Actual work procedures are explained using a DTC as an example. Be careful so that not only the DTC, but
all of the data listed above, are cleared from the ECM memory during work procedures.
MODELS WITHOUT EURO-OBD SYSTEMNJEC0031S07DTC and 1st Trip DTCNJEC0031S0701The 1st trip DTC (whose number is the same as the DTC number) is displayed for the latest self-diagnostic
result obtained. If the ECM memory was cleared previously, and the 1st trip DTC did not reoccur, the 1st trip
DTC will not be displayed.
If a malfunction is detected during the 1st trip, the 1st trip DTC is stored in the ECM memory. If the same mal-
function is not detected in the 2nd trip (meeting the required driving pattern), the 1st trip DTC is cleared from
the ECM memory. If the same malfunction is detected in the 2nd trip, both the 1st trip DTC and DTC are stored
in the ECM memory. In other words, the DTC is stored in the ECM memory when the same malfunction occurs
in two consecutive trips. If a 1st trip DTC is stored and a non-diagnostic operation is performed between the
1st and 2nd trips, only the 1st trip DTC will continue to be stored. For fail-safe items, the DTC is stored in the
ECM memory even in the 1st trip.
Procedures for clearing the DTC and the 1st trip DTC from the ECM memory are described in ªHow to Erase
Emission-related Diagnostic Informationº, EC-71.
When a (1st trip) DTC is detected, check, print out or write down and erase (1st trip) DTC and Freeze Frame
data as specified in ªWork Flowº procedure Step II, refer to EC-96. Then perform ªDTC Confirmation Proce-
dureº or ªOverall Function Checkº to try to duplicate the problem. If the malfunction is duplicated, the item
requires repair.
How to Read DTC and 1st Trip DTC
DTC and 1st trip DTC can be read by the following methods.
Without CONSULT-II
ECM displays the DTC by a set of four digit numbers with MI illumination in the diagnostic test mode II (Self-
diagnostic results). Example: 0100, 0115, 0340, 1335, etc.
With CONSULT-II
CONSULT-II displays the DTC in ªSELF-DIAG RESULTSº mode. Examples: P0100, P0115, P0340, P1335,
etc.
(CONSULT-II also displays the malfunctioning component or system.)
+1st trip DTC No. is the same as DTC No.
+Output of a DTC indicates a malfunction. However, ECM in the diagnostic test mode II (Self-diag-
nostic results) (If so equipped) does not indicate whether the malfunction is still occurring or has
occurred in the past and has returned to normal. CONSULT-II can identify malfunction status as
shown below. Therefore, the use of CONSULT-II (if available) is recommended.
A sample CONSULT-II display for DTC and 1st trip DTC is shown below. DTC or 1st trip DTC of a malfunc-
tion is displayed in the SELF-DIAGNOSTIC RESULTS mode of CONSULT-II. Time data indicates how many
times the vehicle was driven after the last detection of a DTC.
If the DTC is being detected currently, the time data will be ª0º.
If a 1st trip DTC is stored in the ECM, the time data will be ª[1t]º.
SEF992X
Freeze Frame Data and 1st Trip Freeze Frame DataNJEC0031S0702The ECM records the driving conditions such as fuel system status, calculated load value, engine coolant
temperature, short term fuel trim, long term fuel trim, engine speed, vehicle speed, throttle valve opening, base
fuel schedule and intake air temperature at the moment a malfunction is detected.
Data which are stored in the ECM memory, along with the 1st trip DTC, are called 1st trip freeze frame data.
The data, stored together with the DTC data, are called freeze frame data and displayed on CONSULT-II. For
details, see EC-84.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONQG
Emission-related Diagnostic Information (Cont'd)
EC-70
SEF543X
NATS (Nissan Anti-theft System)NJEC0591+If the security indicator lights up with the ignition switch
in the ªONº position or ªNATS MALFUNCTIONº is dis-
played on ªSELF-DIAG RESULTSº screen, perform self-
diagnostic results mode with CONSULT-II using NATS pro-
gram card. Refer to NATS (Nissan Anti-Theft System) in EL
section.
