... , LED display indicates condition 2, when red light is lit, charging is complete. 3,12 ... LED display indicates condition 2, Charger check: when red light is lit, charging is complete.3, Alternator check : ... accelerate your engine to 2000 rpm when the red light is lit ,charging circuit is ok.4, Battery ... in the battery .5, Cranking check : red light must remain lit when starter motor operates.6, 12 ...