What was found
APU FIRE TEST INOP. REMOVED AND REPLACED APU TEST SWITCH S451, NO HELP. RAN WIRES AND FOUND B1 ON S455 GOING TO PIN 1 ON R197, SHOULD BE GOING TO PIN 5. FOUND B2 ON S455 GOING TO PIN 5, SHOULD BE GOING TO PIN 1 SUSPECT BAD RELAY R197 OR ASSY PN. REMOVED AND REPLACED APU POWER UNIT AND FIRE TEST RELAY IAW B727 WDM 49-41-01. OPERATIONAL TEST SERVICEABLE. APU FIRE TEST INOP, SWAPPED APU CONTROL PANEL IAW BMM REF 49-00, NO HELP. SWAPPED APU FIRE TEST BOX IAW BMM REF 49-00, NO HELP. DMI 8108 REMAINS OPEN.