wheel MITSUBISHI LANCER EVOLUTION VI 1999 Owner's Guide

REAR AXLE – Troubleshooting <AYC>27-9
Code No. 26: Wheel speed sensor system (faulty output
signal)Probable cause
This code is output if the speed of one of the four wheels exceeds a specified level
when the vehicle speed is 20 km/h or more. At this time, the warning lamp is turned
on.
Defective harness or connector

Defective AYC-ECU

Defective ABS-ECU
<Vehicles with ABS>
OK
Replace ABS-ECU.
NG
Check harness between AYC-ECU
and ABS-ECU.NG
Repair
NG
Replace AYC-ECU.
OK
Check the trouble symptom.
NG
Check the following connectors:
B-24, B-95NG
Repair
OK
Check the trouble symptom.
NO
Measure at B-95 AYC-ECU connector.

Disconnect the connector and
measure at the harness side.

Ignition switch: ON

Turn tire at 1/2 to 1 revolution/sec.

Voltage across 6/7/8/9 and body
ground.
OK:42 mV or more (when mea-
sured with a circuit tester)
120 mV-P or more (when
measured with an oscillo-
scope)NGCheck the following connector:
B-95
Is ABS diagnosis code No. 15 output?YESRefer to Group 35B – Troubleshooting
NG
Repair
<Vehicles without ABS>
NG
Check and repair the harness between
wheel speed sensor and AYC-ECU.
OK
Check the trouble symptom.
OK
Check the following connectors:
B-95, B-52, B-17, A-26, A-50, D-04,
D-14, D-19NG
Repair
OK
Check wheel bearing.NG
Replace
NG
Replace AYC-ECU.
OK
Check the trouble symptom.
OK
Check the following connector:
B-95NG
Repair
OK
Check wheel speed sensor output volt-
age. (Refer to P.27-37.)NGCheck wheel speed sensor and ABS
rotor. (Refer to Group 35B.)
Check wheel speed sensor for installa-
tion.NG
Repair
NG
Replace

REAR AXLE – Troubleshooting <AYC>27-10
Code No. 31: Steer sensor (ST-1, ST-2, ST-N) systemProbable cause
This code is output when any of the steer sensors ST-1, ST-2, and ST-N is open-circuited
or the steer sensor ground wire is open-circuited.
Defective steer sensor

Defective harness or connector

Defective AYC-ECU
OK
Replace the steer sensor.
NG
Check the harness between steer sen-
sor and AYC-ECU.NG
Repair
NG
Check and repair the harness between
speed sensor and AYC-ECU.
OK
Check the trouble symptom.
OK
Check the trouble symptom.
OK
Check the following connectors:
B-95, B-65, B-98NG
Repair
NG: Voltage remains
at 4 V or more.
Measure at B-98 steer sensor connec-
tor.

Disconnect the connector and
measure at the harness side.

Continuity across 3 and body
ground
OK:ConductingNGCheck the following connectors:
B-98, B-50NG
Repair
NG
Replace AYC-ECU.
OK
Check the trouble symptom.
Measure at B-95 AYC-ECU connector.

Connector connected.

Ignition switch: ON

Voltage across 4/5/17 and body ground.
OK:The voltage alternates between about
3 V and about 0.5 V when the steering
wheel is turned.OKCheck the following connector:
B-95NG
Repair
NG: Voltage alternates
between 4 V or
more and 0.5 V.NG: Voltage
remains
at 0 V.
Code No. 32: Steer sensor (ST-N) systemProbable cause
This code is output when the steering wheel is considered to be turned 40 or more
as determined with ST-1 and ST-2 with ST-N ON (LOW voltage).
Defective steer sensor

Defective harness or connector

Defective AYC-ECU
OK
Replace the steer sensor.
NG
Check the harness between steer sen-
sor and AYC-ECU.NG
Repair
OK
Replace AYC-ECU.
NG
Replace AYC-ECU.
OK
Check the trouble symptom.
OK
Check the trouble symptom.
NG
Measure at B-95 AYC-ECU connector.

Disconnect the connector and
measure at the harness side.

Ignition switch: ON

Turn steering wheel about 90 in
either direction from the straight-
ahead position.

Voltage across 17 and body
ground.
OK:No continuityNGCheck the following connectors:
B-95, B-65, B-98NG
Repair
Measure at B-95 AYC-ECU connector.

Connector connected.

Ignition switch: ON

Turn steering wheel about 90 in
either direction from the straight-
ahead position.

