ECU MITSUBISHI LANCER EVOLUTION VI 1999 Workshop Manual

FULL-AUTOMATIC AIR CONDITIONER – Troubleshooting55-38
Code No.31 Potentiometer system of air mix damper motor
assemblyProbable cause
This diagnosis code is output if no signals are input from air mix damper potentiometer
to A/C-ECU because of short-circuit or open-circuit in the harness.
Malfunction of the air mix damper potentiometer

Malfunction of connector, harness

Malfunction of the A/C-ECU
Air mix damper potentiometer check (Refer to P.55-59.)NG
Replace
OK
Measure at the air mix damper potentiometer connector B-39.

Disconnect the connector, and measure at the harness
side connector.

Voltage between terminal (6) and body earth
OK:5 VNGCheck the following connector:
B-04
NG
Repair OK
Check the trouble symptom.
NG
Check the harness between the air mix damper potentiometer
and the A/C-ECU.
NG
Repair OK
Replace the A/C-ECU.
OK
Measure at the A/C-ECU connector B-04.

Connect the connector.

Air mix damper position: MAX.HOT

Voltage between terminal (5) and body earth
OK:4.7 – 5.0 VNGCheck the following connector:
B-39
NG
Repair OK
Check the trouble symptom.
NG
Check the harness between the air mix damper potentiometer
and the A/C-ECU, and repair if necessary.
OK
Check the following connector: B-04NG
Repair
OK
Check the trouble symptom.NGReplace the A/C-ECU.

FULL-AUTOMATIC AIR CONDITIONER – Troubleshooting55-39
Code No.32 Potentiometer system of air outlet changeover
damper motor assemblyProbable cause
This diagnosis code is output if no signals are input from air outlet changeover
damper potentiometer to A/C-ECU because of short-circuit or open-circuit in the
harness.
Malfunction of the air outlet changeover damper
potentiometer

Malfunction of connector, harness

Malfunction of the A/C-ECU
Air outlet changeover damper potentiometer check (Refer to
P.55-60.)NG
Replace
OK
Measure at the air outlet changeover damper potentiometer con-
nector B-06.

Disconnect the connector, and measure at the harness
side connector.

Voltage between terminal (2) and body earth
OK:5 VNGCheck the following connector:
B-04
NG
Repair OK
Check the trouble symptom.
NG
Check the harness between the air outlet changeover damper
potentiometer and the A/C-ECU.
NG
Repair OK
Replace the A/C-ECU.
OK
Measure at the A/C-ECU connector B-04.

Connect the connector.

Air outlet changeover damper position: DEF

Voltage between terminal (6) and body earth
OK:4.8 – 5.2 VNGCheck the following connector:
B-06
NG
Repair OK
Check the trouble symptom.
NG
Check the harness between the air outlet changeover damper
motor potentiometer and the A/C-ECU, and repair if necessary.
OK
Check the following connector: B-04NG
Repair
OK
Check the trouble symptom.NGReplace the A/C-ECU.

FULL-AUTOMATIC AIR CONDITIONER – Troubleshooting55-40
Code No.41 Drive system of air mix damper motor
assemblyProbable cause
This diagnosis code is output if the air mix damper fails to be turned to the preset
opening.
Malfunction of the air mix damper motor assembly

Malfunction of connector, harness

Malfunction of the A/C-ECU
Air mix damper motor check (Refer to P.55-59.)NG
Replace
OK
Check the following connectors:
B-39, B-05NG
Repair
OK
Check the trouble symptom.NGCheck the harness between the air mix damper motor and the
A/C-ECU.
OK
Replace the A/C-ECU.
NG
Repair
Code No.42 Drive system of air outlet changeover damper
motor assemblyProbable cause
This diagnosis code is output if the air outlet changeover damper fails to be turned
to the preset opening.
Malfunction of the air outlet changeover damper
motor assembly

Malfunction of connector, harness

Malfunction of the A/C-ECU
Air outlet changeover damper motor check (Refer to P.55-60.)NG
Replace
OK
Check the following connectors:
B-06, B-05NG
Repair
OK
Check the trouble symptom.NGCheck the harness between the air outlet changeover damper
motor and the A/C-ECU.
OK
Replace the A/C-ECU.
NG
Repair

