re Re: Fog Light Rigging............

["Smith, Kirby A" <kirby.a.smith@lmco.com>]

Andrew Duane USG <duane@hunch.zk3.dec.com> wrote:
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Hairy green toads from Mars made adamnelson@juno.com say:

> What? If the switch handles all of the power for the lights, why is there
> a relay? The idea of a relay is to reduce the load going through a switch
> or wire. The switch should handle only a small amount of current from the
> low beams, enough to close the connection between #31 (battery power) and
> the given device (87). Bentley is showing you this, so take another look.
> The current coming from the low beam circuit goes through the relay (85
> to 86) and is grounded by the switch, closing the circuit. This makes the
> relay close the other circuit, the one from the battery (31) to the
> lights (87). 

Yup. It is, sort of. It is switching the additional load of the
fog lights away from the wiring for the low beams.

That is what it "protects", not the fog light switch.

It is a boneheaded design, maybe they don't do it this way
on the big-chassis cars, but it is DEFINITELY that way on the
two 90Qs I've done this on. (my 100Q doesn't have fogs, and
my A6QW is off limits for this at the moment).
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I don't think you are correct here, Andy, but unfortunately my Bentley is at
home.  As I recall on the schematic for your 90q, that relay "allows" power
to go to the fog lights if the low beams are on.  I am fairly certain that
that is what the schematic for my 1988 90q shows.

                .... Kirby   (Kirby A. Smith)
                              2 x 1988 90q
                          New Hampshire USA