
TER-
MINAL
NO.WIRE
COLORITEM CONDITIONDATA
(DC Voltage and Pulse
Signal)
15 Y/L Air conditioner relayEngine is running.
Air conditioner switch is ``OFF''.BATTERY VOLTAGE
(11 - 14V)
Engine is running.
Both air conditioner switch and blower fan
switch are ``ON''.
(Compressor is operating.)0-1V
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.
Diagnostic Trouble
Code No.Malfunction is detected when ...Check Items
(Possible Cause)
28+Cooling fan does not operate properly (Overheat).
+Cooling fan system does not operate properly (Over-
heat).
+Engine coolant was not added to the system using
the proper ®lling method.+Harness or connectors
(The cooling fan circuit is open or shorted.)
+Cooling fan
+Radiator hose
+Radiator
+Radiator cap
+Water pump
+Thermostat
+Fan belt
+Engine coolant temperature sensor
For more information, refer to ``MAIN 12
CAUSES OF OVERHEATING'', EC-120.
CAUTION:
When a malfunction is indicated, be sure to replace the coolant following the procedure in the MA
section (``Changing Engine Coolant'', ``ENGINE MAINTENANCE''). Also, replace the engine oil.
a. Fill radiator with coolant up to speci®ed level with a ®lling speed of 2 liters per minute. Be sure to
use coolant with the proper mixture ratio. Refer to MA section (``Anti-freeze Coolant Mixture Ratio'',
``RECOMMENDED FLUIDS AND LUBRICANTS'').
b. After re®lling coolant, run engine to ensure that no water-¯ow noise is emitted.
TROUBLE DIAGNOSIS FOR ``OVER HEAT'' (DTC 28)
Cooling Fan (Overheat) (Cont'd)
EC-114

OVERALL FUNCTION CHECK
Use this procedure to check the overall function of the cooling fan.
During this check, a DTC might not be con®rmed.
WARNING:
Never remove the radiator cap when the engine is hot. Serious
burns could be caused by high pressure ¯uid 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 ``DIAG-
NOSTIC PROCEDURE'', EC-117.
2) Con®rm whether customer ®lled the coolant or not. If customer
®lled the coolant, skip the following steps and go to ``DIAGNOS-
TIC PROCEDURE'', EC-117.
3) Turn ignition switch ``ON''.
4) Perform ``COOLING FAN'' in ``ACTIVE TEST'' mode with
CONSULT and make sure that cooling fan operates
when touching ``ON''.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------OR-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
3) Disconnect engine coolant temperature sensor harness
connector.
4) Connect 150Wresistor to engine coolant temperature
sensor harness connector.
5) Start engine and make sure that cooling fan operates.
Be careful not to overheat engine.
AEC640
SEF758V
SEF979S
TROUBLE DIAGNOSIS FOR ``OVER HEAT'' (DTC 28)
Cooling Fan (Overheat) (Cont'd)
EC-115

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 speci®ed pressure may
cause radiator damage.
OK
cNG
Check the following for
leak.
+Hose
+Radiator
+Water 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:
82ÉC (180ÉF) [standard]
Maximum valve lift:
More than 10 mm/95ÉC
(0.39 in/203ÉF)
3. Check if valve is closed at 5ÉC (9ÉF)
below valve opening temperature.
For details, refer to LC section (``Thermo-
stat'').
OK
cNG
Replace thermostat.
Check engine coolant temperature sensor.
Refer to ``COMPONENT INSPECTION'',
EC-82.
OK
cNG
Replace engine coolant
temperature 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 instrument
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
SLC755AB
SLC343
.
.
.
.
.
TROUBLE DIAGNOSIS FOR ``OVER HEAT'' (DTC 28)
Cooling Fan (Overheat) (Cont'd)
EC-119

MAIN 12 CAUSES OF OVERHEATING
Engine Step Inspection item Equipment Condition Reference page
OFF 1+Blocked radiator
+Blocked radiator grille
+Blocked bumper+Visual No blocking Ð
2+Coolant mixture+Coolant tester 50 - 50% coolant mixture See ``RECOMMENDED
FLUIDS AND LUBRI-
CANTS'' in MA section.
3+Coolant level+Visual Coolant up to MAX level
in reservoir tank and
radiator ®ller neckSee ``Changing Engine
Coolant'', ``ENGINE
MAINTENANCE'' in MA
section.
4+Radiator cap+Pressure tester 78 - 98 kPa
(0.78 - 0.98 bar, 0.8 - 1.0
kg/cm
2, 11 - 14 psi)See ``System Check''
``ENGINE COOLING
SYSTEM'' in LC section.
ON*
25+Coolant leaks+Visual No leaks See ``System Check''
``ENGINE COOLING
SYSTEM'' in LC section.
ON*
26+Thermostat+Touch the upper and
lower radiator hosesBoth hoses should be hot See ``Thermostat'' and
``Radiator'', ``ENGINE
COOLING SYSTEM'' in
LC section.
ON*
17+Cooling fan+CONSULT Operating See ``TROUBLE DIAG-
NOSIS FOR DTC 28'',
EC-113.
OFF 8+Combustion gas leak+Color checker chemical
tester 4 Gas analyzerNegative Ð
ON*
39+Coolant temperature
gauge+Visual Gauge less than 3/4
when drivingÐ
+Coolant over¯ow to res-
ervoir tank+Visual No over¯ow during driving
and idlingSee ``Changing Engine
Coolant'', ``ENGINE
MAINTENANCE'' in MA
section.
OFF*
410+Coolant return from res-
ervoir tank to radiator+Visual Should be initial level in
reservoir tankSee ``ENGINE MAINTE-
NANCE'' in MA section.
OFF 11+Cylinder head+Straight gauge feeler
gauge0.1mm (0.004 in) Maxi-
mum distortion (warping)See ``Inspection'', ``CYL-
INDER HEAD'' in EM
section.
12+Cylinder block and pis-
tons+Visual No scuffing on cylinder
walls or pistonSee ``Inspection'', ``CYL-
INDER BLOCK'' 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 ``OVERHEATING CAUSE ANALYSIS'' in LC section.
TROUBLE DIAGNOSIS FOR ``OVER HEAT'' (DTC 28)
Cooling Fan (Overheat) (Cont'd)
EC-120

