Page 1713 of 3371

EC-522Revision: August 2007
DTC P1564 ASCD STEERING SWITCH
2004 QX56
3. DETECT MALFUNCTIONING PART
Check the following.
Harness connectors M31, E152
Harness connectors E19, F33
Combination switch (spiral cable)
Harness for open and short between ECM and combination switch
>> Repair open circuit or short to ground or short to power in harness or connectors.
4. CHECK ASCD STEERING SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between ECM terminal 99 and combination switch terminal 14.
Refer to Wiring Diagram.
2. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 6.
NG >> GO TO 5.
5. DETECT MALFUNCTIONING PART
Check the following.
Harness connectors M31, E152
Combination switch (spiral cable)
Harness for open and short between ECM and combination switch
>> Repair open circuit or short to ground or short to power in harness or connectors.
6. CHECK ASCD STEERING SWITCH
Refer to EC-522, "
Component Inspection" .
OK or NG
OK >> GO TO 7.
NG >> Replace ASCD steering switch.
7. CHECK INTERMITTENT INCIDENT
Refer to EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>>INSPECTION END
Component InspectionUBS00HBE
ASCD STEERING SWITCH
1. Disconnect combination switch (spiral cable).
2. Check continuity between ASCD steering switch terminals 14
and 15 with pushing each switch.Continuity should exist.
Switch Condition Resistance [Ω]
ON/OFF(MAIN) switchPressed Approx. 0
Released Approx. 4,000
COAST/SET switchPressed Approx. 660
Released Approx. 4,000
PBIB1673E
Page 1714 of 3371
DTC P1564 ASCD STEERING SWITCH
EC-523
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ACCEL/RESUME switchPressed Approx. 1,480
Released Approx. 4,000
CANCEL switchPressed Approx. 250
Released Approx. 4,000 Switch Condition Resistance [Ω]
Page 1715 of 3371

EC-524Revision: August 2007
DTC P1568 ICC FUNCTION
2004 QX56
DTC P1568 ICC FUNCTIONPFP:18995
On Board Diagnosis LogicUBS00HYW
NOTE:
If DTC P1568 is displayed with DTC U1000, U1001, first perform the trouble diagnosis for DTC
U1000, U1001. Refer to EC-135, "
DTC U1000, U1001 CAN COMMUNICATION LINE" .
If DTC P1568 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605.
Refer to EC-351, "
DTC P0605 ECM".
This self-diagnosis has the one trip detection logic.
The MIL will not light up for this self-diagnosis.
DTC Confirmation ProcedureUBS00HYX
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.
Step 4 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.
WITH CONSULT-II
1. Turn ignition switch ON.
2. Select “DATA MONITOR” mode with CONSULT-II.
3. Press ON/OFF (MAIN) switch on ICC steering switch.
4. Drive the vehicle at more than 40 km/h (25 MPH).
5. Press COAST/SET switch.
6. If DTC is detected, go to EC-524, "
Diagnostic Procedure" .
WITH GST
Follow the procedure “WITH CONSULT-II” above.
Diagnostic ProcedureUBS00HYY
1. REPLACE ICC UNIT
1. Replace ICC unit.
2. Perform ACS-9, "
ACTION TEST" .
3. Check DTC of ICC unit. Refer to ACS-36, "
TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMS" .
>>INSPECTION END
DTC No. Trouble Diagnosis Name DTC Detecting Condition Possible Cause
P1568
1568ICC functionECM detects a difference between signals
from ICC unit is out of specified range.
Harness or connectors
(The CAN communication line is open or
shorted.)
ICC unit
ECM
SEF 0 58 Y
Page 1716 of 3371

