2010 INFINITI QX56 brake light

P1805 BRAKE SWITCHEC-353
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P1805 BRAKE SWITCH
DescriptionINFOID:0000000005149417
Brake switch signal is applied to the ECM through t
he stop lamp switch when the brake pedal is depressed.
This signal is used mainly to decrease the engine speed when the vehicle is driving.
On Board Diagnosis LogicINFOID:0000000005149418
The MIL will not light up for this self-diagnosis.
FA I L - S A F E M O D E
When the malfunction is detected, the ECM enters fail-safe mode.
DTC Confirmation ProcedureINFOID:0000000005149419
1. Turn ignition switch ON.
2. Fully depress the brake pedal for at least 5 seconds.
3. Erase the DTC with CONSULT-III.
4. Check 1st trip DTC.
5. If 1st trip DTC is detected, go to EC-353, "
Diagnosis Procedure".
Diagnosis ProcedureINFOID:0000000005149420
1.CHECK OVERALL FUNCTION-II
With CONSULT-III
Check “BRAKE SW2” indication in “DATA MONITOR” mode.
Without CONSULT-III
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P1805
1805 Brake switch A brake switch signal is not sent to ECM for ex-
tremely long time while the vehicle is driving. • Harness or connectors
(Stop lamp switch circuit is open or short-
ed.)
• 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
CONDITIONINDICATION
Brake pedal: Fully released OFF
Brake pedal: Slightly depressed ON
Revision: April 20092010 QX56

EC-354
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P1805 BRAKE SWITCH
Check voltage between ECM terminal 101 and ground under the fol-
lowing conditions.
OK or NG
OK >> GO TO 6.
NG >> GO TO 2.
2.CHECK STOP LAMP SWIT
CH POWER SUPPLY CIRCUIT
1. Disconnect stop lamp switch harness connector.
2. Check voltage between stop lamp switch terminal 3 and ground with CONSULT-III or tester.
OK or NG
OK >> GO TO 4.
NG >> GO TO 3.
3.DETECT MALFUNCTIONING PART
Check the following.
• Harness connectors M31, E152
• Fuse block (J/B) connector M60
• 10 A fuse (No. 20)
• Harness for open and short between stop lamp switch and battery
>> 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.
CONDITION VOLTAGE
Brake pedal: Fully released Approximately 0 V
Brake pedal: Slightly depressed Battery voltage
PBIB1537E
BBIA0373E
Voltage: Battery voltage
PBIB2102E
Continuity should exist.
Revision: April 20092010 QX56

P1805 BRAKE SWITCHEC-355
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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-355, "
Component Inspection".
OK or NG
OK >> GO TO 6.
NG >> Replace stop lamp switch.
6.CHECK INTERMITTENT INCIDENT
Refer to GI-35, "
How to Check Terminal" and GI-38, "Intermittent Incident".
>> INSPECTION END
Component InspectionINFOID:0000000005149421
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-15,
"Inspection and Adjustment", and perform step 2 again.
BBIA0373E
ConditionsContinuity
Brake pedal: Fully released Should not exist.
Brake pedal: Slightly depressed Should exist.
PBIB2103E
Revision: April 20092010 QX56

EC-388
< COMPONENT DIAGNOSIS >[VK56DE]
ASCD BRAKE SWITCH
ASCD BRAKE SWITCH
Component DescriptionINFOID:0000000005149464
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-33
for the ASCD function.
Diagnosis ProcedureINFOID:0000000005149465
1.CHECK OVERALL FUNCTION-I
With CONSULT-III
1. Turn ignition switch ON.
2. Select “BRAKE SW1” in “DAT A MONITOR” mode with CONSULT-III.
3. Check “BRAKE SW1” indication under the following conditions.
Without CONSULT-III
1. Turn ignition switch ON.
2. Check voltage between ECM terminal 108 and ground under the
following conditions.
OK or NG
OK >> INSPECTION END.
NG >> GO TO 2.
2.CHECK ASCD BRAKE SWITCH POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
BBIA0373E
CONDITION INDICATION
Brake pedal: Slightly depressed OFF
Brake pedal: Fully released ON
CONDITIONVOLTAGE
Brake pedal: Slightly depressed Approximately 0 V
Brake pedal: Fully released Battery voltage
MBIB0061E
Revision: April 20092010 QX56

EC-390
< COMPONENT DIAGNOSIS >[VK56DE]
ASCD BRAKE SWITCH
Component Inspection
INFOID:0000000005149466
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-15,
"Inspection and Adjustment", and perform step 3 again.
ConditionContinuity
Brake pedal: Fully released Should exist.
Brake pedal: Slightly depressed Should not exist.
PBIB1536E
Revision: April 20092010 QX56

ICC BRAKE SWITCHEC-403
< COMPONENT DIAGNOSIS > [VK56DE]
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ICC BRAKE SWITCH
Component DescriptionINFOID:0000000005149479
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
CCS-13
for the ICC function.
Diagnosis ProcedureINFOID:0000000005175590
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 voltage between ECM terminal 108 and ground under the
following conditions.
OK or NG
OK >> INSPECTION END
NG >> GO TO 2.
2.CHECK ICC BRAKE SWITCH POWER SUPPLY CIRCUIT-I
1. Turn ignition switch OFF.
2. Disconnect ICC brake switch harness connector.
3. Turn ignition switch ON.
BBIA0470E
CONDITION INDICATION
Brake pedal: Slightly depressed OFF
Brake pedal: Fully released ON
CONDITIONVOLTAGE
Brake pedal: Slightly depressed Approximately 0V
Brake pedal: Fully released Battery voltage
MBIB0061E
BBIA0470E
Revision: April 20092010 QX56

