ECD SYSTEM Pre-heating Control Circuit

DESCRIPTION

The glow plug is mounted inside the engine combustion chamber. To ensure efficient engine starting with a cold engine, the ECM calculates a time interval for 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 relay and permits the current to flow through the glow plug based on the ECM's calculated time of the ECM. The GLOW relay is then heated, and enhances fuel combustion with a cold engine.

A01SB0UE22

Tech Tips


  • These troubleshooting procedures are for the following conditions: 1) difficulty starting the engine in cold weather, and 2) difficulty driving the vehicle or vehicle malfunctions in cold weather immediately after 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.

B00253CE01

WIRING DIAGRAM

A01SD0IE02

CAUTION / NOTICE / HINT

Note

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

PROCEDURE


  1. INSPECT GLOW RELAY


    1. Inspect the glow plug relay (GLOW).

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE GLOW RELAY

    OK

  2. INSPECT GLOW PLUG ASSEMBLY (RESISTANCE)


    1. Inspect the glow plug.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE GLOW PLUG ASSEMBLY Click here

    OK

  3. CHECK GLOW PLUG ASSEMBLY (INSTALLATION)


    1. Check the glow plug installation.

      OK
      Glow plugs are installed securely.
      Torque
      13 N*m{ 130 kgf*cm , 10 ft.*lbf }
      Result
      Proceed to
      OK
      NG

    NG

    TIGHTEN GLOW PLUG

    OK

  4. CHECK HARNESS AND CONNECTOR (GLOW RELAY - ECM AND BODY GROUND)


    1. Disconnect the ECM connector.

    2. Remove the GLOW relay from the engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G121-8 (SREL) - GLOW relay (2) Always Below 1 Ω
      GLOW relay (1) - Body ground Always Below 1 Ω
      G121-8 (SREL) or GLOW relay (2) - Body ground and other terminals Always 10 kΩ or higher

    4. Reinstall the GLOW relay.

    5. Reconnect the ECM connector.

      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. CHECK HARNESS AND CONNECTOR (GLOW RELAY - GLOW PLUG AND BATTERY)


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

    2. Disconnect the glow plug connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      GLOW relay (3) - C72-1 Always Below 1 Ω
      GLOW relay (5) - Positive (+) battery terminal cable Always Below 1 Ω
      GLOW relay (3) or C72-1 - Body ground and other terminals Always 10 kΩ or higher

    4. Reinstall the GLOW relay.

    5. Reconnect the glow plug connector.

      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CHECK ECM (BATT VOLTAGE)


    1. A01SCSRC95
      *a

      Component with harness connected

      (ECM)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      G121-2 (BATT) - C127-5 (E1) Always 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. CHECK ECM (GREL VOLTAGE)


    1. A01SCSRC96
      *a

      Component with harness connected

      (ECM)

      Start the engine.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      G121-8 (SREL) - C127-5 (E1)

      Engine coolant

      temperature 40°C (104°F) or less

      		 11 to 14 V
      Result
      Proceed to
      OK
      NG

    OK

    CHECK FOR INTERMITTENT PROBLEMS Click here

    NG

    REPLACE ECM Click here