Mitsubishi Grandis. Manual - part 306

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-109

INSPECTION PROCEDURE 12: The rear window defogger does not work.

CIRCUIT OPERATION

If the rear window defogger does not operate when 
the rear window defogger switch is turned on, the 
rear window defogger relay system may be 
defective.

TROUBLESHOOTING HINTS

• Malfunction of the A/C-ECU

• Malfunction of the rear window defogger relay

• Damaged the wiring harness or connectors

• Malfunction of the rear window defogger

DIAGNOSIS

Step 1. Check the A/C and outside/inside air 
selection damper control motor operation.

Q: Do the A/C and outside/inside air selection damper 

control motor work normally?

YES : 

Go to Step 2.

NO <LHD> : 

Refer to Inspection procedure 26 

"Malfunction of the A/C-ECU power supply 
system <LHD>

P.55-174

 ."

NO <RHD> : 

Refer to Inspection procedure 27 

"Malfunction of the A/C-ECU power supply 
system <RHD>

P.55-178

 ."

REAR
WINDOW
DEFOGGER
RELAY

REAR WINDOW
DEFOGGER

A/C-ECU

POWER
SOURCE

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

FUSIBLE
LINK

30

IGNITION
SWITCH (IG2)

Rear Window Defogger Circuit

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-110

Step 2. Connector check: C-106 A/C-ECU 
connector and G-07 rear window defogger 

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Repair the connector.

Step 3. Voltage measurement at G-07 rear 
window defogger 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) Measure the voltage between terminal 1 and 

body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

 Go to Step 12.

NO : 

 Go to Step 4.

Step 4. Connector check: C-208 rear window 
defogger relay connector 

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Repair the connector.

AC310613

AB

Connector: C-106 <LHD>

Harness side

AC310631AB

Connectors: C-106 <RHD>

Harness side

AC310222

Connector: G-07

AB

Harness side

G-07 (B)

AC310222

Connector: G-07

AB

Harness side

G-07 (B)

AC310507

Connector G-07 
(Harness side)

BA

AC310623

Connector: C-208 <LHD>

AG

3

4

5

1

2

Junction block side

Junction block (Front view)

AC310618

Connector: C-208 <RHD>

AG

3

4

5

1

2

Junction block side

Junction block (Front view)

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-111

Step 5. Check the rear window defogger relay 
continuity.

 Refer to 

P.55-196

.

Q: Is the rear window defogger relay in good 

condition?

YES : 

Go to Step 6.

NO : 

Replace the rear window defogger relay.

Step 6. Voltage measurement at C-208 rear 
window defogger relay connector. 

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

block side.

(2) Measure the voltage between terminal 5 and 

body earth.

OK: System voltage

Q: Is the check result normal?

YES : 

 Go to Step 8.

NO : 

 Go to Step 7.

AC310623

Connector: C-208 <LHD>

AG

3

4

5

1

2

Junction block side

Junction block (Front view)

AC310618

Connector: C-208 <RHD>

AG

3

4

5

1

2

Junction block side

Junction block (Front view)

AC310507BB

Connector C-208 
(Junction block side)

3

4

5

1

2

TROUBLESHOOTING

HEATER, AIR CONDITIONER AND VENTILATION

55-112

Step 7. Check the wiring harness between C-208 
rear window defogger relay connector terminal 
No.5 and the fusible link (30).

NOTE: 

Prior to the wiring harness inspection, check 
intermediate connectors C-125, and junction block 
connector C-204, and repair if necessary.

• Check the rear window defogger relay power 

supply line for open or short 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.

AC310624

Connectors: C-204, C-208 <LHD>

AI

3

4

5

1

2

Junction block side

Junction block (Front view)

C-208

C-204 (B)

C-208

Harness side

C-204

AC310619

Connectors: C-204, C-208 <RHD>

AJ

3

4

5

1

2

Junction block side

Junction block (Front view)

C-208

C-204 (B)

C-208

Harness side

C-204

AC310613

AD

Connector: C-125 <LHD>

AC310628AB

Connector: C-125 <RHD>