What was found
ON ROLLOUT MAINT LIGHT ILLUMINATED. GROUNDED - YES. ACCOMPLISHED PSU LRU REPLACEMENT TEST REF B737-9 IFIM 32-09-10. TEST FAILS & GIVES MSG 31-52002 "PSEU LEFT TRA LT53 SWITCH IS OPEN DURING TAKEOFF OR TEST" THIS MESSAGE IS ALSO DISPLAYED IN CORRELATION TO MAINT LIGHT STATUS MESSAGE. WHILE ACCOMPLISHING TEST, NOTED THERE WAS NO TAKEOFF WARNING HORN WHEN LH THROTTLE WAS ADVANCED. MOVED LH THROTTLE MULTIPLE TIMES & TAKEOFF WARNING OPERATED INTERMITTENTLY. RH TAKE OFF WARNING OPERATES NORMALLY. FOLLOWING IFIM 31-51-00-810-824, REMOVED AND REPLACED LH AUTO THROTTLE SWITCH PACK REF B737-9 AMM 76-11-07/401.