+Confirm no self-diagnostic results of NATS is displayed
before touching ªERASEº in ªSELF-DIAG RESULTSº
mode with CONSULT-II.
+When replacing ECM, initialization of NATS system and
registration of all NATS ignition key IDs must be carried
out with CONSULT-II using NATS program card.
Therefore, be sure to receive all keys from vehicle owner.
Regarding the procedure of NATS initialization and NATS
ignition key ID registration, refer to CONSULT-II operation
manual, NATS.
Malfunction Indicator (MI)
DESCRIPTIONNJEC0032
SAT652J
The MI is located on the instrument panel.
1. The MI will light up when the ignition switch is turned ON without the engine running. This is a bulb check.
+If the MI does not light up, refer to EL-107, ªWARNING LAMPSº or see EC-488.
2. When the engine is started, the MI should go off.
If the MI remains on, the on board diagnostic system has detected an engine system malfunction.
On Board Diagnostic System FunctionNJEC0032S01The on board diagnostic system has the following four functions.
Diagnostic Test Mode I
1. BULB CHECK:
This function checks the MI bulb for damage (blown, open circuit, etc.).
If the MI does not come on, check MI circuit and ECM test mode selector. (See the following page.)
2. MALFUNCTION WARNING:
MI Condition
ON When the malfunction is detected or the ECM's CPU is malfunctioning.
OFF No malfunction.
Diagnostic Test Mode II (If so equipped)
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONQG
NATS (Nissan Anti-theft System)
EC-72
3. SELF-DIAGNOSTIC RESULTS:
This function allows DTCs and 1st trip DTCs to be read.
4. HEATED OXYGEN SENSOR 1 MONITOR (FRONT):
This function allows the fuel mixture condition (lean or rich), monitored by heated oxygen sensor 1 (front),
to be read.
MI Flashing without DTC
NJEC0032S0101If the ECM is in Diagnostic Test Mode II, MI may flash when engine is running. In this case, check ECM test
mode following ªHow to Switch Diagnostic Test Modesº.
How to switch the diagnostic test (function) modes, and details of the above functions are described later.
(Refer to EC-74.)
Condition Diagnostic Test Mode I Diagnostic Test Mode II
Ignition switch in ªONº position
Engine stopped
BULB CHECK SELF-DIAGNOSTIC RESULTS
Engine running
MALFUNCTION WARNINGHEATED OXYGEN SENSOR 1
MONITOR (FRONT)
The following emission-related diagnostic information is cleared when the ECM memory is erased.
1) Diagnostic trouble codes
2) 1st trip diagnostic trouble codes
3) Freeze frame data
4) 1st trip freeze frame data
5) System readiness test (SRT) codes
6) Test values
7) Distance traveled while MI is activated
8) Others
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONQG
Malfunction Indicator (MI) (Cont'd)
EC-73
MI Fuel mixture condition in the exhaust gas Air fuel ratio feedback control condition
ON Lean
Closed loop system
OFF Rich
*Remains ON or OFF Any condition Open loop system
*: Maintains conditions just before switching to open loop.
To check the heated oxygen sensor 1 (front) function, start engine in the Diagnostic Test Mode II and warm
it up until engine coolant temperature indicator points to the middle of the gauge.
Next run engine at about 2,000 rpm for about 2 minutes under no-load conditions. Then make sure that the
MI comes ON more than 5 times within 10 seconds with engine running at 2,000 rpm under no-load.
OBD System Operation Chart (With Euro-OBD
Models Only)
NJEC0033RELATIONSHIP BETWEEN MI, 1ST TRIP DTC, DTC, AND DETECTABLE ITEMSNJEC0033S01+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 consecutive trips, the DTC and the freeze frame data are
stored in the ECM memory, and the MI will come on. For details, refer to ªTwo Trip Detection Logicº on
EC-57.
+The MI will go off after the vehicle is driven 3 times 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 vehicle is driven 40 times (driving pattern A)
without the same malfunction recurring (except for Misfire and Fuel Injection System). For Misfire and Fuel
Injection System, the DTC and freeze frame data will be stored until the vehicle is driven 80 times (driv-
ing pattern C) without the same malfunction recurring. The ªTIMEº in ªSELF-DIAGNOSTIC RESULTSº
mode of CONSULT-II will count the number of times the vehicle is driven.
