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Author Topic: Trying to troubleshoot a dead bike  (Read 1017 times)

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Offline Kustomizer

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Trying to troubleshoot a dead bike
« on: November 06, 2015, 06:03:00 PM »
Ok, so I'm trying to figure out what is wrong with my k7.  I rode it around last fall and then it died and never started again.  I was looking at another thread and checked a few things in it.  First, my fuse block seems to be bad, so I replaced it with another and got voltage back at the fuse.  Now, I checked for 12v at the ignition switch and there is 12v or I should say 10v and as soon as I switch the key on, the voltage on the red + wire at the switch goes to zero volts.  I think the switch is bad as when I ohm it out it doesn't seem right to me, but I'm not sure.  If I ohm out the switch from the 12v red wire connection, which of the other tabs should go to zero when I turn the switch on?  Hope this makes sense.
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Offline calj737

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Re: Trying to troubleshoot a dead bike
« Reply #1 on: November 07, 2015, 05:00:17 AM »
if you're dropping to 10v at the key, you've got a low charged battery AND a great deal of resistance between the battery and switch.

Start by charging your battery overnight, then let rest 2 hours and test the standing voltage. What is it?
Then, clean every terminal, connector, and ground on your bike/harness. Is your key switch stock? If so, the BLK, BRWN, and BRW/WHT should get 12v with the key turned to ON. Measure the voltage after doing the above.

You replaced the fuse block, with what? A used stock unit or an ATC type? If stock, check the back side of the block and clean the contacts completely.

You didn't indicate whether you had electrical functions with the key active, just that it "doesn't start". What does that mean???
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"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline Kustomizer

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Re: Trying to troubleshoot a dead bike
« Reply #2 on: November 07, 2015, 08:44:18 AM »
Thanks Calj737.  The fuse block was changed with a used factory one.  After that I do have voltage there.  The ignition is stock and when I turned the key on the voltage on the red goes to zerpo and there is nothing of course on any of the other wires, so I used an Ohm meter and tested the switch and when I turn the switch on none of the connections from the red connection zero out, so it's as if all the paths are ope, but why would the voltage drop to zero then if they were open, shouldn't it stay at the current voltage?  Still confused, anyway, does it sound like the switch is bad or is it something else?
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Offline calj737

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Re: Trying to troubleshoot a dead bike
« Reply #3 on: November 07, 2015, 10:10:14 AM »
Sounds like your battery is crap. Follow the previous instructions on charging and metering your battery. Then post those results.

If your key activates and kills the voltage due to a load, probable culprit is a dead battery. Not always, but a known, good battery is a must to determine electrical health.
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"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline Kustomizer

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Re: Trying to troubleshoot a dead bike
« Reply #4 on: November 09, 2015, 12:38:46 PM »
I have the charger on it and will test it tonight, but this is a new battery.
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Offline flybox1

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Re: Trying to troubleshoot a dead bike
« Reply #5 on: November 09, 2015, 12:49:34 PM »
After charge, let it rest for 2+hrs, then check the voltage at the terminals.
It should be north of 12.7v

There are new harnesses for the K7/8 bikes.  I believe cb750supply carries them.
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Offline Kustomizer

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Re: Trying to troubleshoot a dead bike
« Reply #6 on: November 15, 2015, 03:32:58 PM »
Alright, I figured out the problem.  After replacing the ignition switch it powered right up and I thought I solved my problem, but then when I tried it a little while later it did the same thing.  So I started tracing power from the battery and found a corroded connection on the duel B+ cable that comes off of the starter solenoid.
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