Voltage across 17 and body
ground.
OK:The voltage increases from
about 0.5 V or less to about
3 V.OKCheck the following connector:
B-95NG
Repair

REAR AXLE – Troubleshooting <AYC>27-11
Code No. 33: Steer sensor (ST-N) systemProbable cause
This code is output when the steering wheel is turned 400 or more in the same
direction with ST-N OFF (HIGH voltage).
Defective steer sensor

Defective harness or connector

Defective AYC-ECU
NG
Replace AYC-ECU.
Check the trouble symptom.
OK
Replace the steer sensor.
NG
Check the harness between steer sen-
sor and AYC-ECU.NG
Repair
OK
Replace AYC-ECU.
OK
Check the trouble symptom.
Measure at B-95 AYC-ECU connector.

Connector connected.

Ignition switch: ON

Turn steering wheel about 90 in
either direction from the straight-
ahead position.

Voltage across 17 and body
ground.
OK:The voltage increases from
about 0.5 V or less to about
3 V.NGCheck the following connectors:
B-95, B-65, B-98NG
Repair
Code No. 34: Steer sensor (ST-1, ST-2) systemProbable cause
This code is output if a turning condition is detected for a cumulative period of time
of 15 min. or more, during which there is no change in the steer sensor (ST-1, ST-2)
signals with the wheel speed 15 km/h or more.
Defective steer sensor

Defective harness or connector

Defective AYC-ECU
NG
Replace AYC-ECU.
Check the trouble symptom.
OK
Replace the steer sensor.
NG
Check the harness between steer sen-
sor and AYC-ECU.NG
Repair
OK
Replace AYC-ECU.
OK
Check the trouble symptom.
Measure at B-95 AYC-ECU connector.

Connector connected.

Ignition switch: ON

Voltage across 4/5 and body
ground
OK:The voltage alternates
between about 0.5 V and
about 3 V as the steering
wheel is turned.NGCheck the following connectors:
B-95, B-65, B-98NG
Repair

REAR AXLE – Troubleshooting <AYC>27-25
DATA LIST REFERENCE TABLE
The following items can be read by t01he MUT-

from the ECU input data.
Item No.
Check itemChecking requirementsNormal value
01Front-right wheel speedPerform a test run.Vehicle speeds
displayed on the
02Front-left wheel speed
displayed on the
speedometer and
MUTIIare identi03Rear-right wheel speedMUT-II are identi-
cal.
04Rear-left wheel speed
05Front-right wheel speed
(0.2 km/h)
06Front-left wheel speed (0.2
km/h)
07Rear-right wheel speed
(0.2 km/h)
08Rear-left wheel speed (0.2
km/h)
10Vehicle speed
11System voltageIgnition switch: ONBattery voltage
15TPS openingAccelerator pedal position/Igni-
tion switch: ON
Fully closed300 – 1000mV
tion switch: ON
Partially openGradually increases
from the above val-
ue.
Fully open4500 – 5000mV
19Longitudinal acceleration
sensor
Vehicle stands on level ground2.4 – 2.6V
sensor
Perform a test run.Reading fluctuates
up or down with 2.5V
as its center.
20Lateral acceleration sensorVehicle stands on level ground2.4 – 2.6V
Perform a test run.Reading fluctuates
up or down with 2.5V
as its center.
22Steering wheel operationSteering wheel turning direction
Ignition switch: ON90 deg. clock-
wiseR90 deg
90 deg counter-
clockwiseL90 deg
23Steering wheel turning
angular velocity
Steering wheel position
Ignition switch: ON
Not turned0 deg/s
angular velocityIgnition switch: ON
TurnedReading varies ac-
cording to turning
speeds.
45Idle position switchAccelerator pedal position
Ignition position: ON
Not depressedON
Ignition position: ON
DepressedOFF

REAR AXLE – Troubleshooting <AYC>27-26
Item No.Normal value Checking requirements Check item
46Steer sensor (ST-N)Steering wheel position
Ignition switch: ON
Neutral positionON
Ignition switch: ON
90 deg. turned
from neutral
positionOFF
47Steer sensor (ST-1)Steering wheel position: Turn slowly counterclock-
wise.
Ignition switch: ONON and OFF are
indicated alternate-
ly.
48Steer sensor (ST-2)Steering wheel position: Turn slowly clockwise.
Ignition switch: ONON and OFF are
indicated alternate-
ly.
50Stop lamp switchAccelerator pedal position
Ignition switch: ON
DepressedON
Ignition switch: ON
ReleasedOFF
56Pressure switchForced activation No.13 or
No.14 is being executed.Electric pump in
operationLow
Electric pump
not in operationHigh
59ABS monitorABS monitorON
ABS not in operationOFF

