Inspection Procedure 20: Fuel Pump System
OPERATION
- The fuel pump drive power is supplied from engine control relay connector terminal to fuel pump relay (ETACS-ECU connector terminal F/PB) in the ETACS-ECU.
- The battery voltage is applied by the ignition switch to the fuel pump relay coil (ETACS-ECU connector terminal IG1) in the ETACS-ECU. The engine-ECU connector terminal FP/R turns on the relay by turning ON the power transistor in the unit so as to conduct power to the fuel pump relay coil (via the ETACS-ECU connector terminal FP/R).
- When the fuel pump relay is turned ON, the battery voltage will be supplied from the fuel pump relay (ETACS-ECU connector terminal F/P) to the fuel pump.
FUNCTION
- When the ignition switch ON signal is inputted into the engine-ECU, the engine-ECU turns ON the fuel pump relay. This causes the battery voltage to be supplied to the fuel pump.
PROBABLE CAUSES
- Failed fuel pump relay in the ETACS-ECU
- Failed fuel pump
- Open/short circuit or damage in the fuel pump drive circuit or loose connector contact.
- Failed engine-ECU
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STEP 1. Check fuel pump relay.
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- Perform continuity test in fuel pump relay (Refer to
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Q.
Is the check result normal?
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 Go to Step 2.
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 Replace the ETACS-ECU.
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STEP 2. Voltage measurement at engine-ECU connector (FP/R terminal).
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(1)Disconnect the connector, and measure at the wiring harness side.
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(3)Check the voltage between the engine-ECU connector (FP/R terminal) and body earth.
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 3.
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Repair or replace the connector(s), or check and repair the harness of short to earth, and open circuit in FP/R line engine-ECU connector and ETACS-ECU connector.
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STEP 3. Voltage measurement at ETACS-ECU connector (F/PB terminal).
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(1)Disconnect the connector, and measure at the wiring harness side.
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(3)Check the voltage between the ETACS-ECU connector (F/PB terminal) and body earth.
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 4.
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Repair or replace the connector(s), or check and repair the harness of short to earth, and open circuit in F/PB line engine control relay connector and ETACS-ECU connector.
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STEP 4. Check fuel pump operations.
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- Check fuel pump operations (Refer to ).
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Q.
Is the check result normal?
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Go to Step 5.
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Replace the fuel pump and gauge assembly.
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STEP 5. Resistance measurement at fuel pump connector (body earth line).
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Check the resistance between the fuel pump connector (body earth line) and body earth.
OK: Continuity (2 Ω or less)
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Q.
Is the check result normal?
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Go to Step 6.
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Repair or replace the connector(s), or check and repair the harness of open circuit and damage in body earth line fuel pump connector and body earth.
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STEP 6. Voltage measurement at fuel pump connector (F/P line).
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(1)Disconnect the connector, and measure at the wiring harness side.
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(3)Check the voltage between the fuel pump connector (F/P line) and body earth.
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 7.
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Repair or replace the connector(s), or check and repair the harness of short circuit to earth, and open circuit in F/P line fuel pump connector and body earth.
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STEP 7. Check of harness damage in FP/R line between engine-ECU connector and ETACS-ECU connector.
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Q.
Is the check result normal?
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Go to Step 8.
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Repair the connector(s) or wiring harness.
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STEP 8. Check of harness damage in F/PB line between engine control relay connector and ETACS-ECU connector.
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Q.
Is the check result normal?
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Go to Step 9.
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Repair the connector(s) or wiring harness.
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STEP 9. Check of harness damage in F/P line between ETACS-ECU connector and fuel pump connector.
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Q.
Is the check result normal?
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Go to Step 10.
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Repair the connector(s) or wiring harness.
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STEP 10. M.U.T.-III actuator test
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- Refer to Actuator Test Reference Table .
- Item 9: Fuel pump
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
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Replace the engine-ECU.
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