
Diagnostic ProcedureNJEC0491
1 CHECK COOLING FAN OPERATION
1. Start engine and let it idle.
2. Set temperature lever at full cold position.
3. Turn air conditioner switch ªONº.
4. Turn blower fan switch ªONº.
5. Make sure that cooling fans-1 and -2 operate.
SEC163BA
OK or NG
OK©GO TO 11.
NG©GO TO 2.
2 CHECK AIR CONDITIONER OPERATION
Is air conditioner operating?
(Check operation of compressor and blower motor.)
OK or NG
OK©GO TO 3.
NG©Check for failure of air conditioner to operate. Refer to HA section.
DTC P1217 OVERHEAT (COOLING SYSTEM)QG
Diagnostic Procedure
EC-339

SEF552W
COMPONENT DESCRIPTIONNJEC0349S02EGR Volume Control ValveNJEC0349S0201The EGR volume control valve uses a step motor to control the flow
rate of EGR from exhaust manifold. This motor has four winding
phases. It operates according to the output pulse signal of the
ECM. Two windings are turned ON and OFF in sequence. Each
time an ON pulse is issued, the valve opens or closes, changing
the flow rate. When no change in the flow rate is needed, the ECM
does not issue the pulse signal. A certain voltage signal is issued
so that the valve remains at that particular opening.
CONSULT-II Reference Value in Data Monitor
Mode
NJEC0539Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
EGR TEMP SEN+Engine: After warming up Less than 4.5V
EGR VOL CON/V+Engine: After warming up
+Air conditioner switch: ªOFFº
+Shift lever: ªNº
+No-loadIdle 0 step
Revving engine up to 3,000 rpm
quickly10 - 55 step
ECM Terminals and Reference ValueNJEC0540Specification data are reference values, and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TERMI-
NAL NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
8
9
17
18SB
W/B
R/Y
BR/REGR volume control valve[Engine is running.]
+Warm-up condition
+Idle speed0 - 14V
58 B Sensor's ground[Engine is running.]
+Warm-up condition
+Idle speed0V
72 P/B EGR temperature sensor[Engine is running.]
+Warm-up condition
+Idle speedLess than 4.5V
[Engine is running.]
+Warm-up condition
+EGR system is operating.0 - 1.0V
SEF073P
On Board Diagnosis LogicNJEC0350If EGR temperature sensor detects EGR flow under the condition
that does not call for EGR, a high-flow malfunction is diagnosed.
NOTE:
Diagnosis for this DTC will occur when engine coolant temperature
is below 50 to 60ÉC (122 to 140ÉF). Therefore, it will be better to
turn ignition switch ªONº (start engine) at the engine coolant tem-
perature below 30ÉC (86ÉF) when starting DTC confirmation pro-
cedure.
DTC P1402 EGR FUNCTION (OPEN) (WHERE FITTED)QG
Description (Cont'd)
EC-354

DescriptionNJEC1746SYSTEM DESCRIPTIONNJEC1746S01
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor (POS) Engine speed
EGR vol-
ume controlEGR volume control valve Camshaft position sensor (PHASE) Engine speed and cylinder number
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Ignition switch Start signal
Throttle position sensor Throttle position
Vehicle speed sensor Vehicle speed
Battery Battery voltage
Air conditioner switch Air conditioner operation
Power steering oil pressure switch Power steering load signal
Electrical load Electrical load signal
PNP switch Park/Neutral position signal
This system controls flow rate of EGR led from exhaust manifold
to intake manifold. The opening of the EGR by-pass passage in the
EGR volume control valve changes to control the flow rate. A
built-in step motor moves the valve in steps corresponding to the
ECM output pulses. The opening of the valve varies for optimum
engine control. The optimum value stored in the ECM is determined
by considering various engine conditions. The EGR volume control
valve remains close under the following conditions.
+Low engine coolant temperature
+Engine starting
+High-speed engine operation
+Extremely light load engine operation
+Engine idling
+Excessively high engine coolant temperature
+Wide open throttle
+Mass air flow sensor malfunction
+Low battery voltage
SEF551W
EGR VOLUME CONTROL SYSTEM (WHERE FITTED)QG
Description
EC-400

