Description
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 (POS) 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
DTC DETECTION LOGIC
NOTE:
If DTC P0506 is displayed with other DTC, first perform the trouble diagnosis for the other DTC.
DTC No. | CONSULT screen terms (Trouble diagnosis content) | DTC detecting condition | Possible cause |
P0506 | ISC SYSTEM (Idle air control system RPM lower than expected) | The idle speed is less than the target idle speed by 100 rpm or more. |
|
DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next test.
If the target idle speed is out of the specified value, performEC-140, "Work Procedure", before conducting DTC Confirmation Procedure.
TESTING CONDITION:
>> GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE
Is 1st trip DTC detected? YES >> Proceed to EC-334, "Diagnosis Procedure".
NO >> INSPECTION END
Diagnosis Procedure
1.CHECK INTAKE AIR LEAK
Is intake air leak detected? YES >> Discover air leak location and repair.
NO >> Replace ECM. Refer to EC-485, "Removal and Installation".
Eps branch line circuit
Diagnosis procedure
1.Check connector
Turn the ignition switch off.
Disconnect the battery cable from the negative terminal.
Check the terminals and connectors of the eps control unit for damage,
bend and loose connection (unit
side and connector side).
Is the inspection result norm ...
C1607, C1608 EPS Control unit
DTC Logic
DTC DETECTION LOGIC
Dtc
Display item
Malfunction detected condition
Possible cause
C1607
EEPROM
When the memory (EEPROM) system malfunction is
detected in EPS control unit.
Eps control unit
C1608
CONTROL UNIT
When the internal malfuncti ...
Main line between dlc and hvac circuit
Diagnosis procedure
1.Check harness continuity (open circuit)
Turn the ignition switch off.
Disconnect the battery cable from the negative terminal.
Disconnect the following harness connectors.
Ecm
A/C auto amp.
Check the continuity between the data link connector and the A/C ...