2006 INFINITI QX56 brake light

DTC P1805 BRAKE SWITCHEC-523
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EC
Revision: November 2009 2006 QX56
DTC P1805 BRAKE SWITCHPFP:25320
DescriptionUBS00HBX
Brake switch signal is applied to the ECM through the stop lamp switch when the brake pedal is depressed.
This signal is used mainly to decrease the engine speed when the vehicle is driving.
CONSULT-II Reference Value in Data Monitor ModeUBS00HBY
Specification data are reference values.
On Board Diagnosis LogicUBS00HBZ
The MIL will not light up for this diagnosis.
FAIL-SAFE MODE
When the malfunction is detected, the ECM enters fail-safe mode.
DTC Confirmation ProcedureUBS00HC0
WITH CONSULT-II
1. Turn ignition switch ON.
2. Fully depress the brake pedal for at least 5 seconds.
3. Erase the DTC with CONSULT-II.
4. Select “DATA MONITOR ” mode with CONSULT-II.
5. If 1st trip DTC is detected, go to EC-525, "
Diagnostic Procedure"
.
WITH GST
Follow the procedure “WITH CONSULT-II” above.
MONITOR ITEM CONDITION SPECIFICATION
BRAKE SW

Ignition switch: ON Brake pedal: Fully released
OFF
Brake pedal: Slightly depressed ON
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P1805
1805 Brake switch A brake switch signal is not sent to ECM for
extremely long time while the vehicle is driving.

Harness or connectors
(Stop lamp switch circuit is open or
shorted.)

Stop lamp switch
Engine operating condition in fail-safe mode
ECM controls the electric throttle control actuator by regulating the throttle opening to a small range.
Therefore, acceleration will be poor. Vehicle condition Driving condition
When engine is idling Normal When accelerating Poor acceleration
SEF058Y

DTC P1805 BRAKE SWITCHEC-525
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Revision: November 2009 2006 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 ProcedureUBS00HC2
1. CHECK STOP LAMP SWITCH CIRCUIT
1. Turn ignition switch OFF.
2. Check the stop lamp when depressing and releasing the brake pedal.
OK or NG
OK >> GO TO 4.
NG >> GO TO 2.
2. CHECK STOP LAMP SWITCH POWER SUPPLY CIRCUIT
1. Disconnect stop lamp switch harness connector.
2. Check voltage between stop lamp switch terminal 3 and ground with CONSULT-II or tester.
OK or NG
OK >> GO TO 4.
NG >> GO TO 3.
TER-
MINAL NO. WIRE
COLOR ITEM
CONDITION DATA (DC Voltage)
101 R/W Stop lamp switch [Ignition switch: OFF]

Brake pedal: Fully released
Approximately 0V
[Ignition switch: OFF]

Brake pedal: Slightly depressed BATTERY VOLTAGE
(11 - 14V)
Brake pedal
Stop lamp
Fully released Not illuminated
Slightly depressed Illuminated
BBIA0373E
Voltage: Battery voltage
PBIB2102E

DTC P1805 BRAKE SWITCHEC-527
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Revision: November 2009 2006 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
ConditionsContinuity
Brake pedal: Fully released Should not exist.
Brake pedal: Slightly depressed Should exist.
PBIB2103E

EC-586Revision: November 2009
ASCD BRAKE SWITCH
2006 QX56
ASCD BRAKE SWITCHPFP:25320
Component DescriptionUBS00HDO
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-29, "
AUTOMATIC SPEED CONTROL DEVICE (ASCD)"
for the ASCD function.
CONSULT-II Reference Value in Data Monitor ModeUBS00HDP
Specification data are reference values.
BBIA0373E
MONITOR ITEM CONDITIONSPECIFICATION
BRAKE SW 1
(ASCD brake switch)

Ignition switch: ON
Brake pedal: Fully released ON

Brake pedal: Slightly depressedOFF
BRAKE SW 2
(Stop lamp switch)

Ignition switch: ON
Brake pedal: Fully released OFF

Brake pedal: Slightly depressed ON

EC-588Revision: November 2009
ASCD BRAKE SWITCH
2006 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 ProcedureUBS00HDR
1. CHECK OVERALL FUNCTION-I
With CONSULT-II
1. Turn ignition switch ON.
2. Select “BRAKE SW1 ” in “DATA MONITOR ” mode with CONSULT-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.
TER-
MINAL NO. WIRE
COLOR ITEM
CONDITION DATA (DC Voltage)
101 R/W Stop lamp switch [Ignition switch: OFF]

Brake pedal: Fully released
Approximately 0V
[Ignition switch: OFF]

Brake pedal: Slightly depressed BATTERY VOLTAGE
(11 - 14V)
108 BR/W ASCD brake switch [Ignition switch: ON]

Brake pedal: Slightly depressed
Approximately 0V
[Ignition switch: ON]

Brake pedal: Fully released BATTERY VOLTAGE
(11 - 14V)
CONDITION
INDICATION
Brake pedal: Slightly depressed OFF
Brake pedal: Fully released ON
SEC011D
CONDITIONVOLTAGE
Brake pedal: Slightly depressed Approximately 0V
Brake pedal: Fully released Battery voltage
MBIB0061E

ASCD BRAKE SWITCHEC-589
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Revision: November 2009 2006 QX56
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 following conditions.
OK or NG
OK >> INSPECTION END
NG >> GO TO 7.
CONDITION INDICATION
Brake pedal: Fully released OFF
Brake pedal: Slightly depressed ON
SEC013D
CONDITIONVOLTAGE
Brake pedal: Fully released Approximately 0V
Brake pedal: Slightly depressed Battery voltage
PBIB1537E

EC-592Revision: November 2009
ASCD BRAKE SWITCH
2006 QX56
11 . CHECK INTERMITTENT INCIDENT
Refer to EC-144, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>> INSPECTION END
Component InspectionUBS00HDS
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 3and 4 under the following conditions.
If NG, adjust stop lamp switch installation, refer to BR-6,
"BRAKE PEDAL" , and perform step 3 again.
ConditionContinuity
Brake pedal: Fully released Should exist.
Brake pedal: Slightly depressed Should not exist.
PBIB1536E
ConditionContinuity
Brake pedal: Fully released Should not exist.
Brake pedal: Slightly depressed Should exist.
PBIB2103E

EC-610Revision: November 2009
ICC BRAKE SWITCH
2006 QX56
ICC BRAKE SWITCHPFP:25320
Component DescriptionUBS00L23
When depress on the brake pedal, 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 ModeUBS00L24
Specification data are reference values.
BBIA0470E
MONITOR ITEM CONDITIONSPECIFICATION
BRAKE SW 1
(ICC 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