best way is to set alarm with windows open, set alarm.
wait 1min then put arms through windows to trigger alarm...
or . . . .
with doors open, use screwdriver to "flip" the door lock closed, then set alarm. wait 1min then jump in van.
the basic alarm monitors door open/volt drop/tow away/ultrasonic in cab
when set the LED will flash fast for a while (min or so) before slowing down to a slow flash (every 2sec or so)
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side note, the alarm LED has a 2pin connector to the door loom . . . .
has the door card been off for any reason? . . . maybe the cable is disconnected....