is the radio dead?

Discussion in 'Car Audio, Electronics & Security' started by Chuck71RS, Apr 26, 2017.

  1. Chuck71RS

    Chuck71RS Veteran Member Lifetime Gold Member

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    Nov 24, 2012
    Houston, Texas
    Was working while installing new gauges with key in "acc" position

    Completing the gauge install, radio did not come on when the engine started but neither did the gauges. Did not come on with key in "run" or "acc"

    With battery disconnected the radio fuse has almost 0 resistance (multi meter) so it is good

    With battery connected and radio turned on, the radio fuse in the fuse panel has voltage coming into the fuse but none coming out.

    With battery disconnected, checked resistance of the 3amp fuse just before the radio and meter shows almost 0 resistance
     
  2. Rene Melten

    Rene Melten Veteran Member Lifetime Gold Member

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    When you tested the voltage coming out of the fuse with the battery connected, was one test lead from the multimeter connected to a ground? Common mistake is testing from one side of a fuse to the other. Just asking.
     
  3. Chuck71RS

    Chuck71RS Veteran Member Lifetime Gold Member

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    Nov 24, 2012
    Houston, Texas
    At the fuse panel, the black probe was connected to a ground. The red probe was placed on the right side of the fuse (voltage coming in) then the left side (voltage going out). Zero voltage on the left side and 12.6 on the right side

    More concerned about the radio then the gauges
     
  4. Twisted_Metal

    Twisted_Metal Moderator Staff Member Lifetime Gold Member

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    That's exactly how I test for a blown fuse.
    Power on one side and not the other means there is no continuity within the fuse.
     
  5. Chuck71RS

    Chuck71RS Veteran Member Lifetime Gold Member

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    Nov 24, 2012
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    But with the battery disconnected fuse resistance is almost 0 ohms with one probe on one fuse end and the other probe on the other end.

    So doesn't this mean the fuse is good?
     
    Last edited: Apr 26, 2017
  6. Gary S

    Gary S Administrator Lifetime Gold Member

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    You aren't trying to check fuse resistance with it in the circuit , are you? If you want to check resistance, pull it out first.
    Or, simply try another fuse that you know is good.
     
  7. Chuck71RS

    Chuck71RS Veteran Member Lifetime Gold Member

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    Nov 24, 2012
    Houston, Texas
    I was checking resistance with the fuse still in the fuse panel. Removed the fuse and saw it was blown. New fuse in and the radio is working fine again.

    Did not know (and still don't know why) a blow fuse tested for resistance while still in the fuse panel gives a false reading.
     
  8. Green hornet

    Green hornet Veteran Member

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    North Bay, CA
    It is easy to over think things sometimes. The easiest way to check a fuse is with a test light. The light needs work on each side of the fuse with the key on. If it doesn't it's bad. Good to hear problem is fixed.
     
  9. bourbon_scotch

    bourbon_scotch Veteran Member Lifetime Gold Member

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    It's because your reading from one side of the fuse through the circuit till it meets up to the other side of the fuse. If the fuse wasnt blown you would be measuring two circuits together, the one through the fuse and the other through the circuit the fuse controls.
     
  10. Twisted_Metal

    Twisted_Metal Moderator Staff Member Lifetime Gold Member

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