ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-83
2 Is there DTC other than Fuel system (DTC P0171/
P0172) and misfire (DTC P0300-P0304)?Go to applicable DTC
Diag. Flow Table.Go to Step 3.
3 Check Ignition System.
1) Remove spark plugs and check them for;
Air gap : 1.0 – 1.1 mm (0.040 – 0.043 in.) See Fig. 1.
Carbon deposits/Insulator damage/Plug type
If abnormality is found, adjust, clean or replace.
2) Disconnect all injector connectors.
3) Connect spark plugs to high tension cords and then
ground spark plugs.
4) Crank engine and check that each spark plug sparks.
Are above check results satisfactory?Go to Step 4. Check ignition sys-
tem parts (Refer to
Section 6F1)
4 Check Fuel Pressure (Refer to Section 6E1 for details).
1) Release fuel pressure from fuel feed line.
2) Install fuel pressure gauge. See Fig. 2.
3) Check fuel pressure.
With fuel pump operating and engine at stop : 270 –
310 kPa, 2.7 – 3.1 kg/cm
2, 38.4 – 44.0 psi.
At specified idle speed : 270 – 310 kPa, 2.7 – 3.1 kg/
cm
2, 38.4 – 44.0 psi.
Is measured value as specified?Go to Step 5. Go to Diag. Flow
Table B-3 fuel
pressure check.
5 Check Fuel Injectors and Circuit.
1) Using sound scope (1) or such, check operating
sound of each injector (2) when engine is running.
Cycle of operating sound should very according to
engine speed. See Fig 3.
If no sound or an unusual sound is heard, check
injector circuit (wire or connector) or injector.
2) Turn ignition switch OFF and disconnect a fuel injec-
tor connector.
3) Check for proper connection to fuel injector at each
terminal. See Fig. 4.
4) If OK, then check injector resistance.
Injector Resistance : 11.3 – 13.8 ohm at 20°C (68°F)
5) Carry out steps 1) and 3) on each injector.
6) Check each injector for injected fuel volume referring
to Section 6E1. See Fig. 5.
Injected Fuel Volume : 43 – 47 cc/15 sec (1.45/1.51 –
1.58/1.65 US/Imp. oz/15 sec)
7) Check each injector for fuel leakage after injector
closed.
Fuel Leakage : Less than 1 drop/min.
Is check result in step 1) and 3) to 7) satisfactory?Go to Step 6. Check injector cir-
cuit or replace fuel
injector(s).
6 Check PCV Valve for clogging (See Section 6E1).
Is it in good condition?Go to Step 7. Replace PCV
valve. Step Action Yes No
6-84 ENGINE GENERAL INFORMATION AND DIAGNOSIS
Fig. 1 for Step 3
Fig. 2 for Step 47 Check EVAP Canister Purge Valve for Closing.
1) Disconnect purge hose from EVAP canister purge
valve.
2) Place finger against the end of EVAP canister purge
valve.
3) Check that vacuum is not felt there, when engine is
cool and running at idle. See Fig. 6.
Is vacuum felt?Check EVAP control
system (See Section
6E1).Go to Step 8.
8 Check MAP Sensor for performance (See DTC P0105
Diag. Flow Table).
Is it in good condition?Go to Step 9. Repair or replace.
9 Check ECT Sensor for performance (See Section 6E1).
Is it in good condition?Go to Step 10. Replace engine
coolant temp. sen-
sor.
10 Check Parts or System which can cause engine rough
idle or poor performance.
Engine compression (See Section 6A1).
Valve lash (See Section 6A1).
Valve timing (Timing belt installation. See Section
6A1).
Are they in good condition?Check wire harness
and connection of
ECM ground, ignition
system and fuel injec-
tor for intermittent
open and short.Repair or replace. Step Action Yes No
1. Fuel pressure gauge & 3 way joint
2. Fuel feed hose
1
2
1
6-94 ENGINE GENERAL INFORMATION AND DIAGNOSIS
DTC P0400 EXHAUST GAS RECIRCULATION FLOW MALFUNCTION
WIRING DIAGRAM / CIRCUIT DESCRIPTION
DTC CONFIRMATION PROCEDURE
1) Turn ignition switch OFF.
Clear DTC with ignition switch ON, check vehicle and environmental condition for :
–Altitude (barometric pressure) : 2400 m, 8000 ft or less (560 mmHg, 75 kPa or more)
–Ambient temp. : –10°C, 14°F or higher
–Intake air temp. : 70°C, 122°F or lower
2) Start engine and warm it up to normal operating temperature (70 – 110°C, 158 – 230°F) and run it at idle for
5 min.
