ECD SYSTEM Pre-heating Control Circuit

DESCRIPTION

The glow plug assembly is mounted inside the engine combustion chamber. To ensure efficient engine starting with a cold engine, the ECM calculates a time interval of the current that needs to flow through the glow plug depending on the starting engine coolant temperature when the ignition switch is turned to ON. The ECM then turns on the glow plug relay assembly and permits the current to flow through the glow plug based on the ECM's calculated time. The glow plug relay assembly is then heated, which enhances fuel combustion with a cold engine.

A01CH03E08

Tech Tips


  • These troubleshooting procedures are for: 1) difficult engine starting in cold weather, and 2) difficult driving/vehicle malfunctions in cold weather immediately after the engine is started.

  • After the engine is started, the ECM performs an "after-glow" for a certain period of time. In proportion to the actual engine coolant temperature, the time period varies. The after-glow reduces diesel engine knocking, white smoke emissions and engine noises when the engine is cold.

A01CHJ3E01

WIRING DIAGRAM

Refer to DTC P0115 Click here.

A01CHZTE01

INSPECTION PROCEDURE

Note

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE


  1. CHECK GLOW INDICATOR LIGHT (ILLUMINATED)


    1. Turn the ignition switch to ON.

    2. Check if the glow indicator is illuminated.

      OK
      Glow indicator light is illuminated for 0.5 seconds or more.

    NG

    CHECK ECM (GIND VOLTAGE) Click here

    OK

  2. CHECK GLOW INDICATOR LIGHT (ILLUMINATED TIME)


    1. Turn the ignition switch to ON.

    2. Check the period that the glow indicator light is illuminated.

      A01CGWIE01
      OK
      The glow indicator light is illuminated according to the engine coolant temperature as shown in the graph.

      Tech Tips

      Glow plug operation varies depending on the engine coolant temperature.


    NG

    INSPECT ENGINE COOLANT TEMPERATURE SENSOR Click here

    OK

  3. CHECK ECM (SREL VOLTAGE)


    1. A01CHEQE86
      Text in Illustration
      *a

      Component with harness connected

      (ECM)

      Start the engine.

    2. Measure the voltage according to the value(s) in the table below.

      A01CJ4JE01
      Standard Voltage
      Tester Connection Condition Specified Condition
      E36-19 (SREL) - Body ground Engine idling and after glow on 18 to 27 V
      E36-19 (SREL) - Body ground Engine idling and after glow off 0 to 2 V
      OK
      The after-glow operated according to the engine coolant temperature as shown in the graph.

      Tech Tips

      After-glow operation varies depending on the engine coolant temperature.


    NG

    INSPECT ENGINE COOLANT TEMPERATURE SENSOR Click here

    OK

  4. INSPECT GLOW PLUG RELAY ASSEMBLY


    1. A01CHXLE01
      Text in Illustration
      *1

      Component without harness connected

      (Glow Plug Relay Assembly)

      Remove the glow plug relay assembly from the engine room relay block and junction block.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      3 - 5 No battery voltage applied to terminals 1 and 2 10 kΩ or higher
      3 - 5 Battery voltage applied to terminals 1 and 2 Below 1 Ω

    3. Reinstall the glow plug relay assembly.


    NG

    REPLACE GLOW PLUG RELAY ASSEMBLY

    OK

  5. INSPECT GLOW PLUG ASSEMBLY


    1. A01CINKE02
      Text in Illustration
      *1

      Component without harness connected

      (Glow Plug Assembly)

      Remove the glow plug assembly.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      Glow plug terminal - Body ground 20°C (68°F) 2.7 to 3.5 Ω

    3. Reinstall the glow plug assembly.


    NG

    REPLACE GLOW PLUG ASSEMBLY Click here

    OK

  6. CHECK GLOW PLUG ASSEMBLY (INSTALLATION)


    1. Check the glow plug assembly installation Click here.

      OK
      The glow plug assemblies are installed securely.

