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Author Topic: Front Brake Switch  (Read 1962 times)

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Offline DaveInTexas

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  • 1970 CB750
Front Brake Switch
« on: May 31, 2006, 02:30:14 PM »
no longer activates the rear lamp. 
Looking for troubleshooting methods.

Fuse?  (the rear brakes illuminates the stop lamp just fine)
Is there an adjustment on the front switch??
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dave75

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Re: Front Brake Switch
« Reply #1 on: May 31, 2006, 03:07:59 PM »
On my 1975 CB400 there is a hydraulic pressure switch in the front hydraulic brake line.  Right between the forks under the head light (where the upper and lower brake lines come together through a three way manifold).  Looks like an oil sender unit but with two terminals to connect to it.  You can verify this switch is bad by disconnecting the leads.  Turn the ignition on and short across the two leads.  Your light should come on..... if it does you need a new pressure switch.

When you remove it you want to either put a bolt in its place or insert a stopper right away or you'll lose all your brake fluid.  Honda has discontinued the part.  You can get it new from the UK (expensive) or shop around used.  I put an add in the Want to Buy section of this board and got a very nice reply.

Dave
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Offline DaveInTexas

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Re: Front Brake Switch
« Reply #2 on: May 31, 2006, 04:44:57 PM »
I'll check it out, it worked fine an hour earlier when I had the inspection done.
I have worked on that brake (all apart) in the last week if that makes a difference.  (Can an air bubble do this?)
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Offline csendker

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Re: Front Brake Switch
« Reply #3 on: May 31, 2006, 06:07:08 PM »
Quote
it worked fine an hour earlier when I had the inspection done.

Isn't that backwards?  My stuff usually breaks just before the inspection.   ;)

Do your front brakes work?  I believe the switch should work even if they're mushy.  However, if you have enough air to absorb all of the pressure, it may not work.  Or a wire could be busted, disconnected, etc.
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Actually runs --> 1975 CB550-K1
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Offline DaveInTexas

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Re: Front Brake Switch
« Reply #4 on: May 31, 2006, 07:16:30 PM »
I am thinking it was corrosion on the connectors because when I pulled them to test the circuit and then reinstalled them, it was suddenly 'fixed'.
More later if it quits again - and thanks.
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Offline Bob Wessner

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Re: Front Brake Switch
« Reply #5 on: May 31, 2006, 07:22:05 PM »
Dave,

If it was corrosion, it would be worth your while to pull it, clean the connections really well with some fine grit Emory paper or something like that then smear a little dielectric grease on them before shoving them together again. The location of this connection in particular lends itself to exposure to the elements.
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We'll all be someone else's PO some day.

Offline DaveInTexas

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Re: Front Brake Switch
« Reply #6 on: May 31, 2006, 07:35:35 PM »
Points well taken Bob, I will do this - but first I must attend to other things.  Like a fuel leak bigger than the Exxon Valdez.!

Quote from: Bob Wessner on May 31, 2006, 07:22:05 PM
Dave,

If it was corrosion, it would be worth your while to pull it, clean the connections really well with some fine grit Emory paper or something like that then smear a little dielectric grease on them before shoving them together again. The location of this connection in particular lends itself to exposure to the elements.

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