Page 75 of 557

6-24 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
ConditionPossible CauseReferring Item
OverheatingInoperative thermostat
Poor water pump performance
Clogged or leaky radiator
Improper engine oil grade
Clogged oil filter or oil strainer
Poor oil pump performance
Faulty radiator fan control system
Dragging brakes
Slipping clutch
Blown cylinder head gasketThermostat in Section 6B
Water pump in Section 6B
Radiator in Section 6B
Engine oil and oil filter change in
Section 0B
Oil pressure check in Section 6A
Oil pressure check in Section 6A
Radiator fan control system in
Section 6E1
Trouble diagnosis in Section 5
Trouble diagnosis in Section 7C
Cylinder head in Section 6A
Poor gasoline
mileageIgnition system out of order
Leaks or loose connection of high-tension cord
Faulty spark plug (improper gap, heavy deposits
and burned electrodes, etc.)
Engine and emission control system out of
order
High idle speed
Poor performance of TP sensor, ECT sensor or
MAP sensor
Faulty fuel injector
Faulty fuel injector resistor
Faulty ECM (PCM)
Low compression
Others
Poor valve seating
Dragging brakes
Slipping clutch
Thermostat out of order
Improper tire pressure
High-tension cords in Section 6F
Spark plugs in Section 6F
Refer to item “Improper engine
idle speed” previously outlined
TP sensor, ECT sensor or MAP
sensor in Section 6E1
Diagnostic Flow Table B-1
Fuel injector resistor in Section 6E1
Previously outlined
Valves inspection in Section 6A
Trouble diagnosis in Section 5
Trouble diagnosis in Section 7C
Thermostat in Section 6B
Refer to Section 3F
Excessive engine
oil consumptionOil leakage
Blown cylinder head gasket
Leaky camshaft oil seals
Oil entering combustion chamber
Sticky piston ring
Worn piston and cylinder
Worn piston ring groove and ring
Improper location of piston ring gap
Worn or damaged valve stem seal
Worn valve stem
Cylinder head in Section 6A
Camshaft in Section 6A
Piston cleaning in Section 6A
Pistons and cylinders inspection
in Section 6A
Pistons inspection in Section 6A
Pistons assembly in Section 6A
Valves removal and installation in
Section 6A
Valves inspection in Section 6A
Page 77 of 557

6-26 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
ConditionPossible CauseReferring Item
Engine has no
powerIgnition system out of order
Faulty spark plug
Faulty ignition coil with ignitor
Leaks, loose connection or disconnection of
high-tension cord
Engine overheating
Fuel system out of order
Clogged fuel hose or pipe
Malfunctioning fuel pump
Air inhaling from intake manifold gasket or
throttle body gasket
Engine and emission control system out of
order
Maladjusted accelerator cable play
Poor performance of TP sensor, ECT sensor or
MAP sensor
Faulty fuel injector
Faulty ECM (PCM)
Low compression
Others
Dragging brakes
Slipping clutch
Spark plugs in Section 6F
Ignition coil in Section 6F
High-tension cords in Section 6F
Refer to “Overheating” section
Diagnostic Flow Table B-3 in
Section 6
Diagnostic Flow Table B-2
Accelerator cable play in Section
6E1
TP sensor, ECT sensor or MAP
sensor in Section 6E1
Diagnostic Flow Table B-1
Previously outlined
Trouble diagnosis in Section 5
Trouble diagnosis in Section 7C
Page 78 of 557

ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-27
ConditionPossible CauseReferring Item
Improper engine
idling or engine
fails to idleIgnition system out of order
Faulty spark plug
Leaky or disconnected high-tension cord
Faulty ignition coil with ignitor
Fuel system out of order
Fuel pressure out of specification
Leaky manifold, throttle body, or cylinder head
gasket
Engine and emission control system out of
order
Faulty idle control system
Faulty evaporative emission control system
Faulty fuel injector
Faulty fuel injector resistor
Poor performance of ECT sensor, TP sensor or
MAP sensor
Faulty ECM (PCM)
Engine overheating
Low compression
Others
Loose connection or disconnection of vacuum
hoses
Malfunctioning PCV valve
Spark plugs in Section 6F
High-tension cords in Section 6F
Ignition coil in Section 6F
Diagnostic Flow Table B-3 in
Section 6
Diagnostic Flow Table P0505
EVAP control system in Section
6E
Diagnostic Flow Table B-1
Fuel injector resistor in Section 6E1
ECT sensor, TP sensor or MAP
sensor in Section 6E1
Refer to “Overheating” section
Previously outlined
PCV system in Section 6E1
Page 79 of 557