3) Increase vehicle speed to 50 – 55 mph, 80 – 88 km/h in 5th gear or in “D” range.
4) Hold throttle valve at that opening position for 2 min. or longer.
5) Increase engine speed to 4000 r/min. in 3rd gear or in “2” range.
6) Release accelerator pedal and with engine brake applied, keep vehicle coasting (fuel cut condition) till
engine speed reaches 1500 r/min.
1. EGR valve [A] : Case of TYPE A is shown (See NOTE) [B] : Case of TYPE B is shown (See NOTE)
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
+BECM
C42-18
C42-29
C42-28 C42-17
C42-1
GRY
GRN/ORN
WHT/RED
C42-3 BRN/YEL
BLK/ORN
BLK/ORN BLK/RED1
3
1 2
4
6 5
+BECM
C41-2
C41-9
C41-17 C41-8
C42-1
GRN
GRN/ORN
WHT/RED
C42-3 BRN/YEL
BLK/ORN
BLK/ORN BLK/RED1
3
1 2
4
6 5
[A][B]
NOTE:
For TYPE A and TYPE B, refer to NOTE in “ECM VOLTAGE VALUES TABLE” for applicable model.
DTC DETECTING CONDITION POSSIBLE CAUSE
While running at specified vehicle speed after engine warm-up
During deceleration (engine speed high with closed throttle position
ON) in which fuel cut is involved, difference in intake manifold abso-
lute pressure between when EGR valve is opened at specified value
and when it is closed is larger or smaller than specified value.
✱2 driving cycle detection logic, monitoring once/1 drivingEGR valve or its circuit
EGR passage
ECM
WARNING:
When performing a road test, select a place where there is no traffic or possibility of a traffic acci-
dent 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, on a level road.
ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-97
DTC P0420 CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD
WIRING DIAGRAM / CIRCUIT DESCRIPTION
ECM monitors oxygen concentration in the exhaust gas which has passed the three way catalytic converter by
HO2S-2 (2).
When the catalyst is functioning properly, the variation cycle of HO2S-2 (2) output voltage (oxygen concentra-
tion) is slower than that of HO2S-1 (1) output voltage because of the amount of oxygen in the exhaust gas which
has been stored in the catalyst (3).
REFERENCE
[A] : Oscilloscope Waveforms
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
1
2
3
ECM
WHT
ORNC42-10 C42-13
BRN
C41-13
YEL
DTC DETECTING CONDITION POSSIBLE CAUSE
While vehicle running at constant speed under other than
high load.
Time from rich or lean switching command is output till HO2S-
2 output voltage crosses 0.45 V is less than specified value.
✱2 driving cycle detection logic, monitoring once/1 drivingExhaust gas leak
Three way catalytic converter malfunction
Fuel system malfunction
HO2S-2 malfunction
HO2S-1 malfunction
6-98 ENGINE GENERAL INFORMATION AND DIAGNOSIS
DTC CONFIRMATION PROCEDURE
1) Turn ignition switch OFF.
Clear DTC with ignition switch ON, check vehicle and environmental condition for :
–Altitude (barometric pressure) : 2400 m, 8000 ft or less (560 mmHg, 75 kPa or more)
–Ambient temp. : –10°C, 14°F or higher
–Intake air temp. : 70°C, 158°F or lower
–Engine coolant temp. : 70 – 110°C, 158 – 230°F
2) Start engine and drive vehicle at 35 – 45 mph, 55 – 65 km/h for 8 min. or longer.
While this driving, if “Catalyst Monitoring TEST COMPLETED” is displayed in “READINESS TESTS” mode
and DTC is not displayed in “DTC” mode, confirmation test is completed.
If “TEST NOT COMPLETE” is still being displayed, continue test driving.
3) Decrease vehicle speed at 30 – 40 mph, 50 – 60 km/h, and hold throttle valve at that opening position for 2
min. and confirm that short term fuel trim vary within – 20% – +20% range.
4) Stop vehicle (do not turn ignition switch OFF) and confirm test results according to following “Test Result
Confirmation Flow Table”.
TEST RESULT CONFIRMATION FLOW TABLE
WARNING:
When performing a road test, select a place where there is no traffic or possibility of a traffic acci-
dent and be very careful during testing to avoid occurrence of an accident.
Road test should be carried out with 2 persons, a driver and tester, on a level road.
