1999 MITSUBISHI LANCER EVOLUTION VI ECU
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REAR AXLE – Troubleshooting
Code No. 41: TPS systemProbable cause
This code is output when the input from the throttle position sensor falls short of
0.2 V.Defective TPS
Defective harness or connector
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.
Connector connected.
Ignition switch: ON
Voltage across 18 and body ground
Fully open the throttle valve.
OK:4.5 – 5.0 VNGCheck the following connector:
B-95
Is the MPI diagnosis code No. 14 out-
put?YESRefer to GROUP 13A TROUBLE-
SHOOTING.
NG
Repair
Code No. 51: Longitudinal acceleration sensor systemProbable 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.Defective longitudinal acceleration sensor
Defective lateral acceleration sensor
Defective harness or connector
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.
NGReplace 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.
Disconnect the connector and
measure at the harness side.
Ignition switch: ON
Voltage across 1 and body ground
OK:System voltageNGCheck the following connectors:
D-20, D-32, B-49, B-75, B-76NG
Check and repair the harness between
acceleration sensor and AYC-ECU.
NG
Measure at D-20, D-32 acceleration
sensor connector.
Connector connected.
Ignition switch: ON
Voltage across 2 and body ground
OK:0.5 – 4.5 VOKCheck the following connectors:
D-20, D-32NG
Repair
Measure at B-95 AYC-ECU connector.
Connector connected.
Ignition switch: ON
Voltage across 1/3 and body
ground
OK:0.5 – 4.5 VOKCheck the following connector:
B-95NG
Repair
NG
Replace
Page 209 of 558
REAR AXLE – Troubleshooting
Code No. 52: Longitudinal acceleration sensor systemProbable 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.Defective longitudinal acceleration sensor
Defective harness or connector
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-95NG
Repair
OK
Measure at B-95 AYC-ECU connector.
Connector connected
Ignition switch: ON
Voltage across 3 and body ground
OK:2.4 V to 2.6 V (where vehicle
in horizontal position)NGCheck 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 systemProbable cause
This code is output under either of the following conditions:
Stop lamp switch remains ON for 15 min. or more.
There is an open-circuit in the harness between AYC-ECU and stop lamp switch.Defective stop lamp switch
Defective harness or connector
Defective AYC-ECU
NG
Replace AYC-ECU.
OK
Check the trouