Mitsubishi Lancer Evolution VI. Manual - part 54

REAR AXLE – 

Troubleshooting <AYC>

27-10

Code No. 31: Steer sensor (ST-1, ST-2, ST-N) system

Probable 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.

D

Defective steer sensor

D

Defective harness or connector

D

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-98

NG

Repair

NG: Voltage remains

at 4 V or more.

Measure at B-98 steer sensor connec-
tor.

D

Disconnect the connector and
measure at the harness side.

D

Continuity across 3 and body
ground
OK: Conducting

NG

Check the following connectors:
B-98, B-50

NG

Repair

NG

Replace AYC-ECU.

OK

Check the trouble symptom.

Measure at B-95 AYC-ECU connector.

D

Connector connected.

D

Ignition switch: ON

D

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.

OK

Check the following connector:
B-95

NG

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) system

Probable 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).

D

Defective steer sensor

D

Defective harness or connector

D

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.

D

Disconnect the connector and
measure at the harness side.

D

Ignition switch: ON

D

Turn steering wheel about 90

_

 in

either direction from the straight-
ahead position.

D

Voltage across 17 and body
ground.
OK: No continuity

NG

Check the following connectors:
B-95, B-65, B-98

NG

Repair

Measure at B-95 AYC-ECU connector.

D

Connector connected.

D

Ignition switch: ON

D

Turn steering wheel about 90

_

 in

either direction from the straight-
ahead position.

D

Voltage across 17 and body
ground.
OK: The voltage increases from

about 0.5 V or less to about
3 V.

OK

Check the following connector:
B-95

NG

Repair

REAR AXLE – 

Troubleshooting <AYC>

27-11

Code No. 33: Steer sensor (ST-N) system

Probable cause

This code is output when the steering wheel is turned 400

_

 or more in the same

direction with ST-N OFF (HIGH voltage).

D

Defective steer sensor

D

Defective harness or connector

D

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.

D

Connector connected.

D

Ignition switch: ON

D

Turn steering wheel about 90

_

 in

either direction from the straight-
ahead position.

D

Voltage across 17 and body
ground.
OK: The voltage increases from

about 0.5 V or less to about
3 V.

NG

Check the following connectors:
B-95, B-65, B-98

NG

Repair

Code No. 34: Steer sensor (ST-1, ST-2) system

Probable 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.

D

Defective steer sensor

D

Defective harness or connector

D

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.

D

Connector connected.

D

Ignition switch: ON

D

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.

NG

Check the following connectors:
B-95, B-65, B-98

NG

Repair

REAR AXLE – 

Troubleshooting <AYC>

27-12

Code No. 41: TPS system

Probable cause

This code is output when the input from the throttle position sensor falls short of
0.2 V.

D

Defective TPS

D

Defective harness or connector

D

Defective AYC-ECU

OK

Replace AYC-ECU.

NG

Check and repair the harness between
AYC-ECU and TPS.

OK

Check the trouble symptom.

NO

Measure at B-95 AYC-ECU connector.

D

Connector connected.

D

Ignition switch: ON

D

Voltage across 18 and body ground

D

Fully open the throttle valve.
OK: 4.5  – 5.0 V

NG

Check the following connector:
B-95

Is the MPI diagnosis code No. 14 out-
put?

YES

Refer to GROUP 13A TROUBLE-
SHOOTING.

NG

Repair

Code No. 51: Longitudinal acceleration sensor system

Probable cause

Code No. 56: Lateral acceleration sensor system

This code is output when the output from the acceleration sensor becomes 0.5 V
or less or 4.5 V or more.

D

Defective longitudinal acceleration sensor

D

Defective lateral acceleration sensor

D

Defective harness or connector

D

Defective AYC-ECU

NG

Replace the acceleration sensor.

OK

Check the trouble symptom.

OK

Check and repair the harness between
acceleration sensor and ignition
switch.

OK

Check the trouble symptom.

NG

Check and repair the harness between
acceleration sensor and AYC-ECU.

NG

Replace AYC-ECU.

OK

Check the following connectors:
D-20, D-32

OK

Check the trouble symptom.

OK

Check the trouble symptom.

NG: 4.5 V or more

Check the acceleration sensor. (Refer
to P.27-42.)

NG

Replace

NG: 0.5 V or less

Check at D-20, D-32 acceleration sen-
sor connector.

D

Disconnect the connector and
measure at the harness side.

D

Ignition switch: ON

D

Voltage across 1 and body ground
OK: System voltage

NG

Check the following connectors:
D-20, D-32, B-49, B-75, B-76

NG

Check and repair the harness between
acceleration sensor and AYC-ECU.

NG

Measure at D-20, D-32 acceleration
sensor connector.

D

Connector connected.

D

Ignition switch: ON

D

Voltage across 2 and body ground
OK: 0.5  – 4.5 V

OK

Check the following connectors:
D-20, D-32

NG

Repair

Measure at B-95 AYC-ECU connector.

D

Connector connected.

D

Ignition switch: ON

D

Voltage across 1/3 and body
ground
OK: 0.5  – 4.5 V

OK

Check the following connector:
B-95

NG

Repair

NG

Replace

REAR AXLE – 

Troubleshooting <AYC>

27-13

Code No. 52: Longitudinal acceleration sensor system

Probable cause

This code is output when the longitudinal acceleration exceeds a predetermined value
while the vehicle is running with both ABS and brakes being inactive.

D

Defective longitudinal acceleration sensor

D

Defective harness or connector

D

Defective AYC-ECU

NG

Check and repair the harness between
longitudinal acceleration sensor and
AYC-ECU.

OK

Check the trouble symptom.

NG

Replace AYC-ECU.

OK

Check the trouble symptom.

OK

Check the following connector:
B-95

NG

Repair

OK

Measure at B-95 AYC-ECU connector.

D

Connector connected

D

Ignition switch: ON

D

Voltage across 3 and body ground
OK: 2.4 V to 2.6 V (where vehicle

in horizontal position)

NG

Check the following connectors:
B-95, B-52, D-20

Check the acceleration sensor. 
(Refer to P.27-42.)

NG

Replace

NG

Repair

Code No. 61: Stop lamp switch system

Probable cause

This code is output under either of the following conditions:

D

Stop lamp switch remains ON for 15 min. or more.

D

There is an open-circuit in the harness between AYC-ECU and stop lamp switch.

D

Defective stop lamp switch

D

Defective harness or connector

D

Defective AYC-ECU

NG

Replace AYC-ECU.

OK

Check the trouble symptom.

OK

Check the following connector:
B-95

NG

Repair

OK

Measure at the B-95 AYC-ECU con-
nector.

D

Disconnect the connector and
measure at the harness side.

D

Voltage across 11 and body ground

D

Brake pedal not depressed.
OK: 1 V or less

NG

Check and repair the harness between
AYC-ECU and stop lamp switch.

Check the stop lamp switch.

NG

Replace