3Uz-Fe Engine Control System. Sfi System Fuel Pump Control Circuit

When the engine is cranked, a signal is sent from the power source control ECU's STSW terminal to the ECM's STSW terminal. Then voltage travels from the ECM's STAR terminal through the park/neutral position switch to the STARTER relay coil. The STAR terminal also sends a signal to the STA terminal. When the STA signal and NE signal are input to the ECM, the ECM interior's Tr1 turns on, which causes power to be supplied to the C/OPN relay coil (C/OPN on). As a result, the F/PMP relay actuates, which causes the fuel pump to operate. If the engine is operating and NE signals are being output, the ECM interior's Tr1 is on (C/OPN on), and the fuel pump will continue operating. The fuel pump has a high and low speed setting. When the engine is starting or operating with a heavy load, the ECM interior's Tr2 turns on to actuate the F/PMP relay so that the fuel pump operates at the high speed setting. When the engine is idling or operating with a light load, the Tr2 turns off, and current flows through the fuel pump resistor to the fuel pump so that the fuel pump operates at the low speed setting.

Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System.Sfi System Fuel Pump Control Circuit

WIRING DIAGRAM

This troubleshooting procedure is based on the premise that the engine is started. If the engine is not started, proceed to the problem symptoms table (Click here).

INSPECTION PROCEDURE

1.CHECK FUEL PUMP OPERATION

Check if there is pressure in the fuel inlet hose.
HINT:
If there is fuel pressure, you will hear the sound of fuel flowing.

Go to step 12

NG

2.PERFORM ACTIVE TEST (OPERATE C/OPN RELAY)

Connect the intelligent tester to the DLC3.

Turn the engine switch on (IG) and turn the intelligent tester ON.

Enter the following menus: Powertrain / Engine / Active Test / Active the Fuel Pump / Speed.

Check the relay operation while operating it using the intelligent tester.
OK:
Operating noise can be heard from the relay.

Go to step 8

NG

3.INSPECT ECM POWER SOURCE CIRCUIT

CHECK ENGINE TO DETERMINE CAUSE OF LOW COMPRESSION

OK

4.INSPECT FUSE (F/PUMP)

Remove the F/PUMP fuse from the engine room No. 2 junction block.

Measure the resistance of the fuse.
Standard resistance:
Below 1 Ω

REPLACE FUSE

OK

5.INSPECT INTEGRATION RELAY (Marking: EFI NO. 2)

Remove the integration relay from the engine room No. 2 junction block.

Measure the resistance of the EFI NO. 2 relay.
Standard resistance:
Terminal Connections
Specified Condition
2B-8 - 2C-1
10 kΩ or higher
2B-8 - 2C-1
Below 1 Ω
(when battery voltage is applied to terminals 2A-8 and 2B-3)

REPLACE INTEGRATION RELAY

OK

6.INSPECT INTEGRATION RELAY (Marking: C/OPN)

Remove the integration relay from the engine room No. 2 junction block.

Measure the resistance of the C/OPN relay.
Standard resistance:
Terminal Connections
Specified Condition
2B-8 - 2C-1
10 kΩ or higher
2B-8 - 2C-1
Below 1 Ω
(when battery voltage is applied to terminals 2B-7 and 2C-1)

REPLACE INTEGRATION RELAY

OK

7.CHECK ECM (FC VOLTAGE)

Turn the engine switch on (IG).

Measure the voltage of the ECM connector.
Standard voltage:
Tester Connection
Specified Condition
A6-14 (FC) - E7-7 (E1)
9 to 14 V

REPLACE ECM

REPAIR OR REPLACE HARNESS AND CONNECTOR (ECM - C/OPN RELAY)

8.INSPECT RELAY (Marking: F/PMP)

Remove the F/PMP relay from the engine room No. 2 relay block.

Measure the resistance of the relay.
Standard resistance:
Tester Connection
Specified Condition
3 - 4
Below 1 Ω
3 - 4
10 kΩ or more
(when battery voltage is applied to terminals 1 and 2)

REPLACE RELAY

OK

9.INSPECT FUEL PUMP

Check the resistance of the fuel pump.
1. Measure the resistance between terminals 4 and 5.
  Standard resistance:
  0.2 to 3.0 Ω at 20°C (68°F)

Check operation of the fuel pump.
1. Apply battery voltage to both terminals. Check that the pump operates.
  NOTICE:
  1. These tests must be done quickly (within 10 seconds) to prevent the coil from burning out.
  2. Keep fuel pump as far away from the battery as possible.
  3. Always turn the voltage on and off on the battery side, not the fuel pump side.

