My van will not crank no start it just click song coming from automatic shutdown relay

Please explain to me what a TARGET SWITCH is , In my 50 years of working on cars & trucks I've never heard of one , Something is pulling amps ( parasitic drain ) and discharging the battery

I came home I cut the G Caravan SE off. but I for get to cut my voltage regulator, I had bypass my alternator and wire to VR, so it will change the battery, O yes this works find. But I had let the target switch on the VR? I for get to cut it OFF. So now The battery was drained. Next day no power in my battery. The last time this happened I just chage up the battery.. The van started right Up! Now I get is a ticking sound from auto shutdown relay. I did check the starter relay, the engine did not turn over? When I turn the ignition key all I here is a ticking sound from auto shutdown relay... Also a ticking sound under the fuse box and a buzzing sound...