Why are car alarm starter relay normally closed?

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Sam Nickaby - 11 Feb 2006 16:36 GMT

Why are car alarm starter kill relay designed to be normally closed? It
would make practical sense to make the relay normally open because
when the crooks pull the alarm fuse or the alarm unit out of the car, the
car shouldn't be able to start. But in fact it's the opposite and crooks
knows about this. What are the reasons for alarm companies for
making there relay normally open?

Thanks

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Steve Mackie - 11 Feb 2006 16:45 GMT

> Why are car alarm starter kill relay designed to be normally closed? It
> would make practical sense to make the relay normally open because
> when the crooks pull the alarm fuse or the alarm unit out of the car, the
> car shouldn't be able to start. But in fact it's the opposite and crooks
> knows about this. What are the reasons for alarm companies for
> making there relay normally open?

My Alpine SEC-8049 can operate the starter interrupt relay in either N/C or
N/O operation.

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dnoyeB - 13 Feb 2006 16:44 GMT

> Why are car alarm starter kill relay designed to be normally closed? It
> would make practical sense to make the relay normally open because
[quoted text clipped - 4 lines]
>
> Thanks

So they are not liable when the alarm fails and prevents you from
starting your car and you freeze to death in the mountains. My alarm
broke, and all I had to do was unplug it, and im off.

Other way is better for anti-theft and in fact current design makes
aftermarket kill switches virtually pointless.

Signature

Thank you,

"Then said I, Wisdom [is] better than strength: nevertheless the poor
man's wisdom [is] despised, and his words are not heard." Ecclesiastes 9:16

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Alex Rodriguez - 13 Feb 2006 21:06 GMT

>Why are car alarm starter kill relay designed to be normally closed? It
>would make practical sense to make the relay normally open because
>when the crooks pull the alarm fuse or the alarm unit out of the car, the
>car shouldn't be able to start. But in fact it's the opposite and crooks
>knows about this. What are the reasons for alarm companies for
>making there relay normally open?

So that if the alarm unit fails, you can still drive your car.
-------------
Alex

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