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ECD SYSTEM (for DPF), Diagnostic DTC:P0488

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DTC Code DTC Name
P0488 Exhaust Gas Recirculation Throttle Position Control Range / Performance
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DESCRIPTION

The ECM opens and closes the throttle valve using a DC motor type actuator. Due to the opening and closing of the valve, the exhaust gas recirculation volume can be properly controlled. Also, engine vibration and noise will be reduced by closing the valve when the engine is stopped.

Although the DTC title says "Exhaust Gas Recirculation Throttle Position Control Range / Performance", this DTC indicates that the throttle valve is malfunctioning.

Table 1. P0488
DTC Detection Drive Pattern DTC Detection Condition Trouble Area
Perform the following repeatedly for 1 minute: gradually raise the engine speed to 3000 rpm from an idling over approximately 10 seconds, and then release the accelerator pedal to return to an idling state. The throttle motor activation duty is more than specified value for 30 seconds (1 trip detection logic).

  • Throttle valve stuck

  • Throttle valve does not move smoothly

  • Open or short in throttle control motor circuit

  • ECM
Table 2. Related Data List
DTC No. Data List
P0488

  • Actual Throttle Position

  • Target Throttle Position

  • Throttle Motor Duty

  • Throttle Close Learning Val.

  • Diesel Throttle Learn Status
Table 3. Reference
Condition Throttle Valve Position
Moment when accelerator pedal is depressed further or released at 3000 rpm Throttle valve opening angle varies smoothly
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MONITOR DESCRIPTION

The ECM opens and closes the throttle valve by adjusting the current flowing to the DC motor with a duty ratio. If the throttle valve does not move smoothly or is stuck, the duty ratio used during valve movement control increases or decreases greatly. The ECM will determine that the throttle valve is malfunctioning and illuminate the MIL.

Table 4. Normal Condition
Throttle Condition Target Throttle Position Actual Throttle Position Throttle Close Learning Val. Diesel Throttle Learn Status
Throttle Valve Fully Closed 100% 100% 14 to 21.25 deg OK
Throttle Valve Fully Open 0% 0%
Tip:
  • A01IOXBE01

    If carbon deposits exist in the diesel throttle body assembly, the following parts possibly also have deposits inside: The EGR valve assembly, intake manifold, exhaust fuel addition injector, DPF catalyst, and other parts related to the exhaust gas.

    By removing the EGR valve assembly from the intake manifold, the carbon deposit condition between the EGR valve and intake manifold can be checked visually. When checking for deposits in the EGR valve assembly, hold the EGR valve to a light and confirm that the valve contacts the valve seat securely.

  • DPF catalyst diagnosis:

    The value of "Catalyst Differential Press" in the Data List is high when the catalyst is clogged. If this value exceeds approximately 0.4, DTC P244B is stored.

    If the "Catalyst Differential Press" become near about 0.4, the catalyst is probably clogged with PM even if DTC P244B is not present.

    Check the Catalyst differential press when the engine is running at 3000 rpm with no load. Enter the following menus: Powertrain / Engine and ECT / Data List / Catalyst differential press.

    If the value of MAF in the Data List is less than 25 gm/s, a correct value for Catalyst Differential Press is not output due to exhaust gas pulsation.

  • Exhaust fuel addition injector diagnosis:

    When the fuel volume injected by the exhaust fuel addition injector decreases, the value of "Exhaust Fuel Addition FB" in the Data List increases. Exhaust Fuel Addition FB in the Data List is a correction value to increase the fuel volume injected from the exhaust fuel addition injector when the catalyst temperature does not rise to the target during catalyst regeneration. Under normal conditions, the value is between 0.9 and 1.45.

    Check the value by entering the following menus on an intelligent tester: Powertrain / Engine and ECT / Data List / Exhaust Fuel Addition FB. Under normal conditions, the exhaust gas temperature becomes 150 to 350°C (302 to 662°F) when the vehicle is driven in 3rd gear at a constant vehicle speed of about 50 km/h (31 mph). While driving under these conditions, the exhaust gas temperature rises to 500 to 700°C (932 to 1292°F) when the catalyst regeneration function in the Active Test (Activate the DPF Rejuvenate (PM)) is performed. If the temperature does not rise sufficiently, the exhaust fuel addition injector or the DPF catalyst may be damaged.

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WIRING DIAGRAM

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INSPECTION PROCEDURE

Note:

  • When cleaning the EGR valve or diesel throttle body, use a piece of cloth soaked with cleaning solvent. Spraying the solvent directly onto these parts or soaking the parts in solvent may damage the parts.

