What was found
DURING APPROACH IN ICING CONDITIONS MASTER CAUTION LIGHT WITH ANTI-ICE CAUTION ILLUMINATION, EXTINGUISHED 2 SECONDS LATER, UNABLE TO DETERMINE WHICH SYSTEM CAUSED LIGHT. GROUNDED - YES. PERFORMED INSTALLATION TEST OF WINDOW/ PITOT HEAT MODULE (P5-9) IN REFERENCE WITH AMM 30-00-02-400-801, OPS TEST GOOD. NO HISTORY ATA 30 LAST 90 DAYS.