Step Action Yes No
1 Check DTC in “DTC” mode and pending DTC in
“ON BOARD TEST” or “PENDING DTC” mode.
Is DTC or pending DTC displayed?Proceed to applicable
DTC Diag. Flow Table.Go to Step 2.
2 Set scan tool to “READINESS TESTS” mode
and check if testing has been completed.
Is test completed?No DTC is detected (con-
firmation test is com-
pleted).Repeat DTC confirmation
procedure.
ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-99
INSPECTION
Step Action Yes No
1Was “ENGINE DIAG. FLOW TABLE” per-
formed?Go to Step 2. Go to “ENGINE DIAG.
FLOW TABLE”.
2 Check Short Term Fuel Trim.
Did short term fuel trim vary within – 20% –
+20% range in step 3) of DTC confirmation
test?Go to Step 3. Check fuel system.
Go to DTC P0171/P0172
Diag. Flow Table.
3 Check HO2S-2 for Output Voltage.
Perform steps 1) through 9) of DTC confirma-
tion procedure for DTC P0136 (HO2S-2 mal-
function) and check output voltage of HO2S-2
then.
Is over 0.6 V and below 0.3 V indicated?Replace three way cata-
lytic converter.Check “BRN” and “YEL”
wires for open and short,
and connections for poor
connection.
If wires and connections
are OK, replace HO2S-2.
ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-103
DTC P0500 (DTC NO.16) VEHICLE SPEED SENSOR (VSS) MALFUNCTION
WIRING DIAGRAM / CIRCUIT DESCRIPTION
DTC CONFIRMATION PROCEDURE
1) Clear DTC and warm up engine to normal operating temperature.
2) Increase vehicle speed to 50 mph, 80 km/h in 3rd gear or “2” range while observing vehicle speed displayed
on scan tool.
3) Release accelerator pedal and with engine brake applied, keep vehicle coasting (fuel cut condition) for 4
sec. or more.
4) Check pending DTC and DTC.
INSPECTION
1. VSS (vehicle speed sensor) 3. Power supply from ignition switch
2. VSS connector 4. Speedometer, P/S control module and multi information display
[A] : Case of TYPE A is shown (See NOTE) [B] : Case of TYPE B is shown (See NOTE)
ECM
5V+B
BLK/RED
BLK/ORN
PPL
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
1
4 c
a
b2
3
G02-2 [A]
C41-22[B]
NOTE:
For TYPE A and TYPE B, refer to NOTE in “ECM VOLTAGE VALUES TABLE” for applicable model.
DTC DETECTING CONDITION POSSIBLE CAUSE
VSS signal not inputted while vehicle running in “D”
range or during fuel cut at deceleration.
✱2 driving cycle detection logic, continuous monitoring“BLK/ORN” circuit open
“PPL” or “BLK/RED” circuit open or short
VSS malfunction
ECM malfunction
Speedometer malfunction
WARNING:
When performing a road test, select a place where there is no traffic or possibility of a traffic acci-
dent 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.
Step Action Yes No
1Was “ENGINE DIAG. FLOW TABLE” per-
formed?Go to Step 2. Go to “ENGINE DIAG.
FLOW TABLE”.
2 Does speedometer indicate vehicle speed? Go to Step 3. Go to Step 5.
ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-117
TABLE B-1 FUEL INJECTOR CIRCUIT CHECK
WIRING DIAGRAM
INSPECTION
1. No.1 injector 3. No.3 injector
2. No.2 injector 4. No.4 injector
ECM
1
2
3
4
+B
C42-9
C42-21
C42-8 C42-31 BLU/YEL
BLU/WHT
BLU/RED
BLU/ORN
BLK/RED
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
Step Action Yes No
1Was “ENGINE DIAG. FLOW TABLE” per-
formed?Go to Step 2. Go to “ENGINE DIAG.
FLOW TABLE”.
2 Check Injector for operating sound.
Using sound scope, check each injector for
operating sound at engine cranking.
Do all 4 injector make operating sound?Fuel injector circuit is in
good condition.Go to Step 3.
3 Dose none of 4 injectors make operating sound
at Step 2?Go to Step 4. Check coupler connec-
tion and wire harness of
injector not making oper-
ating sound and injector
itself (Refer to Section
6E1).
4 Check power circuit of injectors for open and
short.
Is it normal?Check all 4 injectors for
resistance respectively.
If resistance is OK, substi-
tute a known-good ECM
and recheck.Power circuit open or
short.