Mitsubishi Lancer (4A9 engine). Manual - part 289

AC612706

Connectors: C-60, C-109, C-110 <LHD>

BQ

C-60 (B)

C-109

C-110

AC612709

Connector: C-303<LHD>

AO

ETACS-ECU

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-37

COMMENTS ON TROUBLE SYMPTOM
If the blower motor does not operate, the blower 
motor circuit system may be defective.

PROBABLE CAUSES

• Malfunction of the blower motor

• Malfunction of the power transistor

• Malfunction of the heater control unit

• Damaged wiring harness or connectors

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
Use the M.U.T.-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 
54C 

− Troubleshooting ).

STEP 2. M.U.T.-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 : 

Carry out the diagnosis code procedures. 

Refer to . 

NO : 

Go to Step 3.

STEP 3. Connector check: C-303 blower relay 
connector

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Repair the connector.

STEP 4. Check the blower relay.
Refer to .

Q: Is the blower relay in good condition?

YES : 

Go to Step 5.

NO : 

Replace the blower relay.

STEP 5. Connector check: C-110 blower motor 
connector

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Repair the connector.

STEP 6. Check the blower motor.
Refer to .

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Replace the blower motor.

STEP 7. Voltage measurement at C-110 blower 
motor connector.
(1) Disconnect the connector, and measure at the 

wiring harness side.

(2) Turn the ignition switch to the ON position.
(3) Voltage between terminal 1 and body earth. 

<LHD>

OK: System voltage

(4) Voltage between terminal 2 and body earth. 

<RHD>

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 8.

NO : 

INSPECTION PROCEDURE 7: Refer to 
"Blower motor power supply system" .

STEP 8. Connector check: C-109 power 
transistor controller connector

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Repair the connector.

STEP 9. Resistance measurement at the C-109 
power transistor connector.
(1) Disconnect the connector, and measure at the 

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-38

wiring harness side.

(2) Continuity between terminal 1 and body earth

OK: Continuity exists (2 

Ω or less)

Q: Is the check result normal?

YES : 

Go to Step 10.

NO : 

Repair the wiring harness wires between 
power transistor connector terminal No. 1 
and body earth.

STEP 10. Check the wiring harness between C-
110 blower motor connector terminal No.2 and C-
109 power transistor connector terminal No.2.

• Check the power transistor power supply line for 

open circuit.

Q: Is the check result normal?

YES : 

Go to Step 11.

NO : 

Repair the wiring harness.

STEP 11. Connector check: C-60 heater control 
unit connector

Q: Is the check result normal?

YES : 

Go to Step 12.

NO : 

Repair the connector.

STEP 12. Check the wiring harness between C-
110 blower motor connector terminal No.2 and C-
60 heater control unit connector terminal No.1.

• Check the blower motor power supply line for 

open circuit.

Q: Is the check result normal?

YES : 

Go to Step 13.

NO : 

Repair the wiring harness.

STEP 13. Check the wiring harness between C-
109 power transistor connector terminal No.4 
and C-60 heater control unit connector terminal 
No.2.

• Check the power transistor power supply line for 

open circuit.

Q: Is the check result normal?

YES : 

Go to Step 14.

NO : 

Repair the wiring harness.

STEP 14. Replace the power transistor and 
recheck the trouble symptom
 Check that the blower motor operates normally.

Q: Is the check result normal?

YES : 

This diagnosis is complete.

NO : 

Replace the heater control unit.

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-39

INSPECTION PROCEDURE 3: The blower air volume cannot be changed

Blower Motor Circuit

BLOWER
RELAY

ETACS-
ECU 

HEATER 
CONTROL UNIT

BLOWER
MOTOR

POWER
TRANSISTOR

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     SI : Silver

ACB02708

FUSIBLE
LINK

42

AC612706

Connectors: C-60, C-109, C-110 <LHD>

BQ

C-60 (B)

C-109

C-110

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55A-40

COMMENTS ON TROUBLE SYMPTOM
If air volume cannot be adjusted by using the blower 
control, the heater control panel, the heater control 
unit or the power transistor may be faulty.

PROBABLE CAUSES

• Malfunction of the power transistor

• Damaged wiring harness or connectors

• Malfunction of the heater control unit

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
Use the M.U.T.-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 
54C, Troubleshooting ).

STEP 2. M.U.T.-III diagnosis code
Check that the diagnosis code related to the air con-
ditioner is not set.

Q: Is the diagnosis code set?

YES : 

Carry out the diagnosis code procedures. 

Refer to .

NO : 

Go to Step 3.

STEP 3. Connector check: C-109 power 
transistor controller connector

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Repair the connector.

STEP 4. Resistance measurement at the C-109 
power transistor connector.
(1) Disconnect the connector, and measure at the 

wiring harness side.

(2) Continuity between terminal 1 and body earth

OK: Continuity exists (2 

Ω or less)

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Repair the wiring harness wires between 
power transistor connector terminal No. 1 
and body earth.

STEP 5. Connector check: C-60 heater control 
unit connector

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Repair the connector.

STEP 6. Check the wiring harness between C-110 
blower motor connector terminal No.2 and C-60 
heater control unit connector terminal No.1.

• Check the blower motor earth line for open cir-

cuit.

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Repair the wiring harness.

STEP 7. Check the wiring harness between C-109 
power transistor connector terminal No.4 and C-
60 heater control unit connector terminal No.2.

• Check the blower motor earth line for open cir-

cuit.

Q: Is the check result normal?

YES : 

Go to Step 8.

NO : 

Repair the wiring harness.

STEP 8. Replace the power transistor and check 
the trouble symptom
 Check that the blower motor operates normally.

Q: Does the blower motor work normally? 

YES : 

This diagnosis is complete.

NO : 

Replace the heater control unit.