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FZ600 Resto - the hotrod XJ

Discussion in 'XJ Technical Chat' started by Simmy, Aug 19, 2016.

  1. Simmy

    Simmy Well-Known Member

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    this is what I did. Same results on both sides of the fuse, so no problem with the fuse box.
    Battery connections are all tight. I'm not sure when I'll get around to this as work will take me on the road next week.
    The quarantine was kind of nice while it lasted, got lots done on my bikes.
     
  2. Fuller56

    Fuller56 Well-Known Member

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    Have you checked where the negative battery cable connects to the engine/frame? A real good place for corrosion to block current flow. Sort of hidden connection generally that gets little to no love or care.
    John
     
  3. Simmy

    Simmy Well-Known Member

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    I have not, yet but I'm sure I did a year ago.
    I'm not sure if this would explain good voltage until the key is turned on though.
     
  4. Rooster53

    Rooster53 Well-Known Member Premium Member

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    So it would seem it is before the fuse box if you are attaching the DMM to the battery negative at the battery and you are sure that is a good connection.

    An easy test, with the key set to on connect the DMM negative to the positive terminal of the battery and the DMM positive to the main fuse, it should be zero volts but I suspect it will be close to 12v indicating a poor connection in between those two points.

    If OK with key still on try DMM negative to negative terminal of battery and DMM positive to chassis / engine ground. That should be zero volts unless there is a poor ground as John suggested.
     
  5. Fuller56

    Fuller56 Well-Known Member

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    You can have enough contact for the low current of the quiescence of the key off but then when the key is on there is a much higher current draw that cannot pass the poor or corroded contact.
    John
     
  6. Simmy

    Simmy Well-Known Member

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    this seems to be tight without corrosion. I didn't loosen it and re-tighten, perhaps I should.

    yes makes sense.

    this test just registers .1-.2V
    this registers .04V with the key on.

    IMG_1061.JPG
    I rigged this pigtail up and installed it in place of the main switch.
    There was no difference so nothing to do with the main switch.

    I'll try loosening the main ground and retightening it tomorrow.
     
  7. Rooster53

    Rooster53 Well-Known Member Premium Member

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    So, the above is not really possible, so there must be some communication issues going on. Think of it this way, the third statement "Turn the key on and I get a reading, but <1V." If you have the negative probe on the battery terminal (not the battery cable) you are essentially adding a wire length to the positive terminal and probing that with the meter. It it reads anything less than 12V (battery voltage) then there is a voltage drop somewhere along the way. Now, if you are connecting the DMM negative lead to the battery cable or engine / frame then you are introducing another potential issue for voltage drop - the negative cables / wiring and the quality of the connection to their components.

    I would suggest giving the battery terminals and cables a good cleaning also.
     
    Last edited: Jun 10, 2020
  8. Simmy

    Simmy Well-Known Member

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    OK I re-did this test, I get 0V

    again, reading 0V
     
  9. Hollybrook

    Hollybrook Member

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    If the fuse to ground is 12V with the switch off and then ~0V with the switch on, I would suspect a short to ground of some type beyond the ignition switch. It must not be a direct short or there would be smoke or melting wires if the switch was left on for long.
     
  10. Minimutly

    Minimutly Well-Known Member

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    Wrong - there is a load pulling the supply down.
    Makes sure the battery earth to frame and engine is good, then measure everything wrt earth. Then with the fault present follow allong the path from battery to main fuse, ignition switch, then secondary fuse etc. Don't assume supply at one end of a wire means it will be at the other end - you are looking at a fault after all. Where you lose supply voltage is where the fault is - nothing easier, or less complicated.
     
  11. Hollybrook

    Hollybrook Member

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    Not entirely true, though you make a good point. A poor connection can also cause the same symptom as a short (just a really BIG load in essence) when measuring from ground to a point in a circuit. The bottom line is his battery is unable to supply adequate current to maintain voltage across the load present.

    The best tool I have found for chasing 12V problems is a PowerProbe. Not cheap, but simplifies the troubleshooting process as it provides the tools for many tests to chase down shorts, opens and poor connections in one easy to use tool.
     
  12. Rooster53

    Rooster53 Well-Known Member Premium Member

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    And since we talked about communications before I was assuming you checked battery voltage with the key on, is that correct?

    I wouldn't lean towards a short, unless the battery is toast and then it's not really a short but just a bad battery.

    CCA (Cold Cranking Amperes) is the most popular industry rating and is a measurement of the current a fully charged battery can deliver for 30 seconds and maintain a voltage of 7.2 volts (12 volt battery) at a temperature of -18°C.

    So that battery fully charged could maintain somewhere around 100 amps for 30 seconds and maintain a voltage of 7.2V, which is well above the reported measured voltage and certainly enough to blow fuses and produce flames.

    ^^So true and easy
     
  13. Hollybrook

    Hollybrook Member

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    I have seen a number of cases with symptoms just like this, where a wire's insulation has worn away and it is rubbing against bare metal, making a connection between 12V and ground. Since the connection is not good at all, the resistance at the connection is high and there is still some low voltage present. Certainly something that cannot be discounted, especially since this happened during a ride.

    As others have said, a systematic approach towards identifying exactly where the problem is happening is your best bet. Don't be afraid to disconnect parts of the circuit to isolate where to look next. The ignition switch pigtail was a good example of this.
     
  14. Simmy

    Simmy Well-Known Member

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    I measured the battery tonight and got 12.5V after being on a tender for 2 days. Still no power to light anything.
    Then I measured the new battery in my Seca Turbo and it measured 12.9V.
    I put the new battery in the FZ and everything is working great. :)
     
  15. a100man

    a100man Well-Known Member

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    For the moment.. 12.5 volts is plenty to light up panel lights - even a nadgered battery will do this. I still get the impression there's an underlying fault. If so it could also bugger up your new battery
     
  16. Hollybrook

    Hollybrook Member

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    12.5 volts is a fully charged lead acid battery at rest, but just coming off a charger, it should be somewhere over 13V. Is your battery tender a trickle charger or a Battery Tender brand charger? If it is only a trickle charger, it may not have enough current to charge a depleted battery quickly.

    In any case, a100man is correct and 12.5V should light up an incandescent or LED bulb, so I don't think you have found your problem yet.
     
  17. Rooster53

    Rooster53 Well-Known Member Premium Member

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    So pretty sure the FZ600 utilizes the starter / headlight switch, so with key on the headlight current along with other circuits would be enough current draw to identify a defective battery or battery connection. It's probably time for a new battery but I might clean it up and try again, or have it load tested somewhere just to be sure.
     
  18. Aj ostrawski

    Aj ostrawski New Member

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    Am I able to put that front headlight set up you have on yours on mine is a 89 radian it's kinda quick
     

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