2011 INFINITI QX56 ignition

EC-40
< SYSTEM DESCRIPTION >[VK56VD]
SYSTEM
SYSTEM DESCRIPTION
Low fuel pressure control
 The low fuel pressure pump is controlled by the f
uel pump control module (FPCM) and pumps fuel according
to a driving condition. The pumped fuel passes through t he fuel filter and is sent to the high pressure fuel
pump. FPCM controls the low pressure fuel pump, ac cording to a signal from ECM as shown in the table
below.
 Low fuel pressure is adjusted by the fuel pressure regulator.
High fuel pressure control
 The high pressure fuel pump raises the pressure of the fuel sent from the low pressure fuel pump. Actuated
by the camshaft, the high pressure fuel pump activates the high pressure fuel pump solenoid based on a sig-
nal received from ECM, and adjusts the amount of di scharge by changing the timing of closing the inlet
check valve to control fuel rail pressure.
COOLING FAN CONTROL
JSBIA0235GB
Conditions Amount of fuel flow Supplied voltage
After a laps of 1 second after ignition ON OFF 0 V
 For 1 second after turning ignition switch ON
 Engine is running under low load and low speed conditions Low Approximately 8.5 V
 Engine cranking
 Engine coolant temperature is below 10 °C (50 °F)
 Engine is running under high load and high speed conditions High
Battery voltage
(11 – 14 V)
Except the above Mid Approximately 10 V
Revision: 2010 May2011 QX56

SYSTEMEC-41
< SYSTEM DESCRIPTION > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
COOLING FAN CONTROL : System DiagramINFOID:0000000006217703
COOLING FAN CONTROL : System DescriptionINFOID:0000000006217704
INPUT/OUTPUT SIGNAL CHART
*1: The ECM determines the engine speed by the signals of crankshaft position and camshaft position.
*2: This signal is sent to ECM via the CAN communication line.
SYSTEM DESCRIPTION
 Based on a signal transmitted from each sensor, ECM calc
ulates a target fan speed responsive to a driving
condition. In addition, ECM calculates a fan pulley speed according to an engine speed and transmits a cool-
ing fan request signal to IPDM E/R via the CAN comm unication line to satisfy the target fan speed. Then,
IPDM E/R transmits ON/OFF pulse duty signal to electrically-controlled cooling fan coupling.
The cooling fan speed sensor detects a cooling f an speed and transmits the detection result to ECM.
 ECM judges the start signal state from the engine speed signal and battery voltage.
ELECTRIC IGNITION SYSTEM
JSBIA0237GB
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor Engine speed*
1
Cooling fan speed request
signal*2
IPDM E/R
↓
Electrically-controlled cooling fan
coupling
Camshaft position sensor Camshaft position
Engine coolant temperature sensor Engine coolant temperature
Refrigerant pressure sensor Refrigerant pressure
Intake air temperature sensor Intake air temperature
Battery Battery voltage
Combination meter
Vehicle speed signal*
2
BCMA/C switch signal*2
Cooling fan speed sensor Cooling fan speed
Revision: 2010 May2011 QX56

EC-42
< SYSTEM DESCRIPTION >[VK56VD]
SYSTEM
ELECTRIC IGNITION SYSTEM : System Diagram
INFOID:0000000006217705
ELECTRIC IGNITION SYSTEM : System DescriptionINFOID:0000000006217706
INPUT/OUTPUT SIGNAL CHART
*1: ECM determines the start signal status by the signals of engine speed and battery voltage.
*2: This signal is sent to the ECM via the CAN communication line.
SYSTEM DESCRIPTION
Ignition order: 1 - 8 - 7 - 3 - 6 - 5 - 4 - 2
The ignition timing is controlled by the ECM to maintain the best air-fuel ratio for every running condition of the
engine. The ignition timing data is stored in the ECM.
The ECM receives information such as the injection pulse width and camshaft position sensor signal. Comput-
ing this information, ignition signals are transmitted to the power transistor.
During the following conditions, the ignition timing is re vised by the ECM according to the other data stored in
the ECM.
 At starting
 During warm-up
 At idle
 At low battery voltage
 During acceleration
The knock sensor retard system is designed only for emergencies. The basic ignition timing is programmed
within the anti-knocking zone, if recommended fuel is used under dry conditions. The retard system does not
operate under normal driving conditions. If engine knocking occurs, the knock sensor monitors the condition.
The signal is transmitted to the ECM. The ECM retards the ignition timing to eliminate the knocking condition.
JPBIA3271GB
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor Engine speed*
1
Piston position
Ignition timing
controlIgnition coil
(with power transistor)
Camshaft position sensor
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
TCM Gear position
Battery
Battery voltage*
1
Knock sensor Engine knocking condition
Combination meterVehicle speed*
2
Revision: 2010 May2011 QX56

