NISSAN PRIMERA 1999 Electronic Repair Manual

Cooling Fan (Overheat)
SYSTEM DESCRIPTION
Vehicle speed sensorEVehicle speed
ECM
ECooling
fan
relay(s)Engine coolant temperature sensorEEngine coolant temperature
Air conditioner switch
EAir conditioner ªONº signal
The ECM controls the cooling fan corresponding to the vehicle speed, engine coolant temperature, air con-
ditioner system pressure and air conditioner ON signal. The control system has 3-step control [HIGH/LOW/
OFF]. This system indirectly relates to diagnostic trouble code 28 (Overheat).
Operation
ON-BOARD DIAGNOSIS LOGIC
This diagnosis continuously monitors the engine coolant temperature.
If the cooling fan or another component in the cooling system malfunctions, engine coolant temperature will
rise.
When the engine coolant temperature reaches an abnormally high temperature condition, a malfunction is
indicated.
Malfunction is detected when ...Check Items
(Possible Cause)
lAn excessive high engine coolant temperature sensor sig-
nal is detected by the ECM. (Overheat)lHarness or connectors
(The cooling fan circuit is open or shorted.)
lCooling fan
lRadiator hose
lRadiator
lRadiator cap
lWater pump
lThermostat
lFan belt
lEngine coolant temperature sensor
For more information, refer to ª12 MAIN CAUSES OF
OVERHEATINGº, EC-CD-95.
CAUTION:
When a malfunction is indicated, be sure to replace the coolant following the procedure in the MA
section (ªChanging Engine Coolantº, ªENGINE MAINTENANCEº). Also, replace the engine oil.
a. Fill radiator with coolant up to specified level with a filling speed of 2 liters per minute. Be sure
to use coolant with the proper mixture ratio. Refer to MA section (ªAnti-freeze Coolant Mixture
Ratioº, ªRECOMMENDED FLUIDS AND LUBRICANTSº).
b. After refilling coolant, run engine to ensure that no water-flow noise is emitted.
NEF772
Engine coolant
temperature ÉC (ÉF)
Air conditioner is OFF
.102 (216)
.96 (205)
.20
(12).80
(50)
Vehicle speed km/h (mph)
Cooling fans do not operateCooling fans operate at high speed
Engine coolant
temperature ÉC (ÉF)
Vehicle speed km/h (mph)
.20
(12).80
(50)
.102 (216)
.96 (205)Air conditioner is ON
Cooling fans operate at low speed
TROUBLE DIAGNOSIS 8CD20T
EC-87

OVERALL FUNCTION CHECK
Use this procedure to check the overall function of the cooling
fan. During this check, a DTC might not be confirmed.
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 the 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 steps and go to
ªDIAGNOSTIC PROCEDUREº, EC-CD-90.
2) Confirm whether customer filled the coolant or not. If cus-
tomer filled the coolant, skip the following steps and go to
ªDIAGNOSTIC PROCEDUREº, EC-CD-90.
3) Turn ignition switch to ªONº position.
4) Perform ªCOOLING FANº in ªACTIVE TESTº mode
with CONSULT-II (LOW speed and HI speed).
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------OR--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
3) Start engine.
Be careful not to overheat engine.
4) Set temperature control switch to full cold position.
5) Push Air Conditioner switch to ªONº position.
6) Turn blower fan switch to ªONº position.
7) Run engine at idle for a few minutes with Air Con-
ditioner operating.
Be careful not to overheat engine.
8) Make sure that both cooling fans operate at low
speed.
9) Turn ignition switch to ªLOCKº position.
10) Push Air Conditioner switch and blower fan switch
to ªOFFº position.
11) Disconnect engine coolant temperature sensor
harness connector.
12) Connect 150Wresistor to engine coolant tempera-
ture sensor harness connector.
13) Restart engine and make sure that both cooling
fans operate at higher speed than low speed.
Be careful not to overheat engine.
AEC640 MAX.
MIN.OK
SEF111X
SEC163BA
MEC475B Cooling fan
Engine coolant
temperature sensor
harness connector
150Wresistor
TROUBLE DIAGNOSIS 8CD20T
Cooling Fan (Overheat) (Cont'd)
EC-88

YEC805
BATTERYIGNITION SWITCH
ON or START
FUSE
BLOCK
(J/B)Refer to EL-POWER.
: Detectable line for DTC
: Non-detectable line for DTC
COOLING
FA N
RELAY-3COOLING
FA N
RELAY-2COOLING
FA N
RELAY-1
COOLING
FA N
MOTOR-1
LOWHIGHTRIPLE-
PRESSURE
SWITCHCOOLING
FA N
MOTOR-2
ECM
REFER TO THE FOLLOWING
FUSE BLOCK - Junction Box (J/B)
TROUBLE DIAGNOSIS 8CD20T
Cooling Fan (Overheat) (Cont'd)
EC-89

