What was found
DURING THE AFTER START CHECK LIST, THE #1 ENGINE COWL VALVE OPEN LIGHT FAILED TO ILLUMINATED WHEN COWL A/I SELECTED ON. THE ENGINE #1 ENGINE & WING CONTROL CIRCUIT BREAKER WAS FOUND TRIPPED. GROUNDED - YES. VERIFIED FAULT, OPEN P18-3 AND ACCOMP GVI OF C/B (C148) & PNL NO DEFECTS NOTED. CLOSED P18-3 & CLOSED C/B. ACCOMP ENG COWL TAI VALVE TEST WITH BOTH ENGINES AT IDLE TEST PASS AND C/B (C148) STAYED CLOSED. REF B737-800 AMM 30-21-11-860-009 & AMM 20-60-01-860-801 & B737-800 WDM 30-21-11 & 30-11-11.