  • After replacing the ECM, the new ECM needs registration (Click here) and initialization (Click here).

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PROCEDURE


  1. Click here

    CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0488)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON and turn the tester on.

    3. Enter the following menus: Powertrain / Engine and ECT / DTC.

    4. Read the DTCs.

      Table 5. Result
      Result Proceed to
      DTC P0488 A
      DTC P0488 and other DTCs B
      Tip:

      • If any DTCs other than DTC P0488 are output, troubleshoot those DTCs first.

      • Be sure to also record the values of "Actual Throttle Position" and "Target Throttle Position" listed in the freeze frame data.


  2. Click here

    READ VALUE USING INTELLIGENT TESTER (DIESEL THROTTLE LEARN STATUS)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON and turn the tester on.

    3. Clear the DTCs (Click here).

    4. Turn the ignition switch off for 30 seconds or more.

      Tip:

      Be sure to turn off the ignition switch before performing this inspection. The fully closed position of the diesel throttle valve is learned when the ignition switch is turned off.

    5. Enter the following menus: Powertrain / Engine and ECT / Data List / Diesel Throttle Learn Status.

    6. Read the values when the ignition switch is ON.

      Standard
      Diesel Throttle Learn Status is OK
      Note:

      Extremely cold conditions might cause the throttle valve movement to be delayed.


  3. Click here

    PERFORM ACTIVE TEST USING INTELLIGENT TESTER (DIESEL THROTTLE TARGET ANGLE)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON and turn the tester on.

    3. Enter the following menus: Powertrain / Engine and ECT / Active Test / Diesel Throttle Target Angle.

    4. When changing the Active Test continuously value to 0, 30, 60, 90, 60, 30 and 0%, check that Actual Throttle Position smoothly changes to the set opening angle.

      OK
      Value smoothly changes to set opening angle.

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    REMOVE DEPOSIT (CLEAN EGR PASSAGE)


    1. Remove the EGR valve assembly, No. 2 intake manifold and intake manifold.

    2. A01INS0E03

      Remove the deposits from those parts and clean the parts.

      Table 6. Text in Illustration
      *1 No. 2 Intake Manifold *2 EGR Valve Assembly
      *3 No. 2 Intake Manifold *4 Carbon Deposit
      *5 Intake Manifold *6 Carbon Deposit
      *7 Intake Manifold - -
      Note:

      • When cleaning the EGR valve and diesel throttle body, use a piece of cloth soaked with cleaning solvent. Spraying the solvent directly onto these parts or soaking the parts in solvent may damage the parts.

      • Extreme care must be taken to prevent the removed deposits from falling into the engine unit during cleaning.

      Tip:

      Remove the intake manifold from the cylinder head when it has to be cleaned.

    3. Reinstall the EGR valve assembly, No. 2 intake manifold and intake manifold.


  5. Click here

    INSPECT DIESEL THROTTLE BODY ASSEMBLY (THROTTLE VALVE MOVEMENT)


    1. Using your finger, move the throttle valve from the fully open position to the fully closed position and check that it moves smoothly.

      OK
      Throttle valve moves smoothly.
      Note:

      Take care not to damage the throttle valve or valve housing.


  6. Click here

    REMOVE DEPOSIT (CLEAN EGR PASSAGE)


    1. Remove the EGR valve assembly, No. 2 intake manifold and intake manifold.

    2. A01INS0E03

      Remove the deposits from those parts and clean the parts.

      Table 7. Text in Illustration
      *1 No. 2 Intake Manifold *2 EGR Valve Assembly
      *3 No. 2 Intake Manifold *4 Carbon Deposit
      *5 Intake Manifold *6 Carbon Deposit
      *7 Intake Manifold - -
      Note:

      • When cleaning the EGR valve and diesel throttle body, use a piece of cloth soaked with cleaning solvent. Spraying the solvent directly onto these parts or soaking the parts in solvent may damage the parts.

      • Extreme care must be taken to prevent the removed deposits from falling into the engine unit during cleaning.

      Tip:

      Remove the intake manifold from the cylinder head when it has to be cleaned.

    3. Reinstall the EGR valve assembly, No. 2 intake manifold and intake manifold.


  7. Click here

    INSPECT DIESEL THROTTLE BODY ASSEMBLY (THROTTLE VALVE MOVEMENT)


    1. Using your finger, move the throttle valve from the fully open position to the fully closed position and check that it moves smoothly.

