Wacky gen light

Discussion in 'Old's Cool' started by hogmolly, Mar 21, 2007.

  1. hogmolly

    hogmolly Dude

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    Every now and then, the gen light on my 93 will flash on or half on while I'm cruising down the road. It acts like a loose connection but I've checked every connection in the path and can't seem to fix it. It doesn't happen very often so tracking it down is an act of frustration.

    Open to suggestions.
    #1
  2. Team Dennis

    Team Dennis Certified Troublemaker

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    Check the diode board, mounts and ground wires. You will probably find a broken rubber mount and/or a corroded ground wire.
    #2
  3. BareRider

    BareRider Adventurer

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    Also, check for worn brushes in your alternator.
    #3
  4. jtwind

    jtwind Wisconsin Airhead

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    The above two responses are the best bets. BMW did make an upgraded ground wire for the diode that is a good idea even with solid mounts. JT
    #4
  5. hogmolly

    hogmolly Dude

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    Thanks. I have an omega charging system, solid diode board mounts, and have checked the brushes numerous times. That's what makes this problem so frustrating. It didn't do this for the first year after the omega install.

    Correct me if I'm wrong but doesn't a flashing gen light mean:

    1) an intermitten short in the rotor
    2) an intermitten open to the regulator
    #5
  6. jtwind

    jtwind Wisconsin Airhead

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    If you don't have Rick Jones book it's a good purchase. Also since it's an Omega I'd just call Rick, this is the first time I've heard of a problem with one of his systems. I'd bet he'd help and like to know what's up.

    His charging book doesn't really mention a intermittent problem exactly like this but the half brightness thing could be, loose, corroded connections, partial short in rotor, short in stator, dirty rotor slip rings, worn brushes, weak springs, diode board problems, bad ground, regulator problems. I had a problem like this 3-4 years back on my g/s with a stock system. That one was the regulator. JT
    #6
  7. datchew

    datchew Don't buy from Brad

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    how bout the bulb and associated stuff?
    #7
  8. BareRider

    BareRider Adventurer

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    Just some thoughts here...I also have the Omega on a '93PD.
    Check:
    As mentioned brushes, brush springs, brush solder connnections.

    The three bolt-on connections to the stator.

    If a loose connection changes with road bumps, engine RPM, acceleration/deceleration you might get an idea of the type of connection that's loose.

    Does the gen light come on bright with the other panel lights when you first turn on the ignition? It's "possible" for the gen bulb filament to be bad and bouncing on/off. Turn ignition on so gen light is on and reach up into the panel lights and tap/pull to see if the light goes on/off. The gen bulb is a key part of the charging circuit and if it's burned out (or intermitent) charging doesn't happen. Also, the gen bulb may be loose in the socket.
    #8
  9. El Hombre

    El Hombre Banned

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    The bulb coming on is usually an open in the rotor windings, my stock rotor pulled that 5 years ago. 250 miles from home. The bulb is in the rotor circuit, and when the wire opens, the light goes on. And when it reconnects, it goes out. You could try measuring continuity thru the rotor while heating the rotor with a heat gun or hair dryer. That might get it to open.

    I would probably just wait till it stays on and get out the test equipment. Measure the voltage at the battery while the light is out to make sure it's charging and wait for a failure, this after you've checked the diode board and wiring. Trying to find intermittent electrical problems without having known good parts to substitute is going to drive you crazy.
    #9
  10. kbasa

    kbasa Roubaix! Super Moderator

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    :nod

    Top ones are probably gone and the diode board is flopping against the inside of the cover.
    #10
  11. hogmolly

    hogmolly Dude

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    Good advice.

    I tested the continuity across the brushes/rotor and get around 6 ohms. If I rotate the engine when the meter is hooked up, the resistance jumps around and goes as high as 12 ohms. I guess it could be a contact problem with the brushes.
    #11
  12. kbasa

    kbasa Roubaix! Super Moderator

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    Might be time for new ones.
    #12