Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Idle Control System (P050500)

DESCRIPTION

The idle speed is controlled by the electronic throttle control system. The electronic throttle control system is comprised of: 1) one valve type throttle body with motor assembly; 2) the throttle actuator, which operates the throttle valve; 3) the throttle position sensor, which detects the opening angle of the throttle valve; 4) the accelerator pedal position sensor, which detects the accelerator pedal position; 5) the ECM, which controls the electronic throttle control system. Based on the target idle speed, the ECM controls the throttle actuator to provide the proper throttle valve opening angle.

MONITOR DESCRIPTION

The ECM monitors the idle speed and idling air flow volume to conduct idle speed control. The ECM determines that the idle speed control system is malfunctioning if either of the following conditions is met:

• The difference between the target engine idle speed and actual engine idle speed exceeds the threshold and the idle control correction value is stuck at the upper or lower limit for 5 seconds or more.
• After driving at a vehicle speed of 10 km/h (6 mph) or more, the difference between the target and actual engine idle speed exceeds the threshold 5 times or more during a driving cycle, and then the system determines that the idle control correction value is stuck at the upper or lower limit, or that the idle control correction value has been changed by an amount that exceeds the threshold.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

CONFIRMATION DRIVING PATTERN

HINT:

• After repair has been completed, clear the DTC and then check that the vehicle has returned to normal by performing the following All Readiness check procedure.

  Click here

• When clearing the permanent DTCs, refer to the "CLEAR PERMANENT DTC" procedure.

  Click here

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
5. Turn the power switch off and wait for at least 30 seconds.
6. Turn the power switch on (IG) [A].
7. Turn the Techstream on.
8. Put the engine in Inspection Mode (Maintenance Mode).

   Click here

9. Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher with the A/C switch and all the accessories off [B].
10. Turn the power switch off and wait for at least 30 seconds.
11. Disconnect the cable from the negative (-) auxiliary battery terminal.

    HINT:

    When clearing permanent DTCs, proceed to the next step without disconnecting the cable from the auxiliary battery terminal.

12. Reconnect the cable to the negative (-) auxiliary battery terminal.
13. Turn the power switch on (IG).
14. Turn the Techstream on.
15. Put the engine in Inspection Mode (Maintenance Mode).

    Click here

16. Start the engine and rev the engine for 5 seconds or more with the shift lever in P [C].

    HINT:

    During charge control, the engine speed is set at idle. Therefore, the engine speed will not increase when the accelerator pedal is depressed. In this case, perform step [C] after charge control has completed.

17. Idle the engine for 5 minutes or more [D].

    HINT:

    In order to keep the idling stable, turn off the A/C and all other electric loads and do not perform any shift operations.

18. Enter the following menus: Powertrain / Engine / Trouble Codes [E].
19. Read the pending DTCs.

    HINT:

    • If a pending DTC is output, the system is malfunctioning.
    • If a pending DTC is not output, perform the following procedure.
20. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
21. Input the DTC: P050500.
22. Check the DTC judgment result.

    Techstream Display	Description
    NORMAL	DTC judgment completed System normal
    ABNORMAL	DTC judgment completed System abnormal
    INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions

    HINT:

    • If the judgment result shows NORMAL, the system is normal.
    • If the judgment result shows ABNORMAL, the system is malfunctioning.
    • If the judgment result shows INCOMPLETE, perform steps [F] through [J].
    • [A] to [E]: Normal judgment procedure.

      The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.

    • When clearing the permanent DTCs, do not disconnect the cable from the auxiliary battery terminal or attempt to clear the DTCs during this procedure, as doing so will clear the universal trip and normal judgment histories.
23. With the engine running, accelerate the vehicle to 10 km/h (6.25 mph) or more [F].

    CAUTION:

    When performing the confirmation driving pattern, obey all speed limits and traffic laws.

    HINT:

    If the engine stops, further depress the accelerator pedal to restart the engine.

24. Stop the vehicle and rev the engine for 5 seconds or more with the shift lever in P [G].

    HINT:

    During charge control, the engine speed is set at idle. Therefore, the engine speed will not increase when the accelerator pedal is depressed. In this case, perform step [G] after charge control has completed.

25. Idle the engine for 20 seconds or more [H].
26. Repeat the steps [F] through [H] 10 times [I].
27. Enter the following menus: Powertrain / Engine / Trouble Codes [J].
28. Read the pending DTCs.

    HINT:

    • If a pending DTC is output, the system is malfunctioning.
    • If a pending DTC is not output, perform the following procedure.
29. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
30. Input the DTC: P050500.
31. Check the DTC judgment result.

    Techstream Display	Description
    NORMAL	DTC judgment completed System normal
    ABNORMAL	DTC judgment completed System abnormal
    INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions

    HINT:

    • If the judgment result shows NORMAL, the system is normal.
    • If the judgment result shows ABNORMAL, the system is malfunctioning.
    • [A] to [J]: Normal judgment procedure.

