2009 NISSAN LATIO light

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Check voltage between key switch and ignition knob switch harness
connector and ground.
OK or NG OK >> Replace BCM. Refer to
BCS-18, " Removal and Installa-
tion of BCM " .
NG >> Repair harness or connector.
Lighting Switch Signal Inspection INFOID:0000000004307037OK >> Lighting switch signal is OK. Return to
DI-47, " Trouble Diagnosis " .
NG >> Check the lighting switch. Refer to LT-63, " Combination Switch Inspection " .
Parking Brake Switch Signal Inspection INFOID:0000000004307038OK >> Replace combination meter. Refer to
DI-19, " Removal and Installation " .
NG >> GO TO 2. B

" Fail Safe " .)
TWO TRIP DETECTION LOGIC
When a malfunction is detected for the first time, 1st tr ip DTC and 1st trip Freeze Frame data are stored in the
ECM memory. The MIL will not light up at this stage. <1st trip>
If the same malfunction is detected again during the next drive, the DTC and Freeze Frame data are stored in
the ECM memory, and the MIL lights up. The MIL lights up at the same time when the DTC is stored. <2nd
trip> The “trip” in the “Two Trip Detection Logic” m eans a driving mode in which self-diagnosis is performed
during vehicle operation. Specific on board diagnostic item s will cause the ECM to light up or blink the MIL,
and store DTC and Freeze Frame data, even in the 1st trip, as shown below.
×: Applicable —: Not applicable
DTC AND FREEZE FRAME DATA
DTC and 1st Trip DTC Emission-related diagnostic information Diagnostic service
Diagnostic Trouble Code (DTC) Service $03 of SAE J1979
Freeze Frame data Service $02 of SAE J1979
System Readiness Test (SRT) code Service $01 of SAE J1979
1st Trip Diagnostic Trouble Code (1st Trip DTC) Service $07 of SAE J1979
1st Trip Freeze Frame data
Test values and Test limits Service $06 of SAE J1979
Calibration ID Service $09 of SAE J1979 DTC 1st trip DTC
Freeze
Frame data 1st trip Freeze
Frame data SRT code SRT status Test value
CONSULT-III × × × × × × —
GST × × × —× × ×
ECM × ×* — — — ×— Items
MIL DTC 1st trip DTC
1st trip 2nd trip 1st trip
displaying 2nd trip
displaying 1st trip
displaying 2nd trip
displaying
Blinking Lighting
up Blinking
Lighting
up
Misfire (Possible three way catalyst
damage) — DTC: P0300 - P0304 is
being detected ×
— — — — — ×—
Misfire (Possible three way catalyst
damage) — DTC: P0300 - P0304 is
being detected — —
×— — ×— —
One trip detection diagnoses
(Refer to EC-475, " DTC Index " .)
—
×— — ×— — —
Except above — — — ×— × × —