DIAGNOSTIC PROCEDURE
INSPECTION START
CHECK COOLING FAN LOW
SPEED OPERATION.
1. Disconnect cooling fan relay-3.
2. Turn ignition switch to ªONº
position.
3. Perform ªCOOLING FANº
in ªACTIVE TESTº mode
with CONSULT-II.
-------------------------------------------------------------------------------------------------------------------------OR-------------------------------------------------------------------------------------------------------------------------
2. Start engine.
3. Set temperature switch at
full cold position.
4. Turn Air Conditioner switch
to ªONº position.
5. Turn blower fan switch to
ªONº position.
6. Run engine at idle speed
for a few minutes with Air
Conditioner operating.
7. Make sure that both cool-
ing fans operate at low
speed.
OK
ENG
Check cooling fan low
speed control circuit.
(Go to
PROCEDURE A
.)
CHECK COOLING FAN HIGH
SPEED OPERATION.
1. Turn ignition switch to ªLOCKº
position.
2. Reconnect cooling fan relay-3.
3. Disconnect cooling fan relay-1.
4. Turn ignition switch to ªONº
position.
5. Perform ªCOOLING FANº
in ªACTIVE TESTº mode
with CONSULT-II.
-------------------------------------------------------------------------------------------------------------------------OR-------------------------------------------------------------------------------------------------------------------------
4. Turn Air Conditioner switch
and blower fan switch to
ªOFFº position.
5. Disconnect engine coolant
temperature sensor har-
ness connector.
6. Connect 150Wresistor to
engine coolant temperature
sensor harness connector.
7. Restart engine and make
sure that both cooling fans
operate at higher speed
than low speed.
OK
ENG
Check cooling fan high
speed control circuit.
(Go to
PROCEDURE B
.)
pB
(Go to EC-CD-94.)
.Cooling fan relay 2
Cooling fan relay-1Cooling fan relay-3
YEC383
SEF111X
NEF809
Cooling fan
SEF111X
YEC384
Cooling fan
Engine coolant
temperature sensor
harness connector
resistor
H
H
H
TROUBLE DIAGNOSIS 8CD20T
Cooling Fan (Overheat) (Cont'd)
EC-90

PROCEDURE A
INSPECTION START
CHECK POWER SUPPLY.
1. Turn ignition switch to ªLOCKº posi-
tion.
2. Disconnect cooling fan relay-1 and
fan motor-1 connector.
3. Turn ignition switch to ªONº position.
4. Check voltage between cooling fan
motor-1 connector terminal
p1, fan
relay-1 connector terminal
p1and
ground.
Voltage: Battery voltage
OK
ENG
Check the following:
l10A fuse
l40A, 100A, fusible
links
lHarness for open or
short-circuit between
cooling fan motor-1
and battery.
lHarness for open or
short-circuit between
cooling fan relay-1 and
fuse.
If NG, replace fuse or
fusible links or repair har-
ness or connectors.
CHECK GROUND CIRCUIT.
1. Turn ignition switch to ªLOCKº posi-
tion.
2. Disconnect cooling fan relay-2 and
fan motor-2 harness connector.
3. Check harness continuity
between cooling fan relay-1 con-
nector terminal
p5and cooling
fan relay-2 connector terminal
p4; cooling fan motor-1 con-
nector terminal
p2and cooling
fan relay-2 connector terminal
p3.Continuity should exist.
If OK, check harness for short-
circuit.
4. Check harness continuity
between cooling fan motor-2
connector terminal
p1and
cooling fan relay-1 connector
terminal
p3; cooling fan
motor-2 connector terminal
p2
and ground.Continuity should
exist.
If OK, check harness for short-
circuit.
OK
ENG
Repair harness or con-
nectors.
pC
YEC385 Cooling fan relay-1
connectorCooling fan motor-1
connector
NEF416
.Under the vehicle
A/C compressor
.Cooling fan motor-1
harness connector
NEF417
.Radiator
lower hose
.Cooling fan
motor-2
harness
connector
.Under the vehicle
YEC386
Cooling fan relay-2
connector Cooling fan motor-1
connector
Cooling fan
relay-1 con-
nector
YEC387 Cooling fan
relay-1 connectorCooling fan motor-2
connector
H
H
H
TROUBLE DIAGNOSIS 8CD20T
Cooling Fan (Overheat) (Cont'd)
EC-91

