My mothers -92 SSEi stoppt cranking today.
It won´t engage the starter and if I force the starter to spin it doesn´t help.
I suspect it has something to do with the VATS system as the security light is flashing as soon as I turn on the ignition.
Hope someone can help me.

Try a different key or clean the key you have and the contacts inside the switch with a Qtip and alcohol.

You MUST check the chip on the key. If its foiled in any way the car will not start. Clean the drivers key if its dirty.

I have cleaned and tried both keys without any success :(
Thinking of if it can be something else as the security light is flashing at 1 flash/*?

I still have the car standing down in the city...
Can someone please help me with more tips?

I really would nned to get the car home to try an have a look at it, but to get it towed a mile would cost me $125 and that´* alot of money...

Is there some way to hook it up and tow it myself, can´t find anythink to tow in?

Use the "Search" function at the top of the screen. Type in "vats" and hit "Search". You will get a ton of information. I am going to go look in my FSMs to see if I can find something to help.

I don't really know how to help, but could just resetting the ECM help?

OK, security light flashing once per second and the engine does not start indicates the VATS system sensed an open circuit, a short, or invalid input from the key.

According to the FSM for the '97 Bonneville, steps are:

1. Clean the key pellet AND the contacts inside the switch like willwren said.
2. Visually check contacts in ignitoin cylinder by looking into opening. They should be silver in color.
3. Check relay center fuse #8
4. Check right hand underhood fuse block fuse #4.

Thanks alot!
Now I have alittle more to check out.
Time for bed here now, as it´* past 1 am...

Now I got the car home, hooked it up and towed it home...

I´m have localized the orange loom with two white cables in it, it goes to the 48 pin connector that I´ve taken apart.
Then I put my key in the ignition and measured between the white cables and got the exact same value as when I measured on the key.

But when I turn the key to ON I´m loosing connection, as indicated by not getting any value on the multimeter.

Is this indicating a bad ignition switch?