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The 1st trip DTC (whose number is the same as the DT
C number) is displayed for the latest self-diagnostic
result obtained. If the ECM memory was cleared previously , and the 1st trip DTC did not recur, 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. The MIL will not
light up (two trip detection logic). If the same malfunc tion 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 t he ECM memory and the MIL lights up. In other words,
the DTC is stored in the ECM memory and the MIL light s up when the same malfunction occurs in two consec-
utive 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. Fo r malfunctions that blink or light up the MIL during the
1st trip, the DTC and 1st trip DTC are stored in the ECM memory.
Procedures for clearing the DTC and the 1st trip DTC fr om the ECM memory are described in “How to Erase
DTC and 1st Trip DTC”.
For malfunctions in which 1st trip DTCs are displayed, refer to EC-475, " DTC Index " . These items are
required by legal regulations to c ontinuously monitor the system/component . In addition, the items monitored
non-continuously are also displayed on CONSULT-III.
1st trip DTC is specified in Service $07 of SAE J1979. 1st trip DTC detection occurs without lighting up the MIL
and therefore does not warn the driver of a malfunction. However, 1st trip DTC detection will not prevent the
vehicle from being tested, for example during Inspection/Maintenance (I/M) tests.
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 Work Flow procedure Step 2, refer to EC-22, " Work Flow " . Then perform DTC CONFIR-
MATION PROCEDURE or Component Function Check to tr y to duplicate the malfunction. If the malfunction is
duplicated, the item requires repair.
Freeze Frame Data and 1st Trip Freeze Frame Data The ECM records the driving conditions such as fuel system status, calculated load value, engine coolant tem-
perature, short-term fuel trim, long-term fuel trim, engi ne speed, vehicle speed, absolute throttle position, 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 ca lled freeze frame data and displayed on CONSULT-III or
GST. The 1st trip freeze frame data can only be di splayed on the CONSULT-III screen, not on the GST.
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 (P riority: 2) was detected and the freeze frame data was stored 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. Procedures for clearing the ECM memory are described in “How to Erase DTC and 1st Trip
DTC”.
How to Read DTC and 1st Trip DTC DTC and 1st trip DTC can be read by the following methods.
With CONSULT-III
CONSULT-III displays the DTC in “SELF DIAGNOSTIC RESULT” mode.
Examples: P0340, P0850, P1148, etc. Priority Items
1 Freeze frame data Misfire — DTC: P0300 - P0304
Fuel Injection System Function — DTC: P0171, P0172
2 Except the above items (Includes A/T related items)
3 1st trip freeze frame data

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If a vehicle has failed the state emissions inspection
due to one or more SRT items indicating “INCMP”, review
the flowchart diagnostic sequence on the next figure.
How to Display SRT Status WITH CONSULT-III
Selecting “SRT STATUS” in “DTC CONFIRMATION” mode with CONSULT-III.
For items whose SRT codes are set, a “CMPLT” is di splayed on the CONSULT-III screen; for items whose
SRT codes are not set, “INCMP” is displayed.
NOTE:
Though displayed on the CONSULT-III scr een, “HO2S HTR” is not SRT item.
WITH GST
Selecting Service $01 with GST (Generic Scan Tool)
NO TOOLS
A SRT code itself can not be displayed while only SRT status can be.
1. Turn ignition switch ON and wait 20 seconds.
2. SRT status is indicated as shown below. • When all SRT codes are set, MIL lights up continuously.

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Diagnostic Test Mode I — Bulb Check
In this mode, the MIL on the instrument panel should st ay ON. If it remains OFF, check the bulb. Refer to EC-446, " Description " .
Diagnostic Test Mode I — Malfunction Warning
This DTC number is clarified in Diagnostic Test Mode II (SELF-DIAGNOSTIC RESULTS)
Diagnostic Test Mode II — Self-diagnostic Results In this mode, the DTC and 1st trip DTC are indicated by the number of blinks of the MIL as shown below.
The DTC and 1st trip DTC are displayed at the same time. If the MIL does not illuminate in diagnostic test
mode I (Malfunction warning), all displa yed items are 1st trip DTCs. If only one code is displayed when the MIL
illuminates in diagnostic test mode II (SELF-DIAGNOSTIC RESULTS), it is a DTC; if two or more codes are
displayed, they may be either DTCs or 1st trip DTCs. DTC No. is same as that of 1st trip DTC. These uniden-
Diagnostic Test
Mode KEY and ENG.
Status Function Explanation of Function
Mode I Ignition switch in ON position
Engine stopped BULB CHECK This function checks the MIL bulb for damage (blown, open
circuit, etc.).
If the MIL does not come on, check MIL circuit.
Engine running MALFUNCTION WARNING When a malfunction is detected twice in two consecutive
driving cycles (two trip detection logic), the MIL will light up
to inform the driver that a malfunction has been detected.
The following malfunctions will light up or blink the MIL in
the 1st trip.
• Misfire (Possible three way catalyst damage)
• One trip detection diagnoses
Mode II Ignition switch in ON position
Engine stopped SELF-DIAGNOSTIC
RESULTS This function allows DTCs and 1st trip DTCs to be read.