SEF552W
COMPONENT DESCRIPTIONNJEC1746S02EGR Volume Control ValveNJEC1746S0201The EGR volume control valve uses a step motor to control the flow
rate of EGR from exhaust manifold. This motor has four winding
phases. It operates according to the output pulse signal of the
ECM. Two windings are turned ON and OFF in sequence. Each
time an ON pulse is issued, the valve opens or closes, changing
the flow rate. When no change in the flow rate is needed, the ECM
does not issue the pulse signal. A certain voltage signal is issued
so that the valve remains at that particular opening.
SEF599K
EGR Temperature SensorNJEC1746S0202The EGR temperature sensor detects temperature changes in the
EGR passageway. When the EGR volume control valve opens, hot
exhaust gases flow, and the temperature in the passageway
changes. The EGR temperature sensor is a thermistor that modi-
fies a voltage signal sent from the ECM. This modified signal then
returns to the ECM as an input signal. As the temperature
increases, EGR temperature sensor resistance decreases. This
sensor is not used to control the engine system.
SEF068X
EGR temperature
ÉC (ÉF)Voltage*
VResistance
MW
0 (32) 4.56 0.62 - 1.05
50 (122) 2.25 0.065 - 0.094
100 (212) 0.59 0.011 - 0.015
*: These data are reference values and are measured between ECM terminal 72
(EGR temperature sensor) and ground.
When EGR system is operating.
Voltage: 0 - 1.5V
CAUTION:
Do not use ECM ground terminals when measuring input/
output voltage. Doing so may result in damage to the ECM's
transistor. Use a ground other than ECM terminals, such as
the ground.
CONSULT-II Reference Value in Data Monitor
Mode
NJEC1747Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
EGR TEMP SEN+Engine: After warming up Less than 4.5V
EGR VOL CON/V+Engine: After warming up
+Air conditioner switch: ªOFFº
+Shift lever: ªNº
+No-loadIdle 0 step
Revving engine up to 3,000 rpm
quickly10 - 55 step
EGR VOLUME CONTROL SYSTEM (WHERE FITTED)QG
Description (Cont'd)
EC-401

DescriptionNJEC1758SYSTEM DESCRIPTIONNJEC1758S01
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor (POS) Engine speed
Idle air
controlIACV-AAC valve Camshaft position sensor (PHASE) Engine speed and cylinder number
Engine coolant temperature sensor Engine coolant temperature
Ignition switch Start signal
Throttle position sensor Throttle position
PNP switch Park/Neutral position
Air conditioner switch Air conditioner operation
Power steering oil pressure switch Power steering load signal
Battery Battery voltage
Vehicle speed sensor Vehicle speed
Cooling fan Cooling fan operation
Electrical load Electrical load signal
This system automatically controls engine idle speed to a specified
level. Idle speed is controlled through fine adjustment of the
amount of air which by-passes the throttle valve via IACV-AAC
valve. The IACV-AAC valve changes the opening of the air by-pass
passage to control the amount of auxiliary air. This valve is actu-
ated by a step motor built into the valve, which moves the valve in
the axial direction in steps corresponding to the ECM output sig-
nals. One step of IACV-AAC valve movement causes the respec-
tive opening of the air by-pass passage. (i.e. when the step
advances, the opening is enlarged.) The opening of the valve is
varied to allow for optimum control of the engine idling speed. The
crankshaft position sensor (POS) detects the actual engine speed
and sends a signal to the ECM. The ECM then controls the step
position of the IACV-AAC valve so that engine speed coincides with
the target value memorized in ECM. The target engine speed is the
lowest speed at which the engine can operate steadily. The opti-
mum value stored in the ECM is determined by taking into consid-
eration various engine conditions, such as during warm up,
deceleration, and engine load (air conditioner, power steering, cool-
ing fan operation and electrical load).
SEF937W
COMPONENT DESCRIPTIONNJEC1758S02IACV-AAC ValveNJEC1758S0201The IACV-AAC valve is operated by a step motor for centralized
control of auxiliary air supply. This motor has four winding phases
and is actuated by the output signals of ECM which turns ON and
OFF two windings each in sequence. Each time the IACV-AAC
valve opens or closes to change the auxiliary air quantity, the ECM
sends a pulse signal to the step motor. When no change in the
auxiliary air quantity is needed, the ECM does not issue the pulse
signal. A certain voltage signal is issued so that the valve remains
at that particular opening.
IDLE AIR CONTROL VALVE (IACV) Ð AUXILIARY AIR CONTROL
(AAC) VALVE
QG
Description
EC-418