pC
CHECK OUTPUT SIGNAL CIRCUIT.
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM
terminal
219and cooling fan relay-1 con-
nector terminal
p2.
Continuity should exist.
If OK, check harness for short-circuit.
OK
ENG
Check the following:
lHarness connectorsE43,F2
lHarness for open or short-
circuit between cooling fan
relay-1 and ECM
If NG, repair harness or con-
nectors.
CHECK COMPONENT
(Cooling fan relay-1, 2).
Refer to ªCOMPONENT INSPECTIONº,
EC-CD-96.
OK
ENG
Replace cooling fan relay.
CHECK COMPONENT
(Cooling fan motors).
Refer to ªCOMPONENT INSPECTIONº,
EC-CD-96.
OK
ENG
Replace cooling fan motors.
Disconnect and reconnect harness connec-
tors in the circuit. Then retest.
Trouble is not fixed.
Check ECM pin terminals for damage and
check the connection of ECM harness con-
nector. Reconnect ECM harness connector
and retest.
INSPECTION END
PROCEDURE B
INSPECTION START
CHECK POWER SUPPLY.
1. Turn ignition switch to ªLOCKº position.
2. Disconnect cooling fan relay-2, 3 and
cooling fan motor-1.
3. Turn ignition switch to ªONº position.
4. Check voltage between cooling fan
motor-1 connector terminal
p1; cooling
fan relay-2 connector terminal
p1; cool-
ing fan relay-3 connector terminals
p1&
p3and ground.
Voltage: Battery voltage
OK
ENG
Check the following:
l10A-fusel40A, 50A, 100A fusible
links
lHarness for open or
short-circuit between fan
motor-1, fan relay-3 and
fusible link or fan relay-2,
3 and fuse.
If NG, replace fuse or fus-
ible link or repair harness or
connectors.
pD
NEF207A
Cooling fan relay-1
connector
NEF203A
Cooling fan
relay-2
connector Cooling fan
motor-1
connector Cooling fan
relay-3
connector
H
H
H
H
H
H
H
H
TROUBLE DIAGNOSIS 8CD20T
Cooling Fan (Overheat) (Cont'd)
EC-92

pD
CHECK GROUND CIRCUIT.
1. Turn ignition switch to ªLOCKº position.
2. Disconnect cooling fan motor-2 harness
connector.
3. Check harness continuity between
cooling fan motor-1 connector termi-
nal
p2and cooling fan relay-2 con-
nector terminal
p3; cooling fan
motor-2 connector terminal
p1and
cooling fan relay-3 connector termi-
nal
p5; cooling fan relay-2 connec-
tor terminal
p5and ground.
Continuity should exist.
If OK, check harness for short-circuit.
4. Check harness continuity between
cooling fan motor-2 terminal
p2and
ground.
OK
ENG
Repair harness or connec-
tors.
CHECK OUTPUT SIGNAL CIRCUIT.
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM
terminal
220and cooling fan relay-3
connector terminal
p2& cooling fan
relay-2 connector terminal
p2.
Continuity should exist.
If OK, check harness for short-circuit.
OK
ENG
Check the following:
lHarness connectorsE43,F2
lHarness for open or
short-circuit between
cooling fan relay-2, 3 and
ECM.
If NG, repair harness or
connectors.
CHECK COMPONENT
(Cooling fan relay-2, 3).
Refer to ªCOMPONENT INSPECTIONº, EC-
CD-96.
OK
ENG
Replace cooling fan relays.
CHECK COMPONENTS
(Cooling fan motors).
Refer to ªCOMPONENT INSPECTIONº, EC-
CD-96.
OK
ENG
Replace cooling fan motors.
Disconnect and reconnect harness connec-
tors in the circuit. Then retest.
Trouble is not fixed
Check ECM pin terminals for damage and
check the connection of ECM harness con-
nector. Reconnect ECM harness connector
and retest.
INSPECTION END
NEF876
Cooling fan motor-1
connectorCooling fan relay-2
connector
Cooling fan
motor-2
connectorCooling fan relay-3
connector
YEC389 Cooling fan motor-2
connector
E18
NEF204A
Cooling fan
relay-3
connector
Cooling fan
relay-2
connector
H
H
H
H
H
H
H
TROUBLE DIAGNOSIS 8CD20T
Cooling Fan (Overheat) (Cont'd)
EC-93

