Date:         Sat, 4 Dec 2010 09:12:54 -0500
Reply-To:     Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject:      Re: No brake lights
Comments: To: Mike <mbucchino@CHARTER.NET>
In-Reply-To:  <32BF5E816F2C412D8E791A06FE69AA0E@Mikelaptop1>
Content-Type: text/plain; charset="UTF-8"

Very good description. As a bit of history before they used the float level sensor the brake light switches were three terminal and wired so that if there was pressure in only one circuit the brake warning light would be activated. I have seen both switches fail so that could be a place to look. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Mike
Sent: Saturday, December 04, 2010 6:40 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: No brake lights

  Not 'simply for the sake of redundacy' in case one switch fails, Karl.
It’s a dual hydraulic circuit master cylinder, so if a leak develops in a
line or brake assembly to 2 of the wheels,
you'd still have braking on the other circuit to the other 2 wheels.
If the leaking circuit can't develop pressure to actuate the brake light
switch, the other one still will, as they're wired in parallel.
That's the reason why there's 2 switches, not in case one fails, but in case
your system develops a leak.
'No brake lights' is likely to be a problem in the common power (fuse/
wiring) feeding both switches, not 2 failed switches, which is highly
unlikely.'
It's more likely to be 2 burned-out brake light bulbs, bad grounding at the
taillights, corroded/ loose bulb sockets.
Power feeds from the fuse to both switches in parallel. When you step on the
pedal, the switches close the circuit, sending power back to the taillights.
The power is fed to the center of the bulb sockets, thru the good bulb, then
the outer bulb sockets are wired to chassis ground, completing the circuit,
which lights the lamp.

Mike B.

-----Original Message-----
From: Karl Wolz
Sent: Saturday, December 04, 2010 12:01 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: No brake lights

In lieu of a better answer, the switches are on the side of the master
cylinder in the speedo housing.  There are two, simply for the sake of
redundancy.  When the second one fails, you have no brake lights.  Other
possibilities exist, but you'll have to get those elsewhere than from me.

Karl Wolz


|-----Original Message-----
|From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
|David M
|Sent: Friday, December 03, 2010 8:30 PM
|To: vanagon@GERRY.VANAGON.COM
|Subject: No brake lights
|
|I have no brake lights. I checked the fuse and the bulbs. Both good.
|What next? I looked in my Haynes and Bentley and no information on how the
|brake lights work other than a wiring diagram showing a 'switch'.
|
|-David (1987 Wolfsburg)