[DML] Re: Headlight switch repairs

["twinenginedmc12" <twinenginedmc12@xxxxxxxxxxxxxxxxx>]

Some unmade points.

Hopefully y'all are putting fuses in any unprotected new circuits created by the relays.  

Also, putting a diode across the relay coils activated by the switch will prolong switch life by reducing arcing when the switch is opened.  This improvement is sometimes omitted for cost at design time.

Dielectric grease is good too to slow corrosion, though I can't remember whether it's contraindicated on switch contacts.  It might be.

Electronics is fun.

Rick.





--- In dmcnews@xxxxxxxxxxxxxxx, Marc Levy <malevy_nj@...> wrote:
>
> 
> Good!  So we agree!  :)
> 
> 
> --- On Fri, 5/29/09, David Teitelbaum <jtrealty@...> wrote:
> 
> > From: David Teitelbaum <jtrealty@...>
> > Subject: [DML] Re: Headlight switch repairs
> > To: dmcnews@xxxxxxxxxxxxxxx
> > Date: Friday, May 29, 2009, 5:07 PM
> > The main reason for putting the fuse
> > before the switch is that in the event of a short between
> > the fuse and the switch there is NO protection for the
> > wiring OR the switch as it is currently wired. The fuse can
> > only protect anything *downstream* between the fuse and
> > ground. The headlights are controlled by relays, I just
> > think that if you change the headlights and increase the
> > current the OEM relays may not be able to handle it. To
> > increase the longevity of the headlight switch a relay
> > should be added to control the marker lights and maybe even
> > the low and high beam relays. The less current you run
> > through the switch the longer it will last. That, or follow
> > the Lucas company motto "Get home before dark"! 
> > David Teitelbaum
> > 99 Esprit 
> > 
> > 
> > --- In dmcnews@xxxxxxxxxxxxxxx,
> > Marc Levy <malevy_nj@> wrote:
> > >
> > > 
> > > 
> > > Sorry to nitpick David, but while I agree that proper
> > electrical design should place the fuse as close to the
> > source as possible... and most definite before the switch
> > (in case the switch shorts out), the location of the fuse
> > has no impact on how much current the switch is
> > passing.  Current (amperage) of the circuit is the same
> > no matter where the fuse is placed.  :)
> > > 
> > > I agree, adding a relay will significantly reduce the
> > amount of current the switch is carrying, and will reduce
> > heat and prolong the life of the switch.  LED's will
> > have a similar impact. 
> > > 
> > > IIRC, The headlights already are powered through a
> > relay (one for low beam, one for high beam) so any after
> > market headlights (like "halogen type lights") will not
> > increase the current passing through the headlight switch.
> > > 
> > > 
> > > 
> > > --- On Fri, 5/29/09, David Teitelbaum
> > <jtrealty@> wrote:
> > > 
> > > 
> > > > The design is probably considered a
> > > > "success" since it lasted over 25 years! The
> > problem is not
> > > > only the design (and construction) of the switch
> > but the
> > > > circuit itself. The switch carries the direct
> > current of the
> > > > side markers and they are fused AFTER the switch
> > so if there
> > > > is a short circuit in the marker lights the
> > switch has to
> > > > carry that whole load BEFORE the fuse will blow.
> > Not the
> > > > best way to do it. Using relays will reduce the
> > current
> > > > through the switch reducing the heat and helping
> > the switch
> > > > last a lot longer. Changing over to L.E.D.'s for
> > the marker
> > > > lights will also help a lot. Going with halogen
> > type lights
> > > > will increase the load so if you go that way you
> > really
> > > > should consider relays for the switch to control.
> > You also
> > > > should check from time-to-time the marker light
> > sockets.
> > > > They are prone to corrode and when they do they
> > can cause a
> > > > high current through the headlight switch.
> > > > David Teitelbaum
> > > > vin 10757
> > > > 
> > > >
> > >
> > 
> > 
> > 
> > 
> > ------------------------------------
> > 
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> > 
> > 
> >
>




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