Circuit Description

Fuel pump low and high speed is controlled by condition of engine (starting, light or heavy load). When engine starts, Tr2 circuit in ECM is off. Contact "B" in fuel pump relay closes and positive battery voltage is applied directly to fuel pump. Fuel pump operates as high speed. After engine starts, during idling or light loads, Tr2 circuit in ECM is on. Current flows to fuel pump relay coil, contact "A" closes and power is supplied to fuel pump via fuel pump resistor. Fuel pump operates at low speed. DTC is set when an open or short in fuel pump circuit is detected. Possible causes are:

• Fuel pump relay.
• Fuel pump relay open or short circuit.
• ECM.