two switches for seat belt

The manual for my 2000 Toy. Solara shows 2 switches in parallel to
indicate the driver has buckled his seat belt. Closing either of them
will do the trick.

Not only does the manual show the two switches, it gives them separate
code letters, like B5 and B6, and mentions both twice in the tables of
electrical continuity, etc. So it doesn't seem like a mistake in the
manual.

Why do you suppose this switch duplicated? Is it more important than
all the other switches in the car?

micky wrote:
> The manual for my 2000 Toy. Solara shows 2 switches in parallel to
> indicate the driver has buckled his seat belt. Closing either of them
> will do the trick.
>
> Not only does the manual show the two switches, it gives them separate
> code letters, like B5 and B6, and mentions both twice in the tables of
> electrical continuity, etc. So it doesn't seem like a mistake in the
> manual.
>
> Why do you suppose this switch duplicated? Is it more important than
> all the other switches in the car?

If there were only one switch and it broke, you would not know
if your seatbelt was buckled or not because the warning light
and beeper would either always be on or always off.

"micky" > wrote in message
> The manual for my 2000 Toy. Solara shows 2 switches in parallel to
> indicate the driver has buckled his seat belt. Closing either of
> them
> will do the trick.
>
> Not only does the manual show the two switches, it gives them
> separate
> code letters, like B5 and B6, and mentions both twice in the tables
> of
> electrical continuity, etc. So it doesn't seem like a mistake in
> the
> manual.
>
> Why do you suppose this switch duplicated? Is it more important
> than
> all the other switches in the car?

That sort of thing is common with "fault tolerant design". Duplicate
systems. One switch can stop working and the other will continue to do
the job. That is quality design. A good thing!

And that is certainly a good place to have such a design. Take apart
an older car in that area and you will find spilled soda pop,
cigarette ashes, dust/dirt, bits and pieces of paper, coins, etc.
Quite nasty! And all that crud can easily make a switch in that area
stop working.

For example on my car, the emergency hand brake in the center console
has a switch which turns on the brake light. That switch kept getting
crud in it and would stop working. I finally put plastic over it so
the crud would not fall on the switch.