Page 169 of 1496

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis:  1A-119
DTC Troubleshooting
NOTE
• When measuring circuit voltage, resistance and/or pulse signal at ECM connector, connect the 
special tool to ECM and/or the ECM connectors re ferring to “Inspection of ECM and Its Circuits”.
• Upon completion of inspection and repair work, perform “DTC Confirmation Procedure” and  confirm that the trouble has been corrected.
 
Step Action YesNo
1 Was “Engine and Emission Control System Check” 
performed? Go to Step 2.
Go to “Engine and 
Emission Control 
System Description”.
2 EGR valve power supply circuit check
1) Remove air intake pipe.
2) With ignition switch turned  OFF, disconnect EGR valve 
connector.
3) With ignition switch turned ON, measure voltage  between “BLK/RED” wire terminal of EGR valve 
connector and vehicle body ground.
Is check voltage 10 – 14 V? Go to Step 3.
“BLK/RED” wire is open 
circuit.
3 Wire circuit check
1) Disconnect connectors from ECM with ignition switch 
turned OFF.
2) Turn ON ignition switch.
3) Measure voltage between engine ground and each  “GRN/RED”, “GRN/ORN”, “W HT/RED”, “BRN/YEL” wire 
terminals of EGR valve connector.
Is each voltage 0 V? Go to Step 4.
Faulty wire(s) are 
shorted to other circuit.
If wires are OK, 
substitute a known-
good ECM and recheck.
4 Wire circuit check
1) With ignition switch turned OFF, measure resistance 
between engine ground and each “GRN/RED”, “GRN/
ORN”, “WHT/RED”, “BRN/YEL”  wire terminals of EGR 
valve connector.
Is resistance infinity? Go to Step 5.
Faulty wire(s) are 
shorted to ground 
circuit.
If wires are OK, 
substitute a known-
good ECM and recheck.
5 Short circuit check for EGR valve control circuit
1) With ignition turned OFF, measure resistance between 
each EGR valve control circ uit wire (“GRN/RED”, “GRN/
ORN”, “WHT/RED” and “BRN/ YEL” wire) and each EGR 
valve control circuit wire.
Is each resistance infinity? Go to Step 6.
Faulty wire(s) are short 
circuit.
6 EGR valve stepper motor coil circuit check
1) With ignition switch turned OFF, connect EGR valve 
connector.
2) Measure resistance between “E23-1/16” and each “C37- 4”, “C37-3”, “C37-19”, “C37-18” terminals of ECM 
connector.
Is each resistance 20 – 31 
Ω at 20 °C, 68 °F? Faulty ECM. Substitute 
a known-good ECM and 
recheck.
Go to Step 7.
7 EGR valve check
1) Check EGR valve resistance  referring to “EGR Valve 
Inspection in Section 1B”.
Is resistance within specified value? Faulty wire(s) are open 
or high resistance 
circuit. If wires are OK, 
substitute a known-
good ECM and recheck.Faulty EGR valve.  
         
        
        
     
        
        Page 170 of 1496
Downloaded from www.Manualslib.com manuals search engine 1A-120 Engine General Information and Diagnosis: 
DTC P0420: Catalyst System Efficiency below ThresholdS7RS0B1104046
System and Wiring Diagram
Circuit Description
ECM monitors oxygen concentration in the exhaust gas which has passed the warm up three way catalytic converter 
by HO2S-2. When the catalyst is functioning properly,  the variation cycle of HO2S-2 output voltage (oxygen 
concentration) is slower than that of  HO2S-1 output voltage because of the amount of oxygen in the exhaust gas 
which has been stored in warm up three way catalytic converter.
Reference
Oscilloscope waveforms
C37-11
C37-10
C37-57
WHT
BRN
1
3 2
4
5 VYELYEL
BLUWHTBLUWHT 5
I4RS0A110037-01
1. HO2S-1
3. Warm up three way catalytic converter 5. ECM
2. HO2S-2 4. Three way catalytic converter
I2RH01110102-01  
         
        
        
     
        
        Page 171 of 1496

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis:  1A-121
DTC Detecting Condition and Trouble Area
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 by 2 persons, a driver and a tester, on a level road.
 
