Infiniti QX56 (Z62). Manual - part 520

 

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Infiniti QX56 (Z62). Manual - part 520

 

 

EC-58

< SYSTEM DESCRIPTION >

[VK56VD]

DIAGNOSIS SYSTEM (ECM)

DIAGNOSIS DESCRIPTION : Driving Pattern

INFOID:0000000006217725

DRIVING PATTERN A

• The A counter will be cleared when the malfunction is detected regardless of (1) - (4).
• The A counter will be counted up when (1) - (4) are satisfied without the same malfunction.
• The DTC will not be displayed after the A counter reaches 40.

DRIVING PATTERN B

Driving pattern B means operating vehicle operation as per the following:
All components and systems should be monitored at least once by the OBD system.
• The B counter will be cleared when the malfunction is detected once regardless of the driving pattern.
• The B counter will be counted up when driving pattern B is satisfied without any malfunctions.
• The MIL will turn OFF when the B counter reaches 3.

DRIVING PATTERN C

Driving pattern C means operating vehicle as per the following:
The following conditions should be satisfied at the same time:
Engine speed: (Engine speed in the freeze frame data) 

±

375 rpm

Calculated load value: (Calculated load value in the freeze frame data) x (1

±

0.1) [%]

Engine coolant temperature (T) condition:
• When the freeze frame data shows lower than 70

°

C (158

°

F), T should be lower than 70

°

C (158

°

F).

• When the freeze frame data shows higher than or equal to 70

°

C (158

°

F), T should be higher than or equal to

70

°

C (158

°

F).

• The C counter will be cleared when the malfunction is detected regardless of vehicle conditions above.
• The C counter will be counted up when vehicle conditions above are satisfied without the same malfunction.
• The DTC will not be displayed after C counter reaches 80.
• The 1st trip DTC will be cleared when C counter is counted once without the same malfunction after DTC is

stored in ECM.

DIAGNOSIS DESCRIPTION : System Readiness Test (SRT) Code

INFOID:0000000006217726

System Readiness Test (SRT) code is specified in Service $01 of SAE J1979/ISO 15031-5.
As part of an enhanced emissions test for Inspection & Maintenance (I/M), certain states require the status of
SRT be used to indicate whether the ECM has completed self-diagnosis of major emission systems and com-
ponents. Completion must be verified in order for the emissions inspection to proceed.
If a vehicle is rejected for a State emissions inspection due to one or more SRT items indicating “INCMP”, use
the information in this Service Manual to set the SRT to “CMPLT”.
In most cases the ECM will automatically complete its self-diagnosis cycle during normal usage, and the SRT
status will indicate “CMPLT” for each application system. Once set as “CMPLT”, the SRT status remains
“CMPLT” until the self-diagnosis memory is erased.
Occasionally, certain portions of the self-diagnostic test may not be completed as a result of the customer's
normal driving pattern; the SRT will indicate “INCMP” for these items.
NOTE:

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DIAGNOSIS SYSTEM (ECM)

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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 indicates “CMPLT” for all test items, the inspector will con-
tinue with the emissions test. However, if the SRT indicates “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 emissions inspection, the vehicle is also returned to the customer untested even
though the SRT indicates “CMPLT” for all test items. Therefore, 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. The 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 self-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”

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DIAGNOSIS SYSTEM (ECM)

DIAGNOSIS DESCRIPTION : Malfunction Indicator Lamp (MIL)

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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 Diagnosis Function

INFOID: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 the self-diagnoses of major emission control systems and
components. For SRT, refer to 

EC-58, "DIAGNOSIS DESCRIPTION : System 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 shaft position 
sensor adjustment

The initial position of the VVEL control shaft position sensor can be adjusted. Refer to 

EC-150, "De-

scription"

.

DIAGNOSIS SYSTEM (ECM)

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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 detects a malfunction in the emission control system com-
ponents and/or the powertrain control components (which affect 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 that 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 always released from the “Self-diagnostic results” mode.
1.

Confirm that accelerator pedal is fully released, 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.

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