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".
Brakes
If the brakes do not operate properly, have the
brakes checked by a NISSAN dealer.
Self-adjusting brakes
Your vehicle is equipped with self-adjusting
brakes.
The front (and rear– if so equipped) disc-type
brakes self-adjust every time the brake pedal is
applied. The rear drum-type brakes ...
ASCD Indicator
Component Function Check
1.CHECK ASCD INDICATOR FUNCTION
Check ASCD indicator under the following conditions.
ASCD INDICATOR
CONDITION
SPECIFICATION
CRUISE LAMP
Ignition switch: ON
MAIN switch: Pressed at the 1st time →
at the 2nd ti ...
Vin registration
Description
VIN Registration is an operation to registering VIN in ECM. It must be
performed each time ECM is replaced.
NOTE:
Accurate VIN which is registered in ECM may be required for Inspection &
Maintenance (I/M).
Work Procedure
1.CHECK VIN
Check the VIN of the vehicle and note it. ...