Mitsubishi Grandis. Manual - part 289

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-41

YES : 

Go to Step 4

NO : 

Go to Step 5

Step 4. Check whether the diagnosis code is 
reset.

Recheck if the diagnosis code is set.

1. Erase the diagnosis code.
2. Ignition switch: LOCK (OFF) to ON
3. Check if the diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Replace the ETACS-ECU, and then go to 

Step 6 .

NO : 

A poor connection, open circuit or other 
intermittent malfunction in the CAN bus line 
between the ETACS-ECU and the 
A/C-ECU. (Refer to GROUP 00 

− How to 

Cope with Intermittent Malfunction 

P.00-5

.))

Step 5. Check whether the diagnosis code is 
reset.

Recheck if the diagnosis code is set.

1. Erase the diagnosis code.
2. Ignition switch: LOCK (OFF) to ON
3. Check if the diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Replace the A/C-ECU, and then go to Step 

6 . 

NO : 

A poor connection, open circuit or other 
intermittent malfunction in the CAN bus line 
between the ETACS-ECU and the 
A/C-ECU. (Refer to GROUP 00 

− How to 

Cope with Intermittent Malfunction 

P.00-5

.))

Step 6. Check whether the diagnosis code is 
reset.

Recheck if the diagnosis code is set.

1. Erase the diagnosis code.
2. Ignition switch: LOCK (OFF) to ON
3. Check if the diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Return to Step 1.

NO : 

The procedure is complete.

Code No.U1113 Multi-centre display CAN communication time-out

CAUTION

If diagnosis code No. U1113 is set in the 
A/C-ECU, diagnose the CAN main bus line.

CAUTION

Whenever the ECU is replaced, ensure that the 
communication circuit is normal.

TROUBLE JUDGMENT

The A/C-ECU receives air conditioner 
operation-related signal from the multi-centre display 
via the CAN bus lines. If the A/C-ECU can not 
receive the air conditioner operation-related signal at 
all on the multi-centre display, diagnosis code 
No.U1113 will be set.

COMMENTS ON TROUBLE SYMPTOM

Current trouble

• Connector(s) or wiring harness in the CAN bus 

lines between the multi-centre display and the 
A/C-ECU, the power supply system to the 
multi-centre display, the multi-centre display 
itself, or the A/C-ECU may be defective.

Past trouble

• Carry out diagnosis with particular emphasis on 

connector(s) or wiring harness in the CAN bus 
lines between the multi-centre display and the 
A/C-ECU, and the power supply system to the 
multi-centre display. For diagnosis procedures, 
refer to "How to cope with past trouble" (Refer to 
GROUP 00

− How to Use 

Troubleshooting/Inspection Service Points 

P.00-5

).

NOTE: For a past trouble, you can not find it by the 

MUT-III CAN bus diagnostics even if there is any 
failure in CAN bus lines. In this case, refer to 
GROUP 00 

−

 How to Cope with Intermittent 

Malfunctions 

P.00-5

 and check the CAN bus 

lines. You can narrow down the possible cause of 
the trouble by referring to the diagnosis code, 
which is set regarding the CAN 
communication-linked ECUs (Refer to GROUP 
54D 

−

 Explanation about the MUT-III CAN bus 

diagnostics 

P.54D-9

).

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-42

CAUTION

If the ignition switch is turned to the ON position 
without starting the engine, the diagnosis code 
U1113 (past trouble) may be set to the A/C-ECU 
after three minutes.

POSSIBLE CAUSES

• Damaged harness wires and connectors

• Malfunction of multi-centre display 

• Malfunction of the A/C-ECU

Step 1. MUT-III CAN bus diagnostics

Use the MUT-III to diagnose the CAN bus lines.

Q: Is the check result normal?

YES : 

Go to Step 2

NO : 

Repair the CAN bus lines. (Refer to GROUP 
54D 

− Troubleshooting 

P.54D-16

.) On 

completion, go to Step 6.

Step 2. MUT-III Diagnosis code of other systems

Check that the multi-centre display unit sets a 
diagnosis code.

Q: Is the diagnosis code set?

YES : 

Diagnose the multi-centre display. Refer to 

P.54A-144

.

NO : 

Go to Step 3

Step 3. MUT-III Diagnosis code of other systems

Check if a diagnosis code, which relates to CAN 
communication-linked systems below, is set.

• ETACS

15: Multi-centre display-related time-out diagnosis 

code

Q: Is the diagnosis code set?

YES : 

Go to Step 4

NO : 

Go to Step 5

Step 4. Check whether the diagnosis code is 
reset.

Recheck if the diagnosis code is set.

1. Erase the diagnosis code.
2. Ignition switch: LOCK (OFF) to ON
3. Check if the diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Replace the multi-centre display, and then 

go to Step 6 .

NO : 

A poor connection, open circuit or other 
intermittent malfunction in the CAN bus line 
between the multi-centre display and the 
A/C-ECU. (Refer to GROUP 00 

− How to 

Cope with Intermittent Malfunction 

P.00-5

.)

Step 5. Check whether the diagnosis code is 
reset.

Recheck if the diagnosis code is set.

1. Erase the diagnosis code.
2. Ignition switch: LOCK (OFF) to ON
3. Check if the diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Replace the A/C-ECU, and then go to Step 

6 . 

NO : 

A poor connection, open circuit or other 
intermittent malfunction in the CAN bus line 
between the multi-centre display and the 
A/C-ECU. (Refer to GROUP 00 

− How to 

Cope with Intermittent Malfunction 

P.00-5

.)

Step 6. Check whether the diagnosis code is 
reset.