REAR AXLE – Troubleshooting <AYC>27-27
ACTUATOR TEST REFERENCE TABLE
The following items can be tested by driving the corresponding actuator forcibly using the MUT-II.
Item No.Check itemChecking requirementsNormal value
10Air bleedingSupply current to proportioning
valve in accordance with steering
angle to operate directional valve.No air is to be bled from the
bleeder plug on the torque transfer
differential.
11Oil level checkLet the directional valve operate to
left and right 20 times.To be checked by oil level in
reservoir tank.
12Electric pump operationLet the electric pump operate for 5
seconds.Operation sounds of the electric
pump are to be heard.
13Clutch operation (left)Let the directional valve operate to
supply the maximum pressure to the
left clutch.The operation conditions are to be
checked by the speed difference
between left and right rear wheels
with the wheels raised. For details,
refer to AYC Operation Check on
P.27-34.
14Clutch operation (right)Let the directional valve operate to
supply the maximum pressure to the
right clutch.The operation conditions are to be
checked by the speed difference
between left and right rear wheels
with the wheels raised. For details,
refer to AYC Operation Check on
P.27-34.
15Control OFFTurn off the electric pump relay to
deactivate AYC control.During the test run, some
differences are to be recognized in
running behaviors between when
the system is ON and when it is
OFF.
NOTE
(1) The actuator test is feasible only when the following requirements are all satisfied.

All of inputs from four wheel speed sensors show 20 km/h or lower.

No system failure is registered.

The steering angle is within ±30 deg. from the neutral position.
(2) The actuator test comes to an end when either of the following conditions is met since the forced
actuation is canceled.

Either of inputs from four wheel sensors shows higher than 20 km/h (with exception of Item
No.15 “Control OFF”).

Some trouble with the system is registered.

Forced activation time expires.

MUT-II is removed.

The clear key of MUT-II is operated.

REAR AXLE – Troubleshooting <AYC>27-28
CHECK AT AYC-ECU TERMINALS
TERMINAL VOLTAGE LISTING

The voltage is to be measured across each terminal and ground terminal.

Fig. below shows the arrangement of the terminals.
Terminal
No.Check itemCheck requirementNormally
1Lateral acceleration sensorIgnition switch: ON2.4 – 2.6 V
(horizontal position)
2Longitudinal acceleration
sensor ground
Lateral acceleration sensor
groundAt all times0 V
3Longitudinal acceleration
sensorIgnition switch: ON2.4 – 2.6 V
(horizontal position)
4Steer sensor (ST-2)Engine: Idle speed
Turn steering wheel slowly.0 V ↔ approx. 3 V
flashing
5Steer sensor (ST-1)Engine: Idle speed
Turn steering wheel slowly.0 V ↔ approx. 3 V
flashing
6*1FR wheel speedVehicle stationary1 V or less
Forward vehicle slowly.0 – 5 V
7*1FL wheel speedVehicle stationary1 V or less
Forward vehicle slowly.0 – 5 V
8*1RR wheel speedVehicle stationary1 V or less
Forward vehicle slowly.0 – 5 V
9*1FL wheel speedVehicle stationary1 V or less
Forward vehicle slowly.0 – 5 V
10Diagnosis selection inputWhen MUT-II is connected1 V or less
When MUT-II is disconnectedSystem voltage
11Stop lamp switchIgnition switch:
ON
Stop lamp switch: ONSystem voltage
ON
Stop lamp switch: OFF1 V or less
12*1ABS monitorWhen ABS monitor is activatedSystem voltage
When ABS monitor is deactivated1 V or less

REAR AXLE – Troubleshooting <AYC>27-29
Terminal
No.Normally Check requirement Check item
17Steer sensor (ST-N)Engine:
Idle speed
Steering wheel: Neutral position0.5 V or less
Idle speed
Steering wheel: Turned 90 from
neutral position2.5 – 3.5 V
18TPSIgnition switch:
ON
Accelerator pedal: Fully closed0.3 – 1.0 V
ON
Accelerator pedal: Fully open4.5 – 5.0 V
23Diagnosis data input/outputWhen MUT-II is connectedSerial communica-
tion with MUT-II
When MUT-II is disconnected1 V or less
24Idle position switchIgnition switch:
ON
Accelerator pedal: Fully closed2 V or less
ON
Accelerator pedal: Fully open4.5 – 5.0 V
25Accumulator pressure
switchIgnition switch:
ONAccumulator internal pressure:
Low2 V or less
Accumulator internal pressure:
HighSystem voltage
26ECU groundAt all times0 V
31AYC-ECU power supplyIgnition switch: ONSystem voltage
Ignition switch: OFF0 V
35AYC motor relayIgnition switch:
ON
When motor is energizedSystem voltage
ON
When motor is deenergized2 V or less
36AYC warning lampIgnition switch:
ON
When lamp is OFFSystem voltage
ON
When lamp is ON2 V or less
37Directional control valve
(right)
Ignition switch:
ON
Right clutch: ONSystem voltage
(right)ON
Right clutch: OFF0 V
38Proportioning valveIgnition switch:
ONAYC-ON0 V to system volt-
age
AYC-OFF0 V
39ECU backup power supplyAt all timesSystem voltage
45Directional control valve
(left)
Ignition switch:
ON
Left clutch: ONSystem voltage
(left)ON
Left clutch: OFF0 V
46ECU groundAt all times0 V
NOTE
*1: Indicates the vehicles with ABS.

