Ins INFINITI QX56 2004 Factory Service Manual

DTC P1572 ICC BRAKE SWITCH
EC-533
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Revision: August 20072004 QX56
3. Check continuity between stop lamp switch terminals 3 and 4
under the following conditions.
If NG, adjust stop lamp switch installation, refer to BR-6,
"BRAKE PEDAL" , and perform step 3 again.
ICC BRAKE HOLD RELAY
1. Apply 12V direct current between ICC brake hold relay terminals 1 and 2.
2. Check continuity between relay terminals 3 and 4, 6 and 7 under
the following conditions.
3. If NG, replace ICC brake hold relay.
Condition Continuity
When brake pedal is fully released. Should not exist.
When brake pedal is slightly depressed. Should exist.
PBIB2310E
Condition Between terminals Continuity
12V direct current supply
between terminals 1 and 23 and 4 Should not exist
6 and 7 Should exist
No current supply3 and 4 Should exist
6 and 7 Should not exist
MBIB0063E

EC-534Revision: August 2007
DTC P1572 ASCD BRAKE SWITCH
2004 QX56
DTC P1572 ASCD BRAKE SWITCHPFP:25320
Component DescriptionUBS00HBF
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 this input of two kinds (ON/OFF signal).
Refer to EC-647, "
AUTOMATIC SPEED CONTROL DEVICE
(ASCD)" for the ASCD function.
CONSULT-II Reference Value in Data Monitor ModeUBS00HBG
Specification data are reference values.
On Board Diagnosis LogicUBS00HBH
This self-diagnosis has the one trip detection logic.
The MIL will not light up for this diagnosis.
NOTE:
If DTC P1572 is displayed with DTC P0605, first perform the trouble diagnosis for DTC P0605. Refer to
EC-351, "
DTC P0605 ECM"
BBIA0373E
MONITOR ITEM CONDITION SPECIFICATION
BRAKE SW 1
(ASCD brake switch)

Ignition switch: ON
Brake pedal: Fully released ON

Brake pedal: Slightly depressed OFF
BRAKE SW 2
(stop lamp switch)

Ignition switch: ON
Brake pedal: Fully released OFF

Brake pedal: Slightly depressed ON
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P1572
1572ASCD brake switchWhen 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 open or
shorted.)

Harness or connectors
(The ASCD brake switch circuit is open or
shorted.)

Stop lamp switch

ASCD brake switch

Incorrect stop lamp switch installation

Incorrect ASCD brake switch installation

ECM

DTC P1572 ASCD BRAKE SWITCH
EC-539
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Revision: August 20072004 QX56
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 voltage between ASCD brake switch terminal 1 and
ground with CONSULT-II or tester.
OK or NG
OK >> GO TO 5.
NG >> GO TO 4.
4. DETECT MALFUNCTIONING PART
Check the following.

Harness connectors M31, E152

Fuse block (J/B) connector M4

10A fuse

Harness for open or short between ASCD brake switch and fuse
>> Repair open circuit or 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 harness continuity between ECM terminal 108 and ASCD brake switch terminal 2.
Refer to Wiring Diagram.
4. Also check harness for short to ground or short to power.
OK or NG
OK >> GO TO 6.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
6. CHECK ASCD BRAKE SWITCH
Refer to EC-541, "
Component Inspection" .
OK or NG
OK >> GO TO 11.
NG >> Replace ASCD brake switch.
BBIA0373E
Voltage: Battery voltage
PBIB0857E
Continuity should exist.

EC-540Revision: August 2007
DTC P1572 ASCD BRAKE SWITCH
2004 QX56
7. CHECK STOP LAMP SWITCH POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect stop lamp switch harness connector.
3. Check voltage between stop lamp switch terminal 3 and ground
with CONSULT-II or tester.
OK or NG
OK >> GO TO 9.
NG >> GO TO 8.
8. DETECT MALFUNCTIONING PART
Check the following.

Harness connectors M31, E152

Fuse block (J/B) connector M60

10A fuse

Harness for open or short between stop lamp switch and fuse
>> Repair open circuit or short to ground or short to power in harness or connectors.
9. CHECK STOP LAMP SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminal 101 and stop lamp switch terminal 4.
Refer to Wiring Diagram.
3. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 10.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
10. CHECK STOP LAMP SWITCH
Refer to EC-541, "
Component Inspection"
OK or NG
OK >> GO TO 11.
NG >> Replace stop lamp switch.
BBIA0373E
Voltage: Battery voltage
PBIB2309E
Continuity should exist.

