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).

Malfunction of the A/C control system

Improper connector contact, open circuit or
short-circuited harness wire

Malfunction of the engine-ECU

Repair

Replace the engine-ECU.

Check the A/C system. (Refer to GROUP 55 – On-vehicle Service.)

Check the trouble symptom.

Measure at the engine-ECU connector C-87

Connect the connector.

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)]

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.)

Malfunction of the fan motor relay

Malfunction of the fan motor

Malfunction of the fan controller

Improper connector contact, open circuit or
short-circuited harness wire

Malfunction of the engine-ECU

Replace the engine-ECU.

MUT-

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-

reading.

Check the engine coolant temperature sensor system. (Refer to
P.13C-20, INSPECTION PROCEDURE FOR DIAGNOSIS CODE
P0115.)

Check the radiator fan
and condenser fan cir-
cuit. (Refer to GROUP 14
– Troubleshooting.)

Repair

Check the harness wire
between the engine-ECU
and the fan controller
connector.

Check the trouble symp-
tom.

Check the following
connector: A-91X

Repair

Measure at the engine-ECU connector C-87.

Disconnect the connector, and measure at the harness
side.

Voltage between 21 and earth (Ignition switch: ON)
OK: 4.8 – 5.2 V (Fan rotates at high speed.)

Connect a jumper cable between 21 and earth (Ignition
switch: ON)
OK: Fan stops

Check the following
connector: C-87

Repair

Check the thermostat.

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.

Improper connector contact, open circuit or
short-circuited harness wire in the engine-ECU power
supply circuit.

Open circuit or short-circuited harness wire in the
engine-ECU earth circuit

Malfunction of the engine-ECU

Replace the engine-ECU.

Check the trouble symptom.

Repair

Check the following
connectors:
C-87, C-88, C-89, C-90

Check the harness wire between engine-ECU and battery,
and repair if necessary.

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.

Check the ignition switch.
(Refer to GROUP 54 – Ignition Switch.)

Check the harness wire
between engine-ECU
and ignition switch
connector.

Repair

Check the trouble symptom.

Measure at the engine-ECU connector C-90, C-88, C-87, C-89

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

Repair

(5) NG

Check the following
connectors: A-36, C-90

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.

Malfunction of the ignition switch

Malfunction of the control relay

Improper connector contact, open circuit or
short-circuited harness wire

Disconnected engine-ECU earth wire

Malfunction of the engine-ECU

Check the engine-ECU power supply and earth circuit.
(Refer to P.13C-68, INSPECTION PROCEDURE 25.)

Check the harness wire between battery and control relay connec-
tor, and repair if necessary.

Check the trouble symptom.

Check the following
connector: C-61, A-36, A-43X

Repair

Measure at the control relay connector A-43X.

Disconnect the connector, and measure at the harness side.

Voltage between 3, 4 and earth
OK: System voltage

Check the control relay. (Refer to P.13C-102.)

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.

Malfunction of the fuel pump relay

Malfunction of the fuel pump

Improper connector contact, open circuit or
short-circuited harness wire

Malfunction of the engine-ECU

Check the fuel pump relay. (Refer to
P.13C-102.)

Replace

MUT-

Actuator test

07 Fuel pump (Refer to P.13C-79.)

Normal

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