+The 1st trip DTC is not displayed when the self-diagnosis results in ªOKº for the 2nd trip.
SUMMARY CHARTNJEC0033S02
Items Fuel Injection System Misfire Other
MI (goes off) 3 (pattern B) 3 (pattern B) 3 (pattern B)
DTC, Freeze Frame Data (no display) 80 (pattern 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)
For details about patterns ªBº and ªCº under ªFuel Injection Systemº and ªMisfireº, see EC-78.
For details about patterns ªAº and ªBº under ªOtherº, see EC-80.
*1: Clear timing is at the moment OK is detected.
*2: Clear timing is when the same malfunction is detected in the 2nd trip.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONQG
Malfunction Indicator (MI) (Cont'd)
EC-76
Monitored item [Unit]ECM
input
signalsMain
signalsDescription Remarks
IDL A/V LEARN+Display the condition of idle air volume
learning
YET ... Idle air volume learning has not
been performed yet.
CMPLT ... Idle air volume learning has
already been performed successfully.
INCMP ... Idle air volume learning has not
been performed successfully.
TRVL AFTER MIL
[km] or [Mile]+Distance traveled while MI is activated
VOLTAGE [V]+Voltage measured by the voltage probe.
PULSE
[msec] or [Hz] or [%]+Pulse width, frequency or duty cycle mea-
sured by the pulse probe.+Only ª#º is displayed if item is
unable to be measured.
+Figures with ª#ºs are temporary
ones. They are the same figures as
an actual piece of data which was
just previously measured.
*: If so equipped
NOTE:
Any monitored item that does not match the vehicle being diagnosed is deleted from the display automatically.
DATA MONITOR (SPEC) MODENJEC0034S11
Monitored item [Unit]ECM
input
signalsMain
signalsDescription Remarks
MAS A/F SE-B1 [V]jj+The signal voltage of the mass air flow sen-
sor specification is displayed.+When the engine is running, speci-
fication range is indicated.
B/FUEL SCHDL
[msec]+ªBase fuel scheduleº indicates the fuel
injection pulse width programmed into
ECM, prior to any learned on board correc-
tion.+When the engine is running, speci-
fication range is indicated.
A/F ALPHA-B1 [%]j+Indicates the mean value of the air-fuel
ratio feedback correction factor per cycle.+When the engine is running, speci-
fication range is indicated.
+This data also includes the data for
the air-fuel ratio learning control.
NOTE:
Any monitored item that does not match the vehicle being diagnosed is deleted from the display automatically.
ACTIVE TEST MODENJEC0034S07
TEST ITEM CONDITION JUDGEMENT CHECK ITEM (REMEDY)
FUEL INJECTION+Engine: Return to the original
trouble condition
+Change the amount of fuel injec-
tion using CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.+Harness and connector
+Fuel injectors
+Heated oxygen sensor 1 (front)
IGNITION TIMING+Engine: Return to the original
trouble condition
+Timing light: Set
+Retard the ignition timing using
CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.+ªIdle Air Volume Leaningº (Refer
to EC-55.)
+Camshaft position sensor
(PHASE)
+Crankshaft position sensor
(POS)
+Engine component parts and
installing conditions
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONQG
CONSULT-II (Cont'd)
EC-88
TEST ITEM CONDITION JUDGEMENT CHECK ITEM (REMEDY)
IACV-AAC/V
OPENING+Engine: After warming up, idle
the engine.
+Change the IACV-AAC valve
opening steps using CONSULT-
II.Engine speed changes according
to the opening steps.+Harness and connector
+IACV-AAC valve
POWER BAL-
ANCE+Engine: After warming up, idle
the engine.
