ON BOARD DIAGNOSTIC (OBD) SYSTEM
EC-565
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ON BOARD DIAGNOSTIC (OBD) SYSTEMPFP:00028
IntroductionEBS010WZ
The ECM has an on board diagnostic system, which detects malfunctions related to engine sensors or actua-
tors. The ECM also records various emission-related diagnostic information including:
The above information can be checked using procedures listed in the table below.
×: Applicable —: Not applicable
*1: When DTC and 1st trip DTC simultaneously appear on the display, they cannot be clearly distinguished from each other.
The malfunction indicator (MI) on the instrument panel lights up when the same malfunction is detected in two
consecutive trips (Two trip detection logic), or when the ECM enters fail-safe mode. (Refer to EC-577, "
Fail-
Safe Chart" .)
Two Trip Detection LogicEBS010X0
When a malfunction is detected for the first time, 1st trip DTC and 1st trip Freeze Frame data are stored in the
ECM memory. The MI 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 MI lights up. The MI lights up at the same time when the DTC is stored. <2nd trip>
The “trip” in the “Two Trip Detection Logic” means a driving mode in which self-diagnosis is performed during
vehicle operation. When the ECM enters fail-safe mode (Refer to EC-577, "
Fail-Safe Chart" .), the DTC is
stored in the ECM memory even in the 1st trip.
When there is an open circuit on MI circuit, the ECM can not warn the driver by lighting up MI when there is
trouble on engine control system. Therefore, when Electrical controlled throttle and part of the ECM related
diagnoses are continuously detected as NG for 5-trips, ECM warns the driver that engine control system has
trouble and MI circuit is open by means of operating fail-safe function.
The fail-safe function also operates when above diagnoses except MI circuit are detected and demands the
driver to repair the trouble.
Emission-related Diagnostic InformationEBS010X1
DTC AND 1ST TRIP DTC
The 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. The MI will not
light up (two trip detection logic). If the same malfunction 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 and the MI lights up. In other words,
the DTC is stored in the ECM memory and the MI lights 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. For fail-safe items, 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 EC-566, "
HOW
TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATION" .
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 II, refer to EC-573, "
WORK FLOW" . Then perform DTC Con-
firmation Procedure or Overall Function Check to try to duplicate the malfunction. If the malfunction is dupli-
cated, the item requires repair.
Emission-related diagnostic information
Diagnostic Trouble Code (DTC)
Freeze Frame data
1st Trip Diagnostic Trouble Code (1st Trip DTC)
1st Trip Freeze Frame data
DTC 1st trip DTC Freeze Frame data1st trip Freeze Frame
data
CONSULT-II×× × ×
ECM×
×*
1——
Engine operating condition in fail-safe mode Engine speed will not rise more than 2,500 rpm due to the fuel cut
EC-566
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ON BOARD DIAGNOSTIC (OBD) SYSTEM
How to Read DTC and 1st Trip DTC
DTC and 1st trip DTC can be read by the following methods.
With CONSULT-II
CONSULT-II displays the DTC in “SELF-DIAG RESULTS” mode. Examples: P0117, P0340, P1065, etc.
(CONSULT-II also displays the malfunctioning component or system.)
Without CONSULT-II
The number of blinks of the MI in the Diagnostic Test Mode II (Self-Diagnostic Results) indicates the DTC.
Example: 0117, 0340, 1065 etc.
1st trip DTC No. is the same as DTC No.
Output of a DTC indicates a malfunction. However, the Diagnostic Test Mode II do 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, using CONSULT-II (if avail-
able) is recommended.
A sample of CONSULT-II display for DTC and 1st trip DTC is shown below. DTC or 1st trip DTC of a malfunc-
tion is displayed in “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 [0].
If a 1st trip DTC is stored in the ECM, the time data will be [1t].
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, engine speed, vehicle speed, 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-607, "
Freeze Frame Data and 1st Trip Freeze Frame Data" .
Only one set of freeze frame data (either 1st trip freeze frame data or freeze frame data) can be stored in the
ECM. 1st trip freeze frame data is stored in the ECM memory 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/MI 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.
Both 1st trip freeze frame data and freeze frame data (along with the DTCs) are cleared when the ECM mem-
ory is erased. Procedures for clearing the ECM memory are described in EC-566, "
HOW TO ERASE EMIS-
SION-RELATED DIAGNOSTIC INFORMATION" .
HOW TO ERASE EMISSION-RELATED DIAGNOSTIC INFORMATION
How to Erase DTC
With CONSULT-II
The emission related diagnostic information in the ECM can be erased by selecting “ERASE” in the “SELF-
DIAG RESULTS” mode with CONSULT-II.