DTC P1572 ASCD BRAKE SWITCH
EC-541
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Revision: August 20072004 QX56
11 . CHECK INTERMITTENT INCIDENT
Refer to EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>>INSPECTION END
Component InspectionUBS00HBL
ASCD BRAKE SWITCH
1. Turn ignition switch OFF.
2. Disconnect ASCD brake switch harness connector.
3. Check harness continuity between ASCD brake switch terminals
1 and 2 under the following conditions.
If NG, adjust ASCD brake switch installation, refer to BR-6,
"BRAKE PEDAL" , and perform step 3 again.
STOP LAMP SWITCH
1. Turn ignition switch OFF.
2. Disconnect stop lamp switch harness connector.
3. Check harness continuity between stop lamp switch terminals 3
and 4 under the following conditions.
If NG, adjust stop lamp switch installation, refer to BR-6,
"BRAKE PEDAL" , and perform step 3 again.
Condition Continuity
When brake pedal is fully released. Should exist.
When brake pedal is depressed. Should not exist.
PBIB1536E
Condition Continuity
When brake pedal is fully released. Should not exist.
When brake pedal is depressed. Should exist.
PBIB2310E

DTC P1574 ICC VEHICLE SPEED SENSOR
EC-543
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Revision: August 20072004 QX56
Diagnostic ProcedureUBS00HZ9
1. CHECK DTC WITH TCM
Check DTC with TCM. Refer to AT - 3 9 , "
OBD-II Diagnostic Trouble Code (DTC)" .
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-11, "
TROUBLE DIAGNOSIS" .
OK or NG
OK >> GO TO 3.
NG >> Repair or replace.
3. CHECK DTC WITH “UNIFIED METER AND A/C AMP”
Refer to DI-5, "
COMBINATION METERS" .
>>INSPECTION END

DTC P1574 ASCD VEHICLE SPEED SENSOR
EC-545
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Revision: August 20072004 QX56
Diagnostic ProcedureUBS00HBP
1. CHECK DTC WITH TCM
Check DTC with TCM. Refer to AT - 3 9 , "
OBD-II Diagnostic Trouble Code (DTC)" .
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-11, "
TROUBLE DIAGNOSIS" .
OK or NG
OK >> GO TO 3.
NG >> Repair or replace.
3. CHECK COMBINATION METER
Check combination meter function.
Refer to DI-5, "
COMBINATION METERS" .
>>INSPECTION END

EC-550Revision: August 2007
DTC P1706 PNP SWITCH
2004 QX56
5. CHECK PNP SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT-II
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminal 102 and combination meter terminal 40.
Refer to Wiring Diagram.
3. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 7.
NG >> GO TO 6.
6. DETECT MALFUNCTIONING PART
Check the following.

Harness connectors M31, E152

Harness for open or short between ECM and combination meter
>> Repair open circuit or short to ground or short to power in harness or connectors.
7. CHECK INTERMITTENT INCIDENT
Refer to EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
OK or NG
OK >> GO TO 8.
NG >> Repair or replace.
8. REPLACE COMBINATION METER
Refer to DI-5, "
COMBINATION METERS" .
>>INSPECTION END Continuity should exist.

EC-554Revision: August 2007
DTC P1805 BRAKE SWITCH
2004 QX56
3. DETECT MALFUNCTIONING PART
Check the following.

Harness connectors M31, E152

Fuse block (J/B) connector M60

10A fuse

Harness for open and short between stop lamp switch and fuse
>> Repair open circuit or short to ground or short to power in harness or connectors.
4. CHECK STOP LAMP SWITCH INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between ECM terminal 101 and stop lamp switch terminal 4.
Refer to Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 5.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
5. CHECK STOP LAMP SWITCH
Refer to EC-555, "
Component Inspection" .
OK or NG
OK >> GO TO 7.
NG >> Replace stop lamp switch.
6. CHECK INTERMITTENT INCIDENT
Refer to EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>>INSPECTION END Continuity should exist.

DTC P1805 BRAKE SWITCH
EC-555
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Revision: August 20072004 QX56
Component InspectionUBS00HC3
STOP LAMP SWITCH
1. Disconnect stop lamp switch harness connector.
2. Check continuity between stop lamp switch terminals 3 and 4
under the following conditions.
3. If NG, adjust stop lamp switch installation, refer to BR-6,
"BRAKE PEDAL" , and perform step 2 again.
BBIA0373E
Conditions Continuity
Brake pedal fully released Should not exist.
Brake pedal depressed Should exist.
PBIB2310E