REPLACE FUEL PUMP

OK

10.CHECK WIRE HARNESS (FUEL PUMP - F/PMP RELAY, FUEL PUMP - BODY GROUND)

Check the wire harness between the fuel pump and F/PMP relay.
1. Disconnect the W11 fuel pump connector.
2. Remove the F/PMP relay from the engine room No. 2 relay block.
3. Measure the resistance of the wire harness side connectors.
  Standard resistance:
  Tester Connection
  Specified Condition
  W11-4 - Relay block F/PMP relay terminal 4
  Below 1 Ω
  W11-4 or relay block F/PMP relay terminal 4 - Body ground
  10 kΩ or higher

Check the wire harness between the fuel pump and body ground.
1. Disconnect the W11 fuel pump connector.
2. Measure the resistance of the wire harness side connector.
  Standard resistance:
  Tester Connection
  Specified Condition
  W11-4 - Body ground
  Below 1 Ω

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK

11.CHECK WIRE HARNESS (INTEGRATION RELAY - FUEL PUMP RELAY)

Remove the integration relay from the engine room No. 2 junction block.

Remove the F/PMP relay from the engine room No. 2 relay block.

Measure the resistance of the wire harness side connectors.

Standard resistance:

Tester Connection	Specified Condition
2B-8 - Relay block F/PMP relay terminal 1	Below 1 Ω
2B-8 - Relay block F/PMP relay terminal 3	Below 1 Ω
2B-8 or relay block F/PMP relay terminal 1 - Body ground	10 kΩ or higher
2B-8 or relay block F/PMP relay terminal 3 - Body ground	10 kΩ or higher

REPAIR OR REPLACE HARNESS AND CONNECTOR

REPLACE INTEGRATION RELAY

12.INSPECT RELAY (Marking: F/PMP)

Remove the F/PMP relay from the engine room No. 2 relay block.

Measure the resistance of the relay.
Standard resistance:
Tester Connection
Specified Condition
3 - 4
Below 1 Ω
3 - 4
10 kΩ or higher
(when battery voltage is applied to terminals 1 and 2)

REPLACE RELAY

OK

13.INSPECT FUEL PUMP RESISTOR

Measure the resistance of the fuel pump resistor.
Standard resistance:
0.30 to 0.34 Ω at 20°C (68°F)

REPLACE FUEL PUMP RESISTOR

OK

14.CHECK WIRE HARNESS (F/PMP RELAY - FUEL PUMP RESISTOR)

Remove the F/PMP relay from the engine room No. 2 relay block.

Disconnect the A25 fuel pump resistor connector.

Measure the resistance of the wire harness side connectors.

Standard resistance:

Tester Connection	Specified Condition
Relay block F/PMP relay terminal 4 - A25-2	Below 1 Ω
Relay block F/PMP relay terminal 3 - A25-1	Below 1 Ω
Relay block F/PMP relay terminal 4 or A25-2 - Body ground	10 kΩ or higher
Relay block F/PMP relay terminal 3 or A25-1 - Body ground	10 kΩ or higher

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS TABLE

REPAIR OR REPLACE HARNESS AND CONNECTOR

Terminal Connections	Specified Condition
2B-8 - 2C-1	10 kΩ or higher
2B-8 - 2C-1	Below 1 Ω (when battery voltage is applied to terminals 2A-8 and 2B-3)

Tester Connection	Specified Condition
A6-14 (FC) - E7-7 (E1)	9 to 14 V

Tester Connection	Specified Condition
3 - 4	Below 1 Ω
3 - 4	10 kΩ or more (when battery voltage is applied to terminals 1 and 2)

Tester Connection	Specified Condition
W11-4 - Relay block F/PMP relay terminal 4	Below 1 Ω
W11-4 or relay block F/PMP relay terminal 4 - Body ground	10 kΩ or higher

Tester Connection	Specified Condition
W11-4 - Body ground	Below 1 Ω