Avital 3100LX Starter Interrupt

How does the starter interrupt work? I wired it inline between my ignition switch and starter solenoid, but when the alarm is armed it will still crank when you turn the key. Should I connect this to a different wire? Or am I not understanding correctly how the starter kill works? Thanks! If it matters, it’s a 1966 F100 completely rewired from scratch using an EZ Wiring harness kit.

It's just an internal relay that either connects the wires together when disarmed or breaks the connection when armed. Try unplugging the 2 terminals from the brain module and see if it still starts. If it does then you may have interrupted the wrong wire. If it doesn't then check for continuity across the 2 terminals on the brain for starter interrupt. If working properly you should get continuity across the terminals when disarmed, an no continuity when armed. If the output is damaged then you may still be able to just use an external relay to perform the same task using the orange ground when armed output as a trigger.Steve G

So I got a replacement alarm and the same thing happens- when the alarm is armed, I still have continuity across the starter interrupt terminals. Should that circuit be closed when disarmed, and open when armed? Am I not understanding how the starter kill is supposed to work? Or is there a switch or jumper somewhere to enable the starter kill feature? This is two alarms now that act the same way, it must be me doing something wrong. Any thoughts?

Do you have the ignition wire connected to the Avital and supplying 12v during key on? When the system is armed and the ignition is energized, the starter wires will be interrupted.

I’ve got the red wire connected to a constant 12v source, and the yellow wire connected to a circuit that only gets 12v when the key is in the ON position, if I recall it’s tapped into the heater blower motor wire. Does this sound right or do I have it backwards?

It has to be connected to the ignition wire, the heater/blower motor feed drops out during cranking. The proper ignition wire will show 12v in the RUN and START position.

So I connected the yellow wire directly to the IGN terminal of the starter switch, and now I notice whenever I turn the key to the OFF position, the power door lock actuators unlock. Is this normal/expected?

Yes that’s expected if you have ignition controlled door locks enabled.