1B-12 AIR CONDITIONING (OPTIONAL)
PERFORMANCE DIAGNOSIS TABLE
HIGH PRESSURE GAUGE
LOW PRESSURE GAUGE
THERMOMETER AT CENTER DUCT
NOTE:
If ambient temperature is approximately 30°C (86°F), it is possible to diagnose A/C system in detail
referring to “DETAIL DIAGNOSIS TABLE (AMBIENT TEMPERATURE AT 30 °C (86°F))” under “PER-
FORMANCE DIAGNOSIS” in this section.
Condition Possible Cause Correction
Pressure high
(“A” area of high side
graph)Refrigerant overcharged Recharge.
Expansion valve frozen or clogged Check expansion valve.
Clogged refrigerant passage of high side Clean or replace.
Radiator/condenser cooling fan malfunction (Insufficient
cooling of condenser)Check radiator/condenser cooling fan.
Dirty or bent condenser fins (Insufficient cooling of con-
denser)Clean or repair.
Compressor malfunction (Insufficient oil etc.) Check compressor.
Engine overheat Check engine cooling system referring to
Section 6B.
Pressure low
(“B” area of high side
graph)Insufficient refrigerant (Insufficient charge or leakage) Check for leakage, repair if necessary
and recharge.
Expansion valve malfunction (valve opens too wide) Check expansion valve.
Compressor malfunction (Insufficient compression) Check compressor.
Condition Possible Cause Correction
Pressure high
(“C” area of low side
graph)Expansion valve malfunction (valve opens too wide) Check expansion valve.
Compressor malfunction (Insufficient compression) Check compressor.
Pressure low
(“D” area of low side
graph)Insufficient refrigerant (Insufficient charge or leakage) Check for leakage, repair if necessary
and recharge.
Expansion valve malfunction (valve opens too narrow) Check expansion valve.
Clogged refrigerant passage (crashed pipe) Repair or replace.
Condition Possible Cause Correction
Outlet air temperature at
center duct is high
(Crossing point is in area
“E”)Insufficient or excessive charge of refrigerant Check refrigerant pressure.
Dirty or bent A/C evaporator fins Clean or repair.
Air leakage from cooling (heater) unit or air duct Repair or replace.
Malfunctioning, switch over function of door in cooling
(heater) unitRepair or replace.
Compressor malfunction Check compressor.
Outlet air temperature at
center duct is low
(Crossing point is in area
“F”)Insufficient air volume from center duct (Heater blower
malfunction)Check blower motor and fan.
Compressor malfunction Check compressor.
ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-21
P0340
(No.15)CMP SENSOR ECM changes injection control sys-
tem from sequential injection to simul-
taneous one.Hard starting
P0400 EGR VALVE–Hard starting/rough or incorrect
idle/ excessive fuel consumption/
hesitation/ poor acceleration/
surge/ detonation or spark knock/
engine stall
P0420 CATALYST––
P0443 PURGE CONTROL
VALVE–Rough or incorrect idle/ surge/
hard starting/ engine stall
P0480 RADIATOR FAN
CONTROL SYSTEM–Engine overheating
P0500
(No.16)VEHICLE SPEED
SENSORECM stops idle air control. Rough or incorrect idle
P0505 IDLE CONTROL
SYSTEM–Engine stall/ rough or incorrect idle
P0601
(No.71)ECM INTERNAL–Hard starting/ rough or incorrect
idle/ excessive fuel consumption/
detonation or spark knock/ hesita-
tion poor acceleration/
P1450
(No.29)BAROMETRIC
PRESSURE SEN-
SORECM controls actuators assuming
that barometric pressure is
100 kPa (760 mmHg).Hard starting/ rough or incorrect
idle DTC NO. TROUBLE AREA FAIL-SAFE OPERATION SYMPTOM
ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-27
Engine noise
Note : Before
checking mechani-
cal noise, make sure
that :
Specified spark
plug is used.
Specified fuel is
used.Improper valve lash Valve lash in Section 6A1.
Worn valve stem and guide Valves inspection in Section 6A1.
Weak or broken valve spring Valve springs inspection in Section
6A1.
Warped or bent valve Valves inspection in Section 6A1.
Worn piston, ring and cylinder bore Pistons and cylinders inspection in Sec-
tion 6A1.
