Date: Fri, 4 Aug 2006 15:10:57 -0400
Reply-To: dhaynes@OPTONLINE.NET
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <dhaynes@OPTONLINE.NET>
Subject: Re: Headlamp Relays; Fuse the Relay Control Circuit?
In-Reply-To: <20060804182106.12720.qmail@web50201.mail.yahoo.com>
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You are reading things correctly. One concern for VW's is that there are mnay circuits that are not fuse protected. Worse, there are wires going to those circuits that are not protected. The ignition coil, ECU, fuel pump, etc, are not prtected. I wonder how many fires blamed on fuel lines were actually electrical. Operate the AC wit the fan on high for awhile and ten grab that wire going from the alternator to the AC. Feel how soft the insulation is from the heat. If that wire was to short to the chassis, the full battery and alternator current is available to it. American cars use fuse links at the battery connection. Aisain cars use those Maxi fuses to protect the harness. The VW uses nothing.
I would consider a self reseting braker for the realy circuit so if something happens, you will maybe have flashing lights instead of none at all. If you reaaly want to go crazy you could use separate realys for left and right.
Dennis
----- Original Message -----
From: Kevin Mulligan <mulligan_kevin@YAHOO.COM>
Date: Friday, August 4, 2006 2:21 pm
Subject: Headlamp Relays; Fuse the Relay Control Circuit?
> I have two questions for the group regarding the use
> of relays to power the headlamps. As I understand it,
> the benefit of using relays is a more direct circuit
> path from the fuse box (or other power source) to the
> headlamps via the relay power circuit, and in the
> process removing from the circuit path the current
> flowing through the dashboard light switch and
> headlamp dimmer switch. Current would still flow
> through these switches, of course, but it is much
> lower amperage used only to operate the relay control
> circuit, which switches the power circuit on and off.
> Based on a review of the archives, it sounds as if
> this is a common installation method.
>
> But in looking at the wiring diagram for my 90 syncro
> westy, it looks as if, by using relays in this way,
> the current to the relay control circuit becomes
> un-fused. The existing fuses remain within the
> headlamp circuit paths -- whose current would be
> provided by the relay power circuit -- and nothing
> downstream would need to change except maybe a better
> ground. But, the relay control circuit would get its
> current via the headlamp switch, thus making its
> current path separate from the downstream headlamp
> fuses.
>
> So, questions for the group:
> - Am I reading the diagram correctly, that
> installation of relays as described here makes the
> relay control circuit un-fused?
> - If yes, thoughts on whether a fuse is needed within
> the relay control circuit path, or other ideas on
> relay installation?
>
> I just don’t want to fry anything while driving down a
> logging road, at night, in the north woods, miles from
> anyone, tired, hungry, etc. Thanks.
>
> - Kevin
>
>
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