Recheck if the diagnosis code is set.

1. Erase the diagnosis code.
2. Ignition switch: LOCK (OFF) to ON
3. Check if the diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Return to Step 1.

NO : 

The procedure is complete.

Code No.U1120 Engine-related CAN communication failure information

CAUTION

If diagnosis code No. U1120 is set in the 
A/C-ECU, diagnose the CAN main bus line.

TROUBLE JUDGMENT

The A/C-ECU receives vehicle speed signal from the 
engine-ECU <M/T> or the engine-A/T-ECU <A/T> 
via CAN bus lines. If failure information is sent to the 

vehicle speed signal, diagnosis code U1120 will be 
set.

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-43

COMMENTS ON TROUBLE SYMPTOM

Current trouble

• The vehicle speed sensor, A/C-ECU, 

engine-ECU <M/T> or engine-A/T-ECU <A/T> 
may be defective.

Past trouble

• Carry out diagnosis with particular emphasis on 

connector(s) or wiring harness between the 
engine-ECU <M/T> or engine-A/T-ECU <A/T> 
and the vehicle speed sensor. For diagnosis 
procedures, refer to "How to treat past trouble" 
(Refer to GROUP 00 

− How to Use 

Troubleshooting/Inspection Service Points 

P.00-5

).

POSSIBLE CAUSES

• Damaged harness wires and connectors

• Malfunction of the engine-A/T-ECU

• Malfunction of the A/C-ECU

Step 1. MUT-III CAN bus diagnostics

Use the MUT-III to diagnose the CAN bus lines.

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Repair the CAN bus lines. (Refer to GROUP 
54D 

− Troubleshooting 

P.54D-16

.) On 

completion, go to Step 6.

Step 2. MUT-III Diagnosis code of other systems

Check whether the engine-related diagnosis code is 
set.

Q: Is the diagnosis code set?

YES : 

Diagnose the engine control system. Refer 

to 

P.13A-20

.

NO : 

Go to Step 3.

Step 3. MUT-III Diagnosis code of other systems

Check if a diagnosis code, which relates to CAN 
communication-linked systems below, is set.

• Combination meter

U1120: Diagnosis code of engine-related failure 

information 

Q: Is the diagnosis code set?

YES : 

Go to Step 4.

NO : 

Go to Step 5.

Step 4. MUT-III diagnosis code

Recheck if the diagnosis code is set.

1. Erase the diagnosis code.
2. Ignition switch: LOCK (OFF) to ON
3. Check if the diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Replace the engine-ECU <M/T> or the 

engine-A/T-ECU <A/T>, go to Step 6 .

NO : 

A poor connection, open circuit or other 
intermittent malfunction between the 
engine-ECU <M/T> or the engine-A/T-ECU 
<A/T> and the vehicle speed sensor. (Refer 
to GROUP 00, How to Cope with 
Intermittent Malfunction 

P.00-5

.)

Step 5. MUT-III diagnosis code

Recheck if the diagnosis code is set.

1. Erase the diagnosis code.
2. Ignition switch: LOCK (OFF) to ON
3. Check if the diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Replace the A/C-ECU, and then go to Step 

6 . 

NO : 

A poor connection, open circuit or other 
intermittent malfunction between the 
engine-A/T-ECU <A/T> and the vehicle 
speed sensor. (Refer to GROUP 00, How to 
Cope with Intermittent Malfunction 

P.00-5

.)

Step 6. MUT-III diagnosis code

Recheck if the diagnosis code is set.

1. Erase the diagnosis code.
2. Ignition switch: LOCK (OFF) to ON
3. Check if the diagnosis code is set.

Q: Is the diagnosis code set?

YES : 

Return to Step 1.

NO : 

The procedure is complete.

TROUBLE SYMPTOM CHART

M1554005000247

Trouble symptom

Inspection 
procedure 
number

Reference 
page

Communication with the MUT-III is not possible.

1

P.55-45

Cool air does not come

2

P.55-46

The front blower does not work

3

P.55-47

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-44

The blower air volume cannot be changed

4

P.55-59

The inside/outside air changeover is impossible. <LHD>

5

P.55-63

The inside/outside air changeover is impossible. <RHD>

6

P.55-67

The compressor does not work <LHD>

7

P.55-71

The compressor does not work <RHD>

8

P.55-78

The outlet air temperature can not be changed even if the amount of solar 
radiation changes

9

P.55-84

The PTC heater does not work <LHD>

10

P.55-87

The PTC heater does not work <RHD>

11

P.55-99

The rear window defogger does not work.

12

P.55-109

The A/C indicator flashes

13

P.55-119

Rear blower does not work <Vehicle with rear heater or rear cooler>

14

P.55-120

Rear blower does not work <vehicles with dual automatic A/C>

15

P.55-127

Air volume of rear blower cannot be changed

16

P.55-134

The temperature of rear air conditioner cannot be controlled <vehicles with 
dual automatic A/C>

17

P.55-138

A/C pressure sensor system <LHD>

18

P.55-142

A/C pressure sensor system <RHD>

19

P.55-144

Rear fan switch system <LHD>

20

P.55-146

Rear fan switch system <RHD>

21

P.55-149

Rear blower motor power supply system <LHD>

22

P.55-152

Rear blower motor power supply system <RHD>

23

P.55-160

PTC heater switch system <LHD>

24

P.55-168

PTC heater switch system <RHD>

25

P.55-171

A/C-ECU power supply system <LHD>

26

P.55-174

A/C-ECU power supply system <RHD>

27

P.55-178

Trouble symptom

Inspection 
procedure 
number

Reference 
page