Date: Thu, 29 Mar 2018 09:34:54 -0700
Reply-To: Chuck Theobald <chuckt1961@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Chuck Theobald <chuckt1961@YAHOO.COM>
Subject: Re: headlight switch
In-Reply-To: <485a817c-fbff-8720-a141-5ec7c539cc27@cox.net>
Content-Type: text/plain; charset=windows-1252; format=flowed
Hi David,
Blown fuses indicate a path to ground that bypasses the expected load.
The equation is voltage = current * resistance. Given a constant
voltage, 12 volts, the resistance of the load (headlights, horn, etc.)
limits the current. If the resistance decreases, say a wire with
worn/failed insulation contacting the body, current will exceed the fuse
capacity (8 or 16 amps) and blow the fuse, preventing your wires from
catching on fire.
The upshot is you are probably looking for such a failed wire.
What triggers the blown fuse? Does it happen randomly, or can you
reproduce it reliably?
Chuck
On 3/28/18 5:41 PM, vw_van_fan_Mark wrote:
> Those dimmer light wires also go to other places in the dash and one of
> those other places may be where a short circuit exists. There is a wire
> to the backlight for the dash vent control levers, a light for the cig
> socket, and also it feeds the factory wiring for the radio.
>
> Mark
>
> David Boan wrote:
>> Thanks for the quick reply!� My headlights are working, it is only
>> things on the dimmer circuit that are off.� Does that rule out the
>> headlight part of the switch as the culprit?� I pulled the switch and
>> do not see any obvious problems, but have not attempted to take it
>> apart.� Could the problem be elsewhere, like the circuit foil?� Any
>> suggestions how to test the switch?
>>
>> ________________________________
>> From: KIM BRENNAN <kimbrennan@mac.com>
>> Sent: Wednesday, March 28, 2018 7:51:29 PM
>> To: David Boan
>> Cc: vanagon@GERRY.VANAGON.COM
>> Subject: Re: [VANAGON] headlight switch
>>
>> The most likely problem is that the REST of your headlight switch has
>> melted, and is causing your dimmer switch to malfunction. Once you
>> pull it, you�ll know.
>>
>>
>>> On Mar 28, 2018, at 7:40 PM, David Boan <dboan@OUTLOOK.COM> wrote:
>>>
>>> Hey Vanagon Types ...
>>>
>>>
>>> I have a problem with my instrument panel lighting.� I have
>>> repeatedly blown the fuse that is next to the fuse bus, the one with
>>> the grey and blue wires that Bentley lists as circuit 43 going to
>>> the dimmer switch.� Is it likely that dimmer is the culprit?
>>>
>>>
>>> I am thinking of pulling the wires to the dimmer and connecting them
>>> together to bypass the switch and see if that stops the fuses from
>>> blowing.� Is that going to cause other problems?� Will I lose my
>>> headlights if I do that?� Does anyone know a better way to test if
>>> the problem is the dimmer switch?
>>>
>>>
>>> Thanks
>>>
>>>
>>> Dave B.
>>>
>>> Boise
>>
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