Mitsubishi Lancer Evolution VI. Manual - part 56

REAR AXLE – 

Troubleshooting <AYC>

27-18

Code No. 82: Electric pump system

Probable cause

This code is output if the pressure switch is not set to high-pressure position despite
the AYC-ECU’s command to drive the AYC relay for a given period of time.

D

Low hydraulic oil level

D

Oil leak

D

Defective fusible link

D

Defective AYC relay

D

Defective harness or connector

D

Defective AYC motor

D

Defective accumulator pressure switch

D

Defective AYC-ECU

OK

Replace AYC-ECU.

Check the harness
between AYC relay and
AYC motor, and between
AYC motor and body
ground.

NG

Replace

NG

OK

Check the trouble symptom.

OK

Check the following
connectors:
A-126, B-94, B-27, F-32

NG

Repair

OK

Replace AYC-ECU.

NG

Check the harness
between AYC-ECU and
accumulator pressure
switch.

NG

Repair

NG

Check and repair the har-
ness between fusible link
no. 10 and AYC relay.

OK

Check the trouble symp-
tom.

OK

Replace the hydraulic unit
for a defective accumula-
tor pressure switch.

NO

Repair the leak.

OK

Check the trouble symptom.

NG

Check the following
connector:  A-126

NG

Repair

YES

Add hydraulic oil.

Is the hydraulic oil level correct in the reservoir tank?  
(Refer to P.27-33.)

NO

Is there a hydraulic oil leak?

Measure at A-126 AYC relay connector.

D

Disconnect the connector and measure at the harness side.

D

Voltage across 5 and body ground
OK:  System voltage

NG

NO

MUT-

II

 Actuator test:

No. 12 Electric pump operation check

OK:  Pump operation sounds are heard

OK

Measure at F-31 accumulator pressure switch connector.

D

Disconnect the connector and measure at the harness side.

D

Ignition switch: ON

D

Voltage across 2 and body ground
OK: System voltage

YES

Is diagnosis code no. 81 output?

YES

Check the AYC relay system. (Refer to P.27-17.)

NG

Check the following
connectors:  B-95, B-94,
D-06, F-30, F-31

NG

Repair

OK

D

Check AYC relay for
continuity. 
(Refer to P.27-42.)

D

Check AYC motor for
operation.

NG

Repair

REAR AXLE – 

Troubleshooting <AYC>

27-19

Code No. 83: Electric pump system

Probable cause

This code is output if the pressure switch is not set to low-pressure position despite
the AYC-ECU’s command to change the driving force.

D

Defective accumulator pressure switch

D

Defective harness or connector

OK

Replace AYC-ECU.

NG

Check the harness between AYC-ECU
and accumulator pressure switch.

NG

Repair

OK

Check the trouble symptom.

NG

Check and repair the harness between
accumulator pressure switch and body
ground.

OK

Check the trouble symptom.

(2) NG

Check the following connectors:
F-31, F-30

NG

Repair

NO

Measure at F-31 accumulator pressure
switch connector.

D

Disconnect the connector and
measure at the harness side.

D

Ignition switch: ON

(1) Voltage across 2 and body ground

OK: System voltage

(2) Continuity across 1 and body

ground
OK: Conducting

OK

Replace the hydraulic unit for a defec-
tive accumulator pressure switch.

OK

Check and repair the harness between
AYC relay and AYC motor.

NO

Is diagnosis code no. 71, 72, or 73
output?

YES

D

Check the proportioning valve
system (code no. 71). 
(Refer to P.27-14.)

D

Check the directional control valve
(right) system (code no. 72). 
(Refer to P.27-15.)

D

Check the directional control valve
(left) system (code no. 73). 
(Refer to P.27-16.)

(1) NG

Check the following connectors:
B-95, B-94, D-06, F-30, F-31

NG

Repair

Does the AYC motor continue turning
when the ignition switch is turned ON?

YES

Check the AYC relay for continuity.
(Refer to P.27-42.)

NG

Repair

REAR AXLE – 

Troubleshooting <AYC>

27-20

5. INSPECTION CHART FOR TROUBLE SYMPTOMS

Trouble symptom

Inspection
procedure No.

Ref. page

Communication between MUT-

II

 and the whole system is not possible.

1

27-20

Communicatio between MUT-

II

 and AYC-ECU is not possible.

2

27-21

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

3

27-22

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

4

27-23

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

5

27-23

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

6

27-24

6. INSPECTION PROCEDURE FOR TROUBLE SYMPTOMS

INSPECTION PROCEDURE 1

Communication between MUT-

II

 and the whole system is

not possible.

Probable cause

The cause may be a malfunction of the power supply circuit or the ground circuit
of the diagnosis connector.

D

Defective diagnosis connector

D

Defective harness or connector

NG

Check and repair the harness between
power supply and diagnosis connector.

OK

Check the trouble symptom.

NG

Check and repair the harness between
body ground and diagnosis connector.

OK

Check the trouble symptom.

OK

Replace MUT-

II

.

Check the following connectors:
B-22, B-50

NG

Repair

OK

Measure at B-22 diagnosis connector.

D

Disconnect the connector and
measure at the harness side.

D

Continuity across 4/5 and body
ground
OK: Conducting

NG

Measure at B-22 diagnosis combina-
tion meter connector.

D

Voltage across 16 and body ground
OK: System voltage

NG

Check the following connectors:
B-22, B-49, B-75, B-73

NG

Repair

REAR AXLE – 

Troubleshooting <AYC>

27-21

INSPECTION PROCEDURE 2

Communication between MUT-

II

 and the AYC-ECU is not

possible.

Probable cause

The cause may be a malfunction of the AYC-ECU power supply circuit or an open
circuit in the diagnosis output circuit.

D

Blown fuse

D

Defective harness or connector

D

Defective AYC-ECU

NG

Check and repair the harness between
AYC-ECU and diagnosis connctor.

OK

Check the trouble symptom.

OK

Check the following symptom.

NG

Check and repair the harness between
ignition switch (IG

2

) and AYC-ECU.

OK

Check the trouble symptom.

OK

Replace AYC-ECU.

Check the following connectors:
B-96, B-94, B-49, B-75, B-76

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

Voltage across 31 and body ground
OK: System voltage

NG

Measure at B-22 diagnosis connector
and B-95 AYC-ECU connector.

D

Disconnect the connectors and
measure at the harness side.

D

Continuity across 1 of B-22 and
10 of B-95

D

Continuity across 7 of B-22 and
23 of B-95
OK: Conducting

NG

Check the following connectors:
B-95, B-65, B-22

NG

Repair

OK

Measure at B-95 and B-96 AYC-ECU
connectors.

D

Disconnect the connectors and
measure at the harness side.

D

Continuity across 26/46 and body
ground
OK: Conducting

NG

Check the following connectors:
B-95, B-96

NG

Replace

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

NG