A B737 MECHANIC REPORTS OF SIGNING OFF PAPERWORK REQUIRING AN MEL PROCEDURE THAT INCLUDED THE DISCONNECTING AND STOW OF THE #1 ENG NOSE COWL ANTI-ICE VALVE TAI PRESS SWITCH CONNECTOR; BUT WAS LATER FOUND NOT DISCONNECTED.

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#1 ENG COWL ANTI-ICE VALVE ISSUE WAS THE CAUSE FOR THE GATE CALL WHILE PERFORMING MEL SPECIAL PROCS. I FOUND HIGH STAGE VALVE LOCKOUT BOLT FROZEN. THE BOLT BROKE OFF WHILE TRYING TO LOCK OUT VALVE. WHILE I WAS REPLACING THE VALVE; MY PARTNER; MECH #2; WORKED THE COWL VALVE AND TAI CANNON PLUG. AFTER WE FINISHED THE HIGH STAGE VALVE R&R; I DID THE PAPERWORK WHILE MECH #2 CLOSED THE COWLS FOR DEP. IT SEEMS AS THOUGH MECH #2 DISCONNECTED THE WRONG CANNON PLUG AS PART OF SPECIAL PROCS AND WAS LATER DISCOVERED BY CONTRACT MAINT IN ZZZ1. ONBOARD COMPUTER UNIT HARD TO WORK WITH TO WORK SPECIAL PROCS. I'VE SEEN A COUPLE OF THESE ISSUES. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THE B737-300/500 NOSE COWL ANTI-ICE VALVES HAVE A LONGER SHAPE COMPARED TO THE NEXT GEN SERIES ACFT; BOTH OF WHICH HAVE THE CFM-56 ENGINES. THE NEXT GEN ACFT NOSE COWL VALVE HAS A SHAPE SIMILAR TO A FOOTBALL. HOWEVER; THE CONFUSION AS TO WHICH CANNON PLUG CONNECTOR TO DISCONNECT AND STOW IN ORDER TO SATISFY THEIR MEL PROCEDURE FOR THE NOSE COWL ANTI-ICE VALVE; CONTINUES. REPORTER ALSO STATED HE HOPES A RECENT MAINT ALERT BULLETIN ISSUED WITH BETTER IDENTIFICATION OF THE REQUIRED CONNECTOR TO BE DISCONNECTED REDUCES THE CONFUSION. THE CORRECT CANNON PLUG TO BE DISCONNECTED IS THE THERMAL ANTI-ICE VALVE PRESSURE SWITCH (TAI) CONNECTOR; NOT THE NOSE COWL ANTI-ICE VALVE CONNECTOR.