What was found
ON FLIGHT 2219 DURING DESCENT WITH BOTH POWER LEVERS AT FLIGHT IDLE, THE DE-ICE PRESSURE CAUTION LIGHT ILLUMINATED. AS POWER WAS ADVANCED CAUTION LIGHT WOULD EXTINGUISH. THIS OCCURED WEATHER FAST OR SLOW CYCLE WAS SELECTED AND ALSO AFTER ISO VALVE WAS SELECTED TO ISO AS PER THE CHECKLIST. PRESSURE ON BOTH NEEDLES ON THE DE-ICE PRESSURE GUAGE WAS 10 PSI AT FLIGHT IDLE. COMPLIED WITH AMM TASK 30-10-00-710-801. NO PARTS REPLACED. OPERATIONAL CHECKS GOOD. AIRCRAFT RETURNED TO SERVICE.