DIAGNOSIS SYSTEM (ECM)EC-59
< SYSTEM DESCRIPTION > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
The SRT will also indicate “INCMP” if the self-diagnosis
memory is erased for any reason or if the ECM mem-
ory power supply is interrupted for several hours.
If, during the state emissions inspection, the SRT indica tes “CMPLT” for all test items, the inspector will con-
tinue with the emissions test. However, if the SRT i ndicates “INCMP” for one or more of the SRT items the
vehicle is returned to the customer untested.
NOTE:
If MIL is ON during the state emissi ons inspection, the vehicle is also returned to the customer untested even
though the SRT indicates “CMPLT” for all test items. T herefore, it is important to check SRT (“CMPLT”) and
DTC (No DTCs) before the inspection.
SRT SET TIMING
SRT is set as “CMPLT” after self-diagnosis has been performed one or more times. Completion of SRT is
done regardless of whether the result is OK or NG. T he set timing is different between OK and NG results and
is shown in the table below.
OK: Self-diagnosis is carried out and the result is OK.
NG: Self-diagnosis is carried out and the result is NG.
—: Self-diagnosis is not carried out.
When all SRT related self-diagnoses show OK results in a single cycle (Ignition OFF-ON-OFF), the SRT will
indicate “CMPLT”. → Case 1 above
When all SRT related self-diagnoses show OK results through several different cycles, the SRT will indicate
“CMPLT” at the time the respective se lf-diagnoses have at least one OK result. → Case 2 above
If one or more SRT related self-diagnoses show NG results in 2 consecutive cycles, the SRT will also indicate
“CMPLT”. → Case 3 above
The table above shows that the minimum number of cycles for setting SRT as “INCMP” is the number one (1)
for each self-diagnosis (Case 1 & 2) or the number two (2) for one of self-diagnoses (Case 3). However, in
preparation for the state emissions inspection, it is unnecessary for each self-diagnosis to be executed twice
(Case 3) for the following reasons:
 The SRT will indicate “CMPLT” at the time the respective self-diagnoses have one (1) OK result.
 The emissions inspection requires “CMPLT” of the SRT only with OK self-diagnosis results.
 During SRT driving pattern, the 1st trip DTC (NG) is detected prior to “CMPLT” of SRT and the self-diagnosis
memory must be erased from the ECM after repair.
 If the 1st trip DTC is erased, all the SRT will indicate “INCMP”.
NOTE:
SRT can be set as “CMPLT” together with the DTC(s) . Therefore, DTC check must always be carried out
prior to the state emission inspection even though the SRT indicates “CMPLT”.
Self-diagnosis result Example
Diagnosis Ignition cycle
← ON →OFF ← ON →OFF ← ON →OFF ← ON →
All OK Case 1 P0400 OK (1) — (1) OK (2) — (2) P0402 OK (1) — (1) — (1) OK (2)
P1402 OK (1) OK (2) — (2) — (2)
SRT of EGR “CMPLT” “CMPLT” “CMPLT” “CMPLT”
Case 2 P0400 OK (1) — (1) — (1) — (1) P0402 — (0) — (0) OK (1) — (1)
P1402 OK (1) OK (2) — (2) — (2)
SRT of EGR “INCMP” “INCMP” “CMPLT” “CMPLT”
NG exists Case 3 P0400 OK OK — — P0402 — — — —
P1402 NG — NG NG
(Consecutive
NG)
(1st trip) DTC 1st trip DTC — 1st trip DTC
DTC
(= MIL ON)
SRT of EGR “INCMP” “INCMP” “INCMP” “CMPLT”
Revision: 2010 May2011 QX56

EC-60
< SYSTEM DESCRIPTION >[VK56VD]
DIAGNOSIS SYSTEM (ECM)
DIAGNOSIS DESCRIPTION : Malf unction Indicator Lamp (MIL)
INFOID:0000000006217727
DESCRIPTION
The MIL is located on the instrument panel.
1. The MIL will light up when the ignition switch is turned ON with-
out the engine running. This is a bulb check.
If the MIL does not light up, refer to EC-515, "
Component Func-
tion Check".
2. When the engine is started, the MIL should go off. If the MIL remains on, the on board diagnostic system has
detected an engine system malfunction.
On Board Diagn osis FunctionINFOID:0000000006217728
ON BOARD DIAGNOSIS ITEM
The on board diagnostic system has the following functions.
BLUB CHECK MODE
Description
This function allows damage inspection in the MIL bulb (blown, open circuit, etc.).
Operation Procedure
1. Turn ignition switch ON.
2. The MIL on the instrument panel should stay ON.
If it remains OFF, check MIL circuit. Refer to EC-515, "
Diagnosis Procedure".
SRT STATUS MODE
Description
This function allows to read if ECM has completed t he self-diagnoses of major emission control systems and
components. For SRT, refer to EC-58, "
DIAGNOSIS DESCRIPTION : Syst em Readiness Test (SRT) Code".
Operation Procedure
1. Turn ignition switch ON and wait 20 seconds.
2. SRT status is indicated as shown blow.
 ECM continues to illuminate MIL if all SRT codes are set.
SEF217U
Diagnostic test mode Function
Bulb check MIL can be checked.
SRT status ECM can read if SRT codes are set.
Malfunction warning If ECM detects a malfunction, it illuminates or blinks MIL to inform the driver that a malfunction has been detected.
Self-diagnostic results DTCs or 1st trip DTCs stored in ECM can be read.
Accelerator pedal released po-
sition learning ECM can learn the accelerator pedal released position. Refer to
EC-146, "
Description".
Throttle valve closed position
learning ECM can learn the throttle valve closed position. Refer to
EC-147, "
Description".
Idle air volume learning ECM can learn the idle air volume. Refer to EC-148, "
Description".
VVEL control sh aft position
sensor adjustment The initial position of the VVEL control shaft position sensor can be adjusted. Refer to
EC-150, "
De-
scription".
Revision: 2010 May2011 QX56

