NISSAN PRIMERA 1999 Electronic Repair Manual

Precautions
lBefore connecting or disconnecting the ECM harness
connector, turn ignition switch OFF and disconnect
negative battery terminal. Failure to do so may damage
the ECM because battery voltage is applied to ECM even
if ignition switch is turned off.
lWhen connecting ECM harness connectors, push in
both sides of the connector until you hear a click.
Maneuver the lever until you hear the three connectors
on the inside click. Refer to the figure at left.
lBefore replacing ECM, perform Terminals and Reference
Value inspection and make sure ECM functions properly.
Refer to EC-CD-52.
lIf MI illuminates or blinks irregularly during engine
running, water may have accumulated in fuel filter. Drain
water from fuel filter. If this does not correct the problem,
perform specified trouble diagnostic procedures.
lAfter performing each TROUBLE DIAGNOSIS, perform
ªOVERALL FUNCTION CHECKº or ªDTC (Diagnostic
Trouble Code) CONFIRMATION PROCEDUREº.
The DTC should not be displayed in the ªDTC CONFIR-
MATION PROCEDUREº if the repair is completed. The
ªOVERALL FUNCTION CHECKº should be a good result
if the repair is completed.
SEF289H
SEF881Y
MEF040D
SAT652J
PRECAUTIONS AND PREPARATIONCD20T
EC-7

lWhen measuring ECM signals with a circuit tester, never
allow the two tester probes to contact.
Accidental contact of probes will cause a short circuit
and damage the ECM power transistor.
SEF348N
PRECAUTIONS AND PREPARATIONCD20T
Precautions (Cont'd)
EC-8

Engine Control Module Component Parts
Location
YEC133A
ENGINE AND EMISSION CONTROL OVERALL SYSTEMCD20T
EC-9

YEC134A
ENGINE AND EMISSION CONTROL OVERALL SYSTEMCD20T
Engine Control Module Component Parts
Location (Cont'd)
EC-10

Circuit Diagram
YEC099A
ENGINE AND EMISSION CONTROL OVERALL SYSTEMCD20T
EC-11

System Diagram
YEC125A
ENGINE AND EMISSION CONTROL OVERALL SYSTEMCD20T
EC-12

Vacuum Hose Drawing
p1EGRC-solenoid valves A and B to EGR valve
p2EGRC-solenoid valves A and B to air duct
p3EGRC-solenoid valve A to vacuum pump
Refer to ªSystem Diagramº on previous page for vacuum control system.
YEC131A
ENGINE AND EMISSION CONTROL OVERALL SYSTEMCD20T
EC-13

System Chart
Crankshaft position sensor
(TDC)E
ECM
Control sleeve position sensorE
Fuel temperature sensorE
Mass air flow sensorE
Engine coolant temperature
sensorE
Needle lift sensorE
Accelerator position sensorE
Accelerator position switchE
Air conditioner switchE
Ignition switch (ON & ST POS.)E
Battery voltageE
Vehicle speed sensor or ABS
actuator and electric unit (con-
trol unit)E
Brake switchE
Atmospheric pressure sensorE
EFuel injection controlEElectric governor
EFuel injection timing controlEInjection timing control
valve
EFuel cut controlEFuel cut solenoid valve
EGlow control systemEGlow relay & glow lamp
EOn board diagnostic systemEMalfunction indicator
(On the instrument panel)
EEGR valve controlEEGRC-solenoid valve A & B
ECooling fan controlECooling fan relays
EAir conditioning cut controlEAir conditioner relay
ECooling fan motor controlECooling fan relay
ENGINE AND EMISSION CONTROL OVERALL SYSTEMCD20T
EC-14

Glow Control System
SYSTEM DESCRIPTION
Crankshaft position sensor (TDC)EEngine speed
ECMEGlow relayEGlow plugs
Engine coolant temperature sensorEEngine coolant temperatureEGlow lamp
When coolant temperature is lower than 75ÉC (167ÉF):
lIgnition switch ON
After the ignition switch has been turned to ON, the glow
relay turns ON for a period of time depending on the engine
coolant temperature, allowing current to flow through the
glow plugs.
lStarting
After starting the engine, current will flow through the glow
plugs for 300 seconds, or until the coolant temperature
exceeds 50ÉC (122ÉF).
Fuel Injection System
SYSTEM DESCRIPTION
Three types of fuel injection control are provided to accommodate the engine operating conditions; normal
control, idle control and start control. The ECM determines the appropriate fuel injection control. Under each
control, the amount of fuel injected is compensated to improve engine performance. The ECM performs duty
cycle control on the electric governor (built into the fuel injection pump) according to sensor signals to com-
pensate the amount of fuel injected to the preset value.
START CONTROL
Input/output signal line
Engine coolant temperature sensorEEngine coolant temperature
ECM
EElectric
governorCrankshaft position sensor (TDC)EEngine speed
Control sleeve position sensor
EControl sleeve position
When starting, the ECM adapts the fuel injection system for the
start control. The amount of fuel injected at engine starting is a
preset program value in the ECM. The program is determined by
the engine speed and engine coolant temperature.
For better startability under cool engine conditions, the lower the
coolant temperature becomes, the greater the amount of fuel
injected. The ECM ends the start control when the engine speed
reaches a coolant temperature dependent value.
SEF648S Coolant temperature
getting lower
Engine rpm
Fuel injection volume
ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTIONCD20T
EC-15

IDLE CONTROL
Input/output signal line
Engine coolant temperature sensorEEngine coolant temperature
ECM
EElectric
governor
Crankshaft position sensor (TDC)EEngine speed
Air conditioner switch
EAir conditioner operation
Control sleeve position sensor
EControl sleeve position
Accelerator position switch
EIdle position
Vehicle speed sensor or ABS actuator
and electric unit (control unit)
EVehicle speed
When the ECM determines that the engine speed is at idle, the fuel injection system is adapted for the idle
control. The ECM regulates the amount of fuel injected corresponding to changes in load applied to the
engine to keep engine speed constant. During the first 270s after a cold start, the ECM also provides the
system with a fast idle control in response to the engine coolant temperature.
NORMAL CONTROL
Input/output signal line
Crankshaft position sensor (TDC)EEngine speed
ECM
EElectric
governor
Control sleeve position sensorEControl sleeve position
Accelerator position sensor
EAccelerator position
Vehicle speed sensor or ABS actuator
and electric unit (control unit)
EVehicle speed
The amount of fuel injected under normal driving conditions is
determined according to sensor signals. The crankshaft position
sensor (TDC) detects engine speed and the accelerator position
sensor detects accelerator position. These sensors send signals
to the ECM.
The fuel injection data, predetermined by correlation between
various engine speeds and accelerator positions, are stored in
the ECM memory, forming a map. The ECM determines the
optimal amount of fuel to be injected using the sensor signals in
comparison with the map.
SEF649S
Fuel injection volume
Accelerator
opening larger
Engine rpm
ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTIONCD20T
Fuel Injection System (Cont'd)
EC-16