+Air conditioner switch ªOFFº
+Shift lever ªNº
+Cut off each injector signal one
at a time using CONSULT-II.Engine runs rough or dies.+Harness and connector
+Compression
+Injectors
+Power transistor
+Spark plugs
+Ignition coils
COOLING FAN+Ignition switch: ON
+Turn the cooling fan ªONº and
ªOFFº using CONSULT-II.Cooling fan moves and stops.+Harness and connector
+Cooling fan motor
ENG COOLANT
TEMP+Engine: Return to the original
trouble condition
+Change the engine coolant tem-
perature indication using CON-
SULT-II.If trouble symptom disappears, see
CHECK ITEM.+Harness and connector
+Engine coolant temperature sen-
sor
+Fuel injectors
FUEL PUMP
RELAY+Ignition switch: ON
(Engine stopped)
+Turn the fuel pump relay ªONº
and ªOFFº using CONSULT-II
and listen to operating sound.Fuel pump relay makes the operat-
ing sound.+Harness and connector
+Fuel pump relay
EGR VOL
CONT/V
(If so equipped)+Engine: After warming up, idle
the engine.
+Change the EGR volume control
valve opening step using CON-
SULT-II.Engine speed changes according
to the opening step.+Harness and connector
+EGR volume control valve
VALVE TIMING
SOL+Ignition switch: ON
+Turn intake valve timing control
solenoid valve ªONº and ªOFFº
using CONSULT-II and listen for
operating sound.Intake valve timing control solenoid
valve makes an operating sound.+Harness and connector
+Intake valve timing control sole-
noid valve
PURG VOL
CONT/V+Engine: After warming up, idle
the engine.
+Change the EVAP canister
purge volume control solenoid
valve opening percent using
CONSULT-II.Engine speed changes according
to the opening percent.+Harness and connector
+EVAP canister purge volume
control solenoid valve
DTC AND SRT CONFIRMATION MODENJEC0034S08This mode is not available for models without Euro-OBD system.
SRT STATUS ModeNJEC0034S0801For details, refer to ªSYSTEM READINESS TEST (SRT) CODEº,
EC-60.
SRT Work Support ModeNJEC0034S0803This mode enables a technician to drive a vehicle to set the SRT
while monitoring the SRT status.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONQG
CONSULT-II (Cont'd)
EC-89
MEF036D
SEF233G
SEF234G
IntroductionNJEC0036The engine has an ECM to control major systems such as fuel
control, ignition control, idle air control system, etc. The ECM
accepts input signals from sensors and instantly drives actuators.
It is essential that both input and output signals are proper and
stable. At the same time, it is important that there are no problems
such as vacuum leaks, fouled spark plugs, or other problems with
the engine.
It is much more difficult to diagnose a problem that occurs intermit-
tently rather than continuously. Most intermittent problems are
caused by poor electric connections or improper wiring. In this
case, careful checking of suspected circuits may help prevent the
replacement of good parts.
A visual check only may not find the cause of the problems. A road
test with CONSULT-II (or GST) or a circuit tester connected should
be performed. Follow the ªWork Flowº on EC-96.
Before undertaking actual checks, take a few minutes to talk with
a customer who approaches with a driveability complaint. The cus-
tomer can supply good information about such problems, espe-
cially intermittent ones. Find out what symptoms are present and
under what conditions they occur. A ªDiagnostic Worksheetº like the
example on next page should be used.
Start your diagnosis by looking for ªconventionalº problems first.
This will help troubleshoot driveability problems on an electronically
controlled engine vehicle.
SEF907L
DIAGNOSTIC WORKSHEETNJEC0036S01There are many operating conditions that lead to the malfunction
of engine components. A good grasp of such conditions can make
trouble-shooting faster and more accurate.
In general, each customer feels differently about a problem. It is
important to fully understand the symptoms or conditions for a
customer complaint.
Utilize a diagnostic worksheet like the one on the next page in order
to organize all the information for troubleshooting.
Some conditions may cause the malfunction indicator lamp to
come on steady or blink and DTC to be detected.
Example:
Vehicle ran out of fuel, which caused the engine to misfire.
TROUBLE DIAGNOSIS Ð INTRODUCTIONQG
EC-94
DESCRIPTION FOR WORK FLOWNJEC0563S01
STEP DESCRIPTION
STEP IGet detailed information about the conditions and the environment when the incident/symptom occurred using
the ªDIAGNOSTIC WORK SHEETº, EC-95.
