Mitsubishi Lancer Evolution VI. Manual - part 38

MPI  – 

Troubleshooting

13-40

INSPECTION PROCEDURE 30 <EVOLUTION-IV, EVOLUTION-V>

Fan motor relay system (Radiator fan, A/C condenser fan)

Probable cause

The engine-ECU turns on/off the built-in power transistor to control the fan motor
relay.

D

Malfunction of the fan motor relay

D

Malfunction of the fan motor

D

Improper connector contact, open or short-circuited
harness wire

D

Malfunction of engine-ECU

NG

D

Check the radiator fan circuit.

D

Check the A/C condenser fan circuit.
(Refer to Electrical Wirings.)

NG

Replace the engine-ECU.

OK

Check trouble symptom.

Measure at the engine-ECU connector B-59.

D

Disconnect the connector, and measure at the harness side.

D

Voltage between each of 20 and 21 and earth
(Ignition switch: ON)
OK: System voltage

D

Short the terminal 21 to earth.
(Ignition switch: ON)
OK: Fan operates at low speed.

D

Short the terminals 20 and 21 to earth.
(Ignition switch: ON)
OK: Fan operates at high speed.

OK

Check the following connector: B-59

NG

Repair

MPI  – 

Troubleshooting

13-41

INSPECTION PROCEDURE 30 <EVOLUTION-VI>

Fan motor relay system (Radiator fan, A/C condenser fan)

Probable cause

The engine-ECU turns on/off the built-in power transistor to control the fan motor
relay.

D

Malfunction of the fan motor relay

D

Malfunction of the fan motor

D

Malfunction of thermostat

D

Improper connector contact, open or short-circuited
harness wire

D

Malfunction of engine-ECU

NG

Check the engine coolant temperature sensor. (Refer to P.13-10,
INSPECTION PROCEDURE FOR DIAGNOSIS CODE 21.)

OK

Replace the engine-ECU.

NG

MUT-

II

 Data list

21 Engine coolant temperature sensor

OK: The engine coolant temperature agrees with the reading

of MUT-

II

 when measured with the engine idling in warm

condition.

OK

Check the thermostat.

NG

Replace

OK

Check trouble symptom.

OK

Check the following connector: B-60

NG

Repair

NG

Check the A/C condenser fan circuit. (Refer to Electrical Wirings.)

NG

Measure at the engine-ECU connector B-60.

D

Disconnect the connector, and measure at the harness side.

D

Check the A/C condenser fan for operating condition.
(Ignition switch: ON)
OK: A/C condenser fan is stationary.

D

Voltage between each of 32 and 34 and earth
(Ignition switch: ON)
OK: System voltage

D

Short the terminal 32 to earth. (Ignition switch: ON)
OK: A/C condenser fan operates at high speed.

D

Short the terminal 34 to earth. (Ignition switch: ON)
OK: A/C condenser fan operates at low speed.

Check trouble symptom.

OK

OK

Check the following connector: B-59

NG

Repair

Measure at the engine-ECU connector B-59.

D

Disconnect the connector, and measure at the harness side.

D

Check the radiator fan for operating condition.
(Ignition switch: ON)
OK: Radiator fan is stationary.

D

Voltage between each of 20 and 21 and earth
(Ignition switch: ON)
OK: System voltage

D

Short the terminal 20 to earth.
(Ignition switch: ON)
OK: Radiator fan operates at high speed.

D

Short the terminal 21 to earth.
(Ignition switch: ON)
OK: Radiator fan operates at low speed.

NG

Check the radiator fan circuit. (Refer to Electrical Wirings.)

MPI  – 

Troubleshooting

13-42

INSPECTION PROCEDURE 31 <EVOLUTION-IV>

Oxygen sensor system

Probable cause

When CO or HC concentration is too high, the malfunction of the parts shown at
right may be the cause.

D

The oxygen sensor detects the density of oxygen in exhaust gas and inputs it
to the engine-ECU after converting into a voltage signal.

D

The engine-ECU controls the fuel injection amount based on this signal such that
the stoichiometric air/fuel mixture ratio can be obtained.

D

Malfunction of oxygen sensor

D

Improper connector contact, open or short-circuited
harness wire

D

Malfunction of engine-ECU

OK

Replace the engine-ECU.

Check the harness wire between
engine-ECU and oxygen sensor connector.

NG

Repair

NG

OK

Check trouble symptom.

OK

Replace the engine-ECU.

NG

Check the harness wire between
engine-ECU and oxygen sensor connector.

NG

Repair

OK

Check trouble symptom.

OK

Check the following connector: A-63

NG

Repair

OK

Measure at the oxygen sensor connector A-63.

D

Disconnect the connector, and measure at the harness side.

D

Continuity between 2 and earth
OK: Continuity

NG

Check the following connector: B-62

NG

Repair

Check the oxygen sensor. (Refer to P.13-32.)*

NG

Replace

NOTE
*:

Refer to Workshop Manual for LANCER EVOLUTION-IV and EVOLUTION-V (Pub. No. S9806CNCP9).

MPI  – 

Troubleshooting

13-43

INSPECTION PROCEDURE 31 <EVOLUTION-V, EVOLUTION-VI>

Oxygen sensor system

Probable cause

When CO or HC concentration is too high, the malfunction of the parts shown at
right may be the cause.

D

The oxygen sensor detects the density of oxygen in exhaust gas and inputs it
to the engine-ECU after converting into a voltage signal.

D

The engine-ECU controls the fuel injection amount based on this signal such that
the stoichiometric air/fuel mixture ratio can be obtained.

D

Malfunction of oxygen sensor

D

Improper connector contact, open or short-circuited
harness wire

D

Malfunction of engine-ECU

OK

Replace the engine-ECU.

NG

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

OK

Check trouble symptom.

NG

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

OK

Check trouble symptom.

OK

Check trouble symptom.

NG

Check the harness wire between
engine-ECU and oxygen sensor.

NG

Repair

OK

Check the following connector: B-61

NG

Repair

OK

NG

Measure at the engine-ECU connector B-61.

D

Disconnect the connector, and measure at the harness side.

D

Voltage between 60 and earth 
(Ignition switch: ON)
OK: System voltage

Check the following connector: A-63

NG

Repair

1. NG

Check the harness wire between oxygen sensor and control relay,
and repair if necessary.

OK

2. NG

Measure at the oxygen sensor connector A-63.

D

Disconnect the connector, and measure at the harness side.

1. Voltage between 1 and earth 

(Ignition switch: ON)
OK: System voltage

2. Continuity between 2 and earth

OK: Continuity

Check the following connector: B-62

NG

Repair

Check the oxygen sensor. (Refer to P.13-32)*

NG

Replace

NOTE
*:

Refer to Workshop Manual for LANCER EVOLUTION-IV and EVOLUTION-V (Pub. No. S9806CNCP9).