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HO2S2 (B1) V
• The signal voltage of the heated oxygen sensor 2 is
displayed.
HO2S2 MNTR(B1) RICH/
LEAN • Display of heated oxygen sensor 2 signal:
RICH: means the amount of oxygen after three way
catalyst is relatively small.
LEAN: means the amount of oxygen after three way
catalyst is relatively large. • When the engine is stopped, a certain
value is indicated.
VHCL SPEED SE km/h or
mph • The vehicle speed computed from the vehicle speed
signal sent from combination meter is displayed.
BATTERY VOLT V • The power supply voltage of ECM is displayed.
ACCEL SEN 1 V• The accelerator pedal position sensor signal voltage is
displayed. • ACCEL SEN 2 signal is converted by
ECM internally. Thus, it differs from
ECM terminal voltage signal.
ACCEL SEN 2
TP SEN 1-B1 V• The throttle position sensor signal voltage is dis-
played. • TP SEN 2-B1 signal is converted by
ECM internally. Thus, it differs from
ECM terminal voltage signal.
TP SEN 2-B1
FUEL T/TMP SE °C or °F • The fuel temperature (determined by the signal volt-
age of the fuel tank temperature sensor) is displayed.
INT/A TEMP SE °C or °F • The intake air temperature (determined by the signal
voltage of the intake air temperature sensor) is indicat-
ed.
EVAP SYS PRES V • The signal voltage of EVAP control system pressure
sensor is displayed.
FUEL LEVEL SE V • The signal voltage of the fuel level sensor is displayed.
START SIGNAL ON/OFF • Indicates start signal status [ON/OFF] computed by
the ECM according to the signals of engine speed and
battery voltage. • After starting the engine, [OFF] is dis-
played regardless of the starter sig-
nal.
CLSD THL POS ON/OFF • Indicates idle position [ON/OFF] computed by ECM
according to the accelerator pedal position sensor sig-
nal.
AIR COND SIG ON/OFF • Indicates [ON/OFF] condition of the air conditioner
switch determined by the air conditioner ON signal.
P/N POSI SW ON/OFF • Indicates [ON/OFF] condit
ion from the park/neutral
position (PNP) switch signal.
PW/ST SIGNAL ON/OFF • [ON/OFF] condition of the power steering system (de-
termined by the signal sent from EPS control unit) is
indicated.
LOAD SIGNAL ON/OFF • Indicates [ON/OFF] condition from the electrical load
signal.
ON: Rear window defogger switch is ON and/or light-
ing switch is in 2nd position.
OFF: Both rear window defogger switch and lighting
switch are OFF.
IGNITION SW ON/OFF • Indicates [ON/OFF] condition from ignition switch sig-
nal.
HEATER FAN SW ON/OFF • Indicates [ON/OFF] condition from the heater fan
switch signal.
BRAKE SW ON/OFF • Indicates [ON/OFF] condition from the stop lamp
switch signal.
INJ PULSE-B1 msec • Indicates the actual fuel injection pulse width compen-
sated by ECM according to the input signals. • When the engine is stopped, a certain
computed value is indicated.
IGN TIMING BTDC • Indicates the ignition timing computed by ECM ac-
cording to the input signals. • When the engine is stopped, a certain
value is indicated.
CAL/LD VALUE % • “Calculated load value” indicates the value of the cur-
rent air flow divided by peak air flow.
Monitored item Unit Description Remarks