FULL-AUTOMATIC AIR CONDITIONER – Troubleshooting55-41
INSPECTION CHART FOR TROUBLE SYMPTOMS
Trouble symptomInspection proce-
dure No.Reference page
Communication with the MUT-II is not possible.155-42
Air conditioner does not operate.255-43
A/C graphic display on control panel is blank.355-44
Temperature cannot be set.455-44
A/C outlet air temperature does not increase.555-44
A/C outlet air temperature does not decrease.655-44
Blower does not operate.755-45
Blower does not operate in HI mode.855-46
Blower air amount cannot be changed.955-47
Air outlet port cannot be changed.1055-47
Inside/outside air changeover is not possible.1155-48
Defroster function does not operate.1255-49
Condenser fan does not operate.1355-50
Rear defogger does not operate.1455-51
A/C-ECU power supply circuit check1555-52
A/C compressor control circuit check1655-53

FULL-AUTOMATIC AIR CONDITIONER – Troubleshooting55-42
INSPECTION PROCEDURE FOR TROUBLE SYMPTOMS
Inspection procedure 1
Communication with the MUT-II is not possible.Probable cause
If communication with all other systems is not possible, there is a high
possibility that there is a malfunction of the diagnosis line. If communication
with only the A/C is not possible, the cause is probably a malfunction of the
diagnosis line or of the A/C-ECU power supply system (earth).
Malfunction of connector or harness

Malfunction of A/C-ECU
Is communication between MUT-II and
other system possible?NOCheck the MUT-II diagnosis line, and
repair if necessary.
YES
Measure at the diagnosis connector
B-22.

Voltage between terminal (11)
and body earth
OK:Indication fluctuates be-
tween 0 V and 12 V.OKMeasure at the A/C-ECU connector
B-04.

Disconnect the connector, and
measure at the harness side
connector.

Voltage between terminal (18)
and body earth
OK:System voltage – 2 VNGCheck the following connector:
B-04
OK
Check the trouble symptom.
NG
Repair
NG
Measure at the A/C-ECU connector
B-04.

Connect the connector.

Voltage between terminal (17)
and body earth
OK:Indication fluctuates be-
tween 0 V and 12 V.NGOKCheck the following connector:
B-04
NG
Check the harness between the diagno-
sis connector and the A/C-ECU, and
repair if necessary.
NG
Repair
OK
Check the harness between the diagno-
sis connector and the A/C-ECU.NG
RepairOK
Check the trouble symptom.
OK
Check the following connectors:
B-04, B-22NG
Repair
OK
Check the trouble symptom.
NG
Measure at the A/C-ECU connector
B-05.

Disconnect the connector, and
measure at the harness side
connector.

Voltage between terminal (28)
and body earth
OK:System voltageNGCheck the following connectors:
B-49, B-75NG
Repair
OK
Check the trouble symptom.NGCheck the harness between the junc-
tion block and the A/C-ECU, and repair
if necessary.
OK
Measure at the A/C-ECU connector
B-05.

Disconnect the connector, and
measure at the harness side
connector.

Continuity between terminals
(29), (35) and body earth
OK:ContinuityNGCheck the following connectors:
B-05, B-48, B-19, B-67, B-80NG
Repair
OK
Check the trouble symptom.NGCheck the harness between the
A/C-ECU and the body earth, and repair
if necessary.
OK
Replace the A/C-ECU.
NG
Replace the A/C-ECU.

FULL-AUTOMATIC AIR CONDITIONER – Troubleshooting55-43
Inspection procedure 2
Air conditioner does not operate.
Probable cause
If the A/C does not operate when the A/C switch is on and the temperature
setting is at 17C, the cause is probably insufficient refrigerant, or a
malfunction of the blower or of the magnet clutch power supply.
Malfunction of blower

Insufficient refrigerant

Malfunction of magnetic clutch

Malfunction of air thermo sensor

Malfunction of A/C compressor relay

Malfunction of refrigerant temperature switch

Malfunction of dual pressure switch

Malfunction of water temperature switch

Malfunction of connector or harness

Malfunction of engine-ECU

Malfunction of A/C-ECU
Does the blower operate?NOInspection procedure 7 (Refer to P.55-45.)
YES
A/C system refrigerant pressure check (Refer to P.55-13.)NGRefill the specified amount of refrigerant. (Refer to P.55-6.)
OK
MUT-II Self-Diag code
Is any of the codes 11, 12, 21 and 22 output?YESINSPECTION CHART FOR DIAGNOSIS CODES (Refer to
P.55-34.)
NO

Magnetic clutch check (Refer to P.55-25.)

A/C compressor relay check (Refer to P.55-14.)

Refrigerant temperature switch check (Refer to P.55-25.)

Dual pressure switch check (Refer to P.55-13.)

Water temperature switch check (Refer to P.55-64.)
<2,000>NG
Replace
OK
Measure at the A/C compressor relay connector A-116X.

