Code No. P0204: No. 4 Injector System


OPERATION



  • Power is supplied to the injector (terminal No. 1) from the injector relay (terminal No. 3).
  • The engine-ECU (terminal No. 19) makes the power transistor in the unit be in ON position, and that makes currents go on the injector (terminal No. 2).

FUNCTION



  • The engine-ECU controls the power supply interval of the injector.
  • The fuel injection amount of the injector depends on the power supply interval.

TROUBLE JUDGMENT


Check Conditions
  • The engine speed is less than 1,000 r/min.
  • Not during the fuel cut and the forced injector-driving (actuator test).
  • Throttle position sensor (main) output is less than 1.0 V.
Judgement Criterion
  • Surge voltage of injector coil is not detected for 2 seconds.

FAIL-SAFE AND BACKUP FUNCTION



  • None

PROBABLE CAUSES



  • Failed No. 4 injector
  • Open/short circuit or harness damage in No. 4 injector circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III actuator test

  • Item 1: No. 4 injector
OK: Idling state varies.

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Go to Step 2 .

STEP 2. Connector check: B-106 No. 4 injector connector

Q. Is the check result normal?
Go to Step 3 .
Repair or replace the connector.

STEP 3. Check No. 4 injector itself.

  • Injector check (Refer to ).

Q. Is the check result normal?
Go to Step 4 .
Replace the No. 4 injector.

STEP 4. Perform voltage measurement at B-106 No. 4 injector connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 1 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 6 .
Go to Step 5 .

STEP 5. Connector check: A-70X injector relay connector

Q. Is the check result normal?

    Check intermediate connector A-17, and repair if necessary. If intermediate connector is normal, check and repair harness between A-70X (terminal No. 3) injector relay connector and B-106 (terminal No. 1) No. 4 injector connector.

    • Check power supply line for open/short circuit.
Repair or replace the connector.

STEP 6. Connector check: A-70X injector relay connector

Q. Is the check result normal?
Go to Step 7 .
Repair or replace the connector.

STEP 7. Check injector relay itself.

  • Injector relay continuity check (Refer to ).

Q. Is the check result normal?
Go to Step 8 .
Replace the injector relay.

STEP 8. Connector check: A-37X engine control relay connector

Q. Is the check result normal?
Go to Step 9 .
Repair or replace the connector.

STEP 9. Check harness between A-37X (terminal No. 2) engine control relay connector and A-70X (terminal No. 4) injector relay connector.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 10 .
Repair the damaged harness wire.

STEP 10. Check harness between A-70X (terminal No. 3) injector relay connector and B-106 (terminal No. 1) No. 4 injector connector.
note Before checking harness, check intermediate connector A-17, and repair if necessary.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 11 .
Repair the damaged harness wire.

STEP 11. Connector check: B-26 engine-ECU connector

Q. Is the check result normal?
Go to Step 12 .
Repair or replace the connector.

STEP 12. Check harness between B-106 (terminal No. 2) No. 4 injector connector and B-26 (terminal No. 19) engine-ECU connector.

  • Check output line for open/short circuit and damage.

Q. Is the check result normal?
Go to Step 13 .
Repair the damaged harness wire.

STEP 13. Perform signal wave pattern measurement at B-26 engine-ECU connector (Using an oscilloscope).

  • Disconnect engine-ECU connector, and connect special tool power plant ECU check harness (MB992110) to measure at connector for inspection.
  • Engine: Idling
  • Transmission: Neutral
  • Voltage between terminal No. 19 and earth.
OK: Waveforms should be displayed on inspection procedure using an oscilloscope (Refer to ).

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Replace the engine-ECU.