      OK
      Throttle valve moves smoothly.
      Note:

      Take care not to damage the throttle valve or valve housing.


  8. Click here

    CHECK HARNESS AND CONNECTOR (ECM - DIESEL THROTTLE BODY ASSEMBLY)


    1. Disconnect the diesel throttle body assembly connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      C9-5 (VC) - C69-97 (VCVL) Always Below 1 Ω
      C9-6 (VTA) - C69-119 (VLU) Always Below 1 Ω
      C9-3 (E2) - C69-96 (EVLU) Always Below 1 Ω
      C9-2 (M+) - C69-42 (M+) Always Below 1 Ω
      C9-1 (M-) - C69-43 (M-) Always Below 1 Ω
      C9-5 (VC) or C69-97 (VCVL) - Body ground Always 10 kΩ or higher
      C9-6 (VTA) or C69-119 (VLU) - Body ground Always 10 kΩ or higher
      C9-3 (E2) or C69-96 (EVLU) - Body ground Always 10 kΩ or higher
      C9-2 (M+) or C69-42 (M+) - Body ground Always 10 kΩ or higher
      C9-1 (M-) or C69-43 (M-) - Body ground Always 10 kΩ or higher
      Table 8. Text in Illustration
      *a

      Front view of wire harness connector

      (to Throttle Body)
      *b

      Front view of wire harness connector

      (to ECM)

    4. Reconnect the diesel throttle body assembly connector.

    5. Reconnect the ECM connector.


  9. Click here

    REPAIR OR REPLACE HARNESS OR CONNECTOR


    1. Repair or replace the harness or connector.


  10. Click here

    REPLACE DIESEL THROTTLE BODY ASSEMBLY


    1. Replace the diesel throttle body assembly (Click here).


  11. Click here

    CHECK WHETHER DTC OUTPUT RECURS (DTC P0488)


    1. Start the engine and warm it up.

    2. Connect the intelligent tester to the DLC3.

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / Engine Speed, Target Throttle Position and Actual Throttle Position.

    5. A01IPZAE18

      Take a snapshot with the intelligent tester.

      Tip:

      Detailed graphs can be displayed by transferring the stored snapshot from the tester to a PC (personal computer) with Intelligent Viewer installed.

      Table 9. Text in Illustration
      *1 Snapshot Button

    6. Enter the following menus: Powertrain / Engine and ECT / Active Test / Diesel Throttle Target Angle.

      Tip:

      The movement of the throttle valve can be determined by performing the following inspection.

    7. When changing the Active Test value continuously to 0, 30, 60, 90, 60, 30 and 0%, check that Actual Throttle Position smoothly changes to the set opening angle.

      OK
      Value smoothly changes to set opening angle.

    8. Perform the following repeatedly for 1 minute: gradually raise the engine speed to 3000 rpm from an idling over approximately 10 seconds, and then release the accelerator pedal to return to an idling state.

    9. Enter the following menus: Powertrain / Engine and ECT / DTC.

    10. Read DTCs.

      OK
      No DTCs are output.

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    REPLACE ECM


    1. Replace the ECM (Click here).


  13. Click here

    CHECK WHETHER DTC OUTPUT RECURS (DTC P0488)


    1. Start the engine and warm it up.

    2. Connect the intelligent tester to the DLC3.

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / Engine Speed, Target Throttle Position and Actual Throttle Position.

    5. A01IPZAE18

      Take a snapshot with the intelligent tester.

      Tip:

      Detailed graphs can be displayed by transferring the stored snapshot from the tester to a PC (personal computer) with Intelligent Viewer installed.

      Table 10. Text in Illustration
      *1 Snapshot Button

    6. Enter the following menus: Powertrain / Engine and ECT / Active Test / Diesel Throttle Target Angle.

      Tip:

      The movement of the throttle valve can be determined by performing the following inspection.

    7. When changing the Active Test value continuously to 0, 30, 60, 90, 60, 30 and 0%, check that Actual Throttle Position smoothly changes to the set opening angle.

      OK
      Value smoothly changes to set opening angle.

    8. Perform the following repeatedly for 1 minute: gradually raise the engine speed to 3000 rpm from an idling over approximately 10 seconds, and then release the accelerator pedal to return to an idling state.

    9. Enter the following menus: Powertrain / Engine and ECT / DTC.

    10. Confirm that the DTC is not output again.


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    END

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