Possible cause

Connector terminal disconnection, poor contact, damage, deformation, corrosion
Open circuit in wiring harness between connectors C-55, C-56 and connector C-21
Open circuit in wiring harness between connector C-21 and connector C-07
Open circuit in wiring harness between connector C-07 and branch A
Connectors C-55, C-56 malfunction
Connector C-21 malfunction
Connector C-07 malfunction