2011 INFINITI QX56 ECU

DIAGNOSIS SYSTEM (ECM)EC-53
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Only one set of freeze frame data (either 1st trip freez
e frame data or freeze frame data) can be stored in the
ECM. 1st trip freeze frame data is stored in the ECM me mory along with the 1st trip DTC. There is no priority
for 1st trip freeze frame data and it is updated each time a different 1st trip DTC is detected. However, once
freeze frame data (2nd trip detection/MIL on) is stored in the ECM memory, 1st trip freeze frame data is no
longer stored. Remember, only one set of freeze frame data can be stored in the ECM. The ECM has the fol-
lowing priorities to update the data.
For example, the EGR malfunction (Priority: 2) was detected and the freeze frame data was saved in the 2nd
trip. After that when the misfire (Priority: 1) is detected in another trip, the freeze frame data will be updated
from the EGR malfunction to the misfire. The 1st trip freeze frame data is updated each time a different mal-
function is detected. There is no priority for 1st tr ip freeze frame data. However, once freeze frame data is
stored in the ECM memory, 1st trip freeze data is no longer stored (because only one freeze frame data or 1st
trip freeze frame data can be stored in the ECM). If fr eeze frame data is stored in the ECM memory and freeze
frame data with the same priority occurs later, the first (original) freeze frame data remains unchanged in the
ECM memory.
Both 1st trip freeze frame data and freeze frame dat a (along with the DTCs) are cleared when the ECM mem-
ory is erased.
DIAGNOSIS DESCRIPTION : Counter SystemINFOID:0000000006217724
RELATIONSHIP BETWEEN MIL, 1ST TRIP DTC, DTC, AND DETECTABLE ITEMS
 When a malfunction is detected for the first time, the 1st trip DTC and the 1st trip freeze frame data are
stored in the ECM memory.
 When the same malfunction is detected in two consec utive trips, the DTC and the freeze frame data are
stored in the ECM memory, and the MIL will come on.
 The MIL will turn OFF after the vehicle is driven 3 ti mes (driving pattern B) with no malfunction. The drive is
counted only when the recorded driving pattern is met (as stored in the ECM). If another malfunction occurs
while counting, the counter will reset.
 The DTC and the freeze frame data will be stored until the v ehicle is driven 40 times (driving pattern A) with-
out the same malfunction recurring (except for Misfire and Fuel Injection System). For Misfire and Fuel Injec-
tion System, the DTC and freeze frame data will be stored until the vehicle is driven 80 times (driving pattern
C) without the same malfunction recurring. The “TIM E” in “SELF-DIAGNOSTIC RESULTS” mode of CON-
SULT-III will count the number of times the vehicle is driven.
 The 1st trip DTC is not displayed when the se lf-diagnosis results in OK for the 2nd trip.
COUNTER SYSTEM CHART
For details about patterns B and C under “Fuel Inject ion System” and “Misfire”, see “EXPLANATION FOR
DRIVING PATTERNS FOR “MISFIRE ”, “FUEL INJECTION SYS-
TEM”.
For details about patterns A and B under Other, see “EXPLANATION FOR DRIVING PATTERNS FOR “MIS-
FIRE ”, “FUEL INJECTION SYSTEM”.
 *1: Clear timing is at the moment OK is detected.
 *2: Clear timing is when the same malfunction is detected in the 2nd trip.
Relationship Between MIL, DTC, 1st Trip DTC and Dr iving Patterns for “Misfire terioration>”, “Fuel Injection System”
Priority Items
1 Freeze frame data Misfire — DTC: P0300 - P0308
Fuel Injection System Function — DTC: P0171, P0172, P0174, P0175
2 Except the above items
3 1st trip freeze frame data
Items Fuel Injection System Misfire Other
MIL (turns OFF) 3 (pattern B) 3 (pattern B) 3 (pattern B)
DTC, Freeze Frame Data (no display) 80 (p attern C) 80 (pattern C) 40 (pattern A)
1st Trip DTC (clear) 1 (pattern C), *1 1 (pattern C), *1 1 (pattern B)
1st Trip Freeze Frame Data (clear) *1, *2 *1, *2 1 (pattern B)
Revision: 2010 May2011 QX56

EC-54
< SYSTEM DESCRIPTION >[VK56VD]
DIAGNOSIS SYSTEM (ECM)
Explanation for Driving Patterns for “Misfire ”, “Fuel Injection System”

