Nissan Frontier D22. Manual - part 323

DTC P0505 ISC SYSTEM

EC-395

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EC

Specification data are reference values and are measured between each terminal and ground.

CAUTION:

Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.

: Average voltage for pulse signal (Actual pulse signal can be confirmed by oscilloscope.)

Diagnostic Procedure

UBS00D91

1. 

CHECK POWER SUPPLY

1.

Stop engine.

2.

Disconnect IACV-AAC valve harness connector.

3.

Turn ignition switch ON.

4.

Check voltage between terminal 2 and ground with CONSULT-II
or tester.

OK or NG

OK

>> GO TO 3.

NG

>> GO TO 2.

TER-

MINAL 

NO.

WIRE 

COLOR

ITEM

CONDITION

DATA (DC Voltage)

101

OR/L

IACV-AAC valve

[Engine is running]

●

Warm-up condition

●

Idle speed

NOTE:
The pulse cycle changes depending on rpm at 
idle

10.5 - 11.5V

[Engine is running]

●

Warm-up condition

●

Engine speed is 2,000 rpm

1 - 13V

SEF015W

SEF016W

SEF342V

Voltage

: Battery voltage

SEF247W

EC-396

[KA24DE]

DTC P0505 ISC SYSTEM

2. 

DETECT MALFUNCTIONING PART

Check the following.

●

Harness connectors M59, F27

●

Fuse block (J/B) connector M27

●

10A fuse

●

Harness for open or short between IACV-AAC valve and fuse

>> Repair harness or connectors.

3. 

CHECK OUTPUT SIGNAL CIRCUIT

1.

Turn ignition switch OFF.

2.

Disconnect ECM harness connector.

3.

Check harness continuity between ECM terminal 101 and terminal 1.
Refer to Wiring Diagram.

4.

Also check harness for short to ground and short to power.

OK or NG

OK

>> GO TO 4.

NG

>> Repair open circuit or short to ground or short to power in harness or connectors.

4. 

CHECK IACV-AAC VALVE

Disconnect IACV-AAC valve harness connector.

●

Check IACV-AAC valve resistance.

●

Check plunger for seizing or sticking.

●

Check for broken spring.

OK or NG

OK

>> GO TO 5.

NG

>> Replace IACV-AAC valve.

5. 

CHECK INTERMITTENT INCIDENT 

Perform 

EC-120, "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT"

 .

>> INSPECTION END.

Continuity should exist.

Resistance

: Approximately 10 

Ω [at 25°C (77°F)]

SEF249W

DTC P0506 ISC SYSTEM

EC-397

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EC

DTC P0506 ISC SYSTEM

PFP:23781

Description

UBS00D92

SYSTEM DESCRIPTION

This system automatically controls engine idle speed to a specified level. Idle speed is controlled through fine
adjustment of the amount of air which bypasses the throttle valve via IACV-AAC valve. The IACV-AAC valve
repeats ON/OFF operation according to the signal sent from the ECM. The camshaft position sensor detects
the actual engine speed and sends a signal to the ECM. The ECM then controls the ON/OFF time of the IACV-
AAC valve so that engine speed coincides with the target value memorized in ECM. The target engine speed
is the lowest speed at which the engine can operate steadily. The optimum value stored in the ECM is deter-
mined by taking into consideration various engine conditions, such as during warm up, deceleration, and
engine load (air conditioner, power steering and cooling fan operation). 

COMPONENT DESCRIPTION

The IAC valve-AAC valve is moved by ON/OFF pulses from the
ECM. The longer the ON pulse, the greater the amount of air that will
flow through the valve. The more air that flows through the valve, the
higher the idle speed.

CONSULT-II Reference Value in Data Monitor Mode

UBS00D93

On Board Diagnosis Logic

UBS00D94

Sensor

Input Signal to ECM

ECM function

Actuator

Camshaft position sensor

Engine speed

Idle air control

IACV-AAC valve

Mass air flow sensor

Amount of intake air

Engine coolant temperature sensor

Engine coolant temperature

Ignition switch

Start signal

Throttle position sensor

Throttle position

Park/neutral position (PNP) switch

Park/Neutral position

Air conditioner switch

Air conditioner operation

Power steering oil pressure switch

Power steering load signal

Battery

Battery voltage

Vehicle speed sensor

Vehicle speed

Intake air temperature sensor

Intake air temperature

SEF040E

MONITOR ITEM

CONDITION

SPECIFICATION

IACV-AAC/V

●

Engine: After warming up

●

Air conditioner switch: OFF

●

Shift lever: P or N

●

No-load

Idle

Approx. 30%

2,000 rpm

—

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0506

Idle speed control sys-
tem RPM lower than 
expected

The idle speed is less than the target idle 
speed by 100 rpm or more.

●

Harness or connectors
(The IACV-AAC valve circuit is open or 
shorted)

●

IACV-AAC valve

EC-398

[KA24DE]

DTC P0506 ISC SYSTEM

DTC Confirmation Procedure

UBS00D95

NOTE:
If “DTC Confirmation Procedure” has been previously conducted, always turn ignition switch OFF and wait at
least 5 seconds before conducting the next test.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 11V at idle.

 WITH CONSULT-II

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 again and select “DATA MONITOR”
mode with CONSULT-II.

4.

Start engine and run it for at least 1 minute at idle speed.

5.

If 1st trip DTC is detected, go to 

EC-400, "Diagnostic Procedure"

.

 WITH GST

Follow the procedure “WITH CONSULT-II”.

SEF174Y