Mitsubishi Montero (2004+). Manual - part 631

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-13

NOTE: Also check intermediate connector D-28. If intermediate 
connector D-28 is damaged, repair or replace the connector as 
described in GROUP 00E, Harness Connector Inspection 

P.00E-2

.

Q: Is the wiring harness between ambient air temperature 

sensor connector A-29 (terminals 1 and 2) and A/C-ECU 
D-24 (terminals 22 and 29) in good condition?
YES : Replace the A/C-ECU (Refer to 

P.55B-142

). Then go 

to Step 5.

NO :  Repair the wiring harness. Then go to Step 5.

STEP 5. Recheck for diagnostic trouble code.
Q: Is DTC 13 or 14 set?

YES :  Return to Step 1.
NO :  The procedure is complete.

DTC 15, 16: Heater Water Temperature Sensor System

AC204170

CONNECTOR : D-28

AI

2 3

27

32

28

33

16

15

4 5

19

18

29

17

34

7 8

35

22

21

9 10

30

36

31

37

25

24

23

6

20

1

14

26

11

13

12

38

Heater Water Temperature Sensor Circuit

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-14

.

DTC SET CONDITION

• DTC 15 is set if there is a defective connector 

connection, or if there is an open circuit in the 
harness.

• DTC 16 is set if there is a short circuit in the 

heater water temperature sensor input circuit.

.

TROUBLESHOOTING HINT

• Malfunction of connector.

• Malfunction of the harness.

• Malfunction of the heater water temperature sen-

sor.

• Malfunction of the A/C-ECU.

DIAGNOSIS

Required Special Tools:

• MB991223: Harness Set

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827: MUT-III USB Cable

• MB991911: MUT-III Main Harness B (Vehicles without 

CAN communication system)

STEP 1. Using scan tool MB991958, check data list item 15: 
Heater water temperature sensor.

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
Check the data list.
Item 15: Heater water temperature sensor
Q: Are the heater core wall temperature and indicated 

temperature on scan tool MB991958 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.

AC001535AD

CONNECTORS: D-19, D-24

D-19

D-24

AC307591 AB

MB991911

DATA LINK

CONNECTOR

MB991824

MB991827

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-15

STEP 2. Check the heater water temperature sensor.
 When the resistance between the heater water temperature 
sensor terminals is measured at two or more temperature con-
ditions, the measured resistance should satisfy the value 
shown in the illustration.
NOTE: The temperature conditions at the check shall be within 
the range shown in the characteristic diagram.
Q: Is the check result normal?

YES : Go to Step 3.
NO :  Replace the heater water temperature sensor. Then 

go to Step 5.

STEP 3. Check heater water temperature sensor connector 
D-19 and A/C-ECU connector D-24 for damage.
Q: Is heater water temperature sensor connector D-19 and 

A/C-ECU connector D-24 in good condition?
YES : Go to Step 4.
NO :  Repair or replace the connector. Refer to GROUP 

00E, Harness Connector Inspection 

P.00E-2

. Then go 

to Step 5.

AC204170

CONNECTOR : D-19

CL

2 1

HARNESS 
SIDE

ACX00826AB

RESISTANCE
   (k

Ω)

TEMPERATURE ˚C(˚F)

20

25

30

15

10

5

0

0

20

40

60

80

100

-10

(32)

(68)

(104)

(140) (176) (212)

(14)

AC204188

CONNECTORS : D-19, D-24

D-24(B)

D-24(B)

BX

D-19

D-19

HARNESS SIDE

HARNESS SIDE

2 1

22

23

30

31

25

26

33

34

32

24

28

3635

27

29

21

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-16

STEP 4. Check the wiring harness between heater water 
temperature sensor connector D-19 (terminals 1 and 2) and 
A/C-ECU D-24 (terminals 23 and 29).

Q: Is the wiring harness between heater water temperature 

sensor connector D-19 (terminals 1 and 2) and A/C-ECU 
D-24 (terminals 23 and 29) in good condition?
YES : Replace the A/C-ECU (Refer to 

P.55B-142

). Then go 

to Step 5.

NO :  Repair the wiring harness. Then go to Step 5.

STEP 5. Recheck for diagnostic trouble code.
Q: Is DTC 15 or 16 set?

YES :  Return to Step 1.
NO :  The procedure is complete.

AC204188

CONNECTORS : D-19, D-24

D-24(B)

D-24(B)

BX

D-19

D-19

HARNESS SIDE

HARNESS SIDE

2 1

22

23

30

31

25

26

33

34

32

24

28

3635

27

29

21