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Brake switch blowing fuse

Charging System, Wiring, Lighting
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fab60
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Joined: Tue Oct 06, 2009 12:43 pm
Location: Los Angeles CA

Brake switch blowing fuse

Post by fab60 » Sun Apr 20, 2014 9:56 am

Hey guys, here's my dilema. When I activate the rear brakes it blows the fuse. The only way I've been able to ride the bike is to disconnect the brake switch so that at least I have the brake like running light on when I ride. I hope this makes sense. Could the cause be a bad battery? Bad brake switch? The brake switch is only two wires so I'm not sure how far to look to find the short. The wires do get hot prior to blowin the fuse. Can the wires be backwards? Thanks in advance for all your help!

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Snakeoil
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Location: Upstate NY

Post by Snakeoil » Sun Apr 20, 2014 8:04 pm

Okay, please don't take this the wrong way, but based on your questions I can see that you do not know very much about electrical circuits. So, my suggestion is take it someone who does and they will sort it out for you quickly. You have a short somewhere in the switched hot feed to the stop light. Probably a chafed wire or perhaps a damaged light socket in the tail light.

If you choose to sort this out yourself, I would first Google DC electric circuits or Series Circuits and get some basics on how DC electric circuits work. it's actually quite simple although probably the top area where bike owners know the least. This won't be your last electrical problem if you continue to ride vintage bikes. So, you might as well start learning now.

If you do take it for repair, ask the person to walk you thru the process and teach you a little about how the electrics work.

regards,
Rob

fab60
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Post by fab60 » Thu Apr 24, 2014 11:25 pm

Hi Snake,


Yes I understand however I just wanna ride this bad boy! Haha! Anyways I went through the brake light switch wire and didn't see any loose or frayed connections. Can it be the actual switch that might make this happen? The brake switch looks pretty cruddy. Anyone else out there that might wanna help me out?




Cheers


Rick

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jleewebb
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Location: travis county, tx

wiring diagram

Post by jleewebb » Fri Apr 25, 2014 8:36 am

here's a wiring diagram for cb77...others for cl and dream are in electrical forum..

http://www.honda305.com/forums/download.php?id=4174

note that a switched "hot" wire goes to the brake light switch; the other wire takes that hot to and through brake light filament to ground...evidently yours us going to ground before it gets to the filament...take two wires loose from brake light switch, tie them together with a wire nut and turn key on briefly. If tail light works, problem is switch...if wire gets hot/fuse blows, start tracking down short between switch and taillight bulb...hope this helps, good luck...
'62 CB77. "It's a rider."

fab60
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Posts: 91
Joined: Tue Oct 06, 2009 12:43 pm
Location: Los Angeles CA

Post by fab60 » Fri Apr 25, 2014 9:54 am

Jleeweb thanks for your reply! Ok I will go and double check that switch again. So let me get into more detail what it does. I hook up the switch. The brake light is one and when I step on the brake the brake lights up. This is fine when the bike is not running under load. As soon as I take the bike down the street under load the bike dies and blows the fuse when I press down the brake pedal. Now when I disconnect the brake switch completly the bike does not do this, therefore I came to the conclusion that it has to be with a faulty switch or a short. Can this possibly be also a bad rectifier overloading the power? Thanks for your help.



Rick

fab60
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Posts: 91
Joined: Tue Oct 06, 2009 12:43 pm
Location: Los Angeles CA

Post by fab60 » Fri Apr 25, 2014 8:55 pm

Well bought a replacement switch and it's all gravy! Thanks for your help guys.

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