Lexus NX: Idle Control System (P0505)

Lexus NX Service Manual / Engine & Hybrid System / 2ar-fxe (engine Control) / Sfi System / Idle Control System (P0505)

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.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory
P0505	Idle Control System	Idle speed continues to vary greatly from target idle speed (2 trip detection logic).	Electronic throttle control system Intake system PCV hose connection EGR valve assembly ECM	Comes on	DTC stored

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 IAC flow rate learned value is stuck at the upper or lower limit for 5 seconds or more.
After driving at a vehicle speed of 10 km/h (6.25 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 IAC flow rate learned value is stuck at the upper or lower limit, or that the IAC flow rate learned value has been changed by an amount that exceeds the threshold.

MONITOR STRATEGY

Related DTCs	P0505: Idle air control system functional check
Required Sensors/Components (Main)	Electronic throttle control system
Required Sensors/Components (Related)	Crankshaft position sensor Engine coolant temperature sensor
Frequency of Operation	Once per driving cycle
Duration	5 seconds
MIL Operation	2 driving cycles
Sequence of Operation	None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever the following DTCs are not stored

P0010 (Camshaft timing oil control valve)

P0011 (VVT system - advance)

P0012 (VVT system - retard)

P0016 (VVT system - misalignment)

P0031, P0032, P101D (Air fuel ratio sensor heater)

P0102, P0103 (Mass air flow meter)

P0107, P0108 (Manifold absolute pressure)

P0115, P0117, P0118 (Engine coolant temperature sensor)

P0120, P0121, P0122, P0123, P0220, P0222, P0223, P2135 (Throttle position sensor)

P0125 (Insufficient coolant temperature for closed loop fuel control)

P014C, P014D, P015A, P015B, P2195, P2196, P2237, P2238, P2239, P2252, P2253 (Air fuel ratio sensor)

P0171, P0172 (Fuel system)

P0300, P0301, P0302, P0303, P0304 (Misfire)

P0335 (Crankshaft position sensor)

P0340 (Camshaft position sensor)

P0340, P0342, P0343 (VVT sensor)

P0351, P0352, P0353, P0354 (Igniter)

P0401 (EGR system)

P0451, P0452, P0453 (EVAP system)

P219A, P219C, P219D, P219E, P219F (Air-fuel ratio imbalance)

Engine

Running

TYPICAL MALFUNCTION THRESHOLDS

Either of the following conditions are met	1 or 2
1. Both of the following conditions are met	-
Engine speed - Target engine speed	Less than -100 rpm, or higher than 150 rpm
IAC flow rate learned value	0.9 L/sec. or less, or 7.0 L/sec. or more for 5 seconds or more
2. Both of the following conditions are met	A and B
A. Frequency that both of the following conditions are met	5 times or more
Engine speed - Target engine speed	Less than -100 rpm, or higher than 150 rpm
Vehicle condition	Stopped after vehicle was driven by 10 km/h (6.25 mph) or more
B. Either of the following conditions is met	(a) or (b)
(a) Amount of change of IAC flow rate learning value	+2.2 L/sec. or more, or -3.354 L/sec. or less
(b) IAC flow rate learning value	0.9 L/sec. or less, or 7.0 L/sec. or more

CONFIRMATION DRIVING PATTERN

Connect the Techstream to the DLC3.
Turn the power switch on (IG) and turn the Techstream on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
Turn the power switch off and wait for at least 30 seconds.
Turn the power switch on (IG) and turn the Techstream on [A].
Put the engine in inspection mode (maintenance mode).
Click here
Start the engine and warm it up until the engine coolant temperature is 70°C (158°F) or higher with all the accessories switched off [B].
Turn the power switch off and wait for at least 30 seconds.
Disconnect the cable from the negative (-) auxiliary battery terminal.
Reconnect the cable to the negative (-) auxiliary battery terminal.
Turn the power switch on (IG) and turn the Techstream on.
Put the engine in inspection mode (maintenance mode).
Click here
Start the engine and rev the engine for 5 seconds with shift lever in P [C].
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.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [E].
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.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P0505.

