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Subject: New 641 electrical problem

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Mike in Michigan    Posted 04-12-2019 at 15:55:43 [URL] [DELETE]        [Reply] [Email]  
  • New 641 electrical problem
  • I have had some issues with my 641 and the starter switch, often having to do the screwdriver to ground bypass. I have replaced the starter switch a couple of times already.
    This time I was just getting a little spark when trying the screwdriver bypass. I put the battery on a charger and then she started up right away (no screwdriver needed). And she ran real good thereafter.

    However I did notice a couple of odd things.
    1. The charging light on the tractor was really bright and stayed on the whole time the tractor was running. Typically the light will have a mid-glow when turning the ignition and go off shortly after running.
    2. The fuel gas gauge no longer works (the oil pressure gauge works). Happened at the same time as #1 as far as I noticed.

    The tractor had not been started for a couple of months prior to this. I was wondering if my bypass technique caused something else to short out.

    JMOR    Posted 04-12-2019 at 17:32:52 [URL] [DELETE]        [Reply] [No Email]  
  • Re: New 641 electrical problem
  • Since problems occurred simultaneously, I would look for wire damage, especially rodent chewing. If wires are all OK, the light remaining ON when running at speed, means that the cut out contacts inside the VR are not closing. Could be because generator not outputting high enough voltage (VR field control problem or a generator problem). You can full field the generator by a jumper from battery's non-grounded terminal to gen field terminal & see if battery voltage increases with engine speed. If not, then you can simultaneously jumper same battery terminal to gen ARM terminal and observe fo increase. Apply jumpers after engine already running AND remove before stopping engine. I'll try to interpret your results if you like.

    NAA36663    Posted 04-12-2019 at 16:23:40 [URL] [DELETE]        [Reply] [No Email]  
  • Re: New 641 electrical problem
  • I agree with both posts below. I would also check the output of the generator. If I remember correctly, the 'charge light' is wired between the battery voltage and the generator output. If the generator is putting out voltage, the light goes out. If no genny output, there is enough voltage across the bulb to light. That's why it goes out shortly after starting the engine.

    Jack - Iowa    Posted 04-12-2019 at 16:11:41 [URL] [DELETE]        [Reply] [Email]  
  • Re: New 641 electrical problem
  • I believe it is time for a thorough check of your battery. Auto Parts house should be able to do a load test on it, although may not if it is a 6 volt.

    I doubt your shorting technique had anything to do with it. No answer on the gas gauge.

    Tim Daley(MI)    Posted 04-12-2019 at 16:08:35 [URL] [DELETE]        [Reply] [No Email]  
  • Re: New 641 electrical problem
  • 6V/POS GRN or a 12V switch over job? Either way I'd go thru the entire wiring system. I highly doubt your neutral safety starter button switch is the root cause. What 'charging light' are you referring to?

    Tim Daley(MI)

    Mike in Michigan    Posted 04-12-2019 at 16:19:57 [URL] [DELETE]        [Reply] [Email]  
  • Re: New 641 electrical problem
  • Yes Tim, 6V positive ground. Charging indicator light is the name in the manual. Sits on the front "panel" just left of steering wheel and just below the fuel guage.

    Tim Daley(MI)    Posted 04-13-2019 at 05:48:31 [URL] [DELETE]        [Reply] [No Email]  
  • Re: New 641 electrical problem
  • Yep, I was thinking the post was about an N-Series tractor, not a 600. Once all the wiring is correctly verified, I'd take the generator and the voltage regulator to a good, local starter shop and have them bench test them, tweak the VR if needed.

    Tim Daley(MI)

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