Disconnect the connector, and measure at the harness
side connector.
(1) Continuity between terminal (4) and body earth
OK:Continuity
(2) Voltage between terminal (5) and body earth
OK:System voltageOKInspection procedure 13 (Refer to P.55-50.)
(2) NG
Check the following connector:
A-116X
(1) NG
Check the following connectors:
A-116X, A-106NG
Repair
NG
Repair OK
Check the trouble symptom.
NG
Check the harness between the fusible link and the A/C compressor
relay, and repair if necessary.
OK
Check the trouble symptom.
NG
Check the harness between the magnetic clutch and the A/C
compressor relay, and repair if necessary.

FULL-AUTOMATIC AIR CONDITIONER – Troubleshooting55-44
Inspection procedure 3
A/C graphic display on control panel is blank.
Probable cause
The cause is probably a malfunction of the A/C-ECU power supply system
(earth).
Malfunction of connector or harness

Malfunction of A/C-ECU
Does the A/C operate?NOInspection procedure 15 (Refer to P.55-52.)
YES
Replace the A/C-ECU.
Inspection procedure 4
Temperature cannot be set.
Probable cause
The cause is probably a malfunction of the temperature setting signal input
system or output system.
Malfunction of connector or harness

Malfunction of A/C-ECU
Inspection procedure 15 (Refer to P.55-52.)
Inspection procedure 5
A/C outlet air temperature does not increase.
Probable cause
If the outlet air temperature does not increase when the temperature setting is
increased, the cause is probably a sensor malfunction or a problem with
operation of the air mix damper. The MUT-II can be used to check the
diagnosis codes in order to check the cause of the problem for each separate
system.
Malfunction of air mix damper potentiometer

Malfunction of air mix damper motor

Malfunction of air mix damper

Malfunction of connector or harness

Malfunction of thermostat

Malfunction of A/C-ECU
MUT-II Self-Diag code
Is any of the codes 11, 12, 31 and 41 output?YESINSPECTION CHART FOR DIAGNOSIS CODES (Refer to
P.55-34.)
NO
Thermostat checkNG
Replace
OK
Replace the A/C-ECU.
Inspection procedure 6
A/C outlet air temperature does not decrease.
Probable cause
If the outlet air temperature does not decrease when the temperature setting is
decreased, the cause is probably a problem in A/C system operation due to a
sensor error, or a problem with operation of the air mix damper. The MUT-II
can be used to check the diagnosis codes in order to check the cause of the
problem for each separate system.
Malfunction of outside air temperature sensor

Malfunction of air mix damper potentiometer

Malfunction of air mix damper motor

Malfunction of air thermo sensor

Malfunction of connector or harness

Malfunction of air mix damper

Malfunction of A/C-ECU
Does the A/C operate?NOInspection procedure 2 (Refer to P.55-43.)
YES
MUT-II Self-Diag code
Is any of the codes 11, 12, 13, 14, 21, 22, 31 and 41 output?YESINSPECTION CHART FOR DIAGNOSIS CODES (Refer to
P.55-34.)
NO
Replace the A/C-ECU.

FULL-AUTOMATIC AIR CONDITIONER – Troubleshooting55-45
Inspection procedure 7
Blower does not operate.
Probable cause
If no air comes out of the blower even though the blower switch is on, the
cause is probably a malfunction of the blower motor relay circuit.
Malfunction of blower motor relay

Malfunction of blower motor

Malfunction of connector or harness

Malfunction of A/C-ECU
Can an operating sound be heard when the blower speed change-
over switch is operated?NOInspection procedure 15 (Refer to P.55-52.)
YES

Blower motor relay check (Refer to P.55-13.)

Blower motor check (Refer to P.55-21.)NG
Repair
OK
Measure at the blower motor relay connector B-72.

Disconnect the connector, and measure at the harness
side connector.
(1) Continuity between terminal (1) and body earth
OK:Continuity
(2) Voltage between terminal (3) and body earth (Ignition
switch: ON)
OK:System voltage
(3) Voltage between terminal (5) and body earth
OK:System voltage(1) NGCheck the harness between the blower motor relay and the body
earth, and repair if necessary.
(2) NG
Check the harness between the blower motor relay and the ignition
switch, and repair if necessary.
(3) NG
Check the harness between the blower motor relay and the fusible
link No.1, and repair if necessary.
OK
Measure at the blower motor connector B-33.

Disconnect the connector, and measure at the harness
side connector.

