1998 NISSAN PICK-UP Repair Manual

COMPONENT INSPECTION
Ignition coil
1. Disconnect ignition coil harness connector.
2. Remove distributor cap.
3. Check resistance as shown in the figure.
Terminal Resistance [at 25ÉC (77ÉF)]
V7-V8Less than 1W
V7-V97-13kW
If NG, replace distributor assembly.
Power transistor
1. Disconnect camshaft position sensor & power transistor har-
ness connector and ignition coil harness connector.
2. Check power transistor resistance between terminals
V2and
V8.
Terminals Resistance Result
V2andV8Except 0WOK
0WNG
If NG, replace distributor assembly.
Resistor
1. Disconnect resistor harness connector.
2. Check resistance between terminals
V1andV2.
Resistance: Approximately 2.2 kW
If NG, replace resistor.
AEC150A
AEC152A
AEC151A
SEF151U
TROUBLE DIAGNOSIS FOR ``IGN SIGNAL-PRIMARY'' (DTC 21)KA
Ignition Signal (Cont'd)
EC-105

Overheat
ON BOARD DIAGNOSIS LOGIC
If the cooling fan or another component in the cooling system malfunctions, the engine coolant temperature
will rise.
When the engine coolant temperature reaches an abnormally high temperature condition, a malfunction is
indicated.
Diagnostic trouble
code No.Malfunction is detected when ...Check Items
(Possible Cause)
28
lEngine coolant temperature reaches an abnormally
high temperature.lCooling fan
lRadiator hose
lRadiator
lRadiator cap
lWater pump
lThermostat
For more information, refer to ``MAIN 12
CAUSES OF OVERHEATING'', EC-108.
CAUTION:
When a malfunction is indicated, be sure to replace the coolant following the procedure in MA sec-
tion (``Changing Engine Coolant'', ``ENGINE MAINTENANCE''). Also, replace the engine oil.
lFill radiator with coolant up to specified level with a filling speed of 2 liters per minute like pour-
ing coolant by kettle. Be sure to use coolant with the proper mixture ratio. Refer to MA section
(``Anti-freeze Coolant Mixture Ratio'', ``RECOMMENDED FLUIDS AND LUBRICANTS'').
lAfter refilling coolant, run engine to ensure that no water-flow noise is emitted.
OVERALL FUNCTION CHECK
WARNING:
Never remove the radiator cap when the engine is hot. Seri-
ous burns could be caused by high pressure fluid escaping
from the radiator.
Wrap a thick cloth around cap. Carefully remove the cap by
turning it a quarter turn to allow built-up pressure to escape.
Then turn the cap all the way off.
1. Check the coolant level in the reservoir tank and radiator.
Allow engine to cool before checking coolant level.
If the coolant level in the reservoir tank and/or radiator is
below the proper range, skip the following step and go to
``DIAGNOSTIC PROCEDURE'' on next page.
2. Confirm whether customer filled the coolant or not. If cus-
tomer filled the coolant, go to ``DIAGNOSTIC PROCEDURE''
on next page.
AEC640
TROUBLE DIAGNOSIS FOR ``OVER HEAT'' (DTC 28)KA
EC-106