6-28 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
ConditionPossible CauseReferring Item
Excessive
hydrocarbon (HC)
emission or carbon
monoxide (CO)Ignition system out of order
Faulty spark plug
Leaky or disconnected high-tension cord
Faulty ignition coil with ignitor
Low compression
Engine and emission control system out of
order
Lead contamination of three way catalytic
converter
Faulty evaporative emission control system
Fuel pressure out of specification
Closed loop system (A / F feed back
compensation) fails
–Faulty TP sensor
–Poor performance of ECT sensor or MAP
sensor
Faulty injector
Faulty fuel injector resistor
Faulty ECM (PCM)
Others
Engine not at normal operating temperature
Clogged air cleaner
Vacuum leaks
Spark plugs in Section 6F
High-tension cords in Section 6F
Ignition coil assembly in Section
6F
Refer to “Low compression”
section
Check for absence of filler neck
restrictor
EVAP control system in Section
6E1
Diagnostic Flow Table B-3
TP sensor in Section 6E1
ECT sensor or MAP sensor in
Section 6E1
Diagnostic Flow Table B-1
Fuel injector resistor in Section 6E1
Excessive nitrogen
oxides (NOx)
emissionIgnition system out of order
Improper ignition timing
Engine and emission control system out of
order
Lead contamination of catalytic converter
Fuel pressure out of specification
Closed loop system (A / F feed back
compensation) fails
–Faulty TP sensor
–Poor performance of ECT sensor or MAP
sensor
Faulty injector
Faulty fuel injector resistor
Faulty ECM (PCM)
See section 6F1
Check for absence of filler neck
restrictor.
Diagnostic Flow Table B-3
TP sensor in Section 6E1
ECT sensor or MAP sensor in
Section 6E1
Diagnostic Flow Table B-1
Fuel injector resistor in Section 6E1
Page 90 of 557
ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-39
INFORMATION SENSORS
-1. MAP sensor
-2. TP sensor
-3. IAT sensor
-4. ECT sensor
-5. Heated oxygen sensor-1
-6. VSS
-7. Ignition coil
-8. Battery
-9. CMP sensor (in Distributor)
-10. A/C contoller (if equipped)
-11. CKP sensor
-12. CTP switch (in ISC actuator)
-13. Heated oxygen sensor-2OTHERS
A: ECM (PCM)
B: Main relay
C: EVAP canister
D: Injector resistor
E: EFE heater
F: Electric load diode CONTROL DEVICES
a: Fuel injector
b: EVAP canister purge valve
c: Fuel pump relay
d: Malfunction indicator lamp
e: ISC actuator
f: Radiator fan control relay
g: Igniter
h: EFE heater relay
i: ISC actuator relay
COMPONENT LOCATION
Page 91 of 557

