Gary,
A relay is simply a device that controls a higher current device (in this case
the OD solenoid) by using a lower current circuit.
What happens is that when you flip the OD switch (and all the other conditions
are right.. correct gear, etc.) the winding circuit is
completed and creates an electromagnetic field that closes the control contacts
completing that circuit and energizing the solenoid.
The control circuit remains closed until something interrupts the winding
circuit. (Such as flipping the switch or changing gears into
one that does not support the OD.
Complete testing with a multimeter is not possible, but you can measure between
the W1 and W1 contacts to see if the winding is ok. If
you remove the cover and manually close the control contacts, you can then
measure across the control contacts to see if the points are
making positive contact.
Regards,
Joe
Gary Hutton wrote:
>
> Can someone explain to an electrically-challenged owner the actual
> function of the horn and overdrive relays in our cars. Are they just
> electrical switches instead of mechanical ones? And is there a
> procedure for testing them with a multi-meter?
>
> TIA
>
> Gary Hutton
> Newburgh, IN
> 76 1500
>
> ----- Original Message -----
> From: Joe Curry <spitlist@gte.net>
> To: Chris De Wet <DeWetC1@sapo.co.za>
> Cc: 'Eric Kieboom' <ekieboom@xs4all.nl>; Nolan Penney
> <npenney@erols.com>; Mike Chmura <m.chmura@umassp.edu>;
> <spitfires@autox.team.net>; <triumphs@autox.team.net>
> Sent: Friday, February 16, 2001 10:22 AM
> Subject: Re: Overdrive tranny question
>
> >
> > Chris,
> > Why not simply get an "off the shelf" relay and wire it in until you
> find a period correct one?
> >
> > Joe
> >
> > Chris De Wet wrote:
> > >
> > > The D-type as used on earlier spitfires do need a relay .... which
> I'm
> > > missing of course . I don't have big bucks either :-(
> > > I prefer originality , but can I just run a big wire until I have
> enough
> > > money ? How big ? Any advice would be appreciated . TIA
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