STEP IIBefore confirming the concern, check and write down (print out using CONSULT-II or GST) the (1st trip) DTC
and the (1st trip) freeze frame data, then erase the DTC and the data. (Refer to EC-68, EC-71.) The (1st trip)
DTC and the (1st trip) freeze frame data can be used when duplicating the incident at STEP III & IV.
If the incident cannot be verified, perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-144.
Study the relationship between the cause, specified by (1st trip) DTC, and the symptom described by the cus-
tomer. (The ªSymptom Matrix Chartº will be useful. See EC-124.)
Also check related service bulletins for information.
STEP IIITry to confirm the symptom and under what conditions the incident occurs.
The ªDIAGNOSTIC WORK SHEETº and the freeze frame data are useful to verify the incident. Connect CON-
SULT-II to the vehicle in DATA MONITOR (AUTO TRIG) mode and check real time diagnosis results.
If the incident cannot be verified, perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-144.
If the malfunction code is detected, skip STEP IV and perform STEP V.
STEP IVTry to detect the (1st trip) DTC by driving in (or performing) the ªDTC Confirmation Procedureº. Check and read
the (1st trip) DTC and (1st trip) freeze frame data by using CONSULT-II or GST.
During the (1st trip) DTC verification, be sure to connect CONSULT-II to the vehicle in DATA MONITOR (AUTO
TRIG) mode and check real time diagnosis results.
If the incident cannot be verified, perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-144.
In case the ªDTC Confirmation Procedureº is not available, perform the ªOverall Function Checkº instead. The
(1st trip) DTC cannot be displayed by this check, however, this simplified ªcheckº is an effective alternative.
The ªNGº result of the ªOverall Function Checkº is the same as the (1st trip) DTC detection.
STEP VTake the appropriate action based on the results of STEP I through IV.
If the malfunction code is indicated, proceed to TROUBLE DIAGNOSIS FOR DTC PXXXX.
If the normal code is indicated, proceed refer to ªBASIC INSPECTIONº, EC-98. If CONSULT-II is available, per-
form ªDATA MONITOR (SPEC)º mode with CONSULT-II and proceed to the ªTROUBLE DIAGNOSIS Ð SPECI-
FICATION VALUEº. (Refer to EC-140.) (If malfunction is detected, proceed to ªREPAIR/REPLACEº.) Then per-
form inspections according to the Symptom Matrix Chart. (Refer to EC-124.)
STEP VIIdentify where to begin diagnosis based on the relationship study between symptom and possible causes.
Inspect the system for mechanical binding, loose connectors or wiring damage using (tracing) ªHarness Layoutsº.
Gently shake the related connectors, components or wiring harness with CONSULT-II set in ªDATA MONITOR
(AUTO TRIG)º mode.
Check the voltage of the related ECM terminals or monitor the output data from the related sensors with CON-
SULT-II. Refer to EC-132.
The ªDiagnostic Procedureº in EC section contains a description based on open circuit inspection. A short circuit
inspection is also required for the circuit check in the Diagnostic Procedure. For details, refer to GI section
(ªHOW TO PERFORM EFFICIENT DIAGNOSIS FOR AN ELECTRICAL INCIDENTº, ªCircuit Inspectionº).
Repair or replace the malfunction parts.
If malfunctioning part cannot be detected, perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº,
EC-144.
STEP VIIOnce you have repaired the circuit or replaced a component, you need to run the engine in the same conditions
and circumstances which resulted in the customer's initial complaint.
Perform the ªDTC Confirmation Procedureº and confirm the normal code [DTC No. P0000] is detected. If the
incident is still detected in the final check, perform STEP VI by using a different method from the previous one.
Before returning the vehicle to the customer, be sure to erase the unnecessary (already fixed) (1st trip) DTC in
ECM and TCM (Transmission control module). (Refer to EC-68, EC-71.)
TROUBLE DIAGNOSIS Ð INTRODUCTIONQG
Work Flow (Cont'd)
EC-97