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Old MFD intermittently worked, replacement MFD intermittently working

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Daytripper, Dec 17, 2019.

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  1. Daytripper

    Daytripper Junior Member

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    Hoping some Prius sleuths can help me figure out what to do next. The MFD on our 2008 Prius (105K miles) started acting up a few weeks ago. This was right after it had sat outside at the airport for a week. The MFD would randomly go on and off and was getting worse as time went on - more and more non-working time than working time. So we ordered a used MFD off ebay. At first the replacement MFD worked great, fully functioning. But after a few days, it would stop working part of the drive, and now it's at the point where it's not working most of the time, but some of the time it is fine. Also, the radio randomly goes off. I just went for a 10 min drive and the MFD worked fine most of the time, but the radio went off about 5-6 times (while the MFD appeared to be working ok). Sometimes I click the FM button and it goes right back on. Sometimes I end up clicking the FM button a dozen times before it goes back on. Does this sound like an electrical problem that has nothing to do with the MFD? Is there anything we can do to further diagnose the issue before taking it in somewhere?
     
    #1 Daytripper, Dec 17, 2019
  2. bisco

    bisco cookie crumbler

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    if it isn't another bad mfd, i have to think it's in the connectors. maybe when you swapped them, a bad connector worked for awhile, then came loose again
     
    #2 bisco, Dec 17, 2019
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  3. Daytripper

    Daytripper Junior Member

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    Sounds plausible. Do auto shops typically know how to diagnose electrical stuff like that?
     
    #3 Daytripper, Dec 18, 2019
  4. bisco

    bisco cookie crumbler

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    depends on the mech. you can also look for car audio shops
     
    #4 bisco, Dec 18, 2019
  5. pasadena_commut

    pasadena_commut Senior Member

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    Check the 12V battery. Check it at its terminals and verify that those are tight and that the ground lead there is still good. (Give that a shake with the car running, just in case it is corroded inside or has some other hidden problem.) If the 12V is marginal all sorts of crazy things could happen to the electrical components.

    If you really do have an intermittently bad connection finding it can vary from trivial to impossible. I once sold a car after living with it blacking out while driving for no obvious reason at roughly two month intervals. The electrical problem would never manifest in front of a mechanic. Inspecting the visible wires, grounds, and cleaning the most obvious candidate connections didn't help either. With failures like that at some point one just ends up throwing in the towel.

    Hopefully you will find that it is the 12V battery, because hunting wiring gremlins is not a lot of fun.
     
    #5 pasadena_commut, Dec 19, 2019
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  6. bisco

    bisco cookie crumbler

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    12v is a good idea, since it sat at the airport for a week.
     
    #6 bisco, Dec 19, 2019
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