During the preflight inspection of a single-engine airplane, with the magneto switch OFF and the master switch ON (engine not running), the ammeter indicates a charge rather than a discharge. What is the most appropriate immediate action?
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The METAR at your departure airport reads: KXYZ 101200Z 00000KT 1/4SM FG OVC003 M01/M01 A3002. These conditions indicate a risk of pitot tube icing. Which electrical system component should be turned on prior to takeoff?