DIAGNOSIS SYSTEM (ECM)EC-61
< SYSTEM DESCRIPTION > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
 ECM blinks MIL for about 10 seconds if all SRT codes are not set.
MALFUNCTION WARNING MODE
Description
In this function ECM turns on or blinks MIL when it det
ects a malfunction in the emission control system com-
ponents and/or the powertrain control components (which affe ct vehicle emissions) to inform the driver that a
malfunction has been detected.
Operation Procedure
1. Turn ignition switch ON.
2. Check that MIL illuminates. If it remains OFF, check MIL circuit. Refer to EC-515, "
Diagnosis Procedure".
3. Start engine and let it idle.  For two trip detection logic diagnoses, ECM turns on MIL when it detects the same malfunction twice in
the two consecutive driving cycles.
 For 1st trip detection logic diagnoses, ECM turns on MIL when it detects a malfunction in one driving cycle.
 ECM blinks MIL when it detects a malfunction t hat may damage the three way catalyst (misfire).
SELF-DIAGNOSTIC RESULTS MODE
Description
This function allows to indicate DTCs or 1st trip DTCs stored in ECM according to the number of times MIL is
blinking.
How to Set Self-diagnostic Results Mode
NOTE:
 It is better to count the time accurately with a clock.
 It is impossible to switch the diagnostic mode when an accelerator pedal position sensor circuit has a mal-
function.
 After ignition switch is turned off, ECM is a lways released from the “Self-diagnostic results” mode.
1. Confirm that accelerator pedal is fully releas ed, turn ignition switch ON and wait 3 seconds.
2. Repeat the following procedure quickly five times within 5 seconds.  Fully depress the accelerator pedal.
 Fully release the accelerator pedal.
3. Wait 7 seconds, fully depress the accelerator pedal and keep it depressed for approx. 10 seconds until the
MIL starts blinking.
NOTE:
Do not release the accelerator pedal for 10 seconds if MIL starts blinking during this period. This blinking
is displaying SRT status and is continued for another 10 seconds.
4. Fully release the accelerator pedal. ECM has entered to Self-diagnostic results mode.
JMBIA1515GB
Revision: 2010 May2011 QX56

DIAGNOSIS SYSTEM (ECM)EC-63
< SYSTEM DESCRIPTION > [VK56VD]
C
D
E
F
G H
I
J
K L
M A
EC
NP
O
In this way, all the detected malfunctions are classi
fied by their DTC numbers. The DTC 0000 refers to no mal-
function. Refer to EC-98, "
DTC Index".
How to Erase Self-diagnostic Results
By performing this procedure, ECM memory is erased and the following diagnostic information is erased as
well.
 Diagnostic trouble codes
 1st trip diagnostic trouble codes
 Freeze frame data
 1st trip freeze frame data
 System readiness test (SRT) codes
 Test values
NOTE:
Also, if a battery terminal is disconnected, ECM memory is erased and the diagnostic information as listed
above is erased. (The amount of time required for eras ing may vary from a few seconds to several hours.)
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.
4. Turn ignition switch ON.
5. Set ECM in Self-diagnostic results.
6. The diagnostic information has been erased from the backup memory in the ECM. Fully depress the accelerator pedal and keep it depressed for more than 10 seconds.
7. Fully release the accelerator pedal, and confirm the DTC 0000 is displayed.
CONSULT-III FunctionINFOID:0000000006217729
FUNCTION
*: The following emission-related diagnostic information is cleared when the ECM memory is erased.
 Diagnostic trouble codes
 1st trip diagnostic trouble codes
 Freeze frame data
 1st trip freeze frame data
 System readiness test (SRT) codes
Test values
WORK SUPPORT MODE
Work Item
Diagnostic test mode Function
Work support This mode enables a technician to adjust some devices faster and more accurately by following the in-
dications on the CONSULT-III unit.
Self diagnostic result Self-diagnostic results such as 1st trip DTC, DTCs and 1st trip freeze frame data or freeze frame data
can be read and erased quickly.*
Data monitor Input/Output data in the ECM can be read.
Active test Diagnostic Test Mode in which CONSULT-III drives some actuators apart from the ECMs and also shifts
some parameters in
a specified range.
DTC & SRT confirmation The status of system monitoring tests and the self-diagnosis status/results can be confirmed.
Function test This mode is used to inform customers when the vehicle requires periodic maintenance.
ECU identification ECM part number can be read.
Revision: 2010 May2011 QX56

