A B737-700 CAPT RPTS CONFLICT BTWN FOM MASTER CAUTION LIGHT TEST AND ACTUAL TEST OF CAUTION LIGHT SYS.

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REF FOM 3.1.17/18. THIS SECTION SAYS THAT IT IS NOT NECESSARY FOR ALL OF THE 'SCOREBOARD' LIGHTS TO ILLUMINATE FOR A SUCCESSFUL TEST OF THE MASTER CAUTION LIGHTS. I HAVE FOUND THIS TO BE INCORRECT. I HAVE FOUND THAT ON SEVERAL OF OUR ACFT; IF YOU PERFORM A RECALL TEST OF THE SYS AND THE OPPOSITE SIDE 'SCOREBOARD' IS NOT FULLY ENGAGED IN PLACE (AS OFTEN HAPPENS WHEN A PLT TESTS THE SYS AND ALLOWS THE LIGHT PANEL TO SNAP BACK AFTER THE TEST); THEN THE MASTER CAUTION ANNUNCIATOR LIGHT DOES NOT ILLUMINATE EVEN THOUGH AN OVERHEAD SYS LIGHT IS ON. THIS COULD LEAD TO THE UNLIKELY; BUT POSSIBLE; SCENARIO OF A FLT CREW BEING UNAWARE OF A SYS MALFUNCTION. FOR EXAMPLE: IF A HYD PUMP 'LOW PRESSURE' LIGHT IS ILLUMINATED ON THE OVERHEAD PANEL AND THE FO SIDE SCOREBOARD IS UNSEATED FAR ENOUGH THAT THE HYD LIGHT WILL NOT ILLUMINATE; THEN DEPRESSING THE CAPT SIDE SCOREBOARD TO PERFORM THE RECALL TEST DOES NOT ILLUMINATE THE YELLOW 'MASTER CAUTION' LIGHT. I HAVE FOUND THIS TO BE TRUE ON THE FOLLOWING ACFT (8 ACFT NUMBERS). MY UNSCIENTIFIC TESTING SEEMS TO SHOW THAT THIS IS TRUE ON ABOUT 20-25% OF OUR FLEET. I BELIEVE THAT THE FOM SHOULD BE CHANGED TO EMPHASIZE THAT WHEN A RECALL TEST IS PERFORMED THAT ALL OF THE SCOREBOARD AS WELL AS THE MASTER CAUTION LIGHTS SHOULD ILLUMINATE THEN EXTINGUISH.