under the entire dashboard.
    I could be wrong altogether and it could be related to my adding an aux port with a 68 ohm resistor. After all adding the aux lost my ability to change treble bass and speaker output (front back left and right), never have solved that one but learned to live with the presets.
     
    #8 Gino Veltri, Jan 24, 2022
  9. Gino Veltri

    Gino Veltri Member

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    My car is driven everyday and 12 volt checked and changed religiously so it’s not entirely that, I know it’s the hv battery depicted in the mfd but the car drives normal (and the hv battery is close to new) so it’s not related to battery issues , it’s a connection in a wire seeing as how taking the mfd and center dash apart n fiddling with some wires can fix it till next time. I guess I was hoping for someone with exactly the same issue and a specific connection solution to chime in. I’ll start the hunt for with wire next time it occurs
     
    #9 Gino Veltri, Jan 24, 2022
  10. Tombukt2

    Tombukt2 Senior Member

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    Well I've got a speedometer problem that's been going on for 2 years and the guy in Texas says because it keeps coming back on it's not broke it's not the capacitor resistor soldering problem He says when it fails it'll go blank and never come back on no fiddling will do it so what I was thinking and I'm by no means an electronic circuit designer I was thinking at least for the speedometer part of it that maybe that it needs to feeds of 12 volts to make it light up it seems to me that the two sets of wires that feed that assembly up there maybe it needs to 12 volt feeds and it's only getting one and that's why my display doesn't come on and then when I fool around with the button and take out the SRS remote and this kind of nonsense push the button and all of a sudden I can almost tell by how it sounds that the speedometer is going to light and I'm going to see a radio light many times I'm driving around with the completely blank display You can't even tell it's ready I just know it is
     
    #10 Tombukt2, Jan 24, 2022
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