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  1. #1

    97 polaris 780 charging problem

    Just installed rebuilt engine in 97 polaris 780. Runs fine but doesnt charge battery. Battery is good and holds charge. Mfd shows 14 volts when running. Test of battery shows 12 volts when running. I did install oil block off plate and disconnect oil sending unit wires from electrical box. Could that cause a problem? What else could cause battery not to charge? How do I test?


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome to the Hulk

    Click here for the Polaris Service manuals.

    Proper battery voltage with the engine running should be about 14.5 volts, measured at the battery.

    My first thought is to check and clean the ground connections. Clean the battery negative cable at both ends.

    Also remove, check and clean all the black wire and ground connections inside the electrical box, especially the mounting plate for the LR-23 voltage regulator module.

    With the battery positive disconnected, confirm that you have zero ohms between the battery negative, the engine block, and the black wires inside the electrical box.

    Per the service manual, check the ohms for the stator charging coil. Then make sure both the Yellow and Red/Purple stator wires are properly connected. With engine off, both should have 12 volts.

    The high MFD voltage reading is suspicious.
    Does the RPM display work properly?
    The MFD uses the same Yellow wire to read engine RPM.

    If none of this fixes the problem, then the LR-23 regulator may have failed.

    If the MFD continues to read too high voltage after you have fixed the battery charging voltage problem, then you may need to reset the MFD.

  3. #3
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Like K447 said, check the ground wire connections.

    Then check the red/pur wire is connected properly inside the elec box. (it should be connected at 2 different spots.

    If the engine was replaced, which stator was used? the new engine staor or the old engine stator? Wouldn't hurt to ohm test the stator while you're inside the elec box checking connections.

  4. #4

    97 polaris 780 charging problem

    Checked all connections and tested wires. All checked out good. MFD still shows 14 volts when running and voltmeter shows 12 volts at battery. It looks like I need L23 regulator. Do you know where I might find one? Thanks

  5. #5
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by K447 View Post
    ...Clean the battery negative cable at both ends.

    Also remove, check and clean all the black wire and ground connections inside the electrical box, especially the mounting plate for the LR-23 voltage regulator module.

    With the battery positive disconnected, confirm that you have zero ohms between the battery negative, the engine block, and the black wires inside the electrical box.

    Per the service manual, check the ohms for the stator charging coil. Then make sure both the Yellow and Red/Purple stator wires are properly connected. With engine off, both should have 12 volts.

    The high MFD voltage reading is suspicious.
    Does the RPM display work properly?...
    Did you do these things?

    Quote Originally Posted by xlint89 View Post
    Like K447 said, check the ground wire connections.

    Then check the red/pur wire is connected properly inside the electrical box. (it should be connected at 2 different spots.

    If the engine was replaced, which stator was used? the new engine stator or the old engine stator?

    Wouldn't hurt to ohm test the stator while you're inside the elec box checking connections.
    Quote Originally Posted by mike77 View Post
    Checked all connections and tested wires. All checked out good.

    MFD still shows 14 volts when running and voltmeter shows 12 volts at battery.

    It looks like I need L23 regulator. Do you know where I might find one?...
    That high MFD voltage reading is still bothering me

    Put the voltmeter on the Red/Purple and Black wires inside the electrical box - what is the voltage there when the engine is running?

    You can buy used parts from John Zigler, or new from Watcon or Babbitts.

    P.S. Let's keep this discussion in one thread.

  6. #6
    Red/Purple wire shows same volts as battery with engine running about 12 volts. Grounds are clean and secure.

  7. #7
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by mike77 View Post
    Red/Purple wire shows same volts as battery with engine running about 12 volts. Grounds are clean and secure.
    Was the negative probe of the meter on the black wires inside the electrical box?

    If yes, then it looks like you need to replace the LR module.

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    Just further on this topic what does the LR do?? and where is it located?? sounds like a similar problem i was having last year and i was going to do the same tests as mentioned in this topic.

    thanks

  9. #9
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by paramuir View Post
    Just further on this topic what does the LR do?? and where is it located??
    sounds like a similar problem i was having last year and i was going to do the same tests as mentioned in this topic...
    Welcome back

    The LR voltage regulator module has been described and discussed many times on here, including several recent threads.

    It is located inside the electrical box.

    Be careful when comparing a problem on your machine to those diagnosed for others. Sometimes very similar symptoms can be caused by different things.

    Thorough diagnosis is built upon an understanding how the parts work together. The electrical systems in these machines are actually fairly straightforward.

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