General Precautions
+Do not operate the engine for an extended period of time with-
out proper exhaust ventilation.
Keep the work area well ventilated and free of any in¯ammable
materials. Special care should be taken when handling any
in¯ammable or poisonous materials, such as gasoline, refriger-
ant gas, etc. When working in a pit or other enclosed area, be
sure to properly ventilate the area before working with hazard-
ous materials.
Do not smoke while working on the vehicle.
+Before jacking up the vehicle, apply wheel chocks or other tire
blocks to the wheels to prevent the vehicle from moving. After
jacking up the vehicle, support the vehicle weight with safety
stands at the points designated for proper lifting before work-
ing on the vehicle.
These operations should be done on a level surface.
+When removing a heavy component such as the engine or
transaxle/transmission, be careful not to lose your balance and
drop it. Also, do not allow it to strike adjacent parts, especially
the brake tubes and master cylinder.
+Before starting repairs which do not require battery power:
Turn off ignition switch.
Disconnect the negative battery terminal.
+To prevent serious burns:
Avoid contact with hot metal parts.
Do not remove the radiator cap when the engine is hot.
+Before servicing the vehicle:
Protect fenders, upholstery and carpeting with appropriate cov-
ers.
Take caution that keys, buckles or buttons do not scratch paint.
SGI285
SGI231
SEF289H
SGI233
SGI234
PRECAUTIONS
GI-2

Special Service Tools*: Special tool or commercial equivalent
Tool number
Tool nameDescription
ST25051001*
Oil pressure gauge
NT558
Measuring oil pressure
Maximum measuring range:
2,452 kPa (24.5 bar, 25
kg/cm
2, 356 psi)
ST25052000*
Hose
NT559
Adapting oil pressure gauge
to cylinder block
EG17650301
Radiator cap tester
adapter
NT564
Adapting radiator cap tester
to radiator ®ller neck
a: 28 (1.10) dia.
b: 31.4 (1.236) dia.
c: 41.3 (1.626) dia.
Unit: mm (in)
KV99103510
Radiator plate pliers A
NT224
Installing radiator upper and
lower tanks
KV99103520
Radiator plate pliers B
NT225
Removing radiator upper and
lower tanks
WS39930000
Tube presser
NT052
Pressing the tube of liquid gas-
ket
PRECAUTIONS AND PREPARATION
LC-2

Cooling Circuit
System Check
WARNING:
Never remove the radiator cap when the engine is hot; serious
burns could be caused by high pressure ¯uid escaping from
the radiator.
Wrap a thick cloth around cap and carefully loosen it a quar-
ter turn to release built-up pressure. Then remove the cap
completely.
CHECKING COOLING SYSTEM HOSES
Check hoses for proper attachment, leaks, cracks, damage, loose
connections, cha®ng and deterioration.
CHECKING RADIATOR CAP
Apply pressure to radiator cap by means of a cap tester to see if it
is satisfactory.
Radiator cap relief pressure:
78-98kPa
(0.78 - 0.98 bar, 0.8 - 1.0 kg/cm
2, 11 - 14 psi)
SLC226A
SLC613
ENGINE COOLING SYSTEM
LC-9

Pull the negative pressure valve to open it. Check that it closes
completely when released.
CHECKING COOLING SYSTEM FOR LEAKS
Apply pressure to the cooling system by means of a tester to check
for leakage.
Testing pressure:
98 kPa (0.98 bar, 1.0 kg/cm
2, 14 psi)
CAUTION:
Use of pressure higher than the speci®ed value may cause
damage to radiator.
Water Pump
CAUTION:
+When removing water pump assembly, be careful not to
get coolant on drive belts.
+Water pump cannot be disassembled and should be
replaced as a unit.
+After installing water pump, connect hose and clamp
securely, then check for leaks using radiator cap tester.
REMOVAL
1. Drain coolant from radiator and cylinder block.
Cylinder block drain plug (Use proper sealant):
:34-44Nzm (3.5 - 4.5 kg-m, 25 - 33 ft-lb)
Refer to MA section (``Changing Engine Coolant'', ``ENGINE
MAINTENANCE'').
2. Remove radiator shroud.
3. Remove drive belts. Refer to MA section (``Checking Drive
Belts'').
4. Remove fan coupling with fan.
5. Remove water pump.
SMA967B
SMA007D
SMA003D
ENGINE COOLING SYSTEM
System Check (Cont'd)
LC-10