What was found
AIRCRAFT WAS GROUNDED: - EMERGENCY DECLARED; AIRCRAFT LANDED WITHOUT INCIDENT - DECESION WAS MADE TO DIVERT TO ORD. - ENG NR 1 COWL ANTI-ICE LIGHT ILLUMINATED IN FLIGHT WITH ENG NR 1 COWL ANTI-ICE SELECTED ON. PERFORMED 90-DAY HISTORY CHECK ON NR 1 ENG ANTI-ICE SYSTEM, NO PROBLEMS FOUND. FLIGHT CREW STATED NR 1 ENG ANTI ICE LIGHT ILLUMINATED DURING CLIMB AT APPROX FL20 WHEN SWITCH WAS FLIPPED TO ON AFTER 30 SECONDS. FLIGHT CREW CYCLED SWITCHED AND ASSOCIATED LIGHT EXTINGUISHED AND LIGHT NEVER RETURNED. TROUBLESHOT NR 1 ENG COWL ANTI-ICE IAW FIM 30-21-00-810-809 AND FIM 30-21-00-810-801. FAULT WAS INTERMITTENT AND DID NOT RETURN.