Mitsubishi Grandis. Manual - part 305

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-105

Step 18. Check the wiring harness between C-206 
PTC heater relay 1 connector terminal No.5 and 
C-103 PTC heater connector terminal No.2.

• 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 

P.00-5

).

NO : 

Repair the wiring harness.

Step 19. Measure the voltage at C-103 PTC heater 
connector.

(1) Disconnect the connector, and measure at the 

wiring harness side.

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

(3) Disconnect A/C-ECU connector C-105 and earth 

terminal 46.

(4) Voltage between terminal 4 and body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

 Go to Step 28.

NO : 

 Go to Step 20.

AC310631AF

Connector: C-103 <RHD>

Harness side

AC310618

Connector: C-206 <RHD>

AE

3

4

5

1

2

Junction block side

Junction block (Front view)

AC310631AF

Connector: C-103 <RHD>

Harness side

AC310631AC

Connector: C-105 <RHD>

Harness side

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

AC309471

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

AC309471

Connector C-105
(Harness side)

AE

AC310507

Connector C-103 
(Harness side)

CV

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-106

Step 20. Connector check: C-207 PTC heater 
relay 2 controller connector

Q: Is the check result normal?

YES : 

Go to Step 21.

NO : 

Repair the connector.

Step 21. Check the PTC heater relay 2 continuity.

 Refer to GROUP 55 - On vehicle service, power 
relay 

P.55-196

.

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

YES : 

Go to Step 22.

NO : 

Replace the PTC heater relay 2.

Step 22. Voltage measurement at C-207 PTC 
heater relay 2 connector.

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

side.

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

(3) Voltage between terminal 3 and body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

 Go to Step 24.

NO : 

 Go to Step 23.

Step 23. Check the wiring harness between C-207 
PTC heater relay 2 connector terminal No.3 and 
the ignition switch (IG2).

NOTE: Prior to the wiring harness inspection, check 
junction block connectors C-202 and C-203, and 
repair if necessary.

• Check the PTC heater relay 2 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 

P.00-5

.)

NO : 

Repair the wiring harness.

AC310618

Connector: C-207 <RHD>

AF

3

4

5

1

2

Junction block side

Junction block (Front view)

AC310618

Connector: C-207 <RHD>

AF

3

4

5

1

2

Junction block side

Junction block (Front view)

AC310507AY

Connector C-207
(Junction block side)

3

4

5

1

2

AC310619

Connectors: C-202, C-203, C-207 <RHD>

AH

3

4

5

1

2

Junction block side

Junction block (Front view)

C-203

C-202

C-207

Harness side

C-202

C-207

Harness side

C-203

10

1

6

14

5

12

13

4

11

7

2

3

8

9

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-107

Step 24. Voltage measurement at C-207 PTC 
heater relay 2 connector.

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

side.

(2) Voltage between terminal 4 and body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

 Go to Step 26.

NO : 

 Go to Step 25.

Step 25. Check the wiring harness between C-207 
PTC heater relay 2 connector terminal No.4 and 
the fusible link (28).

NOTE: 

Prior to the wiring harness inspection, check 
intermediate connector C-124, and repair if 
necessary.

• Check the PTC heater relay 2 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 

P.00-5

).

NO : 

Repair the wiring harness.

AC310618

Connector: C-207 <RHD>

AF

3

4

5

1

2

Junction block side

Junction block (Front view)

AC310507

3

4

5

1

2

Connector C-207 
(Junction block side)

AZ

AC310618

Connector: C-207 <RHD>

AF

3

4

5

1

2

Junction block side

Junction block (Front view)

AC310628AK

Connector: C-124 <RHD>

9

21

33

35

24

12

3 4

7

8

5 6

39

28

41

30

18

4243

31

1920

32

40

29

1617

38

27

15

37

36

26

14

13

25

2

1

34

23

11

10

22

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-108

Step 26. Check the wiring harness between C-207 
PTC heater relay 2 connector terminal No.1 and 
C-105 A/C-ECU connector terminal No.46.

• Check the PTC heater relay 2 earth line for open 

or short circuit.

Q: Is the check result normal?

YES : 

 Go to Step 27.

NO : 

Repair the wiring harness.

Step 27. Check the wiring harness between C-207 
PTC heater relay 2 connector terminal No.5 and 
C-103 PTC heater connector terminal No.4.

• Check the PTC heater 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 

P.00-5

).

NO : 

Repair the wiring harness.

STEP 28. Check the trouble symptom

 Check that the PTC heater works normally.

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Replace the A/C-ECU.

AC310631AC

Connector: C-105 <RHD>

Harness side

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

AC310618

Connector: C-207 <RHD>

AF

3

4

5

1

2

Junction block side

Junction block (Front view)

AC310631AF

Connector: C-103 <RHD>

Harness side

AC310618

Connector: C-207 <RHD>

AF

3

4

5

1

2

Junction block side

Junction block (Front view)