What was found
THE HORIZONTAL STABILIZER TRIM FAILED TO OPERATE USING CONTROL WHEEL SWITCHES. MANUAL CONTROL WAS NORMAL. AILERON LOCKOUT AND RUDDER RATIO EICAS MESSAGE DISPLAYED. AUTOPILOT DISENGAGED AND WOULD NOT RE-ENGAGE. ACCOMPLISHED WAS REPAIRING SHORTED WIRING IN THE FIRST OFFICER’S CONTROL WHEEL AND AT BS 710. THE CAUSE OF THE FAULTY WIRE IN THE FIRST OFFICER’S CONTROL WHEEL WAS A SPLICE HAD PARTIALLY SEPARATED. THE CAUSE OF THE FAULTY WIRE AT BS 710 WAS A CEILING PANEL FASTENER SCREW PENETRATED THE WIRE.