Worn rod bearing Crank pin and connecting rod bearing
inspection in Section 6A1.
Worn crank pin Crank pin and connecting rod bearing
inspection in Section 6A1.
Loose connecting rod nuts Connecting rod installation in Section
6A1.
Low oil pressure Previously outlined.
Low oil pressure Previously outlined.
Worn bearing Crankshaft and bearing inspection in
Section 6A1.
Worn crankshaft journal Crankshaft and bearing inspection in
Section 6A1.
Loose bearing cap bolts Crankshaft inspection in Section 6A1.
Excessive crankshaft thrust play Crankshaft thrust play inspection in
Section 6A1.
Overheating
Inoperative thermostat Thermostat in Section 6B.
Poor water pump performance Water pump in Section 6B.
Clogged or leaky radiator Radiator in Section 6B.
Improper engine oil grade Engine oil and oil filter change in Sec-
tion 0B.
Clogged oil filter or oil strainer Oil pressure check in Section 6A1.
Poor oil pump performance Oil pressure check in Section 6A1.
Faulty radiator fan control system Radiator fan control system in Section
6E1.
Dragging brakes Trouble diagnosis in Section 5.
Slipping clutch Trouble diagnosis in Section 7C.
Blown cylinder head gasket Cylinder head in Section 6A1. Condition Possible Cause Correction
6-28 ENGINE GENERAL INFORMATION AND DIAGNOSIS
Poor gasoline mile-
age Leaks or loose connection of high-tension
cordHigh-tension cords in Section 6F1.
Faulty spark plug (improper gap, heavy
deposits and burned electrodes, etc.)Spark plugs in Section 6F1.
Malfunctioning EGR valve (if equipped) EGR system in Section 6E1.
High idle speed Refer to item “Improper engine idle
speed” previously outlined.
Poor performance of TP sensor, ECT sensor
or MAP sensorTP sensor, ECT sensor or MAP sensor
in Section 6E1.
Faulty EGR valve (if equipped) EGR system in Section 6E1.
Faulty fuel injector(s) Diagnostic Flow Table B-1.
Faulty ECM
Poor valve seating Valves inspection in Section 6A1.
Dragging brakes Trouble diagnosis in Section 5.
Slipping clutch Trouble diagnosis in Section 7C.
Thermostat out of order Thermostat in Section 6B.
Improper tire pressure Refer to Section 3F.
Low Compression Previously outlined
Excessive engine
oil consumption Blown cylinder head gasket Cylinder head in Section 6A1.
Leaky camshaft oil seals Camshaft in Section 6A1.
Sticky piston ring Piston cleaning in Section 6A1.
Worn piston and cylinder Pistons and cylinders inspection in Sec-
tion 6A1.
Worn piston ring groove and ring Pistons inspection in Section 6A1.
Improper location of piston ring gap Pistons assembly in Section 6A1.
Worn or damaged valve stem seal Valves removal and installation in Sec-
tion 6A1.
Worn valve stem Valves inspection in Section 6A1.
Engine hesitates
(Momentary lack of
response as accel-
erator is depressed.
Can occur at all
vehicle speeds.
Usually most severe
when first trying to
make vehicle move,
as from a stop sign.)Spark plug faulty or plug gap out of adjust-
mentSpark plugs in Section 6F1.
Leaky high-tension cord High-tension cords in Section 6F1.
Fuel pressure out of specification Diagnostic Flow Table B-3.
Malfunctioning EGR valve (if equipped) EGR system in section 6E1.
Poor performance of TP sensor, ECT sensor
or MAP sensorTP sensor, ECT sensor or MAP sensor
in Section 6E1.
Faulty fuel injector Diagnostic Flow Table B-1.
Faulty ECM
Engine overheating Refer to “Overheating” section.
Low compression Previously outlined.
Surge
(Engine power vari-
ation under steady
throttle or cruise.
Feels like vehicle
speeds up and
down with no
change in accelera-
tor pedal.)Leaky or loosely connected high-tension cord High-tension cords in Section 6F1.
Faulty spark plug (excess carbon deposits,
improper gap, and burned electrodes, etc.)Spark plugs in Section 6F1.
Variable fuel pressure Diagnostic Flow Table B-3.
