2000 MITSUBISHI MONTERO Service Repair Manual

HEATER, AIR CONDITIONER AND VENTILATION -Troubleshooting 55B-6
Code No.31 Potentiometer system for the air mix
damperProbable cause
This diagnosis code is set when the potentiometer for the air mix damper does
not send any signal to the A/C-ECU due to short oropencircuit.DMalfunction of the potentiometer system for the air
mix damper
DMalfunction of connector or harness
DMalfunction of the A/C-ECU
NG
Repair
NG
Repair
NG
Check the harness wire between the air mix damper motor
and the A/C-ECU, and repair if necessary.
OK
Replace the automatic A/C control panelassembly (A/C-ECU).
NG
Repair
OK
Replace the automatic
A/C control panel
assembly (A/C-ECU).
OK
Check the trouble
symptoms.
OK
Measure at A/C-ECU connector D-132.
DConnect the connector.
DIgnition switch: ON
DAir mix damper: MAX HOT position
DVoltage between terminal 24 and body earth
OK:0.7 - 1.3 VNGCheck the following connectors:D-130, D-132
NG
Check the harness wire between the air mix damper motor
and the A/C-ECU.
OK
Check the trouble
symptoms.
OK
Measure at air mix damper motor connector D-130.
DDisconnect the connector and measure at the harness
side.
DIgnition switch: ON
DVoltage between terminal 7 and body earth
OK:5V
DContinuity between terminal 5 and body earth
OK:ContinuityNGCheck the following connectors:D-130, D-132
Check the potentiometer system for the air mix damper
(Refer to P.55B-27).NG
Replace


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HEATER, AIR CONDITIONER AND VENTILATION -Troubleshooting 55B-7
Code No.32 Potentiometer system for the air outlet
changeover damperProbable cause
This diagnosis code is set when the potentiometer for the air outlet changeover
damper does not send any signal to the A/C-ECU due toopen orshort circuit.DMalfunction of the potentiometer for the air outlet
changeover damper
DMalfunction of connector or harness
DMalfunction of the A/C-ECU
NG
Repair
NG
Repair
NG
Check the harness wire between the air outlet changeover
damper motor and the A/C-ECU, and repair if necessary.OK
Replace the automatic A/C control panelassembly (A/C-ECU).
NG
Repair
OK
Replace the automatic
A/C control panel
assembly (A/C-ECU).
OK
Check the trouble
symptoms.
OK
Measure at A/C-ECU connector D-132.
DConnect the connector.
DIgnition switch: ON
DAir outlet changeover damper: DEF position
DVoltage between terminal 32 and body earth
OK:0.7 - 1.3 VNGCheck the following connectors:D-24, D-132
NG
Check the harness wire between the air outlet changeover
damper motor and the A/C-ECU.
OK
Check the trouble
symptoms.
OK
Measure at air outlet changeover damper motor connector
D-24.
DDisconnect the connector and measure at the harness
side.
DIgnition switch: ON
DVoltage between terminal 7 and body earth
OK:5V
DContinuity between terminal 5 and body earth
OK:ContinuityNGCheck the following connectors:D-24, D-132
Check the potentiometer for the air outlet changeover damper
(Refer to P.55B-27).NG
Replace
INSPECTION CHART FOR TROUBLE SYMPTOMS
Trouble symptomInspection pro-
cedure No.Reference
page
Communication with MUT-IIis impossible.155B-8
The air conditioner does not operate at all.255B-9
The air conditioner display does not appear on the center display screen.355B-9
A/C outlet air temperature can not be set.455B-10
The blower does not operate.555B-11
The blower air volume can not be changed.655B-12
Air outlet vent cannot be changed.755B-12
Inside/outside air changeover is not possible.855B-13
The rear defogger does not operate.955B-14
The condenser fan does not operate .1055B-15
The condenser fan does not operate <4D56>.1155B-16


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HEATER, AIR CONDITIONER AND VENTILATION -Troubleshooting 55B-8
INSPECTION PROCEDURES 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 ahigh possibility
that there is a malfunction of the diagnosis line. If only the A/C system can not
communicate with the MUT-
II, the diagnosis line between the diagnosis
connector and the A/C-ECU may be defective.DMalfunction of harness or connector
DMalfunction of the A/C-ECU
OK
Replace the automatic A/C control panelassembly (A/C-ECU).
NOCheck the diagnosis line between the diagnosis connector and
the A/C-ECU, and repair if necessary.
YES
NO
INSPECTION PROCEDURE FOR TROUBLE SYMPTOM 2
(Refer to P.55B-3.)
YES
NG
Repair
OK
NG
Check the harness wire between the A/C-ECU and diagnosis
connector.NG
Repair
Check the trouble symptoms.
Check the following connectors:D-131, D-132, D-222, D-23
Is the air conditioner operating?
Is communication between MUT-
IIand other system is
possible?


