Mitsubishi Lancer Evolution VI. Manual - part 57

REAR AXLE – 

Troubleshooting <AYC>

27-22

INSPECTION PROCEDURE 3

AYC warning lamp does not light up when the ignition key
is turned to “ON” (engine stationary).

Probable cause

The lamp power supply circuit is probably open-circuited, lamp bulb is out, or the
circuit between AYC warning lamp and AYC-ECU or AYC-ECU itself is defective.

D

Blown fuse

D

AYC warning lamp out

D

Defective harness or connector

D

Defective AYC-ECU

NG

Check and repair the harness between
ignition switch (IG

2

) and AYC warning

lamp.

OK

Check the trouble symptom.

OK

Replace combination meter.

NG

Check the harness between AYC
warning lamp and AYC-ECU.

NG

Repair

OK

Check the trouble symptom.

OK

Replace AYC-ECU.

OK

Check the following connectors:
B-96, B-94, B-08

NG

Repair

OK

Measure at B-96 AYC-ECU connector.

D

Disconnect the connector and
measure at the harness side.

D

Ignition switch: ON

D

Warning lamp when 36 is grounded
to body
OK: Lit up

NG

Check the lamp bulb.

NG

Replace

Measure at B-08 combination meter
connector.

D

Disconnect the connector and
measure at the harness side.

D

Ignition switch: ON

D

Voltage across 48 and body ground
OK: Symptom voltage

NG

Check the following connectors:
B-08, B-74, B-76

NG

Repair

REAR AXLE – 

Troubleshooting <AYC>

27-23

INSPECTION PROCEDURE 4

AYC warning lamp remains lit up after the engine has
started.

Probable cause

The AYC warning lamp ON circuit is probably short-circuited.

D

Defective combination meter

D

Defective harness (short-circuit)

D

Defective AYC-ECU

NOTE
This symptom is limited only when the communication with MUT-

II

 is possible with AYC-ECU power supply

in normal condition and the diagnosis code is correct.

OK

Replace combination meter.

NO

Check the harness between AYC
warning lamp and AYC-ECU.

NG

Repair

Does the AYC warning lamp goes out
when the B-96 AYC-ECU connector
is disconnected?

YES

Replace AYC-ECU.

INSPECTION PROCEDURE 5

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

Probable cause

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

D

Low hydraulic oil level

D

Oil leak

D

Defective hydraulic unit

D

Defective torque transfer differential

NOTE
This symptom is limited only when the diagnosis code is correct.

NG

Replace the hydraulic unit.

NG

Replace the torque transfer differential.

Check the trouble symptom.

NG

Replace AYC fluid.

OK

Correct

Check the trouble symptom.

NO

Replace the torque transfer differential.

OK

Is foreign matter trapped in the hydrau-
lic line?

YES

Repair

OK

Check the AYC for operation. 
(Refer to P.27-34.)

OK

Check the AYC fluid.

NG

Add hydraulic oil.

NG

Check hydraulic pressure.. 
(Refer to P.27-35.)

NG

Bleed the system of air. 
(Refer to P.27-34.)

Check the hydraulic oil level.

NG

Check for oil leak.

OK

Repair

REAR AXLE – 

Troubleshooting <AYC>

27-24

INSPECTION PROCEDURE 6

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

Probable cause

The hydraulic unit or torque transfer differential is probably defective.

D

Defective hydraulic unit

D

Defective torque transfer differential

NOTE
This symptom is limited only when the diagnosis code is correct.

NG

Replace the hydraulic unit.

NG

Replace the torque transfer differential.

Check the trouble symptom.

NG

Replace AYC fluid.

OK

Correct

Check the trouble symptom.

NO

Replace the torque transfer differential.

OK

Is foreign matter trapped in the hydrau-
lic line?

YES

Repair

Check the AYC for operation.. 
(Refer to P.27-34.)

OK

Check the AYC fluid.

NG

Check hydraulic pressure. 
(Refer to P.27-35.)

NG

Bleed the system of air.. 
(Refer to P.27-34.)

REAR AXLE – 

Troubleshooting <AYC>

27-25

DATA LIST REFERENCE TABLE

The following items can be read by t01he MUT-

II

 from the ECU input data.

Item No.

Check item

Checking requirements

Normal value

01

Front-right wheel speed

Perform a test run.

Vehicle speeds
displayed on the

02

Front-left wheel speed

displayed on the
speedometer and
MUT

II

are identi

03

Rear-right wheel speed

MUT

-II

 are identi-

cal.

04

Rear-left wheel speed

05

Front-right wheel speed
(0.2 km/h)

06

Front-left wheel speed (0.2
km/h)

07

Rear-right wheel speed
(0.2 km/h)

08

Rear-left wheel speed (0.2
km/h)

10

Vehicle speed

11

System voltage

Ignition switch: ON

Battery voltage

15

TPS opening

Accelerator pedal position/Igni-
tion switch: ON

Fully closed

300 – 1000mV

tion switch: ON

Partially open

Gradually increases
from the above val-
ue.

Fully open

4500 – 5000mV

19

Longitudinal acceleration
sensor

Vehicle stands on level ground

2.4 – 2.6V

sensor

Perform a test run.

Reading fluctuates
up or down with 2.5V
as its center.

20

Lateral acceleration sensor

Vehicle stands on level ground

2.4 – 2.6V

Perform a test run.

Reading fluctuates
up or down with 2.5V
as its center.

22

Steering wheel operation

Steering wheel turning direction
Ignition switch: ON

90 deg. clock-
wise

R90 deg

90 deg counter-
clockwise

L90 deg

23

Steering wheel turning
angular velocity

Steering wheel position  
Ignition switch: ON

Not turned

0 deg/s

angular velocity

Ignition switch: ON

Turned

Reading varies ac-
cording to turning
speeds.

45

Idle position switch

Accelerator pedal position  
Ignition position: ON

Not depressed

ON

Ignition position: ON

Depressed

OFF