Page 465 of 698

6-96 ENGINE GENERAL INFORMATION AND DIAGNOSIS
Fig. 1 for Step 55 EGR Valve Power Supply Circuit Check :
1) With ignition switch OFF, disconnect EGR
valve coupler.
2) With ignition switch ON, check voltage
between terminal 2 and ground terminal 5 of
EGR valve connector and ground.
Is each voltage 10 – 14 V?Go to Step 7. Faulty “BLK/RED” wire.
6 EGR Valve Stepper Motor Coil Circuit Check :
1) With ignition switch OFF, connect EGR
valve coupler and disconnect ECM cou-
plers.
2) Check resistance between C41-5 and C41-
2, 9, 8, 17 (Case of TYPE A. See NOTE) or
C42-17, 18, 28, 29 (Case of TYPE B. See
NOTE).
Is each resistance 20 – 24 Ω at 20°C, 68°F?Go to Step 8. Faulty “GRN” (Case of
TYPE A. See NOTE) or
“GRY” (Case of TYPE B.
See NOTE), “GRN/ORN”,
“WHT/RED”, “BRN/YEL”
wire or EGR valve.
7 MAP sensor Check :
1) Check MAP sensor for performance refer-
ring to Section 6E1.
Is check result satisfactory?EGR passage clogged or
EGR valve malfunction. If
all above are OK, intermit-
tent trouble or faulty ECM.
Check for intermittent
referring to “Intermittent
and Poor Connection” in
Section 0A.Repair or replace. Step Action Yes No
1. EGR valve connector
Page 466 of 698

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
Page 467 of 698

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.
Page 468 of 698
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.
Page 469 of 698

6-100 ENGINE GENERAL INFORMATION AND DIAGNOSIS
DTC P0443 PURGE CONTROL VALVE CIRCUIT MALFUNCTION
WIRING DIAGRAM / CIRCUIT DESCRIPTION
DTC CONFIRMATION PROCEDURE
1) Clear DTC with ignition switch ON.
2) Select “DTC” mode on scan tool and check DTC.
INSPECTION
Fig. 1 for Step 1
1. EVAP canister purge valve [A] : Case of TYPE A is shown (See NOTE) [B] : Case of TYPE B is shown (See NOTE)
ECM
+B
BLK/RED
BLU/BLK
BLK/ORN
BLK/ORNC42-1
C42-3
1
C42-4 [A]
C42-2 [B]
NOTE:
For TYPE A and TYPE B, refer to NOTE in “ECM VOLTAGE VALUES TABLE” for applicable model.
DTC DETECTING CONDITION POSSIBLE CAUSE
Canister Purge control valve circuit is opened or
shorted.“BLU/BLK” circuit open or short
“BLK/RED” circuit open or short
Canister purge valve malfunction
Step Action Yes No
1 Check EVAP Canister Purge Valve operation.
1) With ignition switch OFF, disconnect coupler from
canister purge valve.
2) Check resistance of EVAP canister purge valve.
Resistance between
two terminals : 30 – 34 Ω at 20°C (68°F)
Resistance between
terminal and body : 1 MΩ or higher
Is it as specified?“BLU/BLK” circuit
open or short.
“BLK/RED” circuit
open or short.Replace EVAP canister
purge valve.
Page 470 of 698

ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-101
DTC P0480 RADIATOR COOLING FAN CONTROL SYSTEM MALFUNCTION
WIRING DIAGRAM / CIRCUIT DESCRIPTION
DTC CONFIRMATION PROCEDURE
1) Turn ignition switch OFF.
2) Clear DTC with ignition switch ON.
3) Warm up engine until radiator cooling fan starts to operate.
4) Check pending DTC in “ON BOARD TEST” or “PENDING DTC” mode and DTC in “DTC” mode.
INSPECTION
1. Main relay [A] : Case of TYPE A is shown (See NOTE)
2. Radiator fan relay [B] : Case of TYPE B is shown (See NOTE)
3. Radiator fan motor
BATT
80A30A
15A
BLKBLU/WHT
ECM
BLK/ORN
BLK/ORNC42-1
C42-3
L
L–
H– H
No.1
No.2
No.3
BLU
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
C41-18
GRN/RED [B]PPL/YEL [A]
BLK/RED
BLU/WHT
BLU/RED
BLK
BLU
BLU/BLK
PPL/YEL
BLU/RED
BLK/YEL
1
BRN/WHT
2
3
2
2
G02-3 [A]
C41-9 [B]
NOTE:
For TYPE A and TYPE B, refer to NOTE in “ECM VOLTAGE VALUES TABLE” for applicable model.
DTC DETECTING CONDITION POSSIBLE CAUSE
Low voltage at terminal C41-18 when engine coolant
temp. is below 97.5°C, 207.5°F.
✱2 driving cycle detection logic, continuous monitoring.“BLK/RED” or “BLU” circuit open or short
Radiator cooling fan relay malfunction
ECM malfunction
Step Action Yes No
1Was “ENGINE DIAG. FLOW TABLE” performed? Go to Step 2. Go to “ENGINE DIAG.
FLOW TABLE”.
2 Check Radiator Cooling Fan Relay and Its Circuit.
1) Turn ignition switch ON.
2) Check for voltage at terminal C41-18 of ECM
connector connected, under following condition.
See Fig. 1.
When engine coolant temp. is lower than
97.5°C, 207.5°F and A/C switch turns OFF : 10
– 14 V
Is voltage as specified?Intermittent trouble or
faulty ECM.
Check for intermittent
referring to “Intermittent
and Poor Connection” in
Section 0A.Go to Step 3.
Page 471 of 698
6-102 ENGINE GENERAL INFORMATION AND DIAGNOSIS
Fig. 1 for Step 2
Fig. 2 for Step 3
Fig. 3 for Step 33 Check Radiator Cooling Fan Control Relay.
1) Turn ignition switch OFF and remove radiator
cooling fan relay.
2) Check for proper connection to the relay at
“BLK/RED”, “BLU”, “BLU/RED” and “BLU/BLK”
wire terminals.
3) If OK, then measure resistance between termi-
nals a and b. See Fig. 2 and 3.
Is it 56 – 146 Ω?“BLK/RED” or “BLU” cir-
cuit open or short.
If wires and connections
are OK, substitute a
known-good ECM and
recheck.Replace radiator cool-
ing fan relay. Step Action Yes No
1. Radiator fan relay No.11
Page 472 of 698

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.