2003 NISSAN X-TRAIL OBD port

EC-26
[QR (WITH EURO-OBD)]
ENGINE CONTROL SYSTEM
MIXTURE RATIO SELF-LEARNING CONTROL
The mixture ratio feedback control system monitors the mixture ratio signal transmitted from heated oxygen
sensor 1. This feedback signal is then sent to the ECM. The ECM controls the basic mixture ratio as close to
the theoretical mixture ratio as possible. However, the basic mixture ratio is not necessarily controlled as orig-
inally designed. Both manufacturing differences (i.e., mass air flow sensor hot film) and characteristic changes
during operation (i.e., injector clogging) directly affect mixture ratio.
Accordingly, the difference between the basic and theoretical mixture ratios is monitored in this system. This is
then computed in terms of “injection pulse duration” to automatically compensate for the difference between
the two ratios.
“Fuel trim” refers to the feedback compensation value compared against the basic injection duration. Fuel trim
includes short term fuel trim and long term fuel trim.
“Short term fuel trim” is the short-term fuel compensation used to maintain the mixture ratio at its theoretical
value. The signal from heated oxygen sensor 1 indicates whether the mixture ratio is RICH or LEAN compared
to the theoretical value. The signal then triggers a reduction in fuel volume if the mixture ratio is rich, and an
increase in fuel volume if it is lean.
“Long term fuel trim” is overall fuel compensation carried out long-term to compensate for continual deviation
of the short term fuel trim from the central value. Such deviation will occur due to individual engine differences,
wear over time and changes in the usage environment.
FUEL INJECTION TIMING
Two types of systems are used.
Sequential Multiport Fuel Injection System
Fuel is injected into each cylinder during each engine cycle according to the firing order. This system is used
when the engine is running.
Simultaneous Multiport Fuel Injection System
Fuel is injected simultaneously into all four cylinders twice each engine cycle. In other words, pulse signals of
the same width are simultaneously transmitted from the ECM.
The four injectors will then receive the signals two times for each engine cycle.
This system is used when the engine is being started and/or if the fail-safe system (CPU) is operating.
FUEL SHUT-OFF
Fuel to each cylinder is cut off during deceleration or operation of the engine at excessively high speeds.
SEF337W

EC-28
[QR (WITH EURO-OBD)]
ENGINE CONTROL SYSTEM
lWhen the accelerator pedal is fully depressed.
lWhen cranking the engine.
lAt high engine speeds.
lWhen the engine coolant temperature becomes excessively high.
lWhen operating power steering during low engine speed or low vehicle speed.
lWhen engine speed is excessively low.
lWhen refrigerant pressure is excessively low or high.
Fuel Cut Control (at No Load and High Engine Speed)EBS00B0U
INPUT/OUTPUT SIGNAL CHART
SYSTEM DESCRIPTION
If the engine speed is above 1,800 rpm with no load (for example, in neutral and engine speed over 1,800
rpm) fuel will be cut off after some time. The exact time when the fuel is cut off varies based on engine speed.
Fuel cut will operate until the engine speed reaches 1,500 rpm, then fuel cut is cancelled.
NOTE:
This function is different from deceleration control listed under “Multiport Fuel Injection (MFI) System”,EC-24
.
CAN communicationEBS00B0V
SYSTEM DESCRIPTION
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, control units are connected with 2
communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only.
FOR A/T MODELS
System Diagram
Input/Output Signal Chart
T: Transmit R: Receive Sensor Input Signal to ECMECM func-
tionActuator
Park/neutral position (PNP) switch Neutral position
Fuel cut
controlFuel injectors Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Engine coolant temperature sensor Engine coolant temperature
Crankshaft position sensor (POS) Engine speed
Wheel sensor Vehicle speed
SKIA0884E
Signals ECM TCM
Engine speed signal T R
Engine coolant temperature signal T R

EC-32
[QR (WITH EURO-OBD)]
BASIC SERVICE PROCEDURE
PREPARATION
Before performing “Idle Air Volume Learning”, make sure that all of the following conditions are satisfied.
Learning will be cancelled if any of the following conditions are missed for even a moment.
lBattery voltage: More than 12.9V (At idle)
lEngine coolant temperature: 70 - 100°C (158 - 212°F)
lPNP switch: ON
lElectric load switch: OFF
(Air conditioner, headlamp, rear window defogger)
On vehicles equipped with daytime light systems, set lighting switch to the 1st position to light
only small lamps.
lSteering wheel: Neutral (Straight-ahead position)
lVehicle speed: Stopped
lTransmission: Warmed-up
For A/T models with CONSULT-II, drive vehicle until “FLUID TEMP SE” in “DATA MONITOR” mode of “A/
T” system indicates less than 0.9V.
For A/T models without CONSULT-II and M/T models, drive vehicle for 10 minutes.
OPERATION PROCEDURE
With CONSULT-II
1. PerformEC-31, "Accelerator Pedal Released Position Learning".
2. PerformEC-31, "
Throttle Valve Closed Position Learning".
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic “PRE-CONDITIONING” (previously mentioned) are in good
order.
5. Select “IDLE AIR VOL LEARN” in “WORK SUPPORT” mode.
6. Touch “START” and wait 20 seconds.
SEF452Y
SEF454Y

