Mitsubishi Grandis. Manual - part 774

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-347

Inspection Procedure 25: A/C Compressor Relay System

1

2

3

4

1

AK305581

1

2

3

5

6 7 8 9

4

20

21 22

232425

2627

10111213

14 15

16 1718

19

1 2 3

4 5 6

Fusible link (26)

W

W

IG2

ST

R

LOCK

ACC

IG1

5

7.5A

10

10A

L-R

L-R

L-R

L-R

G-R

Ignition switch

4

C-202

C-205

11

J/B

A/C compressor relay

Relay box

GR

B-O

B-O

4

3

1

1

2

B-16X

A/C-ECU

B-120

MU802653

A/C refrigerant 
temperature 
switch

A/C compressor assembly

Magnetic 
clutch

7

A-16

A/C compressor relay circuit

8

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

AB

C-110

(MU803802)

Engine-ECU <M/T> or
engine-A/T-ECU <A/T>

16 

2

C-17

J/C (5)

C-31(*1)

J/C (6)

C-01(*2)

NOTE

*1: L.H. drive vehicles
*2: R.H. drive vehicles

6

1(*1)
11(*2)

C-307

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-348

OPERATION

• The battery voltage is applied to the A/C 

compressor relay (terminal No. 4).

• The battery voltage is applied to the A/C 

compressor relay (terminal No. 3) from the 
ignition switch. The engine-ECU <M/T> or 
engine-A/T-ECU <A/T> (terminal No. 8) makes 
the power transistor in the unit be in ON position 
and makes currents go on the A/C compressor 
relay coil, and that makes the relay be in ON 
position.

• When the A/C compressor is in ON position, the 

battery voltage is supplied to the A/C compressor 
(terminal No. 1) from the A/C compressor relay 
assembly (terminal No. 1).

FUNCTION

• When the A/C switch ON signal is input to the 

engine-ECU <M/T> or engine-A/T-ECU <A/T>, 
the engine-ECU <M/T> or engine-A/T-ECU 
<A/T> places the A/C compressor relay in the ON 
position. Accordingly, the battery voltage supplied 
to the A/C compressor operates the magnet 
clutch.

PROBABLE CAUSE

• Failed A/C compressor relay

• Failed A/C compressor magnet clutch

• Open/short circuit in A/C compressor relay circuit 

or loose connector contact

• Failed engine-ECU <M/T>

• Failed engine-A/T-ECU <A/T>

DIAGNOSIS PROCEDURE

NOTE: 

.

*1: L.H.drive vehicle
*2: R.H.drive vehicle

STEP 1. Connector check: B-16X A/C 
compressor relay connector

Q: Is the check result normal?

YES : 

Go to Step 2 .

NO : 

Repair or replace.

STEP 2. A/C compressor relay check.

• Check A/C compressor relay (Refer to GROUP 

55 

− On-vehicle Service 

P.55-196

).

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Replace A/C compressor relay.

STEP 3. Perform voltage measurement at B-16X 
A/C compressor relay connector.

• Remove relay, and measure at relay box side.

• Ignition switch: ON

• Voltage between terminal No. 3 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 5 .

NO : 

Go to Step 4 .

AK301005

2

1

3

4

AC

B-16X

Connector: B-16X

Harness side
connector

Relay box’s 
Triangle marks

AK301005

2

1

3

4

AC

B-16X

Connector: B-16X

Harness side
connector

Relay box’s 
Triangle marks

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-349

STEP 4. Connector check: C-307 ignition switch 
connector

Q: Is the check result normal?

YES : 

Check intermediate connectors C-17, 

C-31

*1

, C-01

*2

, C-205 and C-202 and repair 

if necessary. If intermediate connectors are 
normal, check and repair harness between 
B-16X (terminal No. 3) A/C compressor 
relay connector and C-307 (terminal No. 4) 
ignition switch connector.

• Check power supply line for 

open/short circuit.

NO : 

Repair or replace.

STEP 5. Perform voltage measurement at B-16X 
A/C compressor relay connector.

• Remove relay, and measure at relay box side.

• Voltage between terminal No. 4 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 6 .

NO : 

Check intermediate connector A-16, and 

repair if necessary. If intermediate 
connector is normal, check and repair 
harness between B-16X (terminal No. 4) 
A/C compressor relay connector and 
battery.

• Check power supply line for 

open/short circuit.

STEP 6. Connector check: B-120 A/C compressor 
assembly connector

Q: Is the check result normal?

YES : 

Go to Step 7 .

NO : 

Repair or replace.

1

2

3

4

5

6

AK305629

 C-307

 C-307

Connector: C-307

Harness side connector

<R.H.drive vehicle>

<L.H.drive vehicle>

AB

AK301005

2

1

3

4

AC

B-16X

Connector: B-16X

Harness side
connector

Relay box’s 
Triangle marks

AK301005

2

1

3

4

AC

B-16X

Connector: B-16X

Harness side
connector

Relay box’s 
Triangle marks

1

AK305637AB

 B-120 (B)

Connector: B-120

Harness side connector

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-350

STEP 7. Perform voltage measurement at B-120 
A/C compressor assembly connector.

• Disconnect connector, and measure at harness 

side.

• Remove B-16X (terminal No. 1 and No. 4) A/C 

compressor relay and short-circuit of harness 
side connector.

• Ignition switch: ON

• Voltage between terminal No. 1 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 8 .

NO : 

Check and repair harness between B-120 

(terminal No. 1) A/C compressor assembly 
connector and B-16X (terminal No. 1) A/C 
compressor relay connector.

• Check output line for open/short 

circuit.

STEP 8. Perform voltage measurement at C-110 
engine-ECU <M/T> connector or engine-A/T-ECU 
<A/T> connector.

• Disconnect connector, and measure at harness 

side.

• Ignition switch: ON

• Voltage between terminal No. 8 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 12 .

NO : 

Go to Step 9 .

1

AK305637AB

 B-120 (B)

Connector: B-120

Harness side connector

AK301005

2

1

3

4

AC

B-16X

Connector: B-16X

Harness side
connector

Relay box’s 
Triangle marks

AK305618AB

1

2

3

4

5

6

7

8

9

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12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

Connector: C-110

<L.H. drive vehicles>

<R.H. drive vehicles>

C-110 (GR)

C-110 (GR)

Harness side connector