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Author Topic: CB750 Rear brake light  (Read 2695 times)

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Offline exf5003

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CB750 Rear brake light
« on: May 10, 2012, 07:40:33 AM »
So this might be a stupid question, but my break light works perfectly fine when the handle bar, foot pedal, or both are pressed.  But it does not stay on dimmed while I'm ridding around and this is a concern especially if I am out when it gets dark.  Any idea what is causing this? Thanks
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Offline LesterPiglet

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Re: CB750 Rear brake light
« Reply #1 on: May 10, 2012, 07:51:55 AM »
Did you check the bulb? They are dual filament.
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'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


Les Ross.            Certified by a Professional

bollingball

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Re: CB750 Rear brake light
« Reply #2 on: May 10, 2012, 08:14:10 AM »
exf  The brake light is only bright it does not go dim. What Lester is saying is true the bulb has two filaments one is the brake the brighter one the other one is the tail light what you are thinking of as the dim one. This one bulb is operated by two separate circuits. So your problem is the tail light circuit. I may have missed it but what bike size and model and year is your bike. It could be as simple as Lester said bad bulb on one side only. When you take it out look at the contacts at the bottom of the socket  make sure you clean them nice and shiny. Do this and get back with results it will help others later on.

Ken
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Offline exf5003

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Re: CB750 Rear brake light
« Reply #3 on: May 10, 2012, 09:07:58 AM »
I have a 74 CB750. I did not check the bulb so I'll have to do that later on as you have recommended and thanks for the info.  I'm crossing my fingers that its just the bulb and not the circuit.  i will report results once this is done.
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Offline exf5003

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Re: CB750 Rear brake light
« Reply #4 on: June 05, 2012, 09:32:46 AM »
After being away for a good while and finally getting back to take a look... Its definitely the circuit and not the bulb.  Should i be looking for something specific?
I also replaced the fuses with blade fuses and another problem came up. i keep blowing the 5amp fuse.  It snaps them the middle every time i turn the key.
When i first replaced the fuses the other day i turned on the bike and it seemed to work perfectly (no tail/brake light of course), but today i tried turning it back on and my headlight doesn't come on and the bike isn't starting either.  My oil light and neutral light comes on when key is turned, but the bike just wont start.  I'm not sure if the headlight bulb is out, still has the enclosed bulbs in it, but it wont start up at all where before it was very easily turned on.  Is this being caused by the headlight being out at all?
I'm definitely going to recheck the wiring and make sure i put the fuses in currently, but dont know what else could be causing this. Thanks in advance
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Offline exf5003

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Re: CB750 Rear brake light
« Reply #5 on: June 06, 2012, 07:03:56 AM »
?...
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Offline MCRider

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Re: CB750 Rear brake light
« Reply #6 on: June 06, 2012, 07:08:08 AM »
Quote from: exf5003 on June 06, 2012, 07:03:56 AM
?...
I hate electrical problems. In my case, usually self induced.  Back track to the time everything worked. Then walk forward to the first failure. What did you change on the bike? If not, what changed on the bike all on its own?
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Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline LesterPiglet

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Re: CB750 Rear brake light
« Reply #7 on: June 08, 2012, 09:21:50 AM »
You  are going to have to trace the taillight fault with a multimeter, probably the reason your fuse is blowing. Check the wiring to the connection under the seat for continuity, make sure it isn't grounding. Then from here check the wiring to the next connection on the wire. Keep doing this until you find the problem. Once that's done you can move to the other problems.
The only way to find out if a bulb is faulty is to replace it with a known good one.
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'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


Les Ross.            Certified by a Professional

bollingball

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Re: CB750 Rear brake light
« Reply #8 on: June 08, 2012, 10:33:50 AM »
The 5a fuse is the tail light check where you put the wires when changing to the blade type fuse you probably messed up there.

Ken
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