... , If the polarity is negative (-), the green LED lights; and if positive (+),the red LED lights. In the Measurement Mode, the tester measures and ... a spark is detected, the Red LED light flashes and the red or the green LED lights to show the polarity.Notes:If ... beeping sound·The headlight flashes 3 times·The corresponding polarity LED lights·LCD displays the current KV reading for 15 seconds