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Anyone know what this is?

Discussion in 'General Electronics Discussion' started by cnrhome, Oct 11, 2013.

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  1. cnrhome


    Oct 11, 2013
    Hi all,

    I'm not an electronics guru but I hope its OK to post and ask this question. I'm trying to fix a car wiper motor and found this single electronic element inside the 'wiring' for the motor. When its hooked up to the car, 12V goes in but nothing comes out, so I suspect its broken or burned out.

    Does anyone know what it is? I'm guessing/hoping that replacing this piece is cheaper than the $80 for a whole new motor.

    Thanks for any help!


    Attached Files:

  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    That device is almost certainly a diode.

    They normally fail short-circuit unless they've failed in a more explosive way.

    If "12V goes in but doesn't come out" I might suspect something else first.

    Is the motor OK? how is this thing wired up? Is there more we can't see?
  3. shrtrnd


    Jan 15, 2010
    The first thing I'd do is clean-out all that green corrosion from the contact spade-lug
    connector socket, and make sure the corrosion at the diode connection didn't eat
    into the circuit, causing a weak connection.
    Like *steve*, I'd check the diode, but wouldn't suspect it.
    You won't want to hear this, but the motor itself is the most common malfunction.
    If you've got a problem with the $80, consider calling around to some junk yards, or
    auto part recycling yards and try to get one from a crashed vehicle, that's still relatively
  4. cnrhome


    Oct 11, 2013
    Hey guys, thanks for the replies. As I was typing up a longer description of the connections, it occurred to me - if its a diode, then the + and - makes a difference! I didn't think I tried it both ways using my alligator clips from this connector to the battery, so I went outside and voila - it works! I must have put the + on the wrong side of the diode.

    Any suggestions for cleaning the corrosion? I'd prefer not to take all those metal 'wires' out as its more likely they will bend/break.

    The corrosion crap in the motor must have caused it to freeze up. I cleaned that out and used a soft wire wheel on the commutator to shine it up, some light sanding on the brushes, grease on the 'bearings' and then it worked. I fixed a washer machine motor this way a few yrs ago. Why throw out something that just needs some cleaning? Save the landfills and some $... Junkyards were going to be my next step.

    Thanks for the help.
  5. shrtrnd


    Jan 15, 2010
    I use a can of electronics contact cleaner, a small wire brush, emery cloth, nail file, burnishing tool, or whatever I can find that'll reach into the area I'm trying to clean.
    That one spade lug connector socket in your picture might cause you problems if you
    don't clean it, it's got some serious corrosion on it.
    It's a little messy, but (dry) baking soda and a toothbrush works too.
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