Mitsubishi L200. Manual - part 859

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-52

STEP 14. Check the wiring harness between D-10 
rear window defogger connector terminal No.1 
and earth.

AC509961AF

Harness side

D-10 (B)

Connector: D-10 <Single cab>

AC509965AI

Harness side

Connector: D-10 <Club cab>

D-10 (B)

AC509967AQ

Harness side

D-10 (B)

Connector: D-10 <Double cab>

• Check the rear window defogger earth line for 

open or short circuit.

Q: Is the check result normal?

YES : 

The trouble can be an intermittent 

malfunction (Refer to GROUP 00, How to 
Cope with Intermittent Malfunction ).

NO : 

Repair or replace the wiring harness.

STEP 15. Check the rear window defogger.
Refer to GROUP 54A, Rear Window rear window 
defogger Inspection .

Q: Does the rear window defogger work normally? 

YES : 

The trouble can be an intermittent 

malfunction (Refer to GROUP 00, How to 
Cope with Intermittent Malfunction ).

NO : 

Repair the rear window defogger.

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-53

Inspection Procedure 7: The PTC heater does not work <Russia>

PTC Heater Circuit

Wire colour code
B : Black     LG : Light green     G : Green     L : Blue     W : White     Y : Yellow     SB : Sky blue
BR : Brown     O : Orange     GR : Grey     R : Red     P : Pink     V : Violet     PU : Purple

FUSIBLE
LINK

IGNITION
SWITCH (IG2)

PTC
HEATER
RELAY 2

PTC
HEATER
RELAY 1

PTC
HEATER 1

PTC
HEATER 2

ENGINE-
ECU

A/C
SWITCH
MODULE

3

1

4

2

3

1

4

2

ACA00403

25

COMMENTS ON TROUBLE SYMPTOM
When the PTC heater does not work under the fol-
lowing conditions, the heater switch system or the 
PTC heater circuit system may be defective.

PTC heater operating conditions

• heater switch: ON

• Air outlet: FOOT/DEF, FOOT, FACE/FOOT

• Temperature control dial: MAX HOT

• Coolant temperature: 80 degrees celsius or less

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-54

NOTE: When the coolant temperature becomes 
above 80 degrees celsius and PTC heater stops the 
operation, the PTC heater does not operate until 
coolant temperature becomes below 70 degrees cel-
sius.

PROBABLE CAUSES

• Malfunction of the heater switch system

• Damaged the wiring harness or connectors

• Malfunction of the PTC heater relay 1

• Malfunction of the PTC heater relay 2

• Malfunction of the PTC heater 1

• Malfunction of the PTC heater 2

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-105 engine-ECU 
connector

AC509613 CD

Harness side

C-105 (B)

Connector: C-105 <LHD>

35

40

41

42

1817

38

39

15

16

14

3736

12

13

11

32

8

3433

9

10

30

31

7 6

29

5

4

28

3

27

2

26

1

25

19
43

2120

22

23

46

47

4544

24
48

76

52

86

62

63

64

65

66

67

68

69

70

71

72

92

95

96

93

94

89

90

91

8887

53

54

55

56

57

58

59

60

61

83

8584

8281

78

79

80

77

49

50

51

74

75

73

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Repair the connector.

STEP 2. Connector check: C-149 PTC heater 1 
connector

AC509613AT

Harness side

Connector: C-149 <LHD>

C-149 (GR)

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Repair the connector.

STEP 3. Resistance measurement at the C-149 
PTC heater 1 connector.

AC509613AT

Harness side

Connector: C-149 <LHD>

C-149 (GR)

(1) Disconnect the connector, and measure at the 

wiring harness side.

AC310506HU

Connector C-149 
(Harness side)

(2) Continuity between terminal 1 and body earth

OK: Continuity (Less than 2

Ω)

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Go to Step 4.

STEP 4. Check the wiring harness between C-149 
PTC heater 1 connector terminal No.1 and body 
earth.

AC509613AT

Harness side

Connector: C-149 <LHD>

C-149 (GR)

• Check the PTC heater earth line for open circuit.

Q: Is the check result normal?

YES : 

The trouble can be an intermittent 

malfunction (Refer to GROUP 00, How to 
Cope with Intermittent Malfunction .)

NO : 

Repair the wiring harness.

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-55

STEP 5. Resistance measurement at the C-150 
PTC heater 2 connector.

AC509613 AU

Harness side

Connector: C-150 <LHD>

C-150 (GR)

(1) Disconnect the connector, and measure at the 

wiring harness side.

AC310506HV

Connector C-150 
(Harness side)

(2) Continuity between terminal 1 and body earth

OK: Continuity (Less than 2

Ω)

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Go to Step 6.

STEP 6. Check the wiring harness between C-150 
PTC heater 2 connector terminal No.1 and body 
earth.

AC509613 AU

Harness side

Connector: C-150 <LHD>

C-150 (GR)

• Check the PTC heater earth line for open circuit.

Q: Is the check result normal?

YES : 

The trouble can be an intermittent 

malfunction (Refer to GROUP 00, How to 
Cope with Intermittent Malfunction .)

NO : 

Repair the wiring harness.

STEP 7. Voltage measurement at C-149 PTC 
heater 1 connector.

AC509613AT

Harness side

Connector: C-149 <LHD>

C-149 (GR)

(1) Disconnect the connector, and measure at the 

wiring harness side.

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

AC509613 CD

Harness side

C-105 (B)

Connector: C-105 <LHD>

35

40

41

42

1817

38

39

15

16

14

3736

12

13

11

32

8

3433

9

10

30

31

7 6

29

5

4

28

3

27

2

26

1

25

19
43

2120

22

23

46

47

4544

24
48

76

52

86

62

63

64

65

66

67

68

69

70

71

72

92

95

96

93

94

89

90

91

8887

53

54

55

56

57

58

59

60

61

83

8584

8281

78

79

80

77

49

50

51

74

75

73

ACA00423

35

40

41

42

1817

38

39

15

16

14

3736

12

13

11

32

8

3433

9

10

30

31

7 6

29

5

4

28

3

27

2

26

1

25

19
43

2120

22

23

46

47

4544

24
48

76

52

86

62

63

64

65

66

67

68

69

70

71

72

92

95

96

93

94

89

90

91

8887

53

54

55

56

57

58

59

60

61

83

8584

8281

78

79

80

77

49

50

51

74

75

73

Connector C-105 
(Harness side)

AE

(3) Disconnect engine-ECU connector C-105 and 

earth terminal 36.

AC310507JD

Connector C-149 
(Harness side)

(4) Voltage between terminal 2 and body earth.

OK: System voltage

Q: Is the check result normal?