Infiniti FX35, FX50 (S51). Manual - part 720

P1568 ICC FUNCTION

EC-421

< DTC/CIRCUIT DIAGNOSIS >

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P1568 ICC FUNCTION

DTC Logic

INFOID:0000000005237028

DTC DETECTION LOGIC

NOTE:
• If DTC P1568 is displayed with DTC UXXXX, first perform the trouble diagnosis for DTC UXXXX.
• If DTC P1568 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605. Refer

to 

EC-356, "DTC Logic"

.

• If DTC P1568 is displayed with DTC P0607, first perform the trouble diagnosis for DTC P0607. Refer

to 

EC-358, "DTC Logic"

.

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following procedure
before conducting the next test.
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.

TESTING CONDITION:
Step 2 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.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE

1.

Turn ignition switch ON.

2.

Press MAIN switch on ICC steering switch.

3.

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

CAUTION:

Always drive vehicle at a safe speed.

4.

Press SET/COAST switch.

5.

Check DTC.

Is DTC detected?

YES

>> Go to 

EC-421, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000005237029

1.

REPLACE ICC SENSOR INTEGRATED UNIT

1.

Replace ICC sensor integrated unit.

2.

Perform 

CCS-18, "ACTION TEST : Special Repair Requirement (Vehicle-To-Vehicle Distance Control

Mode)"

.

3.

Check DTC of ICC sensor integrated unit. Refer to 

CCS-44, "Diagnosis Description"

.

>> INSPECTION END

DTC No.

Trouble Diagnosis 

Name

DTC Detecting Condition

Possible Cause

P1568

ICC function

ECM detects a difference between signals 
from ICC sensor integrated unit is out of spec-
ified range.

• Harness or connectors

(The CAN communication line is open or 
shorted.)

• ICC sensor integrated unit
• ECM

EC-422

< DTC/CIRCUIT DIAGNOSIS >

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P1572 ASCD BRAKE SWITCH

P1572 ASCD BRAKE SWITCH

Description

INFOID:0000000005237030

When the brake pedal is depressed, ASCD brake switch is turned OFF and stop lamp switch is turned ON.
ECM detects the state of the brake pedal by those two types of input (ON/OFF signal).
Refer to 

EC-66, "System Description"

 for the ASCD function.

DTC Logic

INFOID:0000000005237031

DTC DETECTION LOGIC

NOTE:
• If DTC P1572 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605. Refer

to 

EC-356, "DTC Logic"

.

• This self-diagnosis has the one trip detection logic. When malfunction A is detected, DTC is not

stored in ECM memory. And in that case, 1st trip DTC and 1st trip freeze frame data are displayed.
1st trip DTC is erased when ignition switch is turned OFF. And even when malfunction A is detected
in two consecutive trips, DTC is not stored in ECM memory.

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following procedure
before conducting the next test.
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.

NOTE:
The procedure for malfunction B is not described. It takes an extremely long time to complete the procedure
for malfunction B. By performing the procedure for malfunction A, the condition that causes malfunction B can
be detected.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE-I

With CONSULT-III

1.

Start engine (VDC switch OFF).

2.

Select “DATA MONITOR” mode with CONSULT-III.

3.

Press MAIN switch and make sure that CRUISE lamp illuminates.

4.

Drive the vehicle for at least 5 consecutive seconds under the following conditions.

CAUTION:

Always drive vehicle at a safe speed.
NOTE:
This procedure 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.

DTC No.

Trouble diagnosis 

name

DTC detecting condition

Possible cause

P1572

ASCD brake switch

A)

When the vehicle speed is above 30 km/h 
(19 MPH), ON signals from the stop lamp 
switch and the ASCD brake switch are sent 
to the ECM at the same time.

• Harness or connectors

(The stop lamp switch circuit is shorted.)

• Harness or connectors

(The ASCD brake switch circuit is shorted.)

• Stop lamp switch
• ASCD brake switch
• Incorrect stop lamp switch installation
• Incorrect ASCD brake switch installation
• ECM

B)

ASCD brake switch signal is not sent to 
ECM for extremely long time while the ve-
hicle is being driven.