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HEATER, AIR CONDITIONER AND VENTILATION -Troubleshooting 55B-9
Inspection procedure 2
The air conditioner does not operate at all.
Probable cause
The power supply system (including earth) for the A/C-ECU may be defective. In
addition, the A/C-ECU may be inoperative due to a defective harness (such as
short).DMalfunction of harness or connector
DMalfunction of the A/C-ECU
NG
Repair
NG
Check the harness wire between the A/C-ECU and the ignition
switch (IG2), and repair if necessary.
NG
Repair
NG
Check the harness wire between the A/C-ECU and the ignition
switch (ACC), and repair if necessary.
NG
Repair
NG
Check the harness wire between the A/C-ECU and fusible link
(2), and repair if necessary.
NG
Repair
NG
Check the harness wire between the A/C-ECU and body
earth, and repair if necessary.
OK
Replace the automatic
A/C control panel
assembly (A/C-ECU).
NG
Repair
Check circuit, where the A/C-ECU terminal voltage is
abnormal.
OK
Check at the A/C-ECU terminals (Refer to P.55B-18).
OK
Check the trouble symptoms.
Check the following connectors:D-132, D-30
(4) NG
OK
Check the trouble
symptoms.
Check the following connectors:
D-131, D-31, D-223, D-27
D-131, D-33, D-27
(3) NGOK
Check the trouble
symptoms.
Check the following connectors:D-132, D-33, D-210, D-208(2) NG
OK
Check the trouble
symptoms.
Measure at A/C-ECU connector D-132.
DDisconnect the connector and measure at the harness
side.
DIgnition switch: ON
(1) Voltage between terminal 26 and body earth
OK:System voltage
(2) Voltage between terminal 27 and body earth
OK:System voltage
(3) Voltage between terminal 28 and body earth
OK:System voltage
(4) Continuity between terminal 36 and body earth
OK:Continuity(1) NGCheck the following connectors:D-132, D-32, D-210, D-208
Inspection procedure 3
The air conditioner display does not appear on the
center display screen.
Probable cause
Check the harness wires between the A/C-ECU and the center display, and
repair if necessary.DMalfunction of harness or connector
DMalfunction of the A/C-ECU
OK
Replace the automatic A/C control panelassembly (A/C-ECU).
NG
Check the harness wires between the A/C-ECU and the
center display.NG
Repair
OK
Check the trouble symptoms.
Check the following connectors:D-131, D-06NG
Repair


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HEATER, AIR CONDITIONER AND VENTILATION -Troubleshooting 55B-10
Inspection procedure 4
A/C outlet air temperature can not be set.
Probable cause
If the air outlet temperature can not be changed after a A/C temperature is set,
sensor(s) or the air mix damper may be defective.DMalfunction of the inside air temperature sensor
DMalfunction of the outside air temperature sensor
DMalfunction of the heater water temperature sensor
DMalfunction of the photo sensor
DMalfunction of the electric motor for the air mix
damper
DMalfunction of harness or connector
DMalfunction of the A/C-ECU
NG
Repair
NG
Repair
OK
Replace the automatic A/C control panelassembly (A/C-ECU).
OK
MUT-
IIData list
31 Potentiometer for air mix damperNGCheck the air mix damper potentiometer system
(Refer to P.55B-6, Code No.31).
NG
Check the harness wire between the photo sensor and the
A/C-ECU.
OK
Check the trouble
symptoms.
OK
Check the following connectors:D-132, D-106
OK
MUT-
IIData list
25 Photo sensorNGCheck the photo sensor (Automatic air conditioner).
(Refer to P.55B-30.)
OK
MUT-
IIData list
15 Heater water temperature sensorNGCheck the heater water temperature sensor system.
(Refer to P.55B-5, Code Nos.15, 16.)
OK
MUT-
IIData list
13 Outside air temperature sensorNGCheck the outside air temperature sensor system.
(Refer to P.55B-4, Code Nos.13, 14.)
NO
MUT-
IIData list
11 Inside air temperature sensorNGReplace the automatic A/C control panelassembly (A/C-ECU).
MUT-
IISelf-Diag Code
Are diagnosis codes displayed?YESInspection chart for diagnosis codes (Refer to P.55B-4.)
NG
Repair OKReplace the automatic A/C control panel
assembly (A/C-ECU).
NG
Check the harness wire between the air mix damper motor
and the A/C-ECU.NG
Repair
OK
Check the trouble symptoms.
OK
Check the following connectors:D-130, D-131NG
Repair
Check the air mix damper motor (Refer to P.55B-27).NG
Replace OK