6-40 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
“IG COIL METER”Main relay
Ignition switch
In fuseMalfunction indicator lamp in combination meter
TABLE A-1 MALFUNCTION INDICATOR LAMP CIRCUIT CHECK – LAMP DOES
NOT COME “ON” AT IGNITION SWITCH ON (BUT ENGINE AT STOP)
CIRCUIT DESCRIPTION
When the ignition switch is turned ON, ECM (PCM) causes the main relay to turn ON (close the contact point).
Then, ECM (PCM) being supplied with the main power, turns ON the malfunction indicator lamp (MIL). When the
engine starts to run and no malfunction is detected in the system, MIL goes OFF but if a malfunction was or is de-
tected, MIL remains ON even when the engine is running.
INSPECTION
STEPACTIONYESNO
1MIL Power Supply Check
1) Turn ignition switch ON.
Do other indicator / warning lights in
combination meter comes ON?Go to Step 2.“IG COIL METER” fuse blown,
main fuse blown, ignition
switch malfunction, “B/W”
circuit between “IG COIL
METER” fuse and
combination meter or poor
coupler connection at
combination meter.
2ECM (PCM) Power and Ground Circuit
Check
Does engine start?Go to Step 3.Go to TABLE A-3 ECM (PCM)
POWER AND GROUND
CIRCUIT CHECK.
If engine is not cranked, go to
DIAGNOSIS in SECTION 8A.
3MIL Circuit Check
1) Turn ignition switch OFF and disconnect
connectors from ECM (PCM).
2) Check for proper connection to ECM
(PCM) at terminal C02-17.
3) If OK, then using service wire, ground
terminal C02-17 in connector
disconnected.
Does MIL turn on at ignition switch ON?Substitute a known-
good ECM (PCM) and
recheck.Bulb burned out or “V/Y” wire
circuit open.
Page 93 of 557

Main fuse Ignition switch
Main fuseMalfunction indicator lamp in combination meter
Relay box“IG COIL METER”
6-42 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
TABLE A-3 ECM (PCM) POWER AND GROUND CIRCUIT CHECK – MIL
DOESN’T LIGHT AT IGNITION SWITCH ON AND ENGINE DOESN’T
START THOUGH IT IS CRANKED UP
CIRCUIT DESCRIPTION
When the ignition switch tuned ON, the main relay turns ON (the contact point closes) and the main power is sup-
plied to ECM (PCM).
INSPECTION
STEPACTIONYESNO
1Main Relay Operating Sound Check
Is operating sound of main relay heard at ignition switch ON?Go to Step 5.Go to Step 2.
2Main Relay Check
1) Turn OFF ignition switch and remove main relay (1).
2) Check for proper connection to main relay (1) at terminal
3 and 4.
3) Check resistance between each two terminals. See Fig. 1
and 2.
Between terminals 1 and 2: Infinity
Between terminals 3 and 4: 100 – 120 Ω
4) Check that there is continuity between terminals 1 and 2
when battery is connected to terminals 3 and 4. See Fig. 3.
Is main relay in good condition?Go to Step 3.Replace main
relay.
3Fuse Check
Is main “FI” fuse in good condition?Go to Step 4.Check for short in
circuits connected
to this fuse.
4ECM (PCM) Power Circuit Check
1) Turn OFF ignition switch, disconnect connectors from ECM
(PCM) and install main relay.
2) Check for proper connection to ECM (PCM) at terminals
C03-20, C02-2, C02-15 and C02-22.
3) If OK, then measure voltage between terminal C03-20 and
ground, C02-22 and ground with ignition switch ON.
Is each voltage 10 – 14 V?Go to Step 5.“B/W”, “W/R” or
“Bl / B” circuit
open.
Page 108 of 557

To generatorTo other sensor
Heater Ignition
switch Main
fuse
“IG COIL METER”
ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-57
DTC P0135 HEATED OXYGEN SENSOR (HO2S) HEATER CIRCUIT
MALFUNCTION (SENSOR-1)
CIRCUIT DESCRIPTION
DTC DETECTING CONDITIONPOSSIBLE CAUSE
DTC will set when A or B condition is met.
A:
Low voltage at terminal C01-8 when engine is
running at high load.
B:
High voltage at terminal C01-8 when engine is
running under condition other than above.
2 driving cycle detection logic, Continuous
monitoring.HO2S-1 heater circuit open or shorted to ground
ECM (PCM) malfunction
DTC CONFIRMATION PROCEDURE
WARNING:
When performing a road test, select a place where there is no traffic or possibility of a traffic accident
and be very careful during testing to avoid occurrence of an accident.
Road test should be carried out with 2 persons, a driver and a tester.
1) Turn ignition switch OFF.
2) Clear DTC with ignition switch ON, start engine and keep it at idle for 1 min.
3) Start vehicle and depress accelerator pedal fully for 5 sec. or longer.
4) Stop vehicle.
5) Check DTC in “DTC” mode and pending DTC in “ON BOARD TEST” or “PENDING DTC” mode.