DIAGNOSTIC PROCEDURE
INSPECTION START
CHECK COOLING SYSTEM FOR LEAK.
Apply pressure to the cooling system with a
tester, and check if the pressure drops.
Testing pressure:
157 kPa (1.57 bar, 1.6 kg/cm
2, 23 psi)
Pressure should not drop.
CAUTION:
Higher than the specified pressure may
cause radiator damage.
OK
cNG
Check the following for leak.
lHoselRadiatorlWater pump
Refer to LC section (``Water
Pump'').
CHECK RADIATOR CAP.
Apply pressure to cap with a tester.
Radiator cap relief pressure:
78 - 98 kPa (0.78 - 0.98 bar, 0.8 - 1.0
kg/cm
2, 11 - 14 psi)
OK
cNG
Replace radiator cap.
CHECK THERMOSTAT.
1. Check valve seating condition at normal
room temperatures.
It should seat tightly.
2. Check valve opening temperature and valve
lift.
Valve opening temperature:
76.5ÉC (170ÉF) [standard]
Valve lift:
More than 10 mm/90ÉC
(0.39 in/194ÉF)
3. Check if valve is closed at 5ÉC (9ÉF) below
valve opening temperature.
For details, refer to LC section (``Thermostat'').
OK
cNG
Replace thermostat.
Check engine coolant temperature sensor.
Refer to ``COMPONENT INSPECTION'',
EC-98.
OK
cNG
Replace engine coolant tem-
perature sensor.
If the cause cannot be isolated, go to ``MAIN
12 CAUSES OF OVERHEATING'' on next
page.
INSPECTION END
Perform FINAL CHECK by the following procedure after
repair is completed.
1. Warm up engine. Run the vehicle for at least 20 minutes. Pay
attention to engine coolant temperature gauge on the instru-
ment panel. If the reading shows an abnormally high
temperature, another part may be malfunctioning.
2. Stop vehicle and let engine idle. Check the intake and exhaust
systems for leaks by listening for noise or visually inspecting
the components.
3. Allow engine to cool and visually check for oil and coolant
leaks. Then, perform ``OVERALL FUNCTION CHECK''.
SLC754AA
SLC755AA
SLC343
.
.
.
.
.
.
TROUBLE DIAGNOSIS FOR ``OVER HEAT'' (DTC 28)KA
Overheat (Cont'd)
EC-107

MAIN 12 CAUSES OF OVERHEATING
Engine Step Inspection item Equipment Standard Reference page
OFF 1
lBlocked radiator
lBlocked condenser
lBlocked radiator grille
lBlocked bumper
lVisual No blocking Ð
2
lCoolant mixturelCoolant tester 50 - 50% coolant mixture See ``RECOMMENDED
FLUIDS AND LUBRI-
CANTS'' in MA section.
3
lCoolant levellVisual Coolant up to MAX level
in reservoir tank and
radiator filler neckSee ``Changing Engine
Coolant'', ``ENGINE
MAINTENANCE'' in MA
section.
4
lRadiator caplPressure tester 78 - 98 kPa
(0.78 - 0.98 bar, 0.8 - 1.0
kg/cm
2, 11 - 14 psi)
59 - 98 kPa (0.59 - 0.98
bar, 0.6 - 1.0 kg/cm
2,
9 - 14 psi) (Limit)See ``System Check'',
``ENGINE COOLING
SYSTEM'' in LC section.
ON*2 5
lCoolant leakslVisual No leaks See ``System Check'',
``ENGINE COOLING
SYSTEM'' in LC section.
ON*2 6
lThermostatlTouch the upper and
lower radiator hosesBoth hoses should be hot. See ``Thermostat'' and
``Radiator'', ``ENGINE
COOLING SYSTEM'' in
LC section.
ON*1 7
lCooling fanlVisual Operating See ``Cooling Fan'',
``ENGINE COOLING
SYSTEM'' in LC section.
OFF 8
lCombustion gas leaklColor checker chemical
tester 4 gas analyzerNegative Ð
ON*3 9
lCoolant temperature
gaugelVisual Gauge less than 3/4
when drivingÐ
lCoolant overflow to res-
ervoir tanklVisual No overflow during driving
and idlingSee ``Changing Engine
Coolant'', ``ENGINE
MAINTENANCE'' in MA
section.
OFF*4 10
lCoolant return from res-
ervoir tank to radiatorlVisual Should be initial level in
reservoir tankSee ``ENGINE MAINTE-
NANCE'' in MA section.
OFF 11
lCylinder headlStraight gauge feeler
gauge0.1 mm (0.004 in) Maxi-
mum distortion (warping)See ``Inspection'', ``CYL-
INDER HEAD'' in EM
section.
12
lCylinder block and pis-
tonslVisual No scuffing on cylinder
walls or pistonSee ``Inspection'', ``CYL-
INDER BLOCK'' in EM
section.
*1: Engine running at idle.
*2: Engine running at 3,000 rpm for 10 minutes.
*3: Drive at 90 km/h (55 MPH) for 30 minutes and then let idle for 10 minutes.
*4: After 60 minutes of cool down time.
For more information, refer to ``OVERHEATING CAUSE ANALYSIS'' in LC section.
TROUBLE DIAGNOSIS FOR ``OVER HEAT'' (DTC 28)KA
Overheat (Cont'd)
EC-108

Intake Air Temperature Sensor
The intake air temperature sensor is mounted to the air duct. The
sensor detects intake air temperature and transmits a signal to
the ECM.
The temperature sensing unit uses a thermistor, which is sensi-
tive to the change in temperature. Electrical resistance of the
thermistor decreases in response to the temperature rise.

