typical gps 3 wire how to monitor ign

Typical 3wire gps tracking device: How can I differentiate between the key just being "on" or in "accy" on my white ignition wire. Anytime the key is on, say to just run the radio, but without the engine actually running is being reported as an ign event. I need to know how to deliver 12v to my gps tracker ONLY when the engine is actually running, not just having the key on. The vehicle is an indeterminate year, probably 2008-10 chevy express van.

Charge light (D+ or L from the alternator) is +12V when charging. Else a pulse detection circuit or tachometric relay using the ignition (IgCoil -ve) or injector -ve signals. Could also use a voltage sensor for when voltage is above (say) 13.5V with delays to hold thru voltage sags. Voltage & charge light are classic fuel pump and battery isolator circuits. The pulse system is often used for fuel pumps but they (fuel pumps) will usually have a initial ON when first powered on (to prime the carby/injectors before cranking) and they operate whilst cranking.