A Line Mechanic reports deferring a flight crew write-up about not getting an ECAM display: CIRCUIT BREAKER TRIPPED REAR PNL warning on an A320. Maintenance Controller advised him to use MEL 74-31-03; even though that MEL only states that an ECAM caution ignition fault may be inoperative.

Narrative

An A320 aircraft already had ignition system 'B' deferred; on #1 engine. Crew reported not getting an ECAM warning that: CIRCUIT BREAKER TRIPPED REAR PNL (PANEL). I deferred this discrepancy per MEL 74-31-03; per our Maintenance Control. This MEL states that an ECAM caution ignition fault may be inoperative. After reading the MEL again; I am still not sure whether it could be used to cover the tripped circuit breaker warning on the ECAM; since the circuit breaker is part of the ignition system. I suppose it is only for the ignition fault ECAM warning. However; not getting the CIRCUIT BREAKER TRIPPED REAR PNL ECAM warning for that specific ignition system circuit breaker; is also a fault of that part of the ignition system; meaning the circuit breaker of the ignition system [that was] already deferred; was faulty. I pulled the other ignition system circuit breakers; one at a time; to verify that they gave the ECAM warning: CIRCUIT BREAKER TRIPPED REAR PNL and then reset them. Perhaps an MEL that addresses the ECAM warning: CIRCUIT BREAKER TRIPPED REAR PNL being inoperative; for a system that is already deferred and inoperative with the circuit breaker pulled and collared; would alleviate this issue. I cannot see any reason that the circuit breaker tripped warning needs to work for a specific system that is deactivated and the circuit breaker pulled and collared. In the future; I will do my best to make my own decisions regarding applicability of an MEL and not let a Maintenance Controller misguide me. I am sure though that he did not see a problem with using the MEL as applied.