Chart A-5 - Fuel Pump Relay Circuit: Notes

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 is turned on, ECM cuts off power to relay.

1. This test checks for battery voltage at switching portion of fuel pump relay.
2. This determines if circuit between fuel pump relay (including fuel pump) and ground are okay.
3. This test will check relay circuit for availability of voltage to relay coil.

Fig 1: Chart A-5 - Schematic

Courtesy of ISUZU MOTOR CO.

Fig 2: Chart A-5 - Diagnostic Flowchart

Courtesy of ISUZU MOTOR CO.