Infiniti QX56 (Z62). Manual - part 595
EC-358
< DTC/CIRCUIT DIAGNOSIS >
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P0506 ISC SYSTEM
P0506 ISC SYSTEM
Description
INFOID:0000000006217861
The ECM controls the engine idle speed to a specified level through the fine adjustment of the air, which is let
into the intake manifold, by operating the electric throttle control actuator. The operating of the throttle valve is
varied to allow for optimum control of the engine idling speed. The crankshaft position sensor detects the
actual engine speed and sends a signal to the ECM.
The ECM controls the electric throttle control actuator so that the engine speed coincides with the target value
memorized in the ECM. The target engine speed is the lowest speed at which the engine can operate steadily.
The optimum value stored in the ECM is determined by taking into consideration various engine conditions,
such as during warming up, deceleration and engine load (air conditioner, power steering and cooling fan
operation, etc.).
DTC Logic
INFOID:0000000006217862
DTC DETECTION LOGIC
NOTE:
If DTC P0506 is displayed with other DTC, first perform the trouble diagnosis for the other DTC.
DTC CONFIRMATION PROCEDURE
1.
PRECONDITIONING
1.
Turn ignition switch OFF and wait at least 10 seconds.
2.
Turn ignition switch ON.
3.
Turn ignition switch OFF and wait at least 10 seconds.
If the target idle speed is out of the specified value, perform
, before con-
ducting DTC Confirmation Procedure.
TESTING CONDITION:
• Before performing the following procedure, confirm that battery voltage is 11 V or more at idle.
• Always perform the test at a temperature above
−
10
°
C (14
°
F).
>> GO TO 2.
2.
PERFORM DTC CONFIRMATION PROCEDURE
1.
Start engine and warm it up to normal operating temperature.
2.
Turn ignition switch OFF and wait at least 10 seconds.
3.
Turn ignition switch ON.
4.
Turn ignition switch OFF and wait at least 10 seconds.
5.
Restart engine and run it for at least 1 minute at idle speed.
6.
Check 1st trip DTC.
Is 1st trip DTC detected?
YES
>> Go to
NO
>> INSPECTION END
Diagnosis Procedure
INFOID:0000000006217863
1.
CHECK INTAKE AIR LEAKAGE
1.
Start engine and let it idle.
2.
Listen for an intake air leakage after the mass air flow sensor.
Is intake air leakage detected?
YES
>> Discover air leakage location and repair.
DTC No.
Trouble diagnosis name
(Trouble diagnosis content)
DTC detecting condition
Possible cause
P0506
ISC SYSTEM
(Idle speed control system
RPM lower than expected)
The idle speed is less than the target idle
speed by 100 rpm or more.
• Electric throttle control actuator
• Intake air leakage