Infiniti FX35 / FX45. Manual - part 579

DTC P1574 ASCD VEHICLE SPEED SENSOR

EC-1077

< SERVICE INFORMATION >

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DTC P1574 ASCD VEHICLE SPEED SENSOR

Component Description

INFOID:0000000001326953

The ECM receives two vehicle speed sensor signals via CAN communication line. One is sent from “unified
meter and A/C amp.”, and the other is from TCM (Transmission control module). The ECM uses these signals
for ASCD control. Refer to 

EC-615

 for ASCD functions.

On Board Diagnosis Logic

INFOID:0000000001326954

This self-diagnosis has the one trip detection logic.
The MIL will not light up for this diagnosis.
NOTE:
• If DTC P1574 is displayed with DTC U1000, U1001, first perform the trouble diagnosis for DTC U1000,

U1001. Refer to 

EC-724

.

• If DTC P1574 is displayed with DTC U1010, first perform the trouble diagnosis for DTC U1010. Refer

to 

EC-726

.

• If DTC P1574 is displayed with DTC P0500, first perform the trouble diagnosis for DTC P0500. Refer

to 

EC-992

• If DTC P1574 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605. Refer

to 

EC-1007

DTC Confirmation Procedure

INFOID:0000000001326955

CAUTION:

Always drive vehicle at a safe speed.
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
TESTING CONDITION:
Step 3 may be conducted with the drive wheels lifted in the shop or by driving the vehicle. If a road test
is expected to be easier, it is unnecessary to lift the vehicle.

1.

Start engine (VDC switch OFF).

2.

Drive the vehicle at more than 40 km/h (25 MPH).

3.

Check DTC.

4.

If DTC is detected, go to 

EC-1077, "Diagnosis Procedure"

.

Diagnosis Procedure

INFOID:0000000001326956

1.

CHECK DTC WITH TCM

Check DTC with TCM. Refer to 

AT-38

.

OK or NG

OK

>> GO TO 2.

NG

>> Perform trouble shooting relevant to DTC indicated.

2.

CHECK DTC WITH “ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)”

Refer to 

BRC-13

.

OK or NG

DTC No.

Trouble diagnosis 

name

DTC detecting condition

Possible cause

P1574
1574

ASCD vehicle speed 
sensor

ECM detects a difference between two vehicle 
speed signals is out of the specified range.

• Harness or connectors

(The CAN communication line is open or 
shorted.)

• Unified meter and A/C amp.
• ABS actuator and electric unit (control unit)
• Wheel sensor
• TCM
• ECM

EC-1078

< SERVICE INFORMATION >

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DTC P1574 ASCD VEHICLE SPEED SENSOR

OK

>> GO TO 3.

NG

>> Repair or replace.

3.

CHECK DTC WITH “UNIFIED METER AND A/C AMP.”

Refer to 

DI-26

.

>> INSPECTION END

DTC P1715 INPUT SPEED SENSOR (TURBINE REVOLUTION SENSOR)

EC-1079

< SERVICE INFORMATION >

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DTC P1715 INPUT SPEED SENSOR (TURBINE REVOLUTION SENSOR)

Description

INFOID:0000000001326957

ECM receives turbine revolution sensor signal from TCM through CAN communication line. ECM uses this
signal for engine control.

CONSULT-III Reference Value in Data Monitor Mode

INFOID:0000000001326958

Specification data are reference values.

On Board Diagnosis Logic

INFOID:0000000001326959

NOTE:
• If DTC P1715 is displayed with DTC U1000, U1001 first perform the trouble diagnosis for DTC U1000,

U1001. Refer to 

EC-724

.

• If DTC P1715 is displayed with DTC U1010 first perform the trouble diagnosis for DTC U1010. Refer

to 

EC-726

.

• If DTC P1715 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605. Refer

to 

EC-1007

.

• If DTC P1715 is displayed with DTC P0335, first perform the trouble diagnosis for DTC P0335. Refer

to 

EC-906

.

• If DTC P1715 is displayed with DTC P0340, first perform the trouble diagnosis for DTC P0340. Refer

to 

EC-911

.

The MIL will not lights up for this diagnosis.

Diagnosis Procedure

INFOID:0000000001326960

1.

CHECK DTC WITH TCM

Check DTC with TCM. Refer to 

AT-38, "OBD-II Diagnostic Trouble Code (DTC)"

.

OK or NG

OK

>> GO TO 2.

NG

>> Perform trouble shooting relevant to DTC indicated.

2.

REPLACE TCM

Replace TCM. Refer to 

AT-41

.

>> INSPECTION END

MONITOR ITEM

CONDITION

SPECIFICATION

I/P PULLY SPD

• Vehicle speed: More than 20 km/h (12 MPH)

Almost the same speed as 
the tachometer indication

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P1715
1715

Input speed sensor
(Turbine revolution sen-
sor)
(TCM output)

Turbine revolution sensor signal is differ-
ent from the theoretical value calculated 
by ECM from revolution sensor signal and 
engine rpm signal.

• Harness or connectors

(The CAN communication line is open or short-
ed)

• Harness or connectors

(Turbine revolution sensor circuit is open or 
shorted)

• TCM

EC-1080

< SERVICE INFORMATION >

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DTC P1800 VIAS CONTROL SOLENOID VALVE

DTC P1800 VIAS CONTROL SOLENOID VALVE

Component Description

INFOID:0000000001326961

The VIAS control solenoid valve (1) cuts the intake manifold vacuum
signal for power valve actuator. It responds to ON/OFF signals from
the ECM. When the solenoid is off, the vacuum signal from the
intake manifold is cut. When the ECM sends an ON signal the coil
pulls the plunger downward and feeds the vacuum signal to the
power valve actuator.
• Vacuum tank (2)

CONSULT-III Reference Value in Data Monitor Mode

INFOID:0000000001326962

Specification data are reference values.

On Board Diagnosis Logic

INFOID:0000000001326963

The MIL will not light up for this self-diagnosis.

DTC Confirmation Procedure

INFOID:0000000001326964

NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is between 11V at idle.

1.

Start engine and let it idle for at least 5 seconds.

2.

Check 1st trip DTC.

3.

If 1st trip DTC is detected, go to 

EC-1082, "Diagnosis Procedure"

.

PBIB3236E

MONITOR ITEM

CONDITION

SPECIFICATION

VIAS S/V

• Selector lever: P or N

ON

• Engine speed: More than 5,000 rpm

• Selector lever: Except P or N
• Engine speed: Less than 5,000 rpm

OFF

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P1800
1800

VIAS control solenoid valve cir-
cuit 

An excessively low or high voltage signal 
is sent to ECM through the valve

• Harness or connectors

(The solenoid valve circuit is open or 
shorted.)

• VIAS control solenoid valve