REAR AXLE – On-vehicle Service <Vehicles with AYC>REAR AXLE – On-vehicle Service <Vehicles with AYC>27-34
BLEEDING
1. Lift up the vehicle.
2. Connect the MUT-II to the 16-pin diagnosis connector.
Caution
Before connecting or disconnecting the MUT-II,
always turn off the ignition switch.
3. Turn on the ignition switch.
4. Operate the MUT-II (Item No.10) to activate the hydraulic
unit forcibly.
NOTE
(1) The forced activation (air bleeding mode) will be
automatically canceled after 5 minutes operation. It
can also be canceled forcibly by operating the clear
key on the MUT-II.
(2) While this function is being disabled by the fail-safe
function, the forced activation of the hydraulic unit
can not be executed.
5. Remove the cap of the left bleeder screw on the torque
transfer differential and connect a vinyl hose.
6. Gradually turn the steering wheel clockwise from the
straight-ahead position. At this time, loosen the left bleeder
screw and check that fluid is discharged with air.
7. After air has been completely discharged, tighten the
bleeder screw.
Caution
While the system is being bled of air, add fluid as
necessary to ensure that it is left in the oil reservoir
during the entire procedure.
8. Repeat steps (6) and (7) two to three times until no air
bubbles are recognized in the fluid that comes out. Then,
tighten the bleeder screw to the specified torque.
Tightening torque: 9 Nm
9. Perform steps (5) through (8) for the right bleeder screw.
Note, however, that the steering wheel should be turned
counterclockwise.
10. After the system has been completely bled of air, check
for the fluid level. (Refer to P.27-33.)
Caution
If the system is not completely bled of air, the hydraulic
unit could generate noise, degrading pump durability.
AYC OPERATION CHECK
1. Lift up the vehicle.
2. Connect the MUT-II to the 16-pin diagnosis connector.
Caution
Before connecting or disconnecting the MUT-II, always
turn off the ignition switch.
3. Start the engine.
4. Operate the MUT-II with the transmission in 2nd or a
higher gear and check to ensure that the vehicle speed
is higher than 10 km/h using the Data List (Item 10).
Bleeder
screws Vinyl hose

REAR AXLE – On-vehicle Service <Vehicles with AYC>27-35
NOTE
(1) Hold the steering wheel in the neutral position.
(2) If the steering wheel is turned, it may happen that
the AYC system continues to operate (operation
sounds are heard from the torque transfer differential).
However, it does not mean a system failure. If such
a case is encountered, perform the following
operations with the steering wheel in the neutral
position to cancel the AYC function.

Disengage the clutch.

Set the transmission to neutral.

Stop the engine.
5. Operate the MUT-II (Item Nos.13 and 14) to activate
the torque transfer differential.
NOTE
(1) The forced activation (clutch operation mode) will be
automatically canceled after 1 minute operation.
It can also be canceled forcibly by operating the clear
key on the MUT-II.
(2) While this function is being disabled by the fail-safe
function, the forced activation of the torque transfer
differential can not be executed.
6. Operate the MUT-II to confirm that the several speeds
of the wheels are as shown below, using the Data List
(Item Nos.07 and 08).
<Forced activation Item No.13 is being executed>
The speed of left rear wheel is more than 2 km/h
higher than that of right rear wheel.
<Forced activation Item No.14 is being executed>
The speed of right rear wheel is more than 2 km/h
higher than that of left rear wheel.
NOTE
If the above requirements are not satisfied, the system
is probably failed. Check the hydraulic pressure.
HYDRAULIC PRESSURE CHECK
1. Lift up the vehicle.
2. Connect the MUT-II to the 16-pin diagnosis connector.
Caution
Before connecting or disconnecting the MUT-II,
always turn off the ignition switch.
3. Turn on the ignition switch.
4. Disconnect the joint between the hydraulic unit and the
hydraulic unit hose assembly. Connect the special tool
to the L port. To the R port, attach a blind plug or connect
the L port of the removed hydraulic unit hose assembly.
5. Operate the MUT-II (Item No.13) to activate the hydraulic
unit.
NOTE
(1) The forced activation (clutch left side operation check
mode) will be automatically canceled after 1 minute
operation.
It can also be canceled forcibly by operating the clear
key on the MUT-II.
MB991705
MD998330