What was found
AUTOTHROTTLE WILL NOT ENGAGE. GROUNDED - YES. PERFORMED A/T BITE AND SYSTEM TEST REF B737-800 AMM 22-31-00-710-802. BITE REVEALED FAULTS ON LEGS 1 AND 2, "A/T ENG 28 VDC INV" - MTX MSG - 22-31543, OCCURRED MULTIPLE TIMES ON BOTH LEGS. ALL TESTS PASS. THROTTLES MOVE SMOOTHLY AND WITHIN TORQUE RANGE. A/T ARM AND DISENGAGE TEST PASSES, NO FAULTS. CHECKS GOOD WITH EVERY METHOD. A/C OK FOR SERVICE. IN ADDITION, PERFORMED DFCS BITE IAW AMM 22-11-00-740-806. NO FAULTS PRESENT IN FAULT REVIEW. LRU REPLACE TEST FOR FCC IAW AMM 22-11-00-740-815, TEST PASSES.