Voltage between terminal (1) and body earth (Ignition
switch: ON)
OK:System voltageNGCheck the following connector:
B-76
NG
Repair OK
Check the trouble symptom.
NG
Check the harness between the blower motor relay and the blower
motor, and repair if necessary.
OK
Check the following connector:
B-33NG
Repair
OK
Check the trouble symptom.NGCheck the harness between the blower motor and earth, and
repair if necessary.

FULL-AUTOMATIC AIR CONDITIONER – Troubleshooting55-46
Inspection procedure 8
Blower does not operate in HI mode.
Probable cause
If the blower does not operate in HI mode when the temperature is set to 17 or
32, the cause is probably a malfunction of the blower motor HI relay circuit system.
Malfunction of blower motor HI relay

Malfunction of blower motor

Malfunction of connector or harness

Malfunction of A/C-ECU
NG
Repair OK
Check the trouble symptom.
NG
Check the harness between the blower motor HI relay and the
A/C-ECU, and repair if necessary.
NG
Repair
OK
Check the trouble symptom.
NG
Check the harness between the blower motor HI relay and the
blower motor, and repair if necessary.
OK
Measure at the blower motor HI relay connector B-34.

Disconnect the connector, and measure at the harness
side connector.
(1) Connect terminal (1) to earth.
OK:Blower operates.
(2) Continuity between terminal (3) and body earth
OK:Continuity
(3) Voltage between terminal (4) and body earth (Ignition
switch: ON)
OK:System voltage(1) NGCheck the following connector:
B-34

Blower motor HI relay check (Refer to P.55-57.)

Blower motor check (Refer to P.55-21.)NG
Repair
NG
Repair
OK
Check the trouble symptom.
NG
Check the harness between the blower motor HI relay and the
body earth, and repair if necessary.
(2) NG
Check the following connector:
B-34
NG
Repair
OK
Check the trouble symptom.
NG
Check the harness between the blower motor HI relay and the
junction block, and repair if necessary.
(3) NG
Check the following connector:
B-34
NG
Repair OK
Check the trouble symptom.
YES
Check the following connector:
B-04
OK
Separate A/C-ECU connector B-04 and connect the terminal (12)
of the harness side connector to the earth. Does the blower
operate?NOCheck the following connector:
B-34
NG
Replace the A/C-ECU.

FULL-AUTOMATIC AIR CONDITIONER – Troubleshooting55-47
Inspection procedure 9
Blower air amount cannot be changed.
Probable cause
If the blower does not operate in any mode other than HI setting, the cause is
probably a malfunction of the power transistor system.
Malfunction of power transistor

Malfunction of connector or harness

Malfunction of A/C-ECU
Measure at the power transistor connector B-37.

Blower switch position: LO

Connect the connector.
(1) Continuity between terminal (1) and body earth
OK:Continuity
(2) Voltage between terminal (2) and body earth (Ignition
switch: ON)
OK:System voltage – 2 V
(3) Voltage between terminal (4) and body earth (Ignition
switch: ON)
OK:Approx. 1.3 VOKCheck the following connector:
B-37
NG
Repair OK
Check the trouble symptom.
(1) NG
Check the harness between the power transistor and the body
earth, and repair if necessary.
(2) NG
Check the harness between the power transistor and the blower
motor, and repair if necessary.
(3) NG
Measure at the A/C-ECU connector B-04.

Blower switch position: LO

Connect the connector.
(1) Voltage between terminal (1) and body earth (Ignition
switch: ON)
OK:Approx. 7 V
(2) Voltage between terminal (2) and body earth (Ignition
switch: ON)
OK:Approx. 1.3 VNGCheck the following connector:
B-04
NG
Repair OK
Check the trouble symptom.
OK
Check the harness between the power transistor and the A/C-ECU.NG
Repair
OK
Replace the power transistor.
NG
Replace the power transistor.
NG
Replace the A/C-ECU.
Inspection procedure 10
Air outlet port cannot be changed.
Probable cause
The cause is probably a malfunction of the air outlet port changeover signal
input system or output system. The MUT-II can be used to check the
diagnosis codes in order to check the cause of the problem for each separate
system.
Malfunction of air outlet changeover damper
potentiometer

Malfunction of air outlet changeover damper
motor

Malfunction of air outlet changeover damper

Malfunction of connector or harness

Malfunction of A/C-ECU
Can an operating sound be heard when the air outlet port
changeover switch is operated?NOInspection procedure 15 (Refer to P.55-52.)
YES
MUT-II Self-Diag code
Is either code 32 or code 42 output?YESINSPECTION CHART FOR DIAGNOSIS CODES (Refer to
P.55-34.)
NO
Air outlet changeover damper checkNG
Repair
OK
Replace the A/C-ECU.