A tracking system includes a vehicle tracking unit for a vehicle of a type including an alarm indicator, and a monitoring station receiving the alarm indication alert from the vehicle tracking unit. The vehicle tracking unit may include a vehicle position determining device, a wireless communications device, and a controller connected to the wireless communications device and the vehicle position determining device. The controller may cooperate with the wireless communications device to send an alarm indication alert responsive to at least one of activation of the vehicle alarm indicator continuously for greater than a predetermined time and activation of the vehicle alarm indicator in a repetitive pattern. The controller may also include a dual polarity compatible output for a vehicle device, such as the vehicle alarm indicator.