EC-34
[QR (WITH EURO-OBD)]
BASIC SERVICE PROCEDURE
DIAGNOSTIC PROCEDURE
If idle air volume learning cannot be performed successfully, proceed as follows:
1.Check that throttle valve is fully closed.
2.Check PCV valve operation.
3.Check that downstream of throttle valve is free from air leakage.
4.When the above three items check out OK, engine component parts and their installation condi-
tion are questionable. Check and eliminate the cause of the problem.
It is useful to performEC-103, "
TROUBLE DIAGNOSIS - SPECIFICATION VALUE".
5.If any of the following conditions occur after the engine has started, eliminate the cause of the
problem and perform “Idle air volume learning” all over again:
–Engine stalls.
–Erroneous idle.
Fuel Pressure CheckEBS00B0Z
FUEL PRESSURE RELEASE
Before disconnecting fuel line, release fuel pressure from fuel line to eliminate danger.
NOTE:
Prepare pans or saucers under the disconnected fuel line because the fuel may spill out. The fuel pres-
sure cannot be completely released because QR engine models do not have fuel return system.
With CONSULT-II
1. Turn ignition switch “ON”.
2. Perform “FUEL PRESSURE RELEASE” in “WORK SUPPORT”
mode with CONSULT-II.
3. Start engine.
4. After engine stalls, crank it two or three times to release all fuel
pressure.
5. Turn ignition switch “OFF”.
Without CONSULT-II
1. Remove fuel pump fuse located in fuse box.
2. Start engine.
3. After engine stalls, crank it two or three times to release all fuel
pressure.
4. Turn ignition switch “OFF”.
5. Reinstall fuel pump fuse after servicing fuel system.
FUEL PRESSURE CHECK
CAUTION:
lThe fuel hose connection method used when taking fuel pressure check must not be used for
other purposes.
lTake care for not to scratch and not to put debris around connection area when servicing, so that
the quick connector keeps sealability with O-rings inside.
1. Release fuel pressure to zero. Refer toEC-34, "
FUEL PRESSURE RELEASE".
2. Prepare fuel hose for fuel pressure check, and connect fuel pressure gauge.
lUse suitable fuel hose for fuel pressure check (genuine NISSAN fuel hose without quick connector).
SEF214Y
PBIB0508E

EC-40
[QR (WITH EURO-OBD)]
ON BOARD DIAGNOSTIC (OBD) SYSTEM
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. 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 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 trip 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 freeze 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 data (along with the DTCs) are cleared when the ECM mem-
ory is erased. Procedures for clearing the ECM memory are described inEC-46, "
HOW TO ERASE EMIS-
SION-RELATED DIAGNOSTIC INFORMATION".
SYSTEM READINESS TEST (SRT) CODE
System Readiness Test (SRT) code is specified in Mode 1 of 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:
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 MI 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 Item
The table below shows required self-diagnostic items to set the SRT to “CMPLT”.
Priority Items
1Freezeframedata 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
SRT item
(CONSULT-II
indication)Performance
Priority*1Required self-diagnostic items to set the SRT to “CMPLT” Corresponding DTC No.
CATALYST 2 Three way catalyst function P0420

TROUBLE DIAGNOSIS
EC-57
[QR (WITH EURO-OBD)]
C
D
E
F
G
H
I
J
K
L
MA
EC
TROUBLE DIAGNOSISPFP:00004
Trouble Diagnosis IntroductionEBS00BMH
INTRODUCTION
The engine has an ECM to control major systems such as fuel con-
trol, ignition control, idle air control system, etc. The ECM accepts
input signals from sensors and instantly drives actuators. It is essen-
tial that both input and output signals are proper and stable. At the
same time, it is important that there are no problems such as vac-
uum 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 replace-
ment 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 “Work Flow” onEC-58
.
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, especially
intermittent ones. Find out what symptoms are present and under
what conditions they occur. A “Diagnostic Worksheet” like the exam-
ple onEC-61
should be used.
Start your diagnosis by looking for “conventional” problems first. This
will help troubleshoot driveability problems on an electronically con-
trolled engine vehicle.
MEF036D
SEF233G
SEF234G

EC-60
[QR (WITH EURO-OBD)]
TROUBLE DIAGNOSIS
DIAGNOSTIC WORKSHEET
Description
There are many operating conditions that lead to the malfunction of
engine components. A good grasp of such conditions can make trou-
bleshooting 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 cus-
tomer 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 MI to come on steady or blink and
DTC to be detected. Examples:
lVehicle ran out of fuel, which caused the engine to misfire.
lFuel filler cap was left off or incorrectly screwed on, allowing fuel
to evaporate into the atmosphere.
SEF907L

EC-86
[QR (WITH EURO-OBD)]
TROUBLE DIAGNOSIS
: Average voltage for pulse signal (Actual pulse signal can be confirmed by oscilloscope.)
CONSULT-II FunctionEBS00BMQ
FUNCTION
*1 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. Others11 5 B / YThrottle control motor
ground[Engine is running]
lIdle speedApproximately 0V
11 6 GThrottle control motor
(Close)[Ignition switch "ON"]
lGear position is "D" (A/T model)
lGear position is "1st" (M/T model)
lAccelerator pedal is releasing0 - 14V TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
PBIB0534E
Diagnostic test mode Function
Work supportThis mode enables a technician to adjust some devices faster and more accurately by following the
indications on the CONSULT-II unit.
Self-diagnostic resultsSelf-diagnostic results such as 1st trip DTC, DTCs and 1st trip freeze frame data or freeze frame data
can be read and erased quickly.*1
Data monitor Input/Output data in the ECM can be read.
Data monitor (SPEC)Input/Output of the specification for Basic fuel schedule, AFM, A/F feedback control value and the
other data monitor items can be read.
Active testDiagnostic Test Mode in which CONSULT-II 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/result can be confirmed.
Function test This mode is used to inform customers when their vehicle condition requires periodic maintenance.
ECM part number ECM part number can be read.