Mitsubishi Montero (2002-2004). Manual — part 78

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-5

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to "LOCK" (OFF) position before connect-
ing or disconnecting scan tool MB991502.
1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to "ON" position.
3. Use scan tool MB991502 to check for Full Automatic Air

Conditioning diagnostic trouble codes.

4. Turn the ignition switch to "LOCK" (OFF) position.
5. Disconnect scan tool MB991502.

Erasing Full Automatic Air Conditioning
Diagnostic Trouble Codes

Required Special Tool:

• MB991502: Scan Tool (MUT-II)

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to "LOCK" (OFF) position before connect-
ing or disconnecting scan tool MB991502.
1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to "ON" position.
3. Use scan tool MB991502 to erase Full Automatic Air

Conditioning diagnostic trouble codes.

4. Turn the ignition switch to "LOCK" (OFF) position.
5. Disconnect scan tool MB991502.

DIAGNOSTIC TROUBLE CODE CHART

M1554004900043

ACX01539

16-pin

MB991502

AI

ACX01539

16-pin

MB991502

AI

DIAGNOSTIC
TROUBLE CODE
NO.

DIAGNOSTIC ITEM

REFERENCE
PAGE

11

Inside air temperature sensor system (open circuit)

P.55B-6

12

Inside air temperature sensor system (short circuit)

P.55B-6

13

Outside air temperature sensor system (open circuit)

P.55B-8

14

Outside air temperature sensor system (short circuit)

P.55B-8

15

Heater water temperature sensor system (open circuit)

P.55B-12

16

Heater water temperature sensor system (short circuit)

P.55B-12

21

Air thermo sensor system (open circuit)

P.55B-15

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-6

SYMPTOM CHART

M1554005000054

DIAGNOSTIC TROUBLE CODE PROCEDURES

DTC 11, 12: Inside Air Temperature Sensor System

.

DTC SET CONDITION
DTC 11 or 12 is displayed when the A/C-ECU detects an error
is its own data. This fault is limited to the A/C-ECU.

.

TROUBLESHOOTING HINT

• Malfunction of the A/C-ECU.

• Malfunction of the flexible flat cable.

• Malfunction of the A/C control panel.

22

Air thermo sensor system (short circuit)

P.55B-15

31

Potentiometer system of air mixing damper control motor assembly

P.55B-18

32

Potentiometer system of air outlet changeover damper control
motor assembly

P.55B-21

DIAGNOSTIC
TROUBLE CODE
NO.

DIAGNOSTIC ITEM

REFERENCE
PAGE

SYMPTOM

INSPECTION
PROCEDURE NO.

REFERENCE
PAGE

Communication with the scan tool is not possible.

1

P.55B-24

Air conditioning does not operate.

2

P.55B-29

A/C outlet air temperature cannot be set.

3

P.55B-51

Blower does not operate.

4

P.55B-60

Blower air amount cannot be changed.

5

P.55B-76

Air outlets cannot be changed.

6

P.55B-80

Inside/outside air changeover is not possible.

7

P.55B-85

Rear defogger does not operate.

8

P.55B-92

Condenser fan does not operate.

9

P.55B-105

Malfunction of the A/C-ECU power supply system.

10

P.55B-118

The A/C indicator flashes.

11

P.55B-126

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-7

STEP 1. Using scan tool MB991502, check data list item 11:
Inside air temperature sensor.
Item 11: Inside air temperature sensor
OK: The inside air temperature and indicated temperature on
scan tool MB991502 are almost equal.
Q: Are the inside air temperature and temperature

displayed on scan tool MB991502 almost equal?
YES : It can be assumed that this malfunction is

intermittent. (Refer to GROUP 00 - How to Cope with
Intermittent Malfunction

P.00-6

.)

NO : Go to Step 2.

STEP 2. Check the flexible flat cable (FFC) connection.
(1) The FFC is connected to the A/C control panel assembly.

Check that the FFC connection is not contaminated with
foreign material or loose (Refer to

P.55B-136

).

(2) There should be continuity between the FFC terminals.
Q: Is the FFC normal?

YES : Replace the automatic air conditioning control panel.

Then go to Step 3.

NO : Replace the FFC. Then go to Step 3.

STEP 3. Recheck for diagnostic trouble code.
Q: Is DTC 11 or 12 set?

YES : Replace the A/C-ECU.
NO : The procedure is complete.

AC205264AB

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-8

DTC 13, 14: Outside Air Temperature Sensor System

.

DTC SET CONDITION
DTC 13 is set if there is a defective connector connection, or if
there is an open circuit in the harness.
DTC 14 is set if there is a short circuit in the outside air temper-
ature sensor input circuit.

.

TROUBLESHOOTING HINT

• Malfunction of the harness.

• Malfunction of the outside air temperature sensor.

• Malfunction of connector

• Malfunction of the A/C-ECU.

Outside Air Temperature Sensor Circuit

AC205341

AC001534 AB

CONNECTOR: A-29

AC001536 AB

CONNECTORS: D-24, D-28

D-24

D-28