Mitsubishi Montero (2002-2004). Manual - part 100

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-93

.

CIRCUIT OPERATION
If the defogger does not operate when the defogger 
switch is turned on, the defogger relay system may 
be defective.

.

TROUBLESHOOTING HINTS

• Malfunction of the A/C-ECU

• Malfunction of the flexible flat cable

• Malfunction of the automatic air-conditioning con-

trol panel

• Malfunction of the defogger relay

• Malfunction of the defogger

• Damaged harness wires or connectors

DIAGNOSIS

Required Special Tools:

• MB991223: Test Harness Set

• MB991502: Scan Tool

STEP 1. Check the A/C and outside / inside air selection 
damper control motor operation.
Q: Do the A/C and outside / inside air selection damper 

control motor work normally?
YES : Go to Step 2.
NO :  Refer to Inspection procedure 10 "Malfunction of the 

A/C-ECU power supply system 

P.55B-118

."

AC204173

CONNECTORS : D-208, D-209, D-211, 
D-216, D-217

BM

D-208

D-216

D-217

D-209

D-211(B)

AC204179

CONNECTOR : G-10

AJ

AC204182 AL

E-01(B)

E-03(B)

CONNECTORS : I-01, I-03

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-94

STEP 2. Measure the voltage at defogger connector I-03. 
(1) Disconnect defogger connector I-03, and measure the 

voltage at the junction block side.

(2) Turn the defogger switch to the "ON" position.

(3) Measure the voltage between terminal 1 and ground.

• The measured value should be approximately 12 volts 

(battery positive voltage).

Q: Does the measured voltage correspond with this range?

YES :  Go to Step 18.
NO :   Go to Step 3.

STEP 3. Check the defogger relay continuity.
Follow the table below to check the defogger relay for continu-
ity.

Q: Is the Defogger relay continuity in good condition?

YES : Go to Step 4.
NO :  Replace the defogger relay. The defogger system 

should work normally.

AC204182

CONNECTOR : I-03

AK

I-03(B)

1

HARNESS 
SIDE

I-03(B)

AC204738 ES

JUNCTION BLOCK SIDE : I-03

1

BATTERY VOLTAGE

TESTER 
CONNECTION 

SPECIFIED 
CONDITION

Not applied

2 

− 5

Open circuit

• Connect terminal 1 to 

the positive battery 
terminal

• Connect terminal 3 to 

the negative battery 
terminal

2 

− 5

Less than 2 
ohms

ACX01474

1

2

3

4
5

1

2

3

5

ACX01962

DEFOGGER
RELAY

AB

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-95

STEP 4. Measure the voltage at defogger relay connector 
D-216. 
(1) Disconnect defogger relay connector D-216, and measure 

the voltage at the junction block side.

(2) Measure the voltage between terminal 2 and ground.

• The measured value should be approximately 12 volts 

(battery positive voltage).

Q: Does the measured voltage correspond with this range?

YES :  Go to Step 7.
NO :   Go to Step 5.

STEP 5. Check defogger relay connector D-216 for 
damage.
Q: Is defogger relay connector D-216 in good condition?

YES : Go to Step 6.
NO :  Repair or replace the connector. Refer to GROUP 

00E, Harness Connector Inspection 

P.00E-2

. The 

defogger system should work normally.

AC204173

CONNECTOR : D-216

BD

JUNCTION BLOCK 
SIDE

1

2

5

4

3

AC204738

AC204738 DE

RELAY SIDE : D-216

1

2

5

4

3

AC204173

CONNECTOR : D-216

BD

JUNCTION BLOCK 
SIDE

1

2

5

4

3

AUTO A/C DIAGNOSIS

TSB Revision

AUTOMATIC AIR CONDITIONING

55B-96

STEP 6. Check the wiring harness between defogger relay 
connector D-216 (terminal 2) and the fusible link (2).

NOTE: Also check junction block connector D-211 and interme-
diate connector D-28. If junction block connector D-211 and 
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 defogger relay connector 

D-216 (terminal 2) and the fusible link (2) in good 
condition?
YES : Check that the defogger system works normally.
NO :  Repair the wiring harness. Check that the defogger 

system works normally.

AC204191

JUNCTION BLOCK
(FRONT VIEW)

CONNECTORS : D-211, D-216

D-211(B)

HARNESS SIDE

D-216

RELAY SIDE

AY

D-211(B)

D-216

1

2

5

4

3

1

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