Fuel Pump: Description and Operation

Fuel Tank And Lines

OPERATION

Petrol

Power Distribution
Feed from the positive battery terminal (C0192) is supplied to the Engine Control Module (ECM) relay and the fuel pump relay (C0632) on an R wire. Both are located in the Battery Junction Box (BJB). Operation of the ECM relay (C0570) is controlled by the ECM (C0635) on an NU wire.

The energised ECM relay provides a feed to fuse 13E, which is also located in the BJB. Fuse 13E provides a feed to the fuel pump relay and the ECM (C0635) on a pair of NO wires. The ECM (C0635) is provided a ground path on a B wire.

Fuel Pump
Operation of the fuel pump is controlled by the ECM via the fuel pump relay. The earth path for the fuel pump relay coil (C0570) is controlled by the ECM (C0634) on a YN wire. When energised, the fuel pump relay provides a feed to fuse 1E, which is also located in the BJB. Fuse 1E (C0570) provides a feed to the fuel pump (C0114) on a WP wire (YU then WP on V6 vehicles). The fuel pump (C0114) is provided a ground path on a B wire.

Fuel Gauge
The instrument cluster (C0230) provides a feed to the fuel tank unit (C0114) on an R wire. Two resistive sensors are located within the fuel tank, one at the front and one at the rear. By measuring and taking an average of the voltage returned on a KB wire and a GB wire, the instrument cluster is able to determine how much fuel is in the tank.

The inclination of the vehicle is also taken into account when a fuel level reading is calculated. This message is supplied to the instrument cluster (C0230) via the high speed CAN bus on YN (high) and YB (low) wires.