    NG

    SECURELY REINSTALL GLOW PLUG ASSEMBLY Click here

    OK

  7. CHECK GLOW PLUG RELAY ASSEMBLY (POWER SOURCE)


    1. A01CJHPE01
      Text in Illustration
      *1 Engine Room Relay Block and Junction Block
      *a

      Front view of wire harness connector

      (to Glow Plug Relay Assembly)

      Remove the glow plug relay assembly from the engine room relay block and junction block.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      Glow plug relay terminal 3 - Body ground Always 18 to 27 V

    3. Reinstall the glow plug relay assembly.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GLOW PLUG RELAY ASSEMBLY - BATTERY)

    OK

  8. CHECK HARNESS AND CONNECTOR (GLOW PLUG RELAY ASSEMBLY - GLOW PLUG ASSEMBLY)


    1. Remove the glow plug relay assembly from the engine room relay block and junction block.

    2. Remove the glow plug connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      Glow plug relay terminal 5 - G5-5 (B) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      Glow plug relay terminal 5 or G5-5 (B) - Body ground Always 10 kΩ or higher

    4. Reinstall the glow plug connector.

    5. Reinstall the glow plug relay assembly.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GLOW PLUG RELAY ASSEMBLY - GLOW PLUG ASSEMBLY)

    OK

  9. CHECK HARNESS AND CONNECTOR (GLOW PLUG RELAY ASSEMBLY - ECM)


    1. Remove the glow plug relay assembly from the engine room relay block and junction block.

    2. Disconnect the ECM connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      Glow plug relay terminal 1 - E36-19 (SREL) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      Glow plug relay terminal 1 or E36-19 (SREL) - Body ground Always 10 kΩ or higher

    4. Reconnect the ECM connector.

    5. Reinstall the glow plug relay assembly.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GLOW PLUG RELAY ASSEMBLY - ECM)

    OK

  10. CHECK HARNESS AND CONNECTOR (GLOW PLUG RELAY ASSEMBLY - BODY GROUND)


    1. Remove the glow plug relay assembly from the engine room relay block and junction block.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      Glow plug relay terminal 2 - Body ground Always Below 1 Ω

    3. Reinstall the glow plug relay assembly.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (GLOW PLUG RELAY ASSEMBLY - BODY GROUND)

    OK

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

  11. CHECK ECM (GIND VOLTAGE)


    1. A01CGMCE01
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to ECM)

      Disconnect the ECM connector.

    2. Turn the ignition switch to ON.

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      E39-10 (GIND) - Body ground Ignition switch ON 18 to 27 V

    NG

    CHECK HARNESS AND CONNECTOR (ECM - COMBINATION METER ASSEMBLY) Click here

    OK

    REPLACE ECM Click here

  12. CHECK HARNESS AND CONNECTOR (ECM - COMBINATION METER ASSEMBLY)


    1. Disconnect the ECM connector.

    2. Disconnect the combination meter assembly connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      E39-10 (GIND) - C18-18 (GLW-) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      E39-10 (GIND) or C18-18 (GLW-) - Body ground Always 10 kΩ or higher

    4. Reconnect the combination meter assembly connector.

    5. Reinstall the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (ECM - COMBINATION METER ASSEMBLY)

    OK

    REPLACE COMBINATION METER ASSEMBLY

  13. INSPECT ENGINE COOLANT TEMPERATURE SENSOR


    1. A01CHW0E13
      Text in Illustration
      *1 Ohmmeter
      *2 Engine Coolant Temperature Sensor
      *a Acceptable

      Remove the engine coolant temperature sensor.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      1 - 2 20°C (68°F) 2.32 to 2.59 kΩ
      1 - 2 80°C (176°F) 0.31 to 0.326 kΩ

      Note

      When checking the sensor in water, keep the terminals dry. After the check, wipe the sensor dry.

      Tech Tips

      Alternative procedure: Connect an ohmmeter to the installed engine coolant temperature sensor and read the resistance. Use an infrared thermometer to measure the engine temperature in the immediate vicinity of the sensor. Compare these values with the resistance/ temperature graph. Change the engine temperature (warm up or cool down) and repeat the test.

    3. Reinstall the engine coolant temperature sensor.


    NG

    REPLACE ENGINE COOLANT TEMPERATURE SENSOR Click here

    OK

    REPLACE ECM Click here