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Fuel Pump Circuit Tests

  1. Check Fuel Pump Operation In D-CHECK Mode  - Connect test mode terminal. Turn ignition on. Ensure there is proper fuel pump operation. If fuel pump does not operate properly, go to next step. If fuel pump operates properly, see SVX under FUEL INJECTOR CIRCUIT TESTS.
  2. Check Fuel Pump Relay  - Disconnect fuel pump relay connector and remove fuel pump relay from bracket. Ensure there is 70 ohms of resistance between fuel pump relay terminals No. 1 and 3. See appropriate wiring diagram in the WIRING DIAGRAMS article. Replace fuel pump relay if resistance is not as specified. If resistance is okay, connect positive battery voltage to terminal No. 3 and ground to terminal No. 1. If fuel pump relay does not click, replace it. If fuel pump relay clicks, verify zero ohms resistance between terminals No. 2 and 4. If there is zero ohms resistance, go to next step. If resistance is not zero ohms, replace fuel pump relay.
  3. Check Power Supply To Fuel Pump Relay  - Turn ignition off and connect fuel pump relay. Turn ignition on and check voltage between fuel pump relay connector terminal No. 3 and ground. If at least 10 volts are present, go to next step. If at least 10 volts are not present, repair harness or connectors as necessary.
  4. Check Input Signal For ECM  - Turn ignition on. Ensure there are at least 10 volts between ECM 26-pin connector terminal No. 23 and ground. See appropriate wiring diagram in WIRING DIAGRAMS article. Crank engine while measuring voltage. Ensure there is zero voltage between ECM 26-pin connector terminal No. 23 and ground. If voltage is not as specified, go to next step. If voltage is as specified, go to step 6).
  5. Check Harness Connector Between ECM & Fuel Pump  - Turn ignition off. Disconnect ECM 26-pin harness connector and fuel pump relay 4-pin harness connector. Ensure there is zero ohms resistance between ECM connector terminal No. 23 and fuel pump relay connector terminal No. 3. Ensure there is at least one ohm resistance between fuel pump relay terminal No. 3 and ground. If resistance is not as specified, repair harness or connectors as necessary. If resistance is as specified, inspect ECM connector terminal and repair as necessary. If ECM connector is okay, replace ECM.
  6. Check Voltage For Fuel Pump  - Fold down rear seatback and turn up floor mat. Remove fuel pump access hole cover. Disconnect fuel pump connector. Ensure there is at least 10 volts between fuel pump connector terminal No. 1 and ground. If at least 10 volts are present, go to next step. If at least 10 volts are not present, repair harness or connectors between fuel pump relay and fuel pump as necessary.
  7. Check Fuel Pump Operation  - Connect battery voltage to fuel pump connector terminal No. 1 and ground terminal No. 4. If fuel pump operates, repair or replace harness connector fuel pump ground circuit. If fuel pump does not operate, replace fuel pump.
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