Mitsubishi Lancer Evolution IX. Manual - part 312

TROUBLESHOOTING

REAR AXLE

27-23

STEP 7. Check the harness between direction 
valve (LH) connector F-22 terminal No.2 and 
4WD-ECU connector C-25 terminal No.15.

AC310739

1 2

Connector: F-22

F-22 (2-B)

AB

Hydraulic unit
assembly

AC310721

18

16

1415

17

23

21

1920

22

26

2425

3

1 2

4 5

10

8

6 7

9

13

12

11

4WD-ECU

C-25 (26-Y)

Connector: C-25

AB

Check the output line for short-circuited or open cir-
cuit.

Q: Is the check result normal?

YES : 

Replace the 4WD-ECU.

NO : 

Repair the wiring harness.

SYMPTOM CHART

M1272004200027

Trouble symptom

Inspection 
procedure No.

Reference page

Communication with the M.U.T.-II/III is not possible

1

Refer to GROUP 
22A, 
Troubleshooting

−S

ymptom chart 

P.22A-118

.

Communication between the M.U.T.-II/III and 4WD-ECU is not 
possible

2

Three ACD mode indicator lamps do not light up when the 
ignition key is turned to "ON" position (engine stopped).

3

Three ACD mode indicator lamps remain lit up after the engine 
has started.

4

AYC is inoperative.
Unable to start or accelerate on slippery road surface.

5

P.27-24

Rear tyres are noisy during low-speed cornering.
Vehicle skews.

6

P.27-24

Noise is produced from the torque transfer differential during 
turning.

7

P.27-25

TROUBLESHOOTING

REAR AXLE

27-24

INSPECTION PROCEDURE FOR 
TROUBLE SYMPTOMS

INSPECTION PROCEDURE 5: AYC is inoperative. Unable to start or accelerate on slippery road 
surfaces.

COMMENTS ON TROUBLE SYMPTOM

The hydraulic oil level is probably low, there is an oil 
leak, the hydraulic unit is defective, or the torque 
transfer differential is defective.

POSSIBLE CAUSES

• Low hydraulic oil level

• Oil leak

• Malfunction of the hydraulic unit

• Malfunction of the torque transfer differential

DIAGNOSIS

STEP 1.Gear oil level check
Check the gear oil level of AYC differential part and 
torque transfer mechanism part (Refer to 

P.27-26

).

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

After checking for oil leakage, repair it and 
refill the gear oil (Refer to 

P.27-26

).

STEP 2. Fluid level check
Check the fluid level (Refer to 

P.27-27

).

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

After checking the hydraulic pressure line 
for fluid leakage, repair it and refill the fluid 
(Refer to 

P.27-27

).

STEP 3. AYC operation check
Check the AYC operation (Refer to 

P.27-29

).

Q: Does a malfunction take place again?

YES : 

Go to Step 4.

NO : 

The procedure is complete.

STEP 4. Oil pump pressure test
Measure the oil pump pressure of the hydraulic unit. 
(Refer to 

P.27-29

).

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Go to Step 5.

STEP 5. AYC bleeding
Bleed the AYC system (Refer to 

P.27-28

).

Q: Does a malfunction take place again?

YES : 

Replace the hydraulic unit (Refer to 

P.27-49

).

NO : 

Go to Step 6.

STEP 6. Hydraulic pressure line check
Check the hydraulic pressure line for entry of foreign 
matter.

Q: Is there foreign matter trapped in the hydraulic 

pressure line?
YES : 

Remove the foreign matter in the hydraulic 

pressure line.

NO : 

Replace the torque transfer differential.

INSPECTION PROCEDURE 6: Rear tyres are noisy during low-speed cornering. Vehicle skews.

COMMENTS ON TROUBLE SYMPTOM

The hydraulic unit or the torque transfer differential is 
probably defective.

POSSIBLE CAUSES

• Malfunction of the hydraulic unit

• Malfunction of the torque transfer differential

DIAGNOSIS

STEP 1. Fluid level check
Check the fluid level (Refer to 

P.27-27

).

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

After checking the hydraulic pressure line 
for fluid leakage, repair it and refill the fluid 
(Refer to 

P.27-27

).

TROUBLESHOOTING

REAR AXLE

27-25

STEP 2. AYC operation check
Check the AYC operation (Refer to 

P.27-29

).

