Mitsubishi L200. Manual - part 860

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-56

YES : 

Go to Step 16.

NO : 

Go to Step 8.

STEP 8. Connector check: A-140X PTC heater 
relay 1 controller connector

AC509815

A-140X

Connector: A-140X

AB

Relay box side

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Repair the connector.

STEP 9. Check the heater switch relay 1 
continuity.
 Refer to 

P.55A-66

.

Q: Is the heater switch relay 1 in good condition?

YES : 

Go to Step 10.

NO : 

Replace the heater switch relay 1.

STEP 10. Voltage measurement at A-140X PTC 
heater relay 1 connector.

AC509815

A-140X

Connector: A-140X

AB

Relay box side

(1) Remove the relay, and measure at the relay box 

side.

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

AC310507

Connector C-140X
(Junction block side)

JX

(3) Voltage between terminal 3 and body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 12.

NO : 

Go to Step 11.

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-57

STEP 11. Check the wiring harness between A-
140X PTC heater relay 1 connector terminal No.3 
and the ignition switch (IG2).

AC509815

A-140X

Connector: A-140X

AB

Relay box side

NOTE: 

AC509975AH

Connector: A-28

A-28 (B)

AC509613AW

Connector: C-148 <LHD>

AC509934 AX

Connectors: C-207, C-210 <LHD>

Harness side

C-207

C-210

Junction block (Front view)

Harness side

C-207

C-210

Prior to the wiring harness inspection, check interme-
diate connectors C-148, A-28, junction block connec-
tors C-207 and C-210, and repair if necessary.

• Check the PTC heater relay 1 earth supply 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 12. Voltage measurement at C-140X PTC 
heater relay 1 connector.

AC509815

A-140X

Connector: A-140X

AB

Relay box side

(1) Remove the relay, and measure at the relay block 

side.

AC310507

Connector C-140X
(Junction block side)

JY

(2) Voltage between terminal 2 and body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 14.

NO : 

Go to Step 13.

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-58

STEP 13. Check the wiring harness between A-
140X PTC heater relay 1 connector terminal No.2 
and the fusible link (25).

AC509815

A-140X

Connector: A-140X

AB

Relay box side

• Check the PTC heater relay 1 power supply 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 14. Check the wiring harness between A-
140X PTC heater relay 1 connector terminal No.1 
and C-105 engine-ECU connector terminal No.36.

AC509815

A-140X

Connector: A-140X

AB

Relay box side

AC509613CE

Connectors: C-105, C-148 <LHD>

C-148

C-148

C-105

Harness side

C-105 (B)

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

NOTE: Prior to the wiring harness inspection, check 
intermediate connector C-148, and repair if neces-
sary.

• Check the PTC heater relay 1 earth line for open 

and short circuit.

Q: Is the check result normal?

YES : 

Go to Step 15.

NO : 

Repair the wiring harness.

STEP 15. Check the wiring harness between A-
140X PTC heater relay 1 connector terminal No.4 
and C-149 PTC heater connector terminal No.2.

AC509815

A-140X

Connector: A-140X

AB

Relay box side

AC509613AT

Harness side

Connector: C-149 <LHD>

C-149 (GR)

• Check the PTC heater relay 1 power supply 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 16. Voltage measurement at 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.

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-59

(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)

AF

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

earth terminal 38.

AC310507

Connector C-150 
(Harness side)

JE

(4) Voltage between terminal 2 and body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 25.

NO : 

Go to Step 17.

STEP 17. Connector check: A-141X PTC heater 
relay 2 controller connector

AC509815

A-141X

Connector: A-141X

AD

Relay box side

Q: Is the check result normal?

YES : 

Go to Step 18.

NO : 

Repair the connector.

STEP 18. Check the PTC heater relay 2 
continuity.
 Refer to 

P.55A-66

.

Q: Is the PTC heater relay 2 in good condition?

YES : 

Go to Step 19.

NO : 

Replace the PTC heater relay 2.

STEP 19. Voltage measurement at A-141X PTC 
heater relay 2 connector.

AC509815

A-141X

Connector: A-141X

AD

Relay box side

(1) Remove the relay, and measure at the relay block 

side.