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HEATER, AIR CONDITIONER AND VENTILATION -Troubleshooting 55B-11
Inspection procedure 5
The 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 front blower relay circuit.DMalfunction of the front blower relay
DMalfunction of the blower linear controller
DMalfunction of the blower motor
DMalfunction of harness or connector
DMalfunction of the A/C-ECU
NG
Repair
NG
Repair
NG
Repair
NG
Check the harness wire between the front blower relay and
the ignition switch (IG2), and repair if necessary.
NG
Check the harness wire between the front blower relay and
the battery, and repair if necessary.
NG
Repair
NG
Check the harness wire between the blower linear controller
and body earth, and repair if necessary.
OK
Replace the automatic A/C control panelassembly (A/C-ECU).
NG
Check the harness wires between the front blower relay and
the blower linear controller, between the front blower relay and
the blower motor, between the blower motor and the blower
linear controller and between the front blower relay and the
A/C-ECU.NG
Repair
OK
Check the trouble symptoms.
OK
Check the following connectors:D-220, D-208, D-126, D-17,
D-131,D-209
OK
Check the trouble symptoms.
OK
Measure at blower linear controller connector D-126.
DDisconnect the connector and measure at the harness
side.
DContinuity between terminal 4 and body earth
OK:ContinuityNGCheck the following connector:D-126
OK
Check the trouble symptoms.
Check the following connectors:D-220, D-208
(2) NG
OK
Check the trouble symptoms.
NG
Measure at front blower relay connector D-220.
DDisconnect the connector, and measure at the J/B side.
DIgnition switch: ON
(1) Voltage between terminal 2 and body earth
OK:System voltage
(2) Voltage between terminal 3 and body earth
OK:System voltage(1) NGCheck the following connectors:D-220, D-211, D-27
OK
Check the blower linear controller (Refer to P.55B-26).NG
Replace
OK
Check the blower motor (Refer to GROUP 55A - Front A/C).NG
Replace
OK
Check the front blower relay
(Refer to GROUP 55A - On-vehicle Service).NG
Replace
MUT-
IIActuator Test
01, 02, 03, 04 Blower motorOKReplace the automatic A/C control panelassembly (A/C-ECU).


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HEATER, AIR CONDITIONER AND VENTILATION -Troubleshooting 55B-12
Inspection procedure 6
The blower air volume can not be changed.
Probable cause
If the air volume can not be controlled, the blower linear controller circuit may be
defective.DMalfunction of the blower linear controller
DMalfunction of harness or connector
DMalfunction of the A/C-ECU
NG
Replace the automatic A/C control panelassembly (A/C-ECU).
OK
Replace the blower linear controller.Check the trouble symptoms.
MUT-
IIActuator Test
01, 02, 03, 04 Blower motorOKReplace the automatic A/C control panelassembly (A/C-ECU).
NG
Check the following connectors:D-126, D-131NG
Repair
OK
Check the trouble symptoms.
NG
Check the harness wire between the blower linear controller
and the A/C-ECU.NG
Repair
Inspection procedure 7
Air outlet vent cannot be changed.
Probable cause
When the air outlet vents cannot be changed even if the changeover switch is
operated, the air outlet changeover damper motor circuit may be defective.DMalfunction of the electric motor for the air outlet
changeover damper
DMalfunction of harness or connector
DMalfunction of the A/C-ECU
OK
Replace the automatic A/C control panelassembly (A/C-ECU).
OK
MUT-
IIActuator Test
08, 09, 10 Air outlet changeover damper motorNGCheck the air outlet changeover damper motor system
(Refer to P.55B-27).
MUT-
IIData list
32 Potentiometer for air outlet changeover damperNGCheck the air outlet changeover damper potentiometer system
(Refer to P.55B-7, Code No.32).
OK
NG
Check the harness wire between the air outlet changeover
damper motor and the A/C-ECU.NG
Repair
OK
Check the trouble symptoms.
OK
Check the following connectors:D-24, D-131NG
Repair
Check the air outlet changeover damper motor
(Refer to P.55B-27).NG
Replace


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HEATER, AIR CONDITIONER AND VENTILATION -Troubleshooting 55B-13
Inspection procedure 8
Inside/outside air changeover is not possible.
Probable cause
When inside air cannot be changed to outside air or vice versa even if its
changeover switch is on, the inside/outside air changeover damper motor system
may be defective.DMalfunction of the inside/outside air changeover
damper motor
DMalfunction of harness or connector
DMalfunction of the A/C-ECU
NG
Repair
NG
Check the harness wire between the ignition switch (IG2) and
the inside/outside air changeover damper motor, and repair if
necessary.
NG
Repair
OK
Replace the automatic A/C control panelassembly (A/C-ECU).
NG
Check the harness wire between the inside/outside air
changeover damper motor and the A/C-ECU.NG
Repair
OK
Check the trouble
symptoms.
OK
Check the following connectors:D-09, D-131
OK
Check the trouble
symptoms.
OK
Measure at inside/outside air changeover damper motor
connector D-09.
DDisconnect the connector and measure at the harness
side.
DIgnition switch: ON
DVoltage between terminal 1 and body earth
OK:System voltageNGCheck the following connectors:D-09, D-32, D-210, D-208
NG
Check the inside/outside air changeover damper motor
(Refer to GROUP 55A - Front A/C).NG
Replace
MUT-
IIActuator Test
13, 14 Inside/outside air changeover damper motorOKReplace the automatic A/C control panelassembly (A/C-ECU).


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