1. If the ignition switch stays ON after repair work, be sure to turn ignition switch OFF once.
Wait at least 10 seconds and then turn it ON (engine stopped) again.
2. Touch “ENGINE”.
3. Touch “SELF-DIAG RESULTS”.
PBIB0911E
ON BOARD DIAGNOSTIC (OBD) SYSTEM
EC-567
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4. Touch “ERASE”. (The DTC in the ECM will be erased.)
Without CONSULT-II
1. If the ignition switch stays ON after repair work, be sure to turn ignition switch OFF once.
2. Wait at least 10 seconds and then turn it ON (engine stopped) again.
3. Change the diagnostic test mode from Mode II to Mode I by depressing the accelerator pedal. Refer to
EC-569, "
HOW TO SWITCH DIAGNOSTIC TEST MODE" .
If the battery is disconnected, the emission-related diagnostic information will be lost within 24
hours.
The following data are cleared when the ECM memory is erased.
–Diagnostic trouble codes
–1st trip diagnostic trouble codes
–Freeze frame data
–1st trip freeze frame data
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.
NATS (Nissan Anti-theft System)EBS010X2
If the security indicator lights up with the ignition switch in
the ON position or “NATS MALFUNCTION” is displayed on
“SELF-DIAG RESULTS” screen, perform self-diagnostic
results mode with CONSULT-II using NATS program card.
Refer to BL-108, "
NATS (NISSAN ANTI-THEFT SYSTEM)" .
Confirm no self-diagnostic results of NATS is displayed
before touching “ERASE” in “SELF-DIAG RESULTS” mode
with CONSULT-II.
When replacing ECM, initialization of NATS system and reg-
istration 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 procedures of NATS initialization and all NATS ignition key ID registration, refer to
CONSULT-II Operation Manual, NATS.
PBIB2454E
SEF515Y
ON BOARD DIAGNOSTIC (OBD) SYSTEM
EC-569
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MI Flashing without DTC
If the ECM is in Diagnostic Test Mode II, MI may flash when engine is running. In this case, check ECM diag-
nostic test mode. EC-569, "
HOW TO SWITCH DIAGNOSTIC TEST MODE" .
How to switch the diagnostic test (function) modes, and details of the above functions are described later, EC-
569, "HOW TO SWITCH DIAGNOSTIC TEST MODE" .
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
HOW TO SWITCH DIAGNOSTIC TEST 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 malfunction.
Always ECM returns to Diagnostic Test Mode I after ignition switch is turned OFF.
How to Set Diagnostic Test Mode II (Self-diagnostic Results)
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.
a. Fully depress the accelerator pedal.
b. Fully release the accelerator pedal.
3. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 10 seconds until the MI starts
blinking.
4. Fully release the accelerator pedal.
ECM has entered to Diagnostic Test Mode II (Self-diagnostic results).
How to Set Diagnostic Test Mode II (Heated Oxygen Sensor 1 Monitor)
1. Set the ECM in Diagnostic Test Mode II (Self-diagnostic results). Refer to EC-569, "How to Set Diagnostic
Test Mode II (Self-diagnostic Results)" .
2. Start Engine.
ECM has entered to Diagnostic Test Mode II (Heated oxygen sensor 1 monitor).
How to Erase Diagnostic Test Mode II (Self-diagnostic Results)
1. Set ECM in Diagnostic Test Mode II (Self-diagnostic results). Refer to EC-569, "How to Set Diagnostic
Test Mode II (Self-diagnostic Results)" .
2. Fully depress the accelerator pedal and keep it for more than 10 seconds.
The emission-related diagnostic information has been erased from the backup memory in the ECM.
3. Fully release the accelerator pedal, and confirm the DTC 0000 is displayed.
DIAGNOSTIC TEST MODE I — BULB CHECK
In this mode, the MI on the instrument panel should stay ON. If it remains OFF, check the bulb. Refer to DI-35,
"WARNING LAMPS" or see EC-958, "MI & DATA LINK CONNECTORS" .
PBIB0092E
EC-570
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ON BOARD DIAGNOSTIC (OBD) SYSTEM
DIAGNOSTIC TEST MODE I — MALFUNCTION WARNING
These DTC numbers are 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 MI as shown below.
The DTC and 1st trip DTC are displayed at the same time. If the MI does not illuminate in diagnostic test mode
I (Malfunction warning), all displayed items are 1st trip DTCs. If only one code is displayed when the MI illumi-
nates in diagnostic test mode II (SELF-DIAGNOSTIC RESULTS), it is a DTC; if two or more codes are dis-
played, they may be either DTCs or 1st trip DTCs. DTC No. is same as that of 1st trip DTC. These unidentified
codes can be identified by using the CONSULT-II. A DTC will be used as an example for how to read a code.