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Test Item
*: Leaving cooling fan OFF with CONSULT-III while engine is running may cause the engine to overheat.
DTC & SRT CONFIRMATION MODE
SRT STATUS Mode For details, refer to EC-90, " Diagnosis Description " .
SRT WORK SUPPORT Mode This mode enables a technician to drive a vehicle to set the SRT while monitoring the SRT status.
DTC WORK SUPPORT Mode TEST ITEM CONDITION JUDGMENT CHECK ITEM (REMEDY)
FUEL INJECTION • Engine: Return to the original
trouble condition
• Change the amount of fuel injec- tion using CONSULT-III. If trouble symptom disappears, see
CHECK ITEM. • Harness and connectors
• Fuel injector
• Air fuel ratio (A/F) sensor 1
IGNITION TIMING • Engine: Return to the original
trouble condition
• Timing light: Set
• Retard the ignition timing using
CONSULT-III. If trouble symptom disappears, see
CHECK ITEM. • Perform Idle Air Volume Learning.
POWER BALANCE • Engine: After warming up, idle
the engine.
• A/C switch OFF
• Selector lever: P or N position (A/ T), Neutral position (M/T)
• Cut off each fuel injector signal
one at a time using CONSULT-
III. Engine runs rough or dies.
• Harness and connectors
• Compression
• Fuel injector
• Power transistor
• Spark plug
• Ignition coil
COOLING FAN* • Ignition switch: ON
• Turn the cooling fan “LOW”, “HI”
and “OFF” using CONSULT-III. Cooling fan moves and stops.
• Harness and connectors
• IPDM E/R (Cooling fan relay)
• Cooling fan motor
ENG COOLANT
TEMP • Engine: Return to the original
trouble condition
• Change the engine coolant tem-
perature using CONSULT-III. If trouble symptom disappears, see
CHECK ITEM. • Harness and connectors
• Engine coolant temperature sen- sor
• Fuel injector
FUEL PUMP RELAY • Ignition switch: ON (Engine
stopped)
• Turn the fuel pump relay “ON”
and “OFF” using CONSULT-III
and listen to operating sound. Fuel pump relay makes the operat-
ing sound. • Harness and connectors
• Fuel pump relay
PURG VOL CONT/V • Engine: After warming up, run
engine at 1,500 rpm.
• Change the EVAP canister purge volume control solenoid
valve opening percent using
CONSULT-III. Engine speed changes according
to the opening percent. • Harness and connectors
• Solenoid valve
FUEL/T TEMP SEN • Change the fuel tank temperature using CONSULT-III.
VENT CONTROL/V • Ignition switch: ON (Engine
stopped)
• Turn solenoid valve “ON” and “OFF” using th e CONSULT-III
and listen to operating sound. Solenoid valve makes an operating
sound. • Harness and connectors
• Solenoid valve
V/T ASSIGN ANGLE • Engine: Return to the original
trouble condition
• Change intake valve timing us-
ing CONSULT-III. If trouble symptom disappears, see
CHECK ITEM. • Harness and connectors
• Intake valve timing control sole- noid valve

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P0171 FUEL INJECTION SYSTEM FUNCTION
DTC Logic INFOID:0000000004780135
DTC DETECTION LOGIC With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the
theoretical mixture ratio based on the mixture ratio f eedback signal from the A/F sensors 1. The ECM calcu-
lates the necessary compensation to correct the of fset between the actual and the theoretical ratios.
In case the amount of the compensation value is extrem ely large (The actual mixture ratio is too lean.), the
ECM judges the condition as the fuel injection system malfunction and lights up the MIL (2 trip detection logic).
DTC CONFIRMATION PROCEDURE MIXTURE RATIO SELF-LEARNING VALUE
CLEAR : Special Repair Requirement " .
2. Start engine.
Is it difficult to start engine? YES >> GO TO 3.
NO >> GO TO 4. YES >> Go to
EC-231, " Diagnosis Procedure " .
NO >> Check exhaust and intake air leak visually. YES >> Go to
EC-231, " Diagnosis Procedure " .
NO >> GO TO 5. Sensor Input signal to ECM ECM function Actuator
A/F sensor 1 Density of oxygen in exhaust gas
(Mixture ratio feedback signal) Fuel injection control Fuel injectorDTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0171 Fuel injection system too
lean • Fuel injection system does not operate properly.
• The amount of mixture ratio compensation is too large. (The mixture ratio is too lean.) • Intake air leaks
• A/F sensor 1
• Fuel injector
• Exhaust gas leaks
• Incorrect fuel pressure
• Lack of fuel
• Mass air flow sensor
• Incorrect PCV hose connection