DTC P1572 ICC BRAKE SWITCH
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DTC P1572 ICC BRAKE SWITCHPFP:25320
Component DescriptionUBS00HYZ
When the brake pedal is depressed, ICC brake switch is turned OFF
and stop lamp switch is turned ON. ECM detects the state of the
brake pedal by this input of two kinds (ON/OFF signal).
Refer to ACS-6, "
DESCRIPTION" for the ICC function.
CONSULT-II Reference Value in Data Monitor ModeUBS00HZ0
Specification data are reference values.
On Board Diagnosis LogicUBS00HZ1
NOTE:
If DTC P1572 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605.
Refer to EC-351, "
DTC P0605 ECM" .
This diagnosis has the one trip detection logic.
The MIL will not light up for this self-diagnosis.
DTC Confirmation ProcedureUBS00HZ2
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:
Steps 3 and 4 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.
WITH CONSULT-II
1. Start engine.
BBIA0470E
MONITOR ITEM CONDITION SPECIFICATION
BRAKE SW1
(ICC brake switch)
Ignition switch: ONBrake pedal: Fully released ON
Brake pedal: Slightly depressed OFF
BRAKE SW2
(stop lamp switch)
Ignition switch: ONBrake pedal: Fully released OFF
Brake pedal: Slightly depressed ON
DTC No. Trouble Diagnosis Name DTC Detecting Condition Possible Cause
P1572
1572ICC brake switchON signals from the stop lamp switch and the
ICC brake switch are sent to ECM at the same
time.
Harness or connectors
(The stop lamp switch circuit is open or
shorted.)
Harness or connectors
(The ICC brake switch circuit is open or
shorted.)
Stop lamp switch
ICC brake switch
ICC brake hold relay
Incorrect stop lamp switch installation
Incorrect ICC brake switch installation
ECM
Page 1717 of 3371
EC-526Revision: August 2007
DTC P1572 ICC BRAKE SWITCH
2004 QX56
2. Select “DATA MONITOR” mode with CONSULT-II.
3. Drive the vehicle for at least 5 consecutive seconds under the following condition.
If DTC is detected, go to EC-528, "
Diagnostic Procedure" .
If DTC is not detected, go to the following step.
4. Drive the vehicle for at least 5 consecutive seconds under the following condition.
5. If DTC is detected, go to EC-528, "
Diagnostic Procedure" .
WITH GST
Follow the procedure “WITH CONSULT-II” above.
VHCL SPEED SE More than 30 km/h (19 MPH)
Selector lever Suitable position
VHCL SPEED SE More than 30 km/h (19 MPH)
Selector lever Suitable position
Driving locationDepress the brake pedal for more than
five seconds so as not to come off from
the above-mentioned condition.
Page 1718 of 3371
DTC P1572 ICC BRAKE SWITCH
EC-527
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Wiring Diagram UBS00HZ3
BBWA2028E
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EC-528Revision: August 2007
DTC P1572 ICC BRAKE SWITCH
2004 QX56
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.
Diagnostic ProcedureUBS00HZ4
1. CHECK OVERALL FUNCTION-I
With CONSULT-II
1. Turn ignition switch ON.
2. Select “BRAKE SW1” in “DATA MONITOR” mode with CON-
SULT-II.
3. Check “BRAKE SW1” indication under the following conditions.
Without CONSULT-II
1. Turn ignition switch ON.
2. Check voltage between ECM terminal 108 and ground under the
following conditions.
OK or NG
OK >> GO TO 2.
NG >> GO TO 3.
TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
101 R/W Stop lamp switch[Ignition switch: OFF]
Brake pedal: Fully releasedApproximately 0V
[Ignition switch: OFF]
Brake pedal: Slightly depressedBATTERY VOLTAGE
(11 - 14V)
108 BR/W ICC brake switch[Ignition switch: ON]
Brake pedal: Slightly depressedApproximately 0V
[Ignition switch: ON]
Brake pedal: Fully releasedBATTERY VOLTAGE
(11 - 14V)
CONDITION INDICATION
When brake pedal is slightly depressed OFF
When brake pedal is fully released ON
SEC0 11D
CONDITION VOLTAGE
When brake pedal is slightly depressed Approximately 0V
When brake pedal is fully released Battery voltage
MBIB0061E
Page 1720 of 3371
DTC P1572 ICC BRAKE SWITCH
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2. CHECK OVERALL FUNCTION-II
With CONSULT-II
Check “BRAKE SW2” indication in “DATA MONITOR” mode.
Without CONSULT-II
Check voltage between ECM terminal 101 and ground under the fol-
lowing conditions.
OK or NG
OK >> GO TO 15.
NG >> GO TO 10.
3. CHECK DTC WITH ICC UNIT
Refer to ACS-26, "
TROUBLE DIAGNOSIS — GENERAL DESCRIPTION" .
OK or NG
OK >> GO TO 4.
NG >> Repair or replace.
CONDITION INDICATION
When brake pedal is fully released OFF
When brake pedal is slightly depressed ON
SEC0 13 D
CONDITION VOLTAGE
When brake pedal is fully released Approximately 0V
When brake pedal is slightly depressed Battery voltage
MBIB0060E