VHCL SPEED SE

More than 30 km/h (19 mph)

Selector lever

Suitable position 

P1572 ASCD BRAKE SWITCH

EC-423

< DTC/CIRCUIT DIAGNOSIS >

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5.

Check 1st trip DTC.

With GST

Follow the procedure “With CONSULT-III” above.
Is 1st trip DTC detected?

YES

>> Go to 

EC-423, "Diagnosis Procedure"

.

NO

>> GO TO 3.

3.

PERFORM DTC CONFIRMATION PROCEDURE-II

With CONSULT-III

1.

Drive the vehicle for at least 5 consecutive seconds under the following conditions.

CAUTION:

Always drive vehicle at a safe speed.
NOTE:
This procedure 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.

2.

Check 1st trip DTC.

With GST

Follow the procedure “With CONSULT-III” above.

Is 1st trip DTC detected?

YES

>> Go to 

EC-423, "Diagnosis Procedure"

.

NO

>> INSPECTION END

Diagnosis Procedure

INFOID:0000000005237032

1.

CHECK OVERALL FUNCTION-I

 With CONSULT-III

1.

Turn ignition switch ON.

2.

Select “BRAKE SW1” in “DATA MONITOR” mode with CONSULT-III.

3.

Check “BRAKE SW1” indication under the following conditions.

 Without CONSULT-III

1.

Turn ignition switch ON.

2.

Check the voltage between ECM harness connector terminals as follows.

Is the inspection result normal?

YES

>> GO TO 2.

NO

>> GO TO 3.

2.

CHECK OVERALL FUNCTION-II

VHCL SPEED SE

More than 30 km/h (19 mph)

Selector lever

Suitable position 

Driving location

Depress the brake pedal for more than 5 
seconds so as not to come off from the 
above-mentioned vehicle speed.

Monitor item

Condition

Indication

BRAKE SW1

Brake pedal

Slightly depressed

OFF

Fully released

ON

ECM

Condition

Voltage (V)

Connector

+

–

Terminal

Terminal

M107

126

(ASCD brake switch signal)

128

Brake pedal

Slightly depressed

Approx. 0

Fully released

Battery voltage

EC-424

< DTC/CIRCUIT DIAGNOSIS >

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P1572 ASCD BRAKE SWITCH

 With CONSULT-III

Select “BRAKE SW2” and check indication under the following conditions.

 Without CONSULT-III

Check the voltage between ECM harness connector terminals under the following conditions.

Is the inspection result normal?

YES

>> GO TO 13.

NO

>> GO TO 8.

3.

CHECK ASCD BRAKE SWITCH POWER SUPPLY CIRCUIT

1.

Turn ignition switch OFF.

2.

Disconnect ASCD brake switch harness connector.

3.

Turn ignition switch ON.

4.

Check the voltage between ASCD brake switch harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 5.

NO

>> GO TO 4.

4.

DETECT MALFUNCTIONING PART

Check the following.
• Fuse block (J/B) connector E103
• 10 A fuse (No. 3)
• Harness for open or short between ASCD brake switch and fuse

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

5.

CHECK ASCD BRAKE SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Disconnect ECM harness connector.

3.

Check the continuity between ASCD brake switch harness connector and ECM harness connector.

4.

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

Is the inspection result normal?

YES

>> GO TO 7.

NO

>> GO TO 6.

Monitor item

Condition

Indication

BRAKE SW2

Brake pedal

Slightly depressed

ON

Fully released

OFF

ECM

Condition

Voltage (V)

Connector

+

–

Terminal

Terminal

M107

122

(Stop lamp switch signal)

128

Brake pedal

Slightly depressed

Battery voltage

Fully released

Approx. 0

ASCD brake switch

Ground

Voltage

Connector

Terminal

E109

1

Ground

Battery voltage

ASCD brake switch

ECM

Continuity

Connector

Terminal

Connector

Terminal

E109

2

M107

126

Existed