This is an immobilizer that operates as follows.
- Turn it on by pressing the switch (momentary on button). The DPDT is then supposed to stay activated and disengage the std relay and at the same time powering the led, which flashes.
- To turn it off you hold a magnet infront of the reed switch (hidden behind dash somwhere) and the power returns to the std relay and completes the circuit that has been immobilised. The led is also turned off.
The std relay is no drama, I just could not make sense of the crappy diagram, mainly for the terminals for the DPDT relay.
This is the link for the whole caboodle http://autospeed.drive.com.au/A_107975/cms/article.html
The idea is that even if someone steals your keys, they cannot bypass the kill switch, except by using tow truck.