ECD SYSTEM, Diagnostic DTC:P0488

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

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.

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

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

Reference
Condition	Throttle Valve Position
Moment when accelerator pedal is depressed further or released at 3000 rpm	Throttle valve opening angle varies smoothly

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.

Normal Condition
Throttle Condition	Target Throttle Position	Actual Throttle Position	Throttle Close Learning Val.	Diesel Throttle Learn Status
Throttle Valve Fully Closed	100%	100%	14.25 to 21.25 deg	OK
Throttle Valve Fully Open	0%	0%	14.25 to 21.25 deg	OK

Tech Tips

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

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

WIRING DIAGRAM

INSPECTION PROCEDURE

Note

When cleaning the electric EGR control valve assembly 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.

PROCEDURE

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

Connect the intelligent tester to the DLC3.
Turn the ignition switch to ON and turn the tester on.
Enter the following menus: Powertrain / Engine and ECT / DTC.

Read the DTCs.

Result
Result	Proceed to
DTC P0488	A
DTC P0488 and other DTCs	B

Tech Tips

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.

GO TO DTC CHART 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.
  
  Tech Tips
  
  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.
NG
REMOVE DEPOSIT (CLEAN EGR PASSAGE) Click here

OK
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.
NG
REMOVE DEPOSIT (CLEAN EGR PASSAGE) Click here

OK
REMOVE DEPOSIT (CLEAN EGR PASSAGE)
1. Remove the electric EGR control valve assembly, No. 2 intake manifold and intake manifold.
2. Remove the deposits from those parts and clean the parts.
  Note
  
  When cleaning the electric EGR control valve assembly 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.
  Tech Tips
  
  Remove the intake manifold from the cylinder head when it has to be cleaned.
3. Reinstall the electric EGR control valve assembly, No. 2 intake manifold and intake manifold.
NEXT
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.
OK
CHECK WHETHER DTC OUTPUT RECURS (DTC P0488) Click here

NG
REPLACE DIESEL THROTTLE BODY ASSEMBLY Click here
REMOVE DEPOSIT (CLEAN EGR PASSAGE)
1. Remove the electric EGR control valve assembly, No. 2 intake manifold and intake manifold.
2. Remove the deposits from those parts and clean the parts.
  Note
  
  When cleaning the electric EGR control valve assembly 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.
  Tech Tips
  
  Remove the intake manifold from the cylinder head when it has to be cleaned.
3. Reinstall the electric EGR control valve assembly, No. 2 intake manifold and intake manifold.
NEXT
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.
NG
REPLACE DIESEL THROTTLE BODY ASSEMBLY Click here

OK

Standard
Diesel Throttle Learn Status is OK

OK
Value smoothly changes to set opening angle.

OK
Throttle valve moves smoothly.

OK
Throttle valve moves smoothly.

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

Text in Illustration
*a	Front view of wire harness connector (to Throttle Body)
*b	Front view of wire harness connector (to ECM)

Disconnect the diesel throttle body assembly connector.
Disconnect the ECM connector.

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

Standard Resistance (Check for Open)

Tester Connection	Condition	Specified Condition
B7-5 (VC) - B39-97 (VCVL)	Always	Below 1 Ω
B7-6 (VTA) - B39-119 (VLU)	Always	Below 1 Ω
B7-3 (E2) - B39-96 (EVLU)	Always	Below 1 Ω
B7-2 (M+) - B39-42 (M+)	Always	Below 1 Ω
B7-1 (M-) - B39-43 (M-)	Always	Below 1 Ω

Standard Resistance (Check for Short)

Tester Connection	Condition	Specified Condition
B7-5 (VC) or B39-97 (VCVL) - Body ground	Always	10 kΩ or higher
B7-6 (VTA) or B39-119 (VLU) - Body ground	Always	10 kΩ or higher
B7-3 (E2) or B39-96 (EVLU) - Body ground	Always	10 kΩ or higher
B7-2 (M+) or B39-42 (M+) - Body ground	Always	10 kΩ or higher
B7-1 (M-) or B39-43 (M-) - Body ground	Always	10 kΩ or higher

Reconnect the diesel throttle body assembly connector.
Reconnect the ECM connector.

REPLACE DIESEL THROTTLE BODY ASSEMBLY Click here

REPAIR OR REPLACE HARNESS OR CONNECTOR Click here

REPAIR OR REPLACE HARNESS OR CONNECTOR
1. Repair or replace the harness or connector.
NEXT
CHECK WHETHER DTC OUTPUT RECURS (DTC P0488) Click here
REPLACE DIESEL THROTTLE BODY ASSEMBLY
1. Replace the diesel throttle body assembly Click here.
NEXT
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. Take a snapshot with the intelligent tester.
  
  Tech Tips
  
  Detailed graphs can be displayed by transferring the stored snapshot from the tester to a PC (personal computer) with Intelligent Viewer installed.
6. Enter the following menus: Powertrain / Engine and ECT / Active Test / Diesel Throttle Target Angle.
  
  Tech Tips
  
  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.
NG
REPLACE ECM Click here

OK

END
REPLACE ECM
1. Replace the ECM Click here.
NEXT
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. Take a snapshot with the intelligent tester.
  
  Tech Tips
  
  Detailed graphs can be displayed by transferring the stored snapshot from the tester to a PC (personal computer) with Intelligent Viewer installed.
6. Enter the following menus: Powertrain / Engine and ECT / Active Test / Diesel Throttle Target Angle.
  
  Tech Tips
  
  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.
NEXT

END