Chart A-5: Fuel Pump Relay Circuit (Impulse)

When ignition switch is turned to ON position, ECM activates fuel pump relay to run fuel pump. ECM activates relay as long as it receives ignition reference signals or starter crank signal. If no reference signals are received by ECM within 2 seconds after ignition key is turned on, ECM turns off power to relay.

1. If fuse is blown, this test checks for short to ground on circuit No. 120. To prevent misdiagnosis, ensure fuel pump is disconnected and ignition is off before testing.
2. Determines if ECM and fuel pump relay circuit are operating correctly. ECM should turn on fuel pump relay. Since engine is not cranking or running, ECM will turn off relay within 2 seconds after ignition is turned on.

Fig 1: Fuel Pump Relay Circuit Diagram, Chart A-5 (Impulse)

Courtesy of ISUZU MOTOR CO.

Fig 2: Fuel Pump Relay Circuit Flow Chart A-5 (Impulse)

Courtesy of ISUZU MOTOR CO.