NOTE
Check to make sure that following conditions ar e satisfied when using this “DTC Confirmation 
Procedure”.
• Intake air temperature at engine start: –10  °C (14 ° F) to 80  °C (176  °F)
• Intake air temperature: –10  °C (14  °F) to 70  °C (158  °F)
• Engine coolant temp.: 70  °C, 158  °F to 150  °C (302  °F)
• Altitude (barometric pressure): 2400 m, 8000 ft or less (500 mmHg, 75 kPa or more)
 
1) Connect scan tool to DLC with  ignition switch turned OFF.
2) Turn ON ignition switch and clear DTC using scan tool.
3) Increase vehicle speed to 37 – 62 mph, 60  – 100 km/h. (engine speed: 2500 – 3000 r/min.)
4) Keep above vehicle speed for 10 min. or more (Thr ottle valve opening is kept constant in this step).
5) Stop vehicle and check if DTC / pending DTC exists using sc an tool. If not, check if catalyst monitoring test has 
been completed using scan tool. If not in both of above checks (i.e., no DTC / pending DTC and catalyst 
monitoring test not completed), check vehicle cond ition (environmental) and repeat Step 3) through 5).
DTC Troubleshooting
NOTE
• When measuring circuit voltage, resistance and/ or pulse signal at ECM connector, connect the 
special tool to ECM and/or the ECM connectors re ferring to “Inspection of ECM and Its Circuits”.
• Upon completion of inspection and repair work, perform “DTC Confirmation Procedure” and  confirm that the trouble has been corrected.
 
DTC detecting condition Trouble area
Response delay of HO2S-2 signal (shifting delay from rich to lean and 
from lean to rich with threshold at 0.45 V) compared to switching cycle 
(rich-lean) of A/F feed back is less than specified while vehicle is 
running at constant speed and except with high engine load after 
warmed up.
(*2 driving cycle detection logic, monitoring once per driving cycle) • Exhaust gas leak
• Warm up three way catalytic converter 
malfunction
• HO2S-2 malfunction
• HO2S-1 malfunction
Step Action YesNo
1 Was “Engine and Emission Control System Check” 
performed? Go to Step 2.
Go to “Engine and 
Emission Control 
System Check”.
2 Exhaust system visual check
1) Check exhaust system for leaks, damage and loose 
connection.
Is it in good condition? Go to Step 3.
Repair or replace 
defective part.  
         
        
        
     
        
        Page 172 of 1496

Downloaded from www.Manualslib.com manuals search engine 1A-122 Engine General Information and Diagnosis: 
DTC P0443: Evaporative Emission System Purge Control Valve CircuitS7RS0B1104047
Wiring Diagram 
DTC Detecting Condition and Trouble Area3
HO2S-2 output voltage check
1) Check output voltage of HO2S-2 referring to “DTC 
P0137 / P0138: O2 Sensor (HO2S) Circuit Low Voltage / 
High Voltage (Sensor-2)” and “DTC P0137 / P0138: O2 
Sensor (HO2S) Circuit Low Voltage / High Voltage 
(Sensor-2)”.
Is check result satisfactory? Replace exhaust 
manifold (built in warm 
up three way catalytic 
converter) and exhaust 
center pipe (built in 
three way catalytic 
converter).
Check “BRN” and / or 
“YEL” wires for open 
and short, and 
connections for poor 
connection.
If wires and connections 
are OK, replace HO2S-
2.
Step Action Yes No
E23
C37
34
1819
567
1011
17
20
47 46
495051
2122
52 16
25 9
24
14
29
55
57 54 53
59
60 58 2
262728
15
30
56 4832 31
34353637
40
42 39 38
44
45 43 41 33 1
1213
238
34
1819
567
1011
17
20
47 46
495051
2122
52 16
25 9
24
14
29
55
57 54 53
59
60 58 2
262728
15
30
56 48 32 31
34353637
40
42 39 38
44
45 43 41 331
1213
238
BLK/WHT
BLK/RED
BLK/RED
WHTBLK/YELBLK/YEL
BLK/YEL
GRN
BRN/WHT
12V 5V
5
4 2
3 6E23-29  
E23-1  
E23-60  
C37-58  
C37-15  C37-30  
BLK/ORN
BLKBLKE23-31  BLK
7
8
BLK/REDBLK/REDE23-16  
1
C37-29  BLU/BLK
I6RS0C110020-02
1. EVAP canister purge valve
4. Main fuse box7. “FI” fuse
2. Main relay 5. Ignition switch8. “IG ACC” fuse
3. “IG COIL” fuse 6. ECM
DTC detecting conditionTrouble area
Monitor signal of EVAP canister purge valve is different from 
command signal. (Circuit open or short)
(2 driving cycle detection logic) • EVAP canister purge valve
• EVAP canister purge valve circuit
•ECM  
         
        
        
     
        
        Page 173 of 1496

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis:  1A-123
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 by 2 persons, a driver and a tester, on a level road.
 
