Fuel Pump Control Circuit

3MZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: Fuel Pump Control Circuit

Fuel Pump Control Circuit

DESCRIPTION

The fuel pump is operated by the engine control system according to the vehicle running condition. After the engine control system receives the engine start requirement signal from the HV control system, an NE signal comes in immediately when the engine is cranked by MG1 (basically, the fuel pump can operate while the NE signal is generated).
The engine control system grounds the FC terminal line after receiving an NE signal. It causes to energize the coil in the circuit opening relay, and the current flows to the fuel pump.
When the signal to stop the engine comes from the HV control system to the engine control system, or when the fuel cut operation is performed such as decelerating by the engine brake, the fuel pump is stopped.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. PERFORM ACTIVE TEST BY TECHSTREAM (OPERATE C/OPN RELAY)
(a) Connect Techstream to the DLC3.
(b) Turn the ignition switch to the ON position and turn Techstream ON.
(c) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Fuel Pump / Speed.
(d) Check the operation of the relay while operating it using the Techstream.
OK:
Operating noise can be heard from the relay.
OK -- INSPECT FUEL PUMP
NG -- Continue to next step.
2. INSPECT ECM POWER SOURCE CIRCUIT
NG -- REPAIR OR REPLACE POWER SOURCE CIRCUIT COMPONENTS
OK -- Continue to next step.
3. INSPECT FUSE (IGCT NO. 3 FUSE)





(a) Remove the IGCT No. 3 fuse from the R/B No. 3.
(b) Measure the resistance in the IGCT No. 3 fuse.
Standard resistance:
Below 1 Ohms
NG -- CHECK FOR SHORT IN ALL HARNESS AND COMPONENTS CONNECTED TO FUSE
OK -- Continue to next step.
4. INSPECT C/OPN RELAY





(a) Remove the C/OPN relay from the engine room R/B.
(b) Measure the C/OPN relay resistance.
Standard resistance:






NG -- REPLACE C/OPN RELAY
OK -- Continue to next step.
5. INSPECT HV CONTROL ECU (FC VOLTAGE)





(a) Turn the ignition switch to the ON position.
(b) Measure the voltage between the terminals of the H34 and H31 HV control ECU connectors.
Standard voltage:






OK -- REPLACE HV CONTROL ECU
NG -- CHECK AND REPAIR HARNESS AND CONNECTOR (HV CONTROL ECU - CIRCUIT OPENING RELAY)
6. INSPECT FUEL PUMP





(a) Inspect fuel pump resistance.
(1) Measure the resistance between terminals 4 and 5.
Standard resistance:
0.2 to 3.0 Ohms at 20°C (68°F)
(b) Inspect fuel pump operation.
(1) Apply battery voltage to both the terminals. Check that the pump operates.
NOTICE:
- These tests must be done quickly (within 10 seconds) to prevent the coil from burning out.
- Keep fuel pump as far away from the battery as possible.
- Always switch at the battery side.

NG -- REPLACE FUEL PUMP
OK -- Continue to next step.
7. CHECK HARNESS AND CONNECTOR (FUEL PUMP - C/OPN RELAY)





(a) Check the harness and the connectors between the fuel pump and the C/OPN relay.
(1) Disconnect the fuel pump connector.
(2) Remove the C/OPN relay from the engine room R/B.
(3) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):






Standard resistance (Check for short):





(b) Check the harness and the connectors between the fuel pump and the body ground.
(1) Disconnect the fuel pump connector.
(2) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE C/OPN RELAY