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xrotaryguy Samba Member
Joined: August 15, 2019 Posts: 12 Location: Pomona, California
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Posted: Thu Aug 15, 2019 8:59 pm Post subject: 67 Bug Has Two Brake Switches - Why? |
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I have two brake light switches on my 67. The wiring diagram shows they're wired in parallel. Why would that be?
Also, one of my switches closes when I press the brake. The other does not. Is this correct? Or do I have one bad switch?
The wiring in this car is a mess. I intend to replace it all! But I want to understand this circuit better before I dive in. |
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Pruneman99 Samba Member
Joined: February 22, 2012 Posts: 5013 Location: Oceanside
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Posted: Thu Aug 15, 2019 9:01 pm Post subject: Re: 67 Bug Has Two Brake Switches - Why? |
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It's a redundant system in case one fails |
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xrotaryguy Samba Member
Joined: August 15, 2019 Posts: 12 Location: Pomona, California
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Posted: Thu Aug 15, 2019 9:03 pm Post subject: Re: 67 Bug Has Two Brake Switches - Why? |
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Simple enough. Thanks.
Makes perfect sense considering one has failed haha. |
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sjbartnik Samba Member
Joined: September 01, 2011 Posts: 5994 Location: Brooklyn
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Posted: Fri Aug 16, 2019 8:04 am Post subject: Re: 67 Bug Has Two Brake Switches - Why? |
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To expand on what pruneman99 said:
The brake system in a '67 is split into two independent hydraulic circuits.
That way if you have a failure somewhere in the system (like a hose rupture or a wheel cylinder blowout) you will only lose braking on two wheels while the other hydraulic circuit will continue to function and provide you with some braking ability (though much reduced).
The brake light switches are operated by hydraulic pressure. If there is no hydraulic pressure in the system, then the lights will not work.
The way VW has designed it, the system is set up so that even if you completely lose the hydraulics in one circuit, both brake lights will still work, as there is one switch per hydraulic circuit. _________________ 1965 Volkswagen 1500 Variant S
2000 Kawasaki W650 |
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xrotaryguy Samba Member
Joined: August 15, 2019 Posts: 12 Location: Pomona, California
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Posted: Fri Aug 16, 2019 9:47 am Post subject: Re: 67 Bug Has Two Brake Switches - Why? |
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Great. I guess the alternate solution is to put a switch on the pedal. Then the brake lights work regardless of if one circuit has lost fluid. |
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Cusser Samba Member
Joined: October 02, 2006 Posts: 31360 Location: Hot Arizona
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Posted: Fri Aug 16, 2019 11:37 am Post subject: Re: 67 Bug Has Two Brake Switches - Why? |
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xrotaryguy wrote: |
Great. I guess the alternate solution is to put a switch on the pedal. Then the brake lights work regardless of if one circuit has lost fluid. |
Just get good-quality brake switches, easier and less expensive. _________________ 1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
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