Mitsubishi Pajero Pinin. Manual — part 120
MPI <4G9> –
Troubleshooting
13C-66
INSPECTION PROCEDURE 23
Idling speed is improper when A/C is operating
Probable cause
If the engine-ECU detects that the air conditioner is on, it activates the idle
speed control (ISC) servo to control idle-up operation.
The A/C-ECU judges if the load caused by air conditioner operation is high or
low, and converts it to voltage signal (high or low voltage) and inputs the
signal to the engine-ECU.
Based on this voltage signal, the engine-ECU controls the idle-up speed (for
high or low load).
D
Malfunction of the A/C control system
D
Improper connector contact, open circuit or
short-circuited harness wire
D
Malfunction of the engine-ECU
NG
Repair
NG
Replace the engine-ECU.
NG
Check the A/C system. (Refer to GROUP 55 – On-vehicle Service.)
OK
Check the trouble symptom.
Measure at the engine-ECU connector C-87
D
Connect the connector.
D
Voltage between 8 and earth (Engine: at idle, outside air
temperature: 25
_
C or more)
OK: 0 – 3 V [When A/C is MAX. COOL condition (when
the load by A/C is high)]
System voltage [When A/C is MAX. HOT condition
(when the load by A/C is low)]
OK
Check the following connector:
C-87
MPI <4G9> –
Troubleshooting
13C-67
INSPECTION PROCEDURE 24
Fans (radiator fan, A/C condenser fan) are inoperative
Probable cause
The engine-ECU outputs a duty signal to the fan controller depending on the
engine coolant temperature, vehicle speed, and air conditioner switch condition.
Based on this signal, the fan controller controls the radiator fan and condenser
fan speeds (The more the average voltage at the terminal approaches 5 V, the
higher the fan speed become.)
D
Malfunction of the fan motor relay
D
Malfunction of the fan motor
D
Malfunction of the fan controller
D
Improper connector contact, open circuit or
short-circuited harness wire
D
Malfunction of the engine-ECU
OK
Replace the engine-ECU.
NG
MUT-
II
Data list
21 Engine coolant temperature sensor
OK: After the engine has been warmed up, the engine
coolant temperature during idling is identical to the
MUT-
II
reading.
NG
Check the engine coolant temperature sensor system. (Refer to
P.13C-20, INSPECTION PROCEDURE FOR DIAGNOSIS CODE
P0115.)
OK
Check the radiator fan
and condenser fan cir-
cuit. (Refer to GROUP 14
– Troubleshooting.)
NG
Repair
Check the harness wire
between the engine-ECU
and the fan controller
connector.
NG
OK
Check the trouble symp-
tom.
OK
Check the trouble symp-
tom.
OK
Check the following
connector: A-91X
NG
Repair
Measure at the engine-ECU connector C-87.
D
Disconnect the connector, and measure at the harness
side.
D
Voltage between 21 and earth (Ignition switch: ON)
OK: 4.8 – 5.2 V (Fan rotates at high speed.)
D
Connect a jumper cable between 21 and earth (Ignition
switch: ON)
OK: Fan stops
NG
Check the following
connector: C-87
NG
Repair
OK
Check the thermostat.
NG
Replace
MPI <4G9> –
Troubleshooting
13C-68
INSPECTION PROCEDURE 25
Engine-ECU power supply and earth circuit system
Probable cause
The engine-ECU may be defective, or that one of the malfunctions listed at right
has occurred.
D
Improper connector contact, open circuit or
short-circuited harness wire in the engine-ECU power
supply circuit.
D
Open circuit or short-circuited harness wire in the
engine-ECU earth circuit
D
Malfunction of the engine-ECU
NG
Replace the engine-ECU.
OK
Check the trouble symptom.
NG
Repair
Check the following
connectors:
C-87, C-88, C-89, C-90
OK
NG
Check the harness wire between engine-ECU and battery,
and repair if necessary.
OK
Check the trouble symptom.
(4) NG
Check the harness wire between engine-ECU and earth, and
repair if necessary.
(2), (3) NG
Check the harness wire between engine-ECU and control relay
connector, and repair if necessary.
OK
Check the ignition switch.
(Refer to GROUP 54 – Ignition Switch.)
OK
Check the harness wire
between engine-ECU
and ignition switch
connector.
NG
Repair
OK
Check the trouble symptom.
Measure at the engine-ECU connector C-90, C-88, C-87, C-89
D
Disconnect the connector and measure at the harness side
(1) Voltage between 82 and earth (Ignition switch: ON)
OK: System voltage
(2) Voltage between 38 and earth
OK: System voltage
(3) Voltage between 12, 25 and earth (Ignition switch: ON)
OK: System voltage (when the terminal 38 is earthed)
(4) Continuity between 13, 26 and earth
OK: Continuity
(5) Voltage between 80 and earth
OK: System voltage
(1) NG
Check the following
connectors:
C-90, C-72, C-74
NG
Repair
(5) NG
Check the following
connectors: A-36, C-90
NG
Repair
MPI <4G9> –
Troubleshooting
13C-69
INSPECTION PROCEDURE 26
Power supply system and ignition switch-IG system
Probable cause
When an ignition switch ON signal is input to the engine-ECU, the engine-ECU
turns the control relay ON. This causes battery voltage to be supplied to the
engine-ECU, injectors and air flow sensor.
D
Malfunction of the ignition switch
D
Malfunction of the control relay
D
Improper connector contact, open circuit or
short-circuited harness wire
D
Disconnected engine-ECU earth wire
D
Malfunction of the engine-ECU
OK
Check the engine-ECU power supply and earth circuit.
(Refer to P.13C-68, INSPECTION PROCEDURE 25.)
NG
Check the harness wire between battery and control relay connec-
tor, and repair if necessary.
OK
Check the trouble symptom.
NG
Check the following
connector: C-61, A-36, A-43X
NG
Repair
OK
Measure at the control relay connector A-43X.
D
Disconnect the connector, and measure at the harness side.
D
Voltage between 3, 4 and earth
OK: System voltage
Check the control relay. (Refer to P.13C-102.)
NG
Replace
INSPECTION PROCEDURE 27
Fuel pump system
Probable cause
The engine-ECU turns the control relay ON when the engine is cranking or running,
and this supplies power to drive the fuel pump.
D
Malfunction of the fuel pump relay
D
Malfunction of the fuel pump
D
Improper connector contact, open circuit or
short-circuited harness wire
D
Malfunction of the engine-ECU
NG
Check the fuel pump relay. (Refer to
P.13C-102.)
NG
Replace
MUT-
II
Actuator test
07 Fuel pump (Refer to P.13C-79.)
OK
Normal
OK
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