Kinky or damaged fuel hose and lines
Faulty fuel pump (clogged fuel filter)
Malfunctioning EGR valve EGR system in Section 6E1.
Poor performance of MAP sensor MAP sensor in Section 6E1.
Faulty fuel injector Diagnostic Flow Table B-1.
Faulty ECM Condition Possible Cause Correction
ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-29
Excessive detona-
tion
(Engine makes con-
tinuously sharp
metallic knocks that
change with throttle
opening. Sounds
like pop corn pop-
ping.)Faulty spark plug Spark plugs in Section 6F1.
Loose connection of high-tension cord High-tension cords in Section 6F1.
Engine overheating Refer to “Overheating” section.
Clogged fuel filter (faulty fuel pump) or fuel
linesDiagnostic Flow Table B-1 or B-2.
Air inhaling from intake manifold or throttle
body gasket
Malfunctioning EGR valve (if equipped) EGR system in Section 6E1.
Poor performance of knock sensor, ECT sen-
sor or MAP sensorKnock sensor in Section 6, ECT sensor
or MAP sensor in Section 6E1.
Faulty fuel injector(s) Diagnostic Flow Table B-1.
Faulty ECM
Excessive combustion chamber deposits Piston and cylinder head cleaning in
Section 6A1.
Engine has no
powerFaulty spark plug Spark plugs in Section 6F1.
Faulty ignition coil with ignitor Ignition coil in Section 6F1.
Leaks, loose connection or disconnection of
high-tension cordHigh-tension cords in Section 6F1.
Faulty knock sensor Knock sensor malfunction in this sec-
tion.
Clogged fuel hose or pipe Diagnostic Flow Table B-3.
Malfunctioning fuel pump Diagnostic Flow Table B-2.
Air inhaling from intake manifold gasket or
throttle body gasket
Engine overheating Refer to “Overheating” section.
Engine has no
powerMalfunctioning EGR valve (if equipped) EGR system inspection in Section 6E1.
Maladjusted accelerator cable play Accelerator cable play in Section 6E1.
Poor performance of TP sensor, ECT sensor
or MAP sensorTP sensor, ECT sensor or MAP sensor
in Section 6E1.
Faulty fuel injector(s) Diagnostic Flow Table B-1.
Faulty ECM
Dragging brakes Trouble diagnosis in Section 5.
Slipping clutch Trouble diagnosis in Section 7C.
Low compression Previously outlined. Condition Possible Cause Correction
6-30 ENGINE GENERAL INFORMATION AND DIAGNOSIS
Improper engine
idling or engine fails
to idleFaulty spark plug Spark plugs in Section 6F1.
Leaky or disconnected high-tension cord High-tension cords in Section 6F1.
Faulty ignition coil with ignitor Ignition coil in Section 6F1.
Fuel pressure out of specification Diagnostic Flow Table B-3.
Leaky manifold, throttle body, or cylinder
head gasket
Malfunctioning EGR valve (if equipped) EGR system in Section 6E1.
Faulty idle air control system Diagnostic Flow Table B-4.
Faulty evaporative emission control system EVAP control system in Section 6E1.
Faulty EGR system (if equipped) EGR system in Section 6E1.
Faulty fuel injector(s) Diagnostic Flow Table B-1.
Poor performance of ECT sensor, TP sensor
or MAP sensorECT sensor, TP sensor or MAP sensor
in Section 6E1.
Faulty ECM
Loose connection or disconnection of vacuum
hoses
Malfunctioning PCV valve PCV system in Section 6E1.
Engine overheating Refer to “Overheating” section.
Low compression Previously outlined.
Excessive hydrocar-
bon (HC) emission
or carbon monox-
ide (CO)Faulty spark plug Spark plugs in Section 6F1.
Leaky or disconnected high-tension cord High-tension cords in Section 6F1.
Faulty ignition coil with ignitor Ignition coil assembly in Section 6F1.
Low compression Refer to “Low compression” section.
Lead contamination of three way catalytic
converterCheck for absence of filler neck restric-
tor.
Faulty evaporative emission control system EVAP control system in Section 6E1.
Fuel pressure out of specification Diagnostic Flow Table B-3.