EC-64
< SYSTEM DESCRIPTION >[VK56VD]
DIAGNOSIS SYSTEM (ECM)
*: This function is not necessary
in the usual service procedure.
SELF-DIAG RESULTS MODE
Self Diagnostic Item
Regarding items of DTC and 1st trip DTC, refer to EC-98, "DTC Index".
How to Read DTC and 1st Trip DTC
DTCs and 1st trip DTCs related to the malfunction are displayed in “Self-diag results”.
 When ECM detects a 1st trip DTC, “1t” is displayed for “TIME”.
 When ECM has detected a current DTC, “0” is displayed for “TIME”.
 If “TIME” is neither “0” nor “1t”, the DTC occurred in the past and ECM shows the number of times the vehi-
cle has been driven since the last detection of the DTC.
How to Erase DTC and 1st Trip DTC
NOTE:
 If the ignition switch stays ON after repair work, be su re to turn ignition switch OFF once. Wait at least 10
seconds and then turn it ON (engine stopped) again.
 If the DTC is not for A/T related items (see EC-98, "
DTC Index"), skip step 1.
1. Erase DTC in TCM. Refer to TM-60, "
Diagnosis Description".
2. Select “ENGINE” with CONSULT-III.
3. Select “SELF-DIAG RESULTS”.
4. Touch “ERASE”. (DTC in ECM will be erased.)
WORK ITEM CONDITION USAGE
IDLE AIR VOL LEARN  THE IDLE AIR VOLUME THAT KEEPS THE ENGINE
WITHIN THE SPECIFIED RANGE IS MEMORIZED IN
ECM. When learning the idle air volume
EVAP SYSTEM CLOSE CLOSE THE EVAP CANISTER VENT CONTROL VALVE IN
ORDER TO MAKE EVAP SYSTEM CLOSE UNDER THE
FOLLOWING CONDITIONS.
 IGN SW ON
 ENGINE NOT RUNNING
 AMBIENT TEMPERATURE IS ABOVE 0
°C (32 °F).
 NO VACUUM AND NO HIGH PRESSURE IN EVAP SYS-
TEM
 FUEL TANK TEMP. IS MORE THAN 0 °C (32 °F).
 WITHIN 10 MINUTES AFTER STARTING “EVAP SYS-
TEM CLOSE”
 WHEN TRYING TO EXECUTE “EVAP SYSTEM CLOSE” UNDER THE CONDITION EXCEPT ABOVE, CONSULT-
III WILL DISCONTINUE IT AND DISPLAY APPROPRI-
ATE INSTRUCTION.
NOTE:
WHEN STARTING ENGINE, CONSULT-III MAY DIS-
PLAY “BATTERY VOLTAGE IS LOW. CHARGE BAT-
TERY”, EVEN WHEN USING A CHARGED BATTERY. When detecting EVAP vapor leak
in the EVAP system
FUEL PRESSURE RELEASE  FUEL PUMP WILL STOP BY TOUCHING “START” DUR-
ING IDLING.
CRANK A FEW TIMES AFTER ENGINE STALLS. When releasing fuel pressure from
fuel line
SELF-LEARNING CONT  THE COEFFICIENT OF SELF-LEARNING CONTROL
MIXTURE RATIO RETURNS TO THE ORIGINAL COEF-
FICIENT. When clearing mixture ratio self-
learning value
TARGET IDLE RPM ADJ*  IDLE CONDITION When setting target idle speed
VIN REGISTRATION  IN THIS MODE, VIN IS REGISTERED IN ECM. When registering VIN in ECM
TARGET IGN TIM ADJ*  IDLE CONDITION When adjusting target ignition tim-
ing
CLSD THL POS LEARN  IGNITION ON AND ENGINE STOPPED. When learning the throttle valve
closed position
VVEL POS SEN ADJ PREP  USE THIS ITEM ONLY WHEN REPLACING VVEL ACTU-
ATOR SUB ASSEMBLY.
 IGNITION ON AND ENGINE STOPPED. When adjusting VVEL control
shaft position sensor
Revision: 2010 May2011 QX56