Mitsubishi Grandis. Manual - part 293

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-57

Step 15. Connector check: C-12 front power 
transistor controller connector

Q: Is the check result normal?

YES : 

Go to Step 16.

NO : 

Repair the connector.

Step 16. Resistance measurement at the C-12 
front power transistor connector.

(1) Disconnect the connector, and measure at the 

wiring harness side.

(2) Continuity between terminal 2 and body earth

OK: 2

Ω or less

Q: Is the check result normal?

YES : 

Go to Step 18.

NO : 

Go to Step 17.

Step 17. Check the wiring harness between C-12 
front power transistor connector terminal No.2 
and body earth.

• Check the blower linear controller 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.

AC310615

AG

Connector: C-12 <LHD>

Harness side

AC310628AG

Connector: C-12 <RHD>

Harness side

AC310615

AG

Connector: C-12 <LHD>

Harness side

AC310628AG

Connector: C-12 <RHD>

Harness side

AC310506

Connector C-12
(Harness side)

AP

AC310615

AG

Connector: C-12 <LHD>

Harness side

AC310628AG

Connector: C-12 <RHD>

Harness side

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-58

Step 18. Check the wiring harness between C-13 
front blower motor connector terminal No.2 and 
C-12 front power transistor controller connector 
terminal No.4.

• Check the blower linear controller power supply 

line for open circuit.

Q: Is the check result normal?

YES : 

Go to Step 19.

NO : 

Repair the wiring harness.

Step 19. Check the wiring harness between C-106 
A/C-ECU connector (terminals 2 and 3) and C-12 
front power transistor controller connector 
(terminals 3 and 1).

• Check the blower linear controller power supply 

line for open circuit.

Q: Is the check result normal?

YES : 

Go to Step 20.

NO : 

Repair the wiring harness.

AC310616

AB

Connectors: C-12, C-13 <LHD>

Harness side

C-12

C-13

C-12

Harness side

C-13

AC310629

AB

Connectors: C-12, C-13 <RHD>

Harness side

C-12

C-12

Harness side

C-13

C-13

AB

Connectors: C-12, C-13 <RHD>

Harness side

AC310615

AG

Connector: C-12 <LHD>

Harness side

AC310628AG

Connector: C-12 <RHD>

Harness side

AC310613

AB

Connector: C-106 <LHD>

Harness side

AC310631AB

Connectors: C-106 <RHD>

Harness side

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-59

Step 20. Replace the front power transistor and 
recheck the trouble symptom

 Check that the front blower motor operates normally.

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Replace the A/C-ECU.

INSPECTION PROCEDURE 4: The blower air volume cannot be changed

COMMENTS ON TROUBLE SYMPTOM

If the blower air volume can not be changed when 
the blower switch is operated, the circuit between 
front power transistor and A/C-ECU may be 
defective.

POSSIBLE CAUSES

• Front power transistor

• Damaged the wiring harness or connectors

• Malfunction of the automatic air conditioner 

control panel (A/C-ECU)

Step 1. MUT-III actuator test

Carry out the actuator test. (Refer to 

P.55-186

.)

• Item 01, 02, 03: Blower motor

Q: Does the blower motor work normally? 

YES : 

Go to Step 2.

NO : 

Go to Step 4.

FRONT
BLOWER
RELAY

FRONT POWER
TRANSISTOR

FRONT BLOWER
MOTOR

A/C-ECU

Wire colour code
B : Black     LG : Light green     G : Green     L : Blue
W : White     Y : Yellow     SB : Sky blue     BR : Brown
O : Orange     GR : Gray     R : Red     P : Pink     V : Violet

Blower Motor Circuit

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-60

Step 2. MUT-III data list

Check that the following service data display 
contents are normal. (Refer to 

P.55-183

.)

• Item 20: Front blower fan

• Item 21: Front blower fan (Target)

Q: Does the blower motor work normally? 

YES : 

Go to Step 3.

NO : 

Go to Step 10.

Step 3. Replace the front power transistor and 
check the trouble symptom

 Check that the front blower motor operates normally.

Q: Does the blower motor work normally? 

YES : 

This diagnosis is complete.

NO : 

Replace the automatic air conditioner 
control panel (A/C-ECU)

Step 4. Connector check: C-12 front power 
transistor controller connector

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Repair the connector.

Step 5. Resistance measurement at the C-12 front 
power transistor connector.

(1) Disconnect the connector, and measure at the 

wiring harness side.

(2) Continuity between terminal 2 and body earth

OK: 2

Ω or less

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Go to Step 6.

AC310615

AG

Connector: C-12 <LHD>

Harness side

AC310628AG

Connector: C-12 <RHD>

Harness side

AC310615

AG

Connector: C-12 <LHD>

Harness side

AC310628AG

Connector: C-12 <RHD>

Harness side

AC310506

Connector C-12
(Harness side)

AP