pB
CHECK COOLING SYSTEM FOR LEAK.
Apply pressure to the cooling system with a
tester, and check if the pressure drops.
Testing pressure:
157kPa (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
ENG
Check the following
for leaks:
lHoselRadiatorlWater pump
Refer to LC section
(ªWater Pumpº).
CHECK RADIATOR CAP.
Apply pressure to cap with a tester.
Radiator cap relief pressure:
Standard
78 - 98 kPa (0.78 - 0.98 bar,
0.8 - 1.0 kg/cm
2, 11 - 14 psi)
Limit
59 - 88 kPa (0.59 - 0.88 bar,
0.6 - 0.9 kg/cm
2,9-13psi)
OK
ENG
Replace radiator
cap.
CHECK THERMOSTAT.
1. Check valve seating condition at normal
room temperatures.
It should seat tightly.
2. Check valve opening temperature and
maximum valve lift.
Valve opening temperature:
76.5ÉC (170ÉF) [standard]
Maximum valve lift:
More than 8 mm/90ÉC
(0.31 in/194ÉF)
3. Check if valve is closed at 5ÉC (9ÉF)
below valve opening temperature.
For details, refer to LC section
(ªThermostatº).
OK
ENG
Replace thermostat.
Check engine coolant temperature sensor.
Refer to ªCOMPONENT INSPECTIONº,
EC-69.
OK
ENG
Replace engine cool-
ant temperature sen-
sor.
If the cause can not be isolated, go to ª12
MAIN CAUSES OF OVERHEATINGº 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 ªOVERALL FUNCTION CHECKº.
Hose adapter
.SLC754AA
SLC755AA
SLC343
H
H
H
H
H
H
TROUBLE DIAGNOSIS 8CD20T
Cooling Fan (Overheat) (Cont'd)
EC-94

12 MAIN CAUSES OF OVERHEATING
Engine Step Inspection item Equipment Standard Reference page
OFF 1
lBlocked radiatorlBlocked condenserlBlocked radiator grillelBlocked bumper
lVisual No blocking þ
2
lCoolant mixturelCoolant tester 50 - 50% coolant mix-
tureSee ªRECOMMENDED
FLUIDS AND LUBRI-
CANTSº in MA section.
3
lCoolant levellVisual Coolant up to MAX level
in reservoir tank and
radiator filler neckSee ªChanging Engine
Coolantº, ªENGINE
MAINTENANCEº 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)
59-98kPa
(0.59 - 0.98 bar, 0.6 -
1.0 kg/cm
2,9-14psi)
(Limit)See ªSystem Checkº
ªENGINE COOLING
SYSTEMº in LC section.
ON*2 5
lCoolant leakslVisual No leaks See ªSystem Checkº
ªENGINE COOLING
SYSTEMº in LC section.
ON*2 6
lThermostatlTouch the upper and
lower radiator hosesBoth hoses should be
hotSee ªThermostatº and
ªRadiatorº, ªENGINE
COOLING SYSTEMº in
LC section.
ON*1 7
lCooling fanlCONSULT Operating See ªTROUBLE DIAG-
NOSIS 8º.
OFF 8
lCombustion gas leaklColor checker
chemical tester
4 Gas analyzerNegative þ
ON*3 9
lCoolant temperature
gaugelVisual Gauge less than 3/4
when drivingþ
lCoolant overflow to
reservoir tanklVisual No overflow during driv-
ing and idlingSee ªChanging Engine
Coolantº, ªENGINE
MAINTENANCEº in MA
section.
OFF*4 10
lCoolant return from
reservoir tank to
radiatorlVisual Should be initial level in
reservoir tankSee ªENGINE MAINTE-
NANCEº in MA section.
OFF 11
lCylinder headlStraight gauge feeler
gauge0.1 mm (0.004 in) Maxi-
mum distortion (warping)See ªInspectionº, ªCYL-
INDER HEADº in EM
section.
12
lCylinder block and
pistonslVisual No scuffing on cylinder
walls or pistonSee ªInspectionº, ªCYL-
INDER BLOCKº in EM
section.
*1: Turn the ignition switch ON.
*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 ªOVERHEATING CAUSE ANALYSISº in LC section.
TROUBLE DIAGNOSIS 8CD20T
Cooling Fan (Overheat) (Cont'd)
EC-95

COMPONENT INSPECTION
Cooling fan relays-1, -2, -3
Check continuity between terminalsp3andp5.
Conditions Continuity
12V direct current supply between relay
terminals
p1andp2Ye s
No current supplyNo
If NG, replace cooling fan relay.
Cooling fan relay-2
Check continuity between terminalsp3andp4.
Conditions Continuity
No current supplyYe s
12V direct current supply between relay
terminals
p1andp2No
Cooling fan motors-1 and -2
1. Disconnect cooling fan motor harness connectors.
2. Supply cooling fan motor terminals with battery voltage and
check operation.
Terminals
(!)(@)
Cooling fan motor-1 and -2
p1p2
Cooling fan motor should operate.
If NG, replace cooling fan motor.
3 5
12
3 5
1 4 2
3 5
1 4 2
YEC391
Cooling fan relay 1
Cooling fan relay 3
Cooling fan relay 2
AEC781
FUSE
Cooling fan
motor-1 & -2
TROUBLE DIAGNOSIS 8CD20T
Cooling Fan (Overheat) (Cont'd)
EC-96