Civic L4-1.7L CNG (2003)
Main Relay (Computer/Fuel System): Description and Operation
PGM-FI Main Relay 1 and 2
The PGM-FI relay consists of two separate relays. PGM-FI main relay 1 is energized whenever the ignition switch is ON (II). It supplies battery voltage
to the PCM, powers injectors, and powers PGM-FI main relay 2. PGM-FI main relay 2 is energized to supply power to the fuel pressure regulator
shut-off solenoid valve/fuel tank internal solenoid valve for 2 seconds when the ignition switch is turned ON (II), and when the engine is running.