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Inspection Procedure 12: Fuel Pump System
 
 
 
 
CIRCUIT OPERATION
  • The fuel pump relay is built into the IPDM E/R.
  • The ECM connector terminal number 103 turns ON the relay by turning ON the power transistor in the unit so as to conduct power to the fuel pump relay coil.
  • When the fuel pump relay is turned ON, the 12V battery voltage will be supplied from the fuel pump relay to the fuel pump.
 
 
COMMENT
When the power supply mode of the electric motor switch ON signal is inputted into the ECM, the ECM turns ON the fuel pump relay. This causes the 12V battery voltage to be supplied to the fuel pump.
 
 
TROUBLESHOOTING HINTS (The most likely causes for this case:)
  • IPDM E/R failed.
  • Fuel pump relay failed.
  • Fuel pump failed.
  • Open or shorted fuel pump circuit, harness damage or connector damage.
  • ECM failed.
 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite main harness A
  • MB992747: V.C.I.-Lite USB cable short
  • MB992748: V.C.I.-Lite USB cable long
1.STEP 1. Using scan tool (M.U.T.-III SE), read the other system DTC.
Use scan tool (M.U.T.-III SE) to check and see if a DTC is set in the IPDM E/R [Refer to ELECTRICAL & POWER CONTROL, Power Control System – IPDM E/R – System Description – Diagnosis System (IPDM E/R) M.U.T.-III SE Function (IPDM E/R)].
Q: Is any DTC set in the IPDM E/R?
Perform troubleshooting of IPDM E/R system (Refer to ELECTRICAL & POWER CONTROL, Power Control System – IPDM E/R – System Description – Diagnosis System (IPDM E/R) M.U.T.-III SE Function (IPDM E/R)).
 
2.STEP 2. Perform voltage measurement at ECM connector terminal number 103.
  • Disconnect connector, and measure at harness side.
  • Power supply mode of electric motor switch: ON
  • Voltage between ECM connector terminal number 103 and ground.
OK: 12V battery positive voltage
Q: Is the check result normal?
Repair the wiring harness between IPDM E/R connector terminal number 76 and ECM connector terminal number 103.
 
3.STEP 3. Check fuel pump operations
Fuel pump connector check (Refer to FUEL PUMP OPERATION CHECK).
Q: Is the check result normal?
Replace the fuel pump assembly. (Refer to ENGINE, Fuel Supply – Fuel Tank – On-vehicles Service FUEL PUMP MODULE REPLACEMENT and Refer to ENGINE, Fuel Supply – Fuel Tank – Fuel Tank Pump and Gauge Assembly and FUEL PUMP MODULE DISASSEMBLY AND ASSEMBLY).
 
4.STEP 4. Perform resistance measurement at fuel tank pump and gauge assembly connector terminal number 4.
  • Disconnect connector, and measure at harness side.
  • Resistance between fuel tank pump and gauge assembly connector terminal number 4 and ground.
OK: Continuity (2 ohms or less)
Q: Is the check result normal?
Repair the ground line between the fuel tank pump and gauge assembly connector terminal number 4 and ground.
 
5.STEP 5. Perform voltage measurement at fuel tank pump and gauge assembly connector terminal number 5.
  • Disconnect connector, and measure at harness side.
  • Set the vehicle to the continuous idling mode (Refer to GENERAL INFORMATION, General Information – Precautions CONTINUOUS IDLING MODE).
  • Voltage between fuel tank pump and gauge assembly connector terminal number 5 and ground.
OK: 12V battery positive voltage
Q: Is the check result normal?
Repair the wiring harness between IPDM E/R connector terminal number 46 and fuel tank pump and gauge assembly connector terminal number 5.
 
6.STEP 6. Check of damage in wiring harness between IPDM E/R connector terminal number 76 and ECM connector terminal number 103.
Q: Is the check result normal?
Repair or replace the connector, or repair the damaged harness wire.
 
7.STEP 7. Check of damage in wiring harness between IPDM E/R connector terminal number 46 and fuel tank pump and gauge assembly connector terminal number 5.
Q: Is the check result normal?
Repair or replace the connector, or repair the damaged harness wire.
 
8.STEP 8. Using scan tool (M.U.T.-IIISE), perform the actuator test.
Use scan tool (M.U.T.-III SE) to perform the actuator test (Refer to ACTUATOR TEST REFERENCE TABLE).
  • Item number 20: Fuel Pump
OK: Fuel tank pump operation sound can be heard.
Q: Is the check result normal?
Replace the ECM (Refer to ENGINE CONTROL MODULE (ECM) REMOVAL AND INSTALLATION).
 
9.STEP 9. Check the malfunction symptoms.
Q: Does the malfunction symptom persist?
Replace the ECM (Refer to ENGINE CONTROL MODULE (ECM) REMOVAL AND INSTALLATION).
Intermittent malfunction (Refer to GENERAL INFORMATION, General Information – How to Use Troubleshooting/Inspection Service Points HOW TO COPE WITH INTERMITTENT MALFUNCTIONS).