Mitsubishi Grandis. Manual — part 711
TROUBLESHOOTING
MULTIPORT FUEL INJECTION (MPI)
13A-95
STEP 11. Check the trouble symptoms.
Q: Does trouble symptom persist?
YES :
Replace engine-ECU <M/T> or
engine-A/T-ECU <A/T>.
NO :
Intermittent malfunction (Refer to GROUP
00
− How to Use
Troubleshooting/Inspection Service Points
).
Code No. P0156: Cylinder 2, 3 Oxygen Sensor (Rear) System
OPERATION
• The sensor signal is inputted to the engine-ECU
<M/T> or engine-A/T-ECU <A/T> (terminal No.
116) from the cylinder 2, 3 oxygen sensor (rear)
output terminal (terminal No. 4).
• The cylinder 2, 3 oxygen sensor (rear) (terminal
No. 2) is earthed with engine-ECU <M/T> or
engine-A/T-ECU <A/T> (terminal No. 96).
FUNCTION
• The cylinder 2, 3 oxygen sensor (rear) converts
the concentration of oxygen in the exhaust
emission into a voltage and inputs the signal to
the engine-ECU <M/T> or engine-A/T-ECU
<A/T>.
AK305557
9192
939495
96979899
100
105
113114
115116117
118119120
106
107108109
110111112
101102103
104
1
2
3
4
Cylinder 2, 3 oxygen
sensor (rear)
AB
Cylinder 2, 3 oxygen sensor (rear) circuit
Engine-ECU <M/T> or
engine-A/T-ECU <A/T>
B
G
R
From engine control relay
1
2
3
4
96
116
B-18
MU802605
C-113
(MU803805)
Wire colour code
B: Black LG: Light green G: Green L: Blue W: White Y: Yellow SB: Sky blue BR: Brown O: Orange GR: Gray
R: Red P: Pink V: Violet
To engine-ECU <M/T> or
engine-A/T-ECU <A/T>
5
C-115
TROUBLESHOOTING
MULTIPORT FUEL INJECTION (MPI)
13A-96
• When the air-fuel ratio is richer than the
theoretical air-fuel ratio, the cylinder 2, 3 oxygen
sensor (rear) outputs a voltage of about 1 V.
When it is leaner than the theoretical air-fuel
ratio, it outputs a voltage of about 0 V.
• Based on this signal, the engine-ECU <M/T> or
engine-A/T-ECU <A/T> corrects the deviation in
the signal that is output by the cylinder 2, 3
oxygen sensor (front).
TROUBLE JUDGMENT
Check Conditions
• Above 3 minutes later after the engine has
started up.
• The engine coolant temperature is approx. 82°C
or higher.
• The engine speed is 1200 r/min or more.
• The monitoring time is 5 seconds.
Judgment Criteria
• When the cylinder 2, 3 oxygen sensor (rear)
output voltage is 0.2 V or less and a power
voltage of 5 V is applied to the cylinder 2, 3
oxygen sensor (rear) in the engine-ECU <M/T>
or engine-A/T-ECU <A/T>, the sensor output
voltage is 4.5 V or more.
• To be monitored once per driving cycle.
Check Conditions
• 2 seconds later after lack of circuit continuity is
detected.
• When the cylinder 2, 3 oxygen sensor (rear) is
normally operated.
Judgment Criteria
• When the air-fuel ratio is rich, the cylinder 2, 3
oxygen sensor (rear) output voltage is 0.5 V or
more.
• The cylinder 2, 3 oxygen sensor (rear) output
voltage is less than 0.1 V.
• The maximum and maximum of the cylinder 2, 3
oxygen sensor (rear) output is 0.078 V or less.
PROBABLE CAUSE
• Failed cylinder 2, 3 oxygen sensor (rear)
• Open/short circuit in cylinder 2, 3 oxygen sensor
(rear) circuit or loose connector contact
• Failed engine-ECU <M/T>
• Failed engine-A/T-ECU <A/T>
DIAGNOSIS PROCEDURE
STEP 1. MUT-III data list
• Refer to Data List Reference Table
a. Item 69: Cylinder 2, 3 oxygen sensor (rear)
Q: Is the check result normal?
YES :
Intermittent malfunction (Refer to GROUP
00
− How to Use
Troubleshooting/Inspection Service Points
).
NO :
Go to Step 2 .
STEP 2. Connector check: B-18 cylinder 2, 3
oxygen sensor (rear) connector
Q: Is the check result normal?
YES :
Go to Step 3 .
NO :
Repair or replace.
AK300977
1
2
3
4
AC
Connector: B-18
Harness side
connector
B-18 (B)
Cylinder 2, 3
oxygen sensor
(rear)
TROUBLESHOOTING
MULTIPORT FUEL INJECTION (MPI)
13A-97
STEP 3. Perform resistance measurement at B-18
cylinder 2, 3 oxygen sensor (rear) connector.
• Disconnect connector, and measure at harness
side.
• Resistance between terminal No. 2 and earth.
OK: 2
Ω or less
Q: Is the check result normal?
YES :
Go to Step 7 .
NO :
Go to Step 4 .
STEP 4. Connector check: C-113 engine-ECU
<M/T> connector or engine-A/T-ECU <A/T>
connector
Q: Is the check result normal?
YES :
Go to Step 5 .
NO :
Repair or replace.
AK300977
1
2
3
4
AC
Connector: B-18
Harness side
connector
B-18 (B)
Cylinder 2, 3
oxygen sensor
(rear)
AK305616AB
Connector: C-113
<L.H. drive vehicles>
<R.H. drive vehicles>
C-113 (GR)
C-113 (GR)
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
Harness side connector
TROUBLESHOOTING
MULTIPORT FUEL INJECTION (MPI)
13A-98
STEP 5. Check harness between B-18 (terminal
No. 2) cylinder 2, 3 oxygen sensor (rear)
connector and C-113 (terminal No. 96)
engine-ECU <M/T> connector or engine-A/T-ECU
<A/T> connector.
• Check earthing line for open circuit and damage.
Q: Is the check result normal?
YES :
Go to Step 6 .
NO :
Repair.
STEP 6. MUT-III data list
• Refer to Data List Reference Table
a. Item 69: Cylinder 2, 3 oxygen sensor (rear)
Q: Is the check result normal?
YES :
Intermittent malfunction (Refer to GROUP
00
− How to Use
Troubleshooting/Inspection Service Points
).
NO :
Replace engine-ECU <M/T> or
engine-A/T-ECU <A/T>.
STEP 7. Perform voltage measurement at B-18
cylinder 2, 3 oxygen sensor (rear) connector.
• Use special tool test harness (MD998464) to
connect connector, and measure at pick-up
harness.
• Transmission: Neutral <M/T> or P range <A/T>
• Engine: After warm-up
• Voltage between terminal No. 4 and earth.
OK:
When the engine is 2,500 r/min, the output
voltage should repeat 0 to 0.8 V alternately.
Q: Is the check result normal?
YES :
Go to Step 10 .
NO :
Go to Step 8 .
AK300977
1
2
3
4
AC
Connector: B-18
Harness side
connector
B-18 (B)
Cylinder 2, 3
oxygen sensor
(rear)
AK305616AB
Connector: C-113
<L.H. drive vehicles>
<R.H. drive vehicles>
C-113 (GR)
C-113 (GR)
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
Harness side connector
AK300977
1
2
3
4
AC
Connector: B-18
Harness side
connector
B-18 (B)
Cylinder 2, 3
oxygen sensor
(rear)
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