Sfi System Fuel Pump Control Circuit
DESCRIPTION
WIRING DIAGRAM
INSPECTION PROCEDURE
PERFORM ACTIVE TEST USING INTELLIGENT TESTER (OPERATE C/OPN RELAY)
CHECK ECM POWER SOURCE CIRCUIT
INSPECT ENGINE ROOM J/B (C/OPN RELAY)
INSPECT ECM (FC VOLTAGE)
INSPECT FUEL PUMP
CHECK HARNESS AND CONNECTOR (C/OPN RELAY - FUEL PUMP - BODY GROUND)
SFI SYSTEM - Fuel Pump Control Circuit |
DESCRIPTION
In the diagram below, when the engine is cranked, current flows from terminal ST1 (STR) of the ignition switch (power source control ECU) to the starter relay (Marking: ST) coil and also current flows to terminal STA of ECM (STA signal).When the STA signal and NE signal are input to the ECM, Tr is turned ON, current flows to coil of the circuit opening relay (Marking: C/OPN), the relay switches on, power is supplied to the fuel pump and the fuel pump operates.While the NE signal is generated (engine running), the ECM keeps Tr ON (circuit opening relay ON) and the fuel pump also keeps operating.
WIRING DIAGRAM
INSPECTION PROCEDURE
1.PERFORM ACTIVE TEST USING INTELLIGENT TESTER (OPERATE C/OPN RELAY) |
Connect the intelligent tester to the DLC3.
Turn the ignition switch to the ON position and turn the tester on.
Select the following menu items: Powertrain / Engine and ECT / Active Test / Control the Fuel Pump / Speed.
Check whether the fuel pump operation sound occurs when performing the Active Test on the tester.
- OK:
- Fuel pump operating sound occurs.
OK |
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PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE |
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2.CHECK ECM POWER SOURCE CIRCUIT |
| REPAIR OR REPLACE ECM POWER SOURCE CIRCUIT |
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3.INSPECT ENGINE ROOM J/B (C/OPN RELAY) |
Remove the engine room J/B from the engine room R/B.
Inspect the C/OPN relay.
Measure the C/OPN relay resistance.
- Standard resistance:
Tester Connection
| Specified Condition
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1E-7 - 1E-13
| 10 kΩ or higher
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Below 1 Ω (Apply battery voltage between terminals 1D-12 and 1E-8)
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Reinstall the engine room J/B.
4.INSPECT ECM (FC VOLTAGE) |
Disconnect the A24 and C24 ECM connectors.
Turn the ignition switch to the ON position.
Measure the voltage between the terminals of the A24 and C24 ECM connectors.
- Standard voltage:
Tester Connection
| Specified Condition
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FC (A24-7) - E1 (C24-104)
| 9 to 14 V
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Reconnect the ECM connectors.
| REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - BATTERY) |
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6.CHECK HARNESS AND CONNECTOR (C/OPN RELAY - FUEL PUMP - BODY GROUND) |
Check the harness and the connectors between the engine room J/B and the fuel pump.
Remove the engine room J/B from the engine room R/B.
Disconnect the 1E engine room J/B connector.
Disconnect the N10 fuel pump connector.
Measure the resistance between the terminals.
- Standard resistance (Check for open):
Tester Connection
| Specified Condition
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1E-13 - Fuel pump (N10-4)
| Below 1 Ω
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- Standard resistance (Check for short):
Tester Connection
| Specified Condition
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1E-13 or Fuel pump (N10-4) - Body ground
| 10 kΩ or higher
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Check the harness and the connectors between the fuel pump and body ground.
Disconnect the N10 fuel pump connector.
Measure the resistance between the terminals.
- Standard resistance (Check for open):
Tester Connection
| Specified Condition
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Fuel pump (N10-5) - Body ground
| Below 1 Ω
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Reconnect the fuel pump connector.
Reconnect the engine room J/B connector.
Reinstall the engine room J/B.
| REPAIR OR REPLACE HARNESS OR CONNECTOR |
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