A Line Lead Technician reports that during accomplishment of a landing gear check job card; the system-1 solenoid for the Landing Gear Extend/Retract-1 was found not being powered. No messages or indication of faults on the B777's EICAS displays. If power to the 'alternate' system 2 solenoid had also failed; the B777 landing gears would not extend or retract when selected.

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Reporter stated there were no previous in-flight incidents or inbound write-ups regarding the B777 landing gear. But during the job card check; the Main Landing Gear Selector/Bypass Valve and the Nose Gear Selector/Bypass Valve Solenoid failed to transfer to Alternate Extend/Retract after they pulled the circuit breaker (C/B) to simulate a failed 'normal' landing gear extend procedure. The purpose of the job card was to deliberately 'fail' the 'normal' mode Extend/Retract System-1 Solenoid. Gear pins were installed at the time because the B777 was sitting on the ground and they were not going to actually do a true gear swing.Reporter stated there are two solenoids involved; one for 'normal' and one for the 'alternate' mode that affect the hydraulic control valves for the retract/extension of all three landing gears. Even though the power/down-1 ground switch had faulted inside the Landing Gear Control Lever Module (M32057) in the 'normal' down position and two terminal wire pins were also found pulled from the integration panel terminal block TB3001 at the P105 panel; no messages appeared on the EICAS display or in the gear maintenance page indicating any fault had occurred.Reporter stated that if the 'alternate' system-2 solenoid were to fail and loss of electrical power to the 'normal' system-1 solenoid were to occur; without any cockpit EICAS indication or messages; as happened when they performed the landing gear job card check; then the flight crew would not be aware of of their inability to extend or retract the landing gears.