Intake air temperature
ÉC (ÉF)Resistance kW
þ10 (14) 7.0 - 11.4
20 (68) 2.1 - 2.9
80 (176) 0.27 - 0.38
ON BOARD DIAGNOSIS LOGIC
Diagnostic
Trouble Code
No.Malfunction is detected when ...Check Items
(Possible Cause)
41
lAn excessively low or high voltage from the sensor is
sent to ECM*.lHarness or connectors
(The sensor circuit is open or shorted.)
lIntake air temperature sensor
*: When this malfunction is detected, the ECM enters fail-safe mode.
Engine operating condition in fail-safe modeThe ECM controls on the assumption that the intake temperature
is 20ÉC (68ÉF).
DIAGNOSTIC TROUBLE CODE CONFIRMATION
PROCEDURE
1) Turn ignition switch ``ON''.
2) Select ``DATA MONITOR'' mode with CONSULT.
3) Wait at least 2 seconds.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------OR-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1) Turn ignition switch ``ON'' and wait at least 2 seconds.
2) Turn ignition switch ``OFF'', wait at least 5 seconds and
then turn ``ON''.
3) Perform ``Diagnostic Test Mode II (Self-diagnostic
results)'' with ECM.
SEF086U
SEF012P
SEF002P
TROUBLE DIAGNOSIS FOR ``INT AIR TEMP SEN'' (DTC 41)KA
EC-109

HEC346
TROUBLE DIAGNOSIS FOR ``INT AIR TEMP SEN'' (DTC 41)KA
Intake Air Temperature Sensor (Cont'd)
EC-110

DIAGNOSTIC PROCEDURE
INSPECTION START
CHECK POWER SUPPLY.
1. Turn ignition switch ``OFF''.
2. Disconnect intake air temperature sen-
sor harness connector.
3. Turn ignition switch ``ON''.
4. Check voltage between terminal
V1
and ground.
Voltage:
Approximately 5V
OK
cNG
Repair harness or connec-
tors.
CHECK GROUND CIRCUIT.
1. Turn ignition switch ``OFF''.
2. Check harness continuity between ter-
minal
V2and engine ground.
Continuity should exist.
If OK, check harness for short to
ground and short to power.
OK
cNG
Check the following.
lHarness for open or
short between ECM and
intake air temperature
sensor
If NG, repair open circuit,
short to ground or short to
power in harness or con-
nectors.
CHECK COMPONENT
(Intake air temperature sensor).
Refer to ``COMPONENT INSPECTION''
on next page.
OK
cNG
Replace intake air tem-
perature sensor.
Disconnect and reconnect harness con-
nectors in the circuit. Then retest.
Trouble is not fixed.
Check ECM pin terminals for damage
and check the connection of ECM har-
ness connector.
Reconnect ECM harness connector and
retest.
INSPECTION END
SEF086U
SEF101S
SEF102S
.
.
.
.
.
.
TROUBLE DIAGNOSIS FOR ``INT AIR TEMP SEN'' (DTC 41)KA
Intake Air Temperature Sensor (Cont'd)
EC-111

COMPONENT INSPECTION
Intake air temperature sensor
Check resistance as shown in the figure.

Intake air temperature
ÉC (ÉF)Resistance kW
20 (68) 2.1 - 2.9
80 (176) 0.27 - 0.38
If NG, replace intake air temperature sensor.
SEF103S
SEF012P
TROUBLE DIAGNOSIS FOR ``INT AIR TEMP SEN'' (DTC 41)KA
Intake Air Temperature Sensor (Cont'd)
EC-112