CONSULT-II Reference Value in Data Monitor
Mode
NJEC1759
MONITOR ITEM CONDITION SPECIFICATION
IACV-AAC/V+Engine: After warming up
+Air conditioner switch: OFF
+Shift lever: ªNº
+No-loadIdle 5 - 25 steps
2,000 rpm Ð
ECM Terminals and Reference ValueNJEC1760Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TER-
MINAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
6
7
15
16BR
LG
P
ORIACV-AAC valve[Engine is running]
+Warm-up condition
+Idle speed0.1 - 14V
IDLE AIR CONTROL VALVE (IACV) Ð AUXILIARY AIR CONTROL
(AAC) VALVE
QG
CONSULT-II Reference Value in Data Monitor Mode
EC-419

SEF138X
Component DescriptionNJEC0435The fuel injector is a small, precise solenoid valve. When the ECM
supplies a ground to the injector circuit, the coil in the injector is
energized. The energized coil pulls the needle valve back and
allows fuel to flow through the injector into the intake manifold. The
amount of fuel injected depends upon the injection pulse duration.
Pulse duration is the length of time the injector remains open. The
ECM controls the injection pulse duration based on engine fuel
needs.
CONSULT-II Reference Value in Data Monitor
Mode
NJEC0436
MONITOR ITEM CONDITION SPECIFICATION
INJ PULSE-B1+Engine: After warming up
+Air conditioner switch: OFF
+Shift lever: ªNº
+No-loadIdle 2.0 - 3.5 msec
2,000 rpm 1.5 - 3.5 msec
B/FUEL SCHDL+Engine: After warming up
+Air conditioner switch: OFF
+Shift lever: ªNº
+No-loadIdle 1.5 - 3.0 msec
2,000 rpm 1.2 - 3.0 msec
ECM Terminals and Reference ValueNJEC0437Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
101
103
105
107R/B
Y/B
G/B
L/BInjector No. 1
Injector No. 2
Injector No. 3
Injector No. 4[Engine is running]
+Warm-up condition
+Idle speedBATTERY VOLTAGE
(11 - 14V)
SEF011W
[Engine is running]
+Warm-up condition
+Engine speed is 2,000 rpmBATTERY VOLTAGE
(11 - 14V)
SEF012W
INJECTORQG
Component Description
EC-446

JEF147Y
DescriptionNJEC0580The refrigerant pressure sensor is installed at the liquid tank of the
air conditioner system. The sensor uses an electrostatic volume
pressure transducer to convert refrigerant pressure to voltage. The
voltage signal is sent to ECM, and ECM controls cooling fan sys-
tem.
SEF099X
ECM Terminals and Reference ValueNJEC0581Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
58 B Sensor's ground[Engine is running]
+Warm-up condition
+Idle speedApproximately 0V
74 R/LRefrigerant pressure
sensor[Engine is running]
+Warm-up condition
+Both A/C switch and blower switch are ªONº
(Compressor operates.)1.0 - 4.0V
111 R Sensor's power supply[Ignition switch ªONº]Approximately 5V
REFRIGERANT PRESSURE SENSORQG
Description
EC-475