A particular trouble code can be identified by the number of four-digit numeral flashes. The “zero” is indicated
by the number of ten flashes. The length of time the 1,000th-digit numeral flashes on and off is 1.2 seconds
consisting of an ON (0.6-second) - OFF (0.6-second) cycle.
The 100th-digit numeral and lower digit numerals consist of a 0.3-second ON and 0.3-second OFF cycle.
A change from one digit numeral to another occurs at an interval of 1.0-second OFF. In other words, the later
numeral appears on the display 1.3 seconds after the former numeral has disappeared.
A change from one trouble code to another occurs at an interval of 1.8-second OFF.
In this way, all the detected malfunctions are classified by their DTC numbers. The DTC 0000 refers to no mal-
function. (See EC-533, "
INDEX FOR DTC" )
How to Erase Diagnostic Test Mode II (Self-diagnostic Results)
The DTC can be erased from the back up memory in the ECM by depressing accelerator pedal. Refer to EC-
569, "HOW TO SWITCH DIAGNOSTIC TEST MODE" .
If the battery is disconnected, the DTC will be lost from the backup memory within 24 hours.
Be careful not to erase the stored memory before starting trouble diagnoses.
DIAGNOSTIC TEST MODE II — HEATED OXYGEN SENSOR 1 MONITOR
In this mode, the MI displays the condition of the fuel mixture (lean or rich) which is monitored by the heated
oxygen sensor 1.
*: Maintains conditions just before switching to open loop.MI Condition
ON When the malfunction is detected.
OFF No malfunction.
PBIA3905E
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
ON BOARD DIAGNOSTIC (OBD) SYSTEM
EC-571
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To check the heated oxygen sensor 1 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.
EC-602
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TROUBLE DIAGNOSIS
99*1W/R ASCD steering switch[Ignition switch: ON]
ASCD steering switch: OFFApproximately 4V
[Ignition switch: ON]
MAIN switch: PressedApproximately 0V
[Ignition switch: ON]
CANCEL switch: PressedApproximately 1V
[Ignition switch: ON]
RESUME/ACCELERATE switch: PressedApproximately 3V
[Ignition switch: ON]
SET/COAST switch: PressedApproximately 2V
101 P Stop lamp switch[Ignition switch: OFF]
Brake pedal: Fully releasedApproximately 0V
[Ignition switch: OFF]
Brake pedal: Slightly depressedBATTERY VOLTAGE
(11 - 14V)
102 G/OR PNP switch[Ignition switch: ON]
Shift lever: P or N (A/T), Neutral (M/T)Approximately 0V
[Ignition switch: ON]
Except above positionA/T models
BATTERY VOLTAGE
(11 - 14V)
M/T models
Approximately 5V
104 W/B Throttle control motor relay[Ignition switch: OFF]BATTERY VOLTAGE
(11 - 14V)
[Ignition switch: ON]0 - 1.0V
106 WAccelerator pedal position
sensor 1[Ignition switch: ON]
Engine stopped
Accelerator pedal: Fully released0.5 - 1.0V
[Ignition switch: ON]
Engine stopped
Accelerator pedal: Fully depressed3.9 - 4.7V
108*
1GY/L ASCD brake switch[Ignition switch: ON]
Brake pedal: Slightly depressed
Clutch pedal: Slightly depressed (M/T)Approximately 0V
[Ignition switch: ON]
Brake pedal: Fully released
Clutch pedal: Fully released (M/T)BATTERY VOLTAGE
(11 - 14V)
109 B/R Ignition switch[Ignition switch: OFF]0V
[Ignition switch: ON]BATTERY VOLTAGE
(11 - 14V)
111 G / WECM relay
(Self shut-off)[Engine is running]
[Ignition switch: OFF]
For a few seconds after turning ignition
switch OFF0 - 1.0V
[Ignition switch: OFF]
More than a few seconds after turning igni-
tion switch OFFBATTERY VOLTAGE
(11 - 14V) TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
TROUBLE DIAGNOSIS
EC-603
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: Average voltage for pulse signal (Actual pulse signal can be confirmed by oscilloscope.)
*1: For QR25DE engine models114 B/OR Fuel pump relay[Ignition switch: ON]
For 1 second after turning ignition switch
ON
[Engine is running]0 - 1.0V
[Ignition switch: ON]
More than 1 second after turning ignition
switch ONBATTERY VOLTAGE
(11 - 14V)
11 5
11 6B
BECM ground[Engine is running]
Idle speedBody ground
11 9
120SB
GYPower supply for ECM[Ignition switch: ON]BATTERY VOLTAGE
(11 - 14V)
121 W/LPower supply for ECM
(Back-up)[Ignition switch: OFF]BATTERY VOLTAGE
(11 - 14V) TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)