INCORRECT CANNON PLUGS WERE DISCONNECTED ON ENGINE REVERSER FOR MEL DEFERRAL ON AN AIRBUS A300 WITH CF6-80C ENGINES.

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ACFT X; AN AIRBUS A300; ARRIVED WITH A REPEAT WRITE-UP OF THE #2 ENG HIGH PRESSURE BLEED VALVE OFF ALERT AT CRUISE. WE BEGAN WORKING ON ACFT X'S #2 ENG HIGH PRESSURE VALVE; WHICH WOULD REQUIRE 2 DIFFERENT MEL'S TO BE USED DUE TO THE THRUST REVERSER BEING PNEUMATICALLY OPERATED. WE OPENED THE #2 ENG AND SECURED THE HIGH PRESSURE VALVE CLOSED IN ACCORDANCE WITH MEL 36-11-XX AND CLOSED THE THRUST REVERSER HALVES TO PREPARE FOR THRUST REVERSER DEACTIVATION. WE BEGAN DEACTIVATING #2 THRUST REVERSER IN ACCORDANCE WITH MEL 78-30-XX BY DISCONNECTING THE 1 INCH LINE ON EACH CTR DRIVE UNIT FROM THE RIGID PNEUMATIC TUBE. WE REMOVED THE BLUE ANODIZED CAPS FROM THE UNUSED AIR SUPPLY PORT OF THE CTR DRIVE UNIT AND INSTALLED IT ON THE RIGID PNEUMATIC TUBE. THEN WE INSTALLED DUST CAPS ON THE FLEXIBLE PNEUMATIC TUBE AND ON THE OPEN AIR SUPPLY PORT ON THE LOWER END OF THE CDU. NEXT WE INSTALLED THE RED THRUST REVERSER INOP LOCKING PLATES ON EACH TRANSLATING COWL. THEN WE REMOVED THE STORED CDU LOCK-OUT COVER ON THE L AND R CDU AUX DRIVE PAD AND INSTALLED THE SQUARE DRIVE OF THE CDU LOCK-OUT COVER INTO THE AUX DRIVE UNITS. THE NEXT STEP WAS TO FIND THE DIRECTIONAL PLT VALVE AND PRESSURE SWITCH; REMOVE AND STOW THE ELECTRICAL CONNECTORS. I LOOKED AT THE MEL PICTURE FROM THE GND AND SAW 2 CANNON PLUGS AT THE 10 O'CLOCK POS THAT APPEARED TO BE THE 2 CANNON PLUGS I NEEDED TO REMOVE. I REMOVED THE CANNON PLUGS AND INSTALLED PROTECTIVE COVERS. WE CLOSED THE #2 ENG AND FINISHED THE REMAINING COCKPIT AND THRUST REVERSERS CHKS. WE CLOSED THE FAN COWL AND COMPLETED ALL PAPERWORK. WE WERE NOTIFIED ACFT X WAS RETURNING DUE TO ECAM ADVISORY ENG #2 REVERSER PRESSURIZED ALERT. I REVIEWED THE MEL AND PICTURES AND REALIZED WE HAD TAKEN THE CANNON PLUGS OFF THE CTR DRIVE UNIT INSTEAD OF THE DIRECTIONAL PLT VALVE AND PRESSURE SWITCH. WE MET THE ACFT AT THE GATE AND CORRECTED THE PROB PER MEL 78-30-XX AT WHICH TIME ACFT DEPARTED. I REGRET MY ERROR AND BELIEVE A MORE DETAILED PICTURE OF THE LOCATION OF THE DIRECTIONAL PLT VALVE AND PRESSURE SWITCH WOULD HAVE BEEN HELPFUL. ALSO; I BELIEVE THE USE OF DETAILED ELECTRICAL CONNECTORS IDENT NUMBERS WOULD HELP PREVENT THIS PROB FROM OCCURRING AGAIN. I WOULD ALSO LIKE TO SUGGEST MORE TRAINING AND ANNUAL FOLLOW-UP TRAINING FOR THE TECHNICIAN TO STAY CURRENT ON SUCH ISSUES. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATES CAPPING OF THE AIR SUPPLY LINE CREATES AN AIR PRESSURE DIFFERENTIAL WHEN THE THROTTLES ARE PUSHED FWD EVEN SLIGHTLY. THIS DIFFERENCE IS NOTED BY THE PRESSURE SWITCH AND THE 'REVERSER PRESSURE LIGHT' WILL ILLUMINATE. THE MEL PICTURE AND WORDING IS DIFFERENT FROM THE AMM FOR THE REVERSER DEACTIVATION PROCEDURE. THAT IS NOW CHANGING. THE MEL WILL REFLECT THE AMM PROCEDURE. NEW DIAGRAMS AND PICTURES SHOWING THE 'DUMMY' PLUGS' LOCATION ARE BEING ISSUED. REPORTER ALSO STATES ONLY ONE CONNECTOR NEEDS TO BE DISCONNECTED ON THE MD-11 REVERSER FOR A SIMILAR TYPE CF-6 ENGINE COMPARED TO THE A300 WITH CF-6 ENGINES WHICH REQUIRE TWO CONNECTORS TO BE STOWED.