      The normal judgment procedure is used to complete DTC judgment and also used when clearing permanent DTCs.

    • When clearing the permanent DTCs, do not disconnect the cable from the auxiliary battery terminal or attempt to clear the DTCs during this procedure, as doing so will clear the universal trip and normal judgment histories.

CAUTION / NOTICE / HINT

NOTICE:

• Vehicle Control History may be stored in the hybrid vehicle control ECU assembly if the engine is malfunctioning. Certain vehicle condition information is recorded when Vehicle Control History is stored. Reading the vehicle conditions recorded in both the Freeze Frame Data and Vehicle Control History can be useful for troubleshooting.

  Click here

  (Select Powertrain in Health Check and then check the time stamp data.)

  Click here

• If any "Engine Malfunction" Vehicle Control History item has been stored in the hybrid vehicle control ECU assembly, make sure to clear it. However, as all Vehicle Control History items are cleared simultaneously, if any Vehicle Control History items other than "Engine Malfunction" are stored, make sure to perform any troubleshooting for them before clearing Vehicle Control History.

  Click here

HINT:

• The following conditions may also cause DTC P050500 to be stored:
  1. If the floor carpet or floor mat is resting slightly on the accelerator pedal, causing the accelerator pedal to be slightly depressed and therefore the throttle valve position to be slightly open.
  2. The accelerator pedal is not fully released.
• Refer to "Data List / Active Test" [Engine Speed, Engine Speed and ISC Learning Value].

  Click here

• Read Freeze Frame Data using the Techstream. The ECM records vehicle and driving condition information as Freeze Frame Data the moment a DTC is stored. When troubleshooting, Freeze Frame Data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Trouble Codes.

(e) Read the DTCs.

HINT:

If any DTCs other than P050500 are output, troubleshoot those DTCs first.

B

GO TO DTC CHART

A

(a) Check the PCV hose connections.

(b) Check the PCV valve.

Click here

OK:

PCV hose and PCV valve are connected correctly and are not damaged.

NG

REPAIR OR REPLACE PCV VALVE OR HOSE

OK

(a) Check the intake system for vacuum leaks.

Click here

OK:

No leaks from the intake system.

HINT:

Perform "Inspection After Repair" after repairing or replacing the intake system.

Click here

NG

REPAIR OR REPLACE INTAKE SYSTEM

OK

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Put the engine in Inspection Mode (Maintenance Mode).

(e) Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher.

HINT:

The A/C switch and all accessories should be off.

(f) Enter the following menus: Powertrain / Engine / Active Test / Control the EGR Step Position / Data List / Intake Manifold Absolute Pressure , Coolant Temperature and Engine Independent.

(g) Confirm that the value of Data List item Engine Independent is "Operate" then check the value of Intake Manifold Absolute Pressure while performing the Active Test.

NOTICE:

• Make sure that the value of Data List item Engine Independent is "Operate" while performing the Active Test.
• Do not leave the EGR valve open for 10 seconds or more during the Active Test.
• Be sure to return the EGR valve to step 0 when the Active Test is completed.
• Do not open the EGR valve 30 steps or more during the Active Test.

OK:

The value of Intake Manifold Absolute Pressure changes in response to the EGR step position when the value of Engine Independent is "Operate".

Standard:

HINT:

• If the value of Data List item Engine Independent is "Not Opr" when the engine is idling, charge control is being performed. Perform the Active Test after charge control is complete ("Operate" is displayed).
• While performing the Active Test, if the increase in the value of Intake Manifold Absolute Pressure is small, the EGR valve assembly may be malfunctioning.
• Even if the EGR valve assembly is malfunctioning, rough idling or an increase in the value of Intake Manifold Absolute Pressure may occur while performing the Active Test. However, the amount that the value of Intake Manifold Absolute Pressure increases will be smaller than normal.

OK

GO TO STEP 6

NG

(a) Remove the EGR valve assembly.

Click here

(b) Check if the EGR valve is stuck open.

OK:

EGR valve is tightly closed.

HINT:

Perform "Inspection After Repair" after replacing the EGR valve assembly.

Click here

NG

REPLACE EGR VALVE ASSEMBLY

OK

(a) Check the throttle body with motor assembly condition.

OK:

Throttle valve is not contaminated with foreign matter and moves smoothly.

HINT:

Perform "Inspection After Repair" after replacing the throttle body with motor assembly.

Click here

NG

REPLACE THROTTLE BODY WITH MOTOR ASSEMBLY

OK

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Clear the DTCs.

(e) Turn the power switch off and wait for at least 30 seconds.

NEXT

(a) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

(b) Enter the following menus: Powertrain / Engine / Trouble Codes.

(c) Read the pending DTCs.

A

END

B

REPLACE ECM