Diagnosis Procedure

FUEL PUMP


Description






The ECM activates the fuel pump for several seconds after the ignition switch is turned ON to improve engine startability. If the ECM receives a engine speed signal from the camshaft position sensor, it knows that the engine is rotating, and causes the pump to operate. If the engine speed signal is not received when the ignition switch is ON, the engine stalls. The ECM stops pump operation and prevents battery discharging, thereby improving safety. The ECM does not directly drive the fuel pump. It controls the ON/OFF fuel pump relay, which in turn controls the fuel pump.









FUEL PUMP


Diagnosis Procedure

1.CHECK FUEL PUMP POWER SUPPLY CIRCUIT-I
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Turn ignition switch ON.
4. Check the voltage between ECM harness connector and ground.





Is the inspection result normal?
YES - GO TO 4.
NO - GO TO 2.
2.CHECK FUEL PUMP POWER SUPPLY CIRCUIT-II
Check the voltage between IPDM E/R harness connector and ground.





Is the inspection result normal?
YES - GO TO 3.
NO - GO TO 10.
3.DETECT MALFUNCTIONING PART
Check the following.
- Harness connectors E3, F1
- Harness connectors F104, F105
- Harness for open or short between IPDM E/R and ECM
- Repair open circuit, short to ground or short to power in harness or connectors.
4.CHECK FUEL PUMP POWER SUPPLY CIRCUIT-II
1. Turn ignition switch OFF.
2. Reconnect all harness connectors disconnected.
3. Disconnect "fuel level sensor unit and fuel pump (main)" harness connector.
4. Turn ignition switch ON.
5. Check the voltage between "fuel level sensor unit and fuel pump (main)" harness connector and ground.





Is the inspection result normal?
YES - GO TO 8.
NO - GO TO 5.
5.CHECK 15 A FUSE
1. Turn ignition switch OFF.
2. Disconnect 15 A fuse (No. 41) from IPDM E/R.
3. Check 15 A fuse.
Is the inspection result normal?
YES - GO TO 6.
NO - Replace 15 A fuse.
6.CHECK FUEL PUMP POWER SUPPLY CIRCUIT-IV
1. Disconnect IPDM E/R harness connector E5.
2. Check the continuity between IPDM E/R harness connector and "fuel level sensor unit and fuel pump
(main)" harness connector.





3. Also check harness for short to ground and short to power.
Is the inspection result normal?
YES - GO TO 10.
NO - GO TO 7.
7.DETECT MALFUNCTIONING PART
Check the following.
- Harness connectors E121, B3
- IPDM E/R harness connector E5
- Harness for open or short between IPDM E/R and "fuel level sensor unit and fuel pump (main)"
- Repair open circuit or short to power in harness or connectors.
8.CHECK FUEL PUMP GROUND CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect dropping resistor harness connector.
3. Check the continuity between "fuel level sensor unit and fuel pump (main)" harness connector and ground.





4. Also check harness for short to power.
Is the inspection result normal?
YES - GO TO 9.
NO - Repair open circuit or short to power in harness or connectors.
9.CHECK FUEL PUMP
Refer to Component Inspection.
Is the inspection result normal?
YES - GO TO 10.
NO - Replace fuel pump.
10.CHECK INTERMITTENT INCIDENT
Refer to Intermittent Incident.
Is the inspection result normal?
YES - Replace IPDM E/R.
NO - Repair or replace harness or connectors.