1) With ignition switch OFF, connect scan tool to DLC.
2) Turn ON ignition switch and clear DTC using scan tool.
3) Start engine and warm up normal operating temperature.
4) Drive vehicle at more than 40 km/h, 25 mph for 5 min. or more.
5) Check DTC and pending DTC.
DTC Troubleshooting
WARNING! 
In order to reduce risk of fire and personal injury, this work must be performed in a well ventilated area 
and away from any open flames such as gas water heater.
 
NOTE
• When measuring circuit voltage, resistance and/ or pulse signal at ECM connector, connect the 
special tool to ECM and/or the ECM connectors re ferring to “Inspection of ECM and Its Circuits”.
• Upon completion of inspection and repair work, perform “DTC Confirmation Procedure” and  confirm that the trouble has been corrected.
 
Step Action YesNo
1 Was “Engine and Emission Control System Check” 
performed? Go to Step 2.
Go to “Engine and 
Emission Control 
System Check”.
2 EVAP canister purge power supply circuit check
1) Turn OFF ignition switch and disconnect connector from 
EVAP canister purge valve.
2) Measure voltage between engine ground and “BLK/ RED” wire terminal of EVAP canister purge valve 
connector with ignition switch turned ON.
Is it voltage 10 – 14 V? Go to Step 3.
“BLK/RED” wire is open 
circuit.
3 Wire circuit check
1) Disconnect connectors from ECM with ignition switch 
turned OFF.
2) Measure resistance between “C37-29” terminal of ECM  connector and vehicle body ground.
Is resistance infinity? Go to Step 4.
“BLU/BLK” wire is 
shorted to ground 
circuit.
4 Wire circuit check
1) Measure voltage between “C37-29” terminal of ECM 
connector and vehicle body  ground with ignition switch 
turned ON.
Is voltage 0 V? Go to Step 5.
“BLU/BLK” wire is 
shorted to other circuit.  
         
        
        
     
        
        Page 174 of 1496

Downloaded from www.Manualslib.com manuals search engine 1A-124 Engine General Information and Diagnosis: 
DTC P0480: Fan 1 (Radiator Cooling Fan) Control CircuitS7RS0B1104050
Wiring Diagram5
Wire circuit check
1) Connect connector to purge control valve with ignition 
switch turned OFF.
2) Turn ON ignition switch and measure voltage between  “C37-29” terminal of ECM  connector and vehicle body 
ground.
Is it voltage 10 – 14 V? Go to Step 6. “BLU/BLK” wire is open 
circuit.
6 EVAP canister purge control valve check
1) Check EVAP canister purge control valve referring to 
“EVAP Canister Purge Valve Inspection in Section 1B”.
Is it in good condition? Go to Step 7. Faulty EVAP canister 
purge control valve.
7 EVAP canister purge control circuit check
1) With ignition switch turn OFF, measure resistance 
between “E23-1/16” terminal and “C37-29” terminal of 
ECM connector.
Is resistance below 40 
Ω at 20 °C, 68 °F? Faulty ECM. Substitute 
a known-good ECM and 
recheck.
“BLK/RED” and/or 
“BLU/BLK” wire are high 
resistance circuit.
Step Action Yes No
E23
C37
34
1819
567
1011
17
20
47 46
495051
2122
52 16
25 9
24
14
29
55
57 54 53
59
60 58 2
262728
15
30
56 4832 31
34353637
40
42 39 38
44
45 43 41 331
1213
238
34
1819
567
1011
17
20
47 46
495051
2122
52 16
25 9
24
14
29
55
57 54 53
59
60 58 2
262728
15
30
56 4832 31
34353637
40
42 39 38
44
45 43 41 331
1213
238
BLK/REDBLK/RED
BLK/YELBLK/YEL
BLK/YEL
BRN/WHT
12V
5V5V
2
8
E23-1  
E23-60  
C37-58  
C37-15  C37-30  
BLK/ORN
BLKBLKE23-31BLK
BLK/RED
LT GRN
BLK/REDE23-16  
E23-46  
L+
L–
H–
H
+
BLU/RED
BLK
BLUWHTBLK
BLU/BLK
BLU/RED
4
GRN
GRY
E23-48  
LT GRN
ORN
C37-24  
C37-55  
35
6
7
10
9
1
I6RS0C110022-02
1. Individual circuit fuse box No.1
5. Radiator cooling fan relay No. 3 9. “FI” fuse
2. Main relay 6. Radiator cooling fan motor10. “RDTR FAN” fuse
3. Radiator cooling fan relay No. 1 7. ECT sensor
4. Radiator cooling fan relay No. 2 8. ECM  
         
