Mitsubishi Grandis. Manual - part 304

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-101

wiring harness side.

(2) Continuity between terminal 1 and body earth

OK: 2

Ω or less

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Go to Step 6.

Step 6. Check the wiring harness between C-103 
PTC heater connector terminal No.1 and body 
earth.

• 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 

P.00-5

.)

NO : 

Repair the wiring harness.

Step 7. Measure the resistance at the C-103 PTC 
heater connector.

(1) Disconnect the connector, and measure at the 

wiring harness side.

(2) Continuity between terminal 3 and body earth

OK: 2

Ω or less

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Go to Step 8.

Step 8. Check the wiring harness between C-103 
PTC heater connector terminal No.3 and body 
earth.

• 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 

P.00-5

).

NO : 

Repair the wiring harness.

Step 9. Connector check: C-105 A/C-ECU 
connector

Q:  Is the check result normal?

AC310506AQ

Connector C-106 
(Harness side)

AC310631AF

Connector: C-103 <RHD>

Harness side

AC310631AF

Connector: C-103 <RHD>

Harness side

AC310506AR

Connector C-106 
(Harness side)

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

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-102

YES : 

Go to Step 10.

NO : 

Repair the connector.

Step 10. Voltage measurement 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 2 and body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

 Go to Step 19.

NO : 

 Go to Step 11.

Step 11. Connector check: C-206 PTC heater 
relay 1 controller connector

Q: Is the check result normal?

YES : 

Go to Step 12.

NO : 

Repair the connector.

Step 12. Check the PTC heater switch relay 1 
continuity.

 Refer to GROUP 55 - On vehicle service, power 
relay 

P.55-196

.

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

YES : 

Go to Step 13.

NO : 

Replace the PTC heater switch relay 1.

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

AC310507AU

Connector C-103 
(Harness side)

AC310618

Connector: C-206 <RHD>

AE

3

4

5

1

2

Junction block side

Junction block (Front view)

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-103

Step 13. Voltage measurement at C-206 PTC 
heater relay 1 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 15.

NO : 

 Go to Step 14.

Step 14. Check the wiring harness between C-206 
PTC heater relay 1 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 1 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 

P.00-5

.)

NO : 

Repair the wiring harness.

Step 15. Measure the voltage at C-206 PTC heater 
relay 1 connector.

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

AC310618

Connector: C-206 <RHD>

AE

3

4

5

1

2

Junction block side

Junction block (Front view)

AC310507

3

4

5

1

2

Connector C-206 
(Junction block side)

AV

AC310619

Connectors: C-202, C-203, C-206 <RHD>

AG

3

4

5

1

2

Junction block side

Junction block (Front view)

C-203

C-202

C-206

Harness side

C-202

C-206

Harness side

C-203

10

1

6

14

5

12

13

4

11

7

2

3

8

9

AC310618

Connector: C-206 <RHD>

AE

3

4

5

1

2

Junction block side

Junction block (Front view)

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-104

side.

(2) Voltage between terminal 4 and body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

 Go to Step 17.

NO : 

 Go to Step 16.

Step 16. Check the wiring harness between C-206 
PTC heater relay 1 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 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 17. Check the wiring harness between C-206 
PTC heater relay 1 connector terminal No.1 and 
C-105 A/C-ECU connector terminal No.46.

• Check the PTC heater relay 1 earth line for open 

or short circuit.

Q: Is the check result normal?

YES : 

 Go to Step 18.

NO : 

Repair the wiring harness.

AC310507

3

4

5

1

2

Connector C-206 
(Junction block side)

AW

AC310618

Connector: C-206 <RHD>

AE

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

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-206 <RHD>

AE

3

4

5

1

2

Junction block side

Junction block (Front view)