Closed loop system (A/F feed back compen-
sation) fails
Faulty TP sensor
Poor performance of ECT sensor or MAP
sensorTP sensor in Section 6E1.
ECT sensor or MAP sensor in Section
6E1.
Faulty injector(s) Diagnostic Flow Table B-1
Faulty ECM
Engine not at normal operating temperature
Clogged air cleaner
Vacuum leaks
Excessive nitrogen
oxides (NOx) emis-
sionImproper ignition timing See section 6F1.
Lead contamination of catalytic converter Check for absence of filler neck restric-
tor.
Faulty EGR system (if equipped) EGR system in Section 6E1.
Fuel pressure out of specification Diagnostic Flow Table B-3.
Closed loop system (A/F feed back compen-
sation) fails
Faulty TP sensor
Poor performance of ECT sensor or MAP
sensorTP sensor in Section 6E1.
ECT sensor or MAP sensor in Section
6E1.
Faulty injector(s) Diagnostic Flow Table B-1
Faulty ECM Condition Possible Cause Correction
ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-57
Fig. 3 for Step 4
DTC P0115 (DTC NO.19) ENGINE COOLANT TEMPERATURE (ECT) CIRCUIT
MALFUNCTION
WIRING DIAGRAM / CIRCUIT DESCRIPTION
C42-14
5V
ECM
LT GRN
ORN
YEL/GRN
C42-10
C42 (31P) C41 (24P) G02 (17P)1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16 17 18 19 20 21
22 23 24 25 26 28 27 29 30 315 6
1 2 3 4 5 6 7
11 12
9 10 11 13 12 14 15 16
16 171 2
7 8
13 14 3 4
9 10
15 17 188
19 20 21 22 23 24
DTC DETECTING CONDITION POSSIBLE CAUSE
Low engine coolant temperature (High voltage-High resis-
tance)
or
High engine coolant temperature (Low voltage-Low resis-
tance)“LT GRN” circuit open or shorted to power
“ORN” circuit open
ECT sensor malfunction
ECM malfunction
NOTE:
Before inspecting, be sure to check that coolant temp. meter in combination meter indicates normal
operating temperature (Engine is not overheating).
When this DTC and P1709 are stored together, also clear DTC stored in TCM after completion of
repair.
When DTC P0105 (No.11), P0110 (No.18), P0115 (No.19) and P0120 (No.13) are indicated together, it
is possible that “ORN” circuit open.
ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-81
DTC P0300 RANDOM MISFIRE DETECTED (MISFIRE DETECTED AT 2 OR
MORE CYLINDERS)
DTC P0301 CYLINDER 1 MISFIRE DETECTED
DTC P0302 CYLINDER 2 MISFIRE DETECTED
DTC P0303 CYLINDER 3 MISFIRE DETECTED
DTC P0304 CYLINDER 4 MISFIRE DETECTED
WIRING DIAGRAM
CIRCUIT DESCRIPTION
ECM monitors crankshaft revolution speed and engine speed via the crankshaft position sensor and cylinder No.
via the camshaft position sensor. Then it calculates the change in the crankshaft revolution speed and from how
many times such change occurred in every 200 or 1000 engine revolutions, it detects occurrence of misfire.
When ECM detects a misfire (misfire rate per 200 revolutions) which can cause overheat and damage to the
three way catalytic converter, it makes the malfunction indicator lamp (MIL) flash as long as misfire occurs at
that rate.
After that, however, when the misfire rate drops, MIL remains ON until it has been judged as normal 3 times
under the same driving conditions.
Also, when ECM detects a misfire (misfire rate per 1000 revolutions) which will not cause damage to three way
catalytic converter but can cause exhaust emission to be deteriorated, it makes MIL light according to the 2 driv-
ing cycle detection logic.
1. Ignition coil No. 1
2. Ignition coil No. 2
3. CKP sensor
4. CMP sensor
5. Fuel injector
C42-20
C42-19
ECM
IG1
5V
5V
GRN/YEL
BLK/WHT
GRN/WHT
IG1 2
+B
C42-9
C42-21
C42-8
C42-23 C42-31 BLU/YEL
BLU/WHT
BLU/RED
BLU/ORN
YEL/BLK
5V
C42-11
RED/YEL
5V
BLK/RED
3
45
5
1