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  1. #1
    New Member
    Join Date
    Feb 2005
    Posts
    13
    Location
    Central Florida
    Tractor
    Yanmar YM2000

    Default YM 2000 Electrical Problems

    Hello All:

    I replaced my alternator and regulator about a year ago or so with the 1972 Datsun 510 parts from NAPA as recommended in this forum. The NAPA part numbers are 13-8002 for the alternator and VR521 for the regulator. After finding a short circuit in the fuse block and replacing it with a fuse holder that holds the modern type automotive fuses, the charging system has worked well. That is until several weeks ago when I noticed the voltmeter (aftermarket Sunpro) pegged out to the right. I placed a multimeter across the battery and it was reading 15 to 16 volts so I shut it down. Continuing to look for problems with the motor off I noticed that the factory instrument light bulbs were burned out. I replaced them and they burned out again when turning off the ignition switch (engine not running). They will light up as normal with the engine not running but as soon as I turn off the ignition switch, the bulbs burn out. Then, using the multimeter to check for a voltage spike when turning off the ignition, I was shocked with a voltage that felt like something I use to get from my old lawn mower. The voltage does not register on my old analog voltmeter.

    After talking with several people, some think that the increased voltage could only be generated by a coil and that there may be a diode that is not functioning. A local alternator remanufacture checked the alternator and said it was ok. I installed a new regulator and still have the same conditions, high voltage during the engine operation and instrument lights burning out when the ignition switch is turned off when the engine is not running.

    Checking for short circuits I have stripped the wiring harness down to single wires and looked over all the wiring. The only way I can get the instrument lights not to blow during ignition shut off is to turn on the head lights or disconnect the two prong plug going to the alternator with poles labeled N & F or disconnect the regulator.

    Has anyone experienced this sort of problem? Am I using the right alternator or regulator? This is a great forum and I have learned a lot of good information from all the experience out there. I am considering adapting a Delco one wire alternator to the tractor if I cannot figure it out.

    Any help would be greatly appreciated, thanks Gary

  2. #2
    Super Member California's Avatar
    Join Date
    Jan 2004
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    7,156
    Location
    Sonoma County
    Tractor
    Yanmar YM240, and now just one YM186D

    Default Re: YM 2000 Electrical Problems

    I've used the 70's Datsun alt/VR set since early 2004 without problems, so I don't think mis-application is an issue.

    Could that spike be AC getting past a bad diode?

  3. #3
    Elite Member
    Join Date
    Mar 2002
    Posts
    3,810

    Default Re: YM 2000 Electrical Problems

    If all you are doing to blow out the bulbs is to turn the ignition switch on/off, I would start by replacing the ignition switch, and get a digital meter.

  4. #4
    Veteran Member
    Join Date
    Feb 2005
    Posts
    1,467
    Location
    Olathe, Ks
    Tractor
    Yanmar 1602D

    Default Re: YM 2000 Electrical Problems

    I doubt it's a bad ign switch, and if the alt is not turning because he didn't start the motor, then where would he get a burst of a/c voltage? It's a diesel so there's no ign coil or condesor to feed back.............seems like the only place it could be coming from is the alternator somehow, but the alt checks OK.........
    It's a puzzler for sure................

  5. #5
    Silver Member
    Join Date
    Feb 2006
    Posts
    206
    Location
    Missouri
    Tractor
    Mahindra 6000

    Default Re: YM 2000 Electrical Problems

    Kinda sounds as if the alternator is running full blast all the time. That would mean regulator unable to control alternator - even the new regulator. Possibly a short or ground between regulator and alternator field terminal or same possibilities inside the alternator. If the alternator field is regulated on the hot side then full battery voltage will send it to max output. If it regulates the ground end of the field then a full ground at the field terminal will send it to max output. Might try measuring the voltage at the field terminal of the alternator with it running or maybe disconnecting the field terminal to see if the voltage comes down. If disconnecting the field clears the high voltage then the alternator is OK otherwise not. It is possible that the service guy just tested to see if the alternator would produce full output w/o checking to see if it could be regulated.

