Mitsubishi L200. Manual - part 888

TROUBLESHOOTING

AUTOMATIC AIR CONDITIONER

55B-81

STEP 26. Check the wiring harness between C-43 
A/C-ECU connector terminal No.15 and C-105 
engine-ECU connector terminal No.35.

AC509611AR

Connector: C-43 <LHD>

Harness side

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

NOTE: 

AC509613AV

Connector: C-52 <LHD>

Prior to the wiring harness inspection, check interme-
diate connector C-52, and repair if necessary.

• Check the A/C-ECU input line for open and short 

circuit.

Q: Is the check result normal?

YES : 

Go to Step 27.

NO : 

Repair the wiring harness.

STEP 27. Replace the A/C-ECU, and then recheck 
the trouble symptom
 Check that the PTC heater works normally.

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Replace the engine-ECU.

TROUBLESHOOTING

AUTOMATIC AIR CONDITIONER

55B-82

Inspection Procedure 9: A/C-ECU power supply system

A/C-ECU Power Supply Circuit

IGNITION
SWITCH (IG2)

IGNITION
SWITCH (ACC)

A/C-ECU

POWER SOURCE

BATTERY
BACK-UP

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

20

AC805777

COMMENTS ON TROUBLE SYMPTOM
If a power supply is not provided to the A/C-ECU, the 
A/C-ECU power supply system or the earth system 
may be defective.

PROBABLE CAUSES

• Malfunction of the A/C-ECU

• Damaged harness wires and connectors

TROUBLESHOOTING

AUTOMATIC AIR CONDITIONER

55B-83

DIAGNOSIS PROCEDURE

STEP 1. Connector check: C-43 A/C-ECU 
connector

AC509611AR

Connector: C-43 <LHD>

Harness side

AC509932AS

Harness side

Connector: C-43 <RHD>

Q:  Is the check result normal?

YES : 

Go to Step 2.

NO : 

Repair the connector.

STEP 2. Voltage measurement at C-43 A/C-ECU 
connector.

AC509611AR

Connector: C-43 <LHD>

Harness side

AC509932AS

Harness side

Connector: C-43 <RHD>

(1) Disconnect the connector, and measure at the 

wiring harness side.

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

AC310507

Connector C-43 
(Harness side)

JT

(3) Measure the voltage between terminal 10 and 

body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Go to Step 3.

TROUBLESHOOTING

AUTOMATIC AIR CONDITIONER

55B-84

STEP 3. Check the wiring harness between C-43 
A/C-ECU connector terminal No.10 and the 
ignition switch (IG2).

AC509611AR

Connector: C-43 <LHD>

Harness side

AC509932AS

Harness side

Connector: C-43 <RHD>

NOTE: 

AC509934 AS

Connectors: C-207, C-209 <LHD>

Harness side

C-209

C-207

Harness side

C-209

C-207

Junction block (Front view)

AC509936 AN

Connectors: C-207, C-209 <RHD>

Harness side

C-209

C-207

Harness side

C-209

C-207

Junction block (Front view)

Prior to the wiring harness inspection, check junction 
block connector C-207 and C-209, and repair if nec-
essary.

• Check the A/C-ECU 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 4. Voltage measurement at C-43 A/C-ECU 
connector.

AC509611AR

Connector: C-43 <LHD>

Harness side

AC509932AS

Harness side

Connector: C-43 <RHD>

(1) Disconnect the connector, and measure at the 

wiring harness side.

AC310507

Connector C-43 
(Harness side)

JV

(2) Measure the voltage between terminal 8 and 

body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Go to Step 5.