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
N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

HINT:

If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.
If the judgment result shows INCOMPLETE or N/A, perform steps [F] through [I].

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.
Stop the vehicle and rev the engine for 5 seconds with shift lever in P [G].
Idle the engine for 20 seconds or more [H].
Repeat the steps [F] through [H] 10 times.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [I].
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.
Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
Input the DTC: P0505.

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
N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

HINT:

If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.

If the judgment result is INCOMPLETE or N/A and no pending DTC is output, perform a universal trip and check for permanent DTCs.
Click here
HINT:
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.

CAUTION / NOTICE / HINT

NOTICE:

After the power switch is turned off, there may be a waiting time before disconnecting the negative (-) auxiliary battery terminal.
Click here
When disconnecting and reconnecting the auxiliary battery.
Click here

HINT:

When disconnecting and reconnecting the auxiliary battery, there is an automatic learning function that completes learning when the respective system is used.

Click here

HINT:

The following conditions may also cause DTC P0505 to be stored:
1. The floor carpet overlapping slightly onto 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 being not fully released.
Refer to "Data List / Active Test" [Engine Speed, ISC Feedback Value 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

1.	CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0505)

(a) Connect the Techstream to the DLC3.

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

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

(e) Read the DTCs.

Powertrain > Engine and ECT > Trouble Codes

Result	Proceed to
DTC P0505 is output	A
DTC P0505 and other DTCs are output	B

HINT:

If any DTCs other than P0505 are output, troubleshoot those DTCs first.

GO TO DTC CHART

2.	CHECK PCV HOSE CONNECTIONS

(a) Check the PCV hose connections.

Click here

OK:

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

REPAIR OR REPLACE PCV HOSE

3.	CHECK INTAKE SYSTEM

(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

REPAIR OR REPLACE INTAKE SYSTEM

4.	PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE EGR STEP POSITION)

(a) Connect the Techstream to the DLC3.

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

(d) Put the engine in inspection mode (maintenance mode).

Click here

Powertrain > Hybrid Control > Utility

Tester Display
Inspection Mode

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

HINT:

The A/C switch and all accessory switches should be off.

(f) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position / Primary / MAP and Throttle Idle Position.

Powertrain > Engine and ECT > Active Test

Active Test Display
Control the EGR Step Position

Data List Display
MAP
Throttle Idle Position

(g) Confirm that the Throttle Idle Position is ON and check the MAP values in the Data List while performing the Active Test.

HINT:

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:

MAP change in response to EGR step position when Throttle Idle Position is ON in Data List.

Standard:

-	EGR Step Position (Active Test)
0 Steps	0 to 30 Steps
MAP (Data List)	(EGR valve is fully closed)	MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed

EGR Step Position (Active Test)

0 Steps

0 to 30 Steps

MAP

(Data List)

(EGR valve is fully closed)

MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed

HINT:

While performing the Active Test, if the increase in the value of MAP is small, the EGR valve assembly may be a malfunctioning.
Even if the EGR valve assembly is malfunctioning, rough idling or an increase in the value of MAP may occur while performing the Active Test. However, the amount that the value of MAP increases will be smaller than normal.

GO TO STEP 6

5.	INSPECT EGR VALVE ASSEMBLY

(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

REPLACE EGR VALVE ASSEMBLY

6.	INSPECT THROTTLE BODY WITH MOTOR ASSEMBLY (THROTTLE VALVE)

(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

REPLACE THROTTLE BODY WITH MOTOR ASSEMBLY

7.	CONFIRM WHETHER DTC OUTPUT RECURS (DTC P0505)

(a) Connect the Techstream to the DLC3.

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

(d) Clear the DTCs.

Click here

Powertrain > Engine and ECT > Clear DTCs

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

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

(g) Turn the Techstream on.

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

(i) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(j) Read the pending DTCs.

Powertrain > Engine and ECT > Trouble Codes

Result	Proceed to
DTC P0505 is output	A
DTCs are not output	B

REPLACE ECM

END

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