Circuit Function

The fuel pump relay coil ground is controlled by the powertrain control module (PCM) with vehicle power (VPWR) supplied to the relay coil by the PCM power relay. Energizing the fuel pump relay closes the internal switch contacts and supplies B+ voltage through the inertia switch to the electric fuel pump. Fuel pump voltage is monitored by the PCM through the fuel pump monitor (FPM) circuit which is downstream of the inertia switch. When the ignition switch is turned on, the electric fuel pump will operate for approximately 20 seconds and will then be commanded off by the PCM if an RPM signal is not detected.

Fig 1: Identifying Central Junction Box (CJB) C270A Connector Terminals

Courtesy of FORD MOTOR CO.

Fig 2: Identifying Central Junction Box (CJB) C270F Connector Terminals

Courtesy of FORD MOTOR CO.

Fig 3: Identifying Fuel Pump Relay Connector Terminals

Courtesy of FORD MOTOR CO.

Fig 4: Identifying PCM Body Harness Connector Terminals

Courtesy of FORD MOTOR CO.

Fig 5: Identifying Inertia Switch (F-Superduty/Excursion) Connector Terminals

Courtesy of FORD MOTOR CO.

Fig 6: Identifying Inertia Switch Connector (E-Series) Terminals

Courtesy of FORD MOTOR CO.