        
        
     
        
        Page 175 of 1496

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis:  1A-125
DTC Detecting Condition and Trouble Area
DTC Confirmation Procedure1) Turn OFF ignition switch.
2) Clear DTC with ignition switch turned ON.
3) Run engine at idle speed.
4) Check DTC.
DTC Troubleshooting
NOTE
• When measuring circuit voltage, resistance and/ or pulse signal at ECM connector, connect the 
special tool to ECM and/or the ECM connectors re ferring to “Inspection of ECM and Its Circuits”.
• Upon completion of inspection and repair work, perform “DTC Confirmation Procedure” and  confirm that the trouble has been corrected.
 
DTC detecting condition Trouble area
Monitor signal of radiator cooling fan relay is different from 
command signal.
(1 driving cycle detection logic) • Radiator cooling fan relay circuit malfunction
• Radiator cooling fa
n relay malfunction
• ECM malfunction
Step Action YesNo
1 Was “Engine and Emission Control System Check” 
performed? Go to Step 2.
Go to “Engine and 
Emission Control 
System Check”.
2 Circuit fuse check
1) Check “RDTR FAN” fuse (1) in individual circuit fuse box 
No.1 with ignition switch turned OFF.
Is “RDTR FAN” fuse in good condition? Go to Step 3.
Check for short in 
circuits connected to 
this fuse.
1
I4RS0A110022-01  
         
        
        
     
        
        Page 176 of 1496

Downloaded from www.Manualslib.com manuals search engine 1A-126 Engine General Information and Diagnosis: 
3Wire circuit check
1) Disconnect radiator cooling fan relay No. 1 (1) from 
individual circuit fuse box No .1 (2) with ignition switch 
turned OFF.
2) Turn ON ignition switch, measure voltage between each  engine ground to “BLK/RED” and “GRY” wire terminal.
Is voltage 10 – 14 V? Go  to  Step  4. Open wire in “BLK/RED” 
and/or “GRY” wire are 
open circuit.
4 Wire circuit check
1) Connect radiator cooling fan relay No. 1 to individual 
circuit fuse box No.1 with ignition switch turned OFF.
2) Remove ECM from its br acket with ECM connectors 
connected.
3) Turn ON ignition switch, ma ke sure that A/C switch is 
OFF position.
4) Measure voltage between vehicle body ground and  “E23-46” terminal of ECM connector when engine 
coolant temp. is below 95  °C, 203  °F.
Is voltage 10 – 14 V? Go to Step 8.
Go to Step 5.
5 Wire circuit check
1) Disconnect connectors from ECM with ignition switch 
turned OFF.
2) Disconnect radiator cooling fan relay No. 1 from  individual circuit fuse box No.1.
3) Measure resistance between “E23-46” terminal of ECM  connector and vehicle ground.
Is resistance infinity? Go to Step 6.
“LT GRN” wire is 
shorted to ground 
circuit.
6 Wire circuit check
1) Turn ON ignition switch.
2) Measure voltage between “E23-46” terminal of ECM 
connector and vehicle body ground.
Is voltage 0 V? Go to Step 7.
“LT GRN” wire is 
shorted to other circuit.
7 Radiator cooling fan relay No. 1 check
1) Check radiator cooling fan relay No. 1 referring to 
“Radiator Cooling Fan Relay  Inspection in Section 1F”.
Is check result satisfactory? “LT GRN” wire is open 
circuit.
Replace relay.
Step
Action YesNo
1
2
I7RS0A110010-01