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Discussion Starter · #1 ·
Hey guys, I've hit a bit of a wall and need some help/advice.

I was out riding my 1971 CB350 last week and all was completely normal. 15 minute ride to a store, then I made a 10 minute stop and headed to another destination to make a second stop which lasted 5 minutes. The bike gave no indication that anything was out of whack while riding but when I came back to my bike I found that the bike was unresponsive when I turned the key to the ON position. No lights, no starter, just dead. I figured that the issue was a dead battery so I walked the bike home and charged it up. Now, with a fully charged battery, I tried again and found the same issue. No lights, no starter, nothing.

Anyone have an idea as to what could have occurred to have caused this? And, beyond that where should I start in terms of troubleshooting this to get it up and running again?

Thanks in advance for any and all help.
JB
 

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Did you check the fuses?

Can you give an overview of what you have done so far?

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If not done already, I'd check the battery voltage with a multimeter to make sure it's still good. If the battery tests good, I would agree with the above post. It sounds like the main fuse blew.
 

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Fuse blown, battery, or ignition switch is bad
 

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Discussion Starter · #5 ·
I just checked and the main fuse has indeed been blown. I just replaced it, tried turning the bike to ON and watched the new fuse blow in front of my eyes. What I don't understand is that the bike was running perfect and now its suddenly blowing fuses. Why?

Regardless, I have to find a way to rectify the issue. Where should I begin?
 

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Well that means you have a short somewhere in your wiring. Start at the headlight bucket and work your way back. Make sure all connections are clean and snug. Make sure all the wires are good, check the insulation and make sure nothing is exposed touching the frame, etc....

Electrical shorts are some of toughest to troubleshoot. There is really no quick cheat for this but to check the harness and wiring from top to bottom.

The other thing you could do is start disconnect stuff one by one (headlight, turn signals, horns, etc....) and turn the switch on and narrow down the culprit. You're gonna need a lot of fuses :)
 

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You could also approach from the other direction. Unplug everything then plug stuff back in one at a time until the fuse blows.
 

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I agree with all of the guys above. I would add that it sounds like the insulation cracked or rubbed through to the frame, shorting the positive and negative terminals of the battery. Be cautious if you do this too many times you may need to replace the battery as well.


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Discussion Starter · #11 ·
I agree with all of the guys above. I would add that it sounds like the insulation cracked or rubbed through to the frame, shorting the positive and negative terminals of the battery. Be cautious if you do this too many times you may need to replace the battery as well.


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Are you referring to the insulation of a specific wire or just saying that in general it could be the insulation around one of the wires?
 

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Discussion Starter · #12 ·
Well that means you have a short somewhere in your wiring. Start at the headlight bucket and work your way back. Make sure all connections are clean and snug. Make sure all the wires are good, check the insulation and make sure nothing is exposed touching the frame, etc....

Electrical shorts are some of toughest to troubleshoot. There is really no quick cheat for this but to check the harness and wiring from top to bottom.

The other thing you could do is start disconnect stuff one by one (headlight, turn signals, horns, etc....) and turn the switch on and narrow down the culprit. You're gonna need a lot of fuses :)
I currently don't have my brake light or turn signals (front or back) connected. The terminal connections at those point are not touch anything, but the lights are not hooked up. Would that cause the short?
 

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Are you referring to the insulation of a specific wire or just saying that in general it could be the insulation around one of the wires?
The insulation in general. Good luck and please post the problem and the solution to help future users


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Discussion Starter · #14 ·
I tracked down the culprit. My right hand controls for the headlight seem to be the root cause. At the moment, if the light switch is in the OFF or High Beam position, everything works as normal. When the switch is in the Low Beam position the fuse blows. So, given this information, what should I do to fix this? Is it likely just a misconnected wire in the headlight bucket?
 

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I tracked down the culprit. My right hand controls for the headlight seem to be the root cause. At the moment, if the light switch is in the OFF or High Beam position, everything works as normal. When the switch is in the Low Beam position the fuse blows. So, given this information, what should I do to fix this? Is it likely just a misconnected wire in the headlight bucket?


You're going to need to open up the right hand control to see what's going on in there.
Check that nothing is grounded through the handle bar that shouldn't be and then start tracing back all the wires to it and make sure it connects to the right places.

http://www.hondatwins.net/forums/at...um-71-cb350-wiring-harness-cb250_350-flip.jpg
 

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You're going to need to open up the right hand control to see what's going on in there.
Check that nothing is grounded through the handle bar that shouldn't be and then start tracing back all the wires to it and make sure it connects to the right places.

http://www.hondatwins.net/forums/at...um-71-cb350-wiring-harness-cb250_350-flip.jpg
Before opening the switch pod, checlk the headlight low beam wiring behind the headlight. Track that wiring back...it may be just a wire off and shorting to ground...I only say start there as it is easier to get to.....If no wire issues, then look at the pod....The pod is fed 12V, so if high and off don;t short, it is likely to be low beam wiring or bulb.
 

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Discussion Starter · #17 ·
Before opening the switch pod, checlk the headlight low beam wiring behind the headlight. Track that wiring back...it may be just a wire off and shorting to ground...I only say start there as it is easier to get to.....If no wire issues, then look at the pod....The pod is fed 12V, so if high and off don;t short, it is likely to be low beam wiring or bulb.

So, this issue expedited my desire to replace my tail light/brake and turn signals. In doing so, I meticulously checked the wiring in my HL bucket against the several schematics that I've seen associated with my bike (CB350 K3) and found a few things that were off. I've fixed those and all systems seems to be functioning normally exception of two things:

- at the hand control, putting the switch to Low Beam continues to blow a fuse every time.
- my turn signals will turn on but will not flash. (this was the case with the OEM lights as well)

Mydlyfkryzis, the Low Beam wire the White one coming from the hand control, correct? Are you suggesting that I test that wire with a multimeter? Sorry for the handholding, I haven't done much work with electrics and the foundational knowledge isn't there yet.

I appreciate the help very much!
 

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Make sure you didn't confuse (swap) the White wire (low beam) and the White wire with yellow "tag" (alternator connection)....
They both go up into the right-hand switch unit.....
 

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Hey partner, if yer turn signals ain't flashing, check yer turn signal flasher. Have you got a multi meter? First, unhook your flashing unit, then check it with your multi meter on ohms. You should have continuity. If not, replace. Try taking your headlite bulb out, and see if you blow a fuse then...Good luck..Its really a simple problem once you feel comfortable troubleshooting electrics...
 

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Discussion Starter · #20 ·
Make sure you didn't confuse (swap) the White wire (low beam) and the White wire with yellow "tag" (alternator connection)....
They both go up into the right-hand switch unit.....
Yup, checked these out and they're going where they're supposed to be going.
 
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