ICC BRAKE SWITCHEC-405
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1. Turn ignition switch OFF.
2. Disconnect ECM harness connector.
3. Check harness continuity between ICC brake switch terminal 2 and ECM terminal 108, ICC brake switch
terminal 2 and ICC unit terminal 29.
Refer Wiring Diagram.
4. Also check harness for short to ground and short to power.
OK or NG
OK >> GO TO 7.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
7.CHECK ICC BRAKE SWITCH
Refer to EC-343, "
Component Inspection".
OK or NG
OK >> GO TO 10.
NG >> Replace ICC brake switch.
8.CHECK ICC BRAKE HOLD RELAY POWER SUPPL Y AND GROUND CIRCUIT FOR OPEN AND SHORT
1. Check harness continuity between ICC brake hold relay terminal 1 and ICC unit terminal 47, ICC brake hold relay terminal 2 and ground.
Refer to Wiring Diagram
2. Also check harness for short to ground or short to power in harness or connectors.
OK or NG
OK >> GO TO 9.
NG >> Repair or replace.
9.CHECK ICC BRAKE HOLD RELAY
Refer to EC-343, "
Component Inspection".
OK >> GO TO 10.
NG >> Replace ICC brake hold relay.
10.CHECK INTERMITTENT INCIDENT
Refer to GI-35, "
How to Check Terminal" and GI-38, "Intermittent Incident".
>> INSPECTION END
Component InspectionINFOID:0000000005149481
ICC BRAKE SWITCH
1. Turn ignition switch OFF.
2. Disconnect ICC brake switch harness connector.
3. Check continuity between ICC brake switch terminals 1 and 2
under the following conditions.
If NG, adjust ICC brake switch installation, refer to BR-15,
"Inspection and Adjustment", and perform step 3 again.
Continuity should exist.
Continuity should exist
Condition
Continuity
Brake pedal: Fully released. Should exist.
Brake pedal: Slightly depressed. Should not exist.
PBIB1536E
Revision: April 20092010 QX56

ECM
EC-423
< ECU DIAGNOSIS > [VK56DE]
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LOAD SIGNAL • Ignition switch: ON
Rear window defogger switch is ON
and/or lighting switch is in 2nd.
ON
Rear window defogger switch is OFF
and lighting switch is OFF. OFF
IGNITION SW • Ignition switch: ON → OFF → ON ON → OFF → ON
HEATER FAN SW • Engine: After warming up, idle the
engine Heater fan control switch: ON ON
Heater fan control switch: OFF OFF
BRAKE SW • Ignition switch: ON Brake pedal: Fully released
OFF
Brake pedal: Slightly depressed ON
INJ PULSE-B1
INJ PULSE-B2 • Engine: After warming up
• Selector lever: P or N
• Air conditioner switch: OFF
• No load Idle
2.0 - 2.8 msec
2,000 rpm 1.9 - 2.9 msec
IGN TIMING • Engine: After warming up
• Selector lever: P or N
• Air conditioner switch: OFF
• No load Idle
10° - 20 ° BTDC
2,000 rpm 25° - 45 ° BTDC
CAL/LD VALUE • Engine: After warming up
• Selector lever: P or N
• Air conditioner switch: OFF
• No load Idle
14% - 33%
2,500 rpm 12% - 25%
MASS AIRFLOW • Engine: After warming up
• Selector lever: P or N
• Air conditioner switch: OFF
• No load Idle
3.0 - 9.0 g·m/s
2,500 rpm 9.0 - 28.0 g·m/s
PURG VOL C/V • Engine: After warming up
• Selector lever: P or N
• Air conditioner switch: OFF
• No load Idle
(Accelerator pedal: Not depressed
even slightly, after engine starting.)
0%
2,000 rpm —
INT/V TIM (B1)
INT/V TIM (B2) • Engine: After warming up
• Selector lever: P or N
• Air conditioner switch: OFF
• No load Idle
−5° - 5 °CA
2,000 rpm Approx. 0° - 20°CA
INT/V SOL (B1)
INT/V SOL (B2) • Engine: After warming up
• Selector lever: P or N
• Air conditioner switch: OFF
• No load Idle
0% - 2%
2,000 rpm Approx. 25% - 50%
AIR COND RLY • Engine: After warming up, idle the
engine Air conditioner switch: OFF
OFF
Air conditioner switch: ON
(Compressor: Operates) ON
FUEL PUMP RLY • For 1 second after turning ignition switch ON
•
E

ngine running or cranking ON
• Except above conditions OFF
VENT CONT/V • Ignition switch: ON OFF
THRTL RELAY • Ignition switch: ON ON
COOLING FAN • Engine: After warming up, idle the
engine
• Air conditioner switch: OFF Engine coolant temperature: 99
°C
(210 °F) or less OFF
Engine coolant temperature: 100 °C
(212 °F) or more HI
HO2S2 HTR (B1)
HO2S2 HTR (B2) • Engine speed: Below 3,600 rpm after the following conditions are met.
- Engine: After warming up
- Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and
at idle for 1 minute under no load ON
• Engine speed: Above 3,600 rpm OFF
MONITOR ITEM
CONDITION SPECIFICATION
Revision: April 20092010 QX56