Q: Does a malfunction take place again?

YES : 

Go to Step 3.

NO : 

The procedure is complete.

STEP 3. Oil pump pressure test
Measure the oil pump pressure of the hydraulic unit. 
(Refer to 

P.27-29

).

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Go to Step 4.

STEP 4. AYC bleeding
Bleed the AYC system (Refer to 

P.27-28

).

Q: Does a malfunction take place again?

YES : 

Replace the hydraulic unit (Refer to 

P.27-49

).

NO : 

Go to Step 5.

STEP 5. Hydraulic pressure line check
Check the hydraulic pressure line for entry of foreign 
matter.

Q: Is there foreign matter trapped in the hydraulic 

pressure line?
YES : 

Remove the foreign matter in the hydraulic 

pressure line.

NO : 

Replace the torque transfer differential.

INSPECTION PROCEDURE 7: Noise is produced from the torque transfer differential during turning

COMMENTS ON TROUBLE SYMPTOM

The torque transfer differential is probably defective.

POSSIBLE CAUSES

• Malfunction of the torque transfer differential

DIAGNOSIS

STEP 1. M.U.T.-II/III actuator test
(1) Replace the torque transfer gear oil (Refer to 

P.27-26

).

(2) Set M.U.T.-II/III to actuator test mode, and drive 

the vehicle in straight with the speed 20 km/h or 
less and with the steering wheel on neutral 
position.

(3) Test the following items for 5 times respectively.

• Item 06: Clutch operation (left)

• Item 07: Clutch operation (right)

OK: Noise is not produced.

Q: Is the check result normal?

YES : 

The procedure is complete and replace the 

torque transfer gear oil (Refer to 

P.27-26

). 

NO : 

Go to Step 2.

STEP 2. M.U.T.-II/III actuator test
Test again the following items for 5 times respectively 
with the same condition described in STEP 2.

• Item 06: Clutch operation (left)

• Item 07: Clutch operation (right)

OK: Noise is not produced.

Q: Is the check result normal?

YES : 

The procedure is complete and replace the 

torque transfer gear oil (Refer to 

P.27-26

). 

NO : 

Replace the torque transfer differential.

DATA LIST REFERENCE TABLE

M1272004300024

Refer to GROUP 22A, Data list reference table 

P.22A-142

.

ACTUATOR TEST REFERENCE TABLE

M1272005200020

Refer to GROUP 22A, Actuator test reference table 

P.22A-145

.

CHECK AT 4WD-ECU TERMINAL

M1272004500028

Refer to GROUP 22A, Check at 4WD-ECU terminal 

P.22A-146

.

ON-VEHICLE SERVICE

REAR AXLE

27-26

ON-VEHICLE SERVICE

REAR AXLE TOTAL BACKLASH CHECK

M1271001200252

1. Park the vehicle on a flat, level surface.
2. Move the transmission gearshift lever to the 

neutral position. Apply the parking brake and jack 
up the vehicle.

ACX00962

Mating marks

AC

3. Turn the propeller shaft clockwise as far as it will 

go. Make the mating marks on the companion 
flange and on the differential carrier.

ACX00964 AC

4. Turn the propeller shaft counterclockwise as far 

as it will go, and measure the amount of distance 
between the mating marks.

Limit: 6 mm

5. If the backlash exceeds the limit value, replace 

the differential carrier assembly.

GEAR OIL LEVEL CHECK

M1272001200330

DIFFERENTIAL PART

AC310749 AB

Filler plug

1. Remove the filler plug.

AC102739

Gear oil

Upper
limit

Lower
limit

6 mm

AF

2. Check that the gear oil level is within the specified 

range from the bottom end of the filler plug hole.

3. If the gear oil level exceeds the standard value, 

add the specified gear oil up to the bottom end of 
the filler plug hole.

Specified gear oil: DIA QUEEN LSD gear oil

4. Fit the filler plug and tighten it to the specified 

torque.

Tightening torque: 49 

± 10 N⋅m

TORQUE TRANSFER MECHANISM PART

AC310750 AB

Filler plug

1. Remove the filler plug.

AC102739

Gear oil

Upper
limit

Lower
limit

6 mm

AF

2. Check that the gear oil level is within the specified 

range from the bottom end of the filler plug hole.