Immobiliser malfunction

[bundubasher]

Hi - I've posted under electrickery, but I'd thought I'd post here as well to pick up more feedback:

Don't know if my imobiliser is an aftermarket fitment or an OE Toyota one but something is giving me problems. After putting the widget in the hole the immobilser is usually disabled - lights come on, engine starts, but recently the lights have been coming on but the engine, she no start! Is this the immobiliser or the starter solenoid?