Driving pattern B means the vehicl
e operation as per the following:
All components and systems should be monito red at least once by the OBD system.
*1: When the same malfunction is de-
tected in two consecutive trips, MIL
will light up. *2: MIL will turn OFF after vehicle is driv-
en 3 times (pattern B) without any
malfunctions. *3: When the same malfunction is de-
tected in two consecutive trips, the
DTC and the freeze frame data will be
stored in ECM.
*4: The DTC and the freeze frame data will not be displayed any longer after
vehicle is driven 80 times (pattern C)
without the same malfunction. (The
DTC and the freeze frame data still
remain in ECM.) *5: When a malfunction is detected for
the first time, the 1st trip DTC and the
1st trip freeze frame data will be
stored in ECM. *6: The 1st trip DTC and the 1st trip
freeze frame data will be cleared at
the moment OK is detected.
*7: When the same malfunction is de- tected in the 2nd trip, the 1st trip
freeze frame data will be cleared. *8: 1st trip DTC will
be cleared when ve-
hicle is driven once (pattern C) with-
out the same malfunction after DTC
is stored in ECM.
JMBIA1417GB
Revision: 2010 May2011 QX56

EC-56
< SYSTEM DESCRIPTION >[VK56VD]
DIAGNOSIS SYSTEM (ECM)
*1: When the same malfunction is de-
tected in two consecutive trips, MIL
will light up. *2: MIL will turn OFF after vehicle is driv-
en 3 times (pattern B) without any
malfunctions. *3: When the same malfunction is de-
tected in two consecutive trips, the
DTC and the freeze frame data will be
stored in ECM.
JMBIA1418GB
Revision: 2010 May2011 QX56

DIAGNOSIS SYSTEM (ECM)EC-59
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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

DIAGNOSIS SYSTEM (ECM)EC-61
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 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
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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.
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EC-64
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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

EC-72
< ECU DIAGNOSIS INFORMATION >[VK56VD]
ECM
ECU DIAGNOSIS INFORMATION
ECM
Reference ValueINFOID:0000000006217730
VALUES ON THE DIAGNOSIS TOOL
NOTE:
 Specification data are reference values.
 Specification data are output/input values which are
detected or supplied by the ECM at the connector.
* Specification data may not be directly relat ed to their components signals/values/operations.
i.e. Adjust ignition timing with a timing light before monitoring IGN TIMING, because the monitor may show
the specification data in spite of the ignition timing not being adjusted to the specification data. This IGN TIM-
ING monitors the data calculated by the ECM accordi ng to the signals input from the camshaft position sen-
sor and other ignition timing related sensors.
CONSULT-III MONITOR ITEM
Monitor Item Condition Values/Status
ENG SPEED  Run engine and compare CONSULT-III value with the tachometer indication. Almost the same speed as
the tachometer indication
MAS A/F SE-B1 See EC-161, "
Description".
B/FUEL SCHDL See EC-161, "
Description".
A/F ALPHA-B1 See EC-161, "
Description".
A/F ALPHA-B2 See EC-161, "
Description".
COOLAN TEMP/S  Ignition switch: ON Indicates engine coolant
temperature
A/F SEN1 (B1)  Engine: After warming up Maintaining engine speed at 2,000 rpm Fluctuates around 1.5 V
A/F SEN1 (B2)  Engine: After warming up Maintaining engine speed at 2,000 rpm Fluctuates around 1.5 V
HO2S2 (B1)  Revving engine from idle up to 3,000 rpm quickly after the following condi-
tions are met.
- Engine: After warming up
- After keeping engine speed between 3,500 and 4,000 rpm for 1 minute and at idle for 1 minute under no load 0 - 0.3 V
⇔ Approx. 0.6 - 1.0
V
HO2S2 (B2)  Revving engine from idle up to 3,000 rpm quickly after the following condi-
tions are met.
- Engine: After warming up
- After keeping engine speed between 3,500 and 4,000 rpm for 1 minute and at idle for 1 minute under no load 0 - 0.3 V
⇔ Approx. 0.6 - 1.0
V
HO2S2 MNTR (B1)  Revving engine from idle up to 3,000 rpm quickly after the following condi-
tions are met.
- Engine: After warming up
- After keeping engine speed between 3,500 and 4,000 rpm for 1 minute and
at idle for 1 minute under no load LEAN
⇔ RICH
HO2S2 MNTR (B2)  Revving engine from idle up to 3,000 rpm quickly after the following condi-
tions are met.
- Engine: After warming up
- After keeping engine speed between 3,500 and 4,000 rpm for 1 minute and at idle for 1 minute under no load LEAN
⇔ RICH
VHCL SPEED SE  Turn drive wheels and compare CONSULT-III value with the speedometer in-
dication. Almost the same speed as
speedometer indication
BATTERY VOLT  Ignition switch: ON (Engine stopped) 11 - 14 V
ACCEL SEN 1  Ignition switch: ON
(Engine stopped) Accelerator pedal: Fully released 0.65 - 0.87 V
Accelerator pedal: Fully depressed 4.3 - 4.8 V
ACCEL SEN 2*
1 Ignition switch: ON (Engine stopped) Accelerator pedal: Fully released 0.56 - 0.96 V
Accelerator pedal: Fully depressed 4.0 - 4.8 V
Revision: 2010 May2011 QX56