  6. #6
    Silver Member
    Join Date
    Feb 2006
    Posts
    122
    Location
    FL, Bay County
    Tractor
    YM 2000

    Default Re: YM 2000 Electrical Problems

    I think this is how it goes. The external regulator feeds some voltage back to the Field winding for regulation, the F terminal you see. I think the N is neutral for the windings. The external regulators take care of the voltage sense, IG connections etc.

    I don't know if this charging system uses a grounded field input or if it regulates B+ input to the F input, but either way, if it isn't right, the voltage will be too high.

    The regulator picks up the sense voltage from some point and gets an ignition sense line too. The IG line is provided by the Fuse box you ran
    into...I think.

    If both check good out of the tractor, then I would say your A connection or the IG sense line isn't making a good connection and trying to adjust the Field coil and Alternator up.

    So, I would start checking continuity of these inputs to the regulator with a meter. When the ignition switch is "on", there should be voltage at the IG input to the regulator. The A input to the regulator is tied to the Batt B+ and I would assume this is the sense line by which the regulator makes adjustments.

    I'm pretty sure this is close to how it goes,,,

    FL_Jerry

  7. #7
    Super Member California's Avatar
    Join Date
    Jan 2004
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    7,156
    Location
    Sonoma County
    Tractor
    Yanmar YM240, and now just one YM186D

    Default Re: YM 2000 Electrical Problems

    Quote Originally Posted by FL_Jerry
    I think this is how it goes. ...
    If it might help clarify anything here, I recently put a YM2000 wiring diagram in oldgrizzlybear's 'thermostat' (thermostart) thread.

  8. #8
    New Member
    Join Date
    Feb 2005
    Posts
    13
    Location
    Central Florida
    Tractor
    Yanmar YM2000

    Default Re: YM 2000 Electrical Problems

    Fredex:

    I checked the voltage at the alternator F terminal with the engine running and it was between 5 and 8 V. The running voltage across the battery was 15. Disconnecting F the voltage at the battery went down to 12 to 13 V and did not seem to be charging. Also, with everything connected and running, I turned the ignition switch off and on and the engine seemed to be laboring more than you would expect from a charging alternator with the switch on.

    FL_Jerry:

    The following conditions were tested with the engine not running.

    1. The F terminal (white/black wire) has 12 V with the ignition switch on. There is continuity to ground with the ignition switch off.
    2. The N terminal is grounded.
    3. The new fuse block is wired the same as the original with the IG line (yellow wire) taken off a 10A fuse. There is 12 V at the back of the regulator with the ignition switch on. There is continuity to ground with the ignition switch off. In just checking this line I was shocked when I turned off the ignition switch.
    4. The white/red wire has 12 V at the A terminal of the alternator, the starter solenoid, the B terminal of the ignition switch and the regulator.

    Fredex and FL_Jerry, I am not the sharpest when comes to dealing with electricity; I hope I have checked what you were looking for, if not I can easily check something else. Any idea what is going on?

    Could the alternator shop have missed a bad diode? After they checked it the first time I checked the A terminal at the alternator and found it had continuity to the housing so I took it back and they said that was ok.

    California, thanks for the wiring diagram.

  9. #9
    Silver Member
    Join Date
    Feb 2006
    Posts
    122
    Location
    FL, Bay County
    Tractor
    YM 2000

    Default Re: YM 2000 Electrical Problems

    "There is continuity to ground with the ignition switch off. In just checking this line I was shocked"

    So the engine wasn't running and you turned the switch off and it shocked you?

    FL_Jerry

  10. #10
    Silver Member
    Join Date
    Feb 2006
    Posts
    122
    Location
    FL, Bay County
    Tractor
    YM 2000

    Default Re: YM 2000 Electrical Problems

    Also, make sure there isn't any AC coming out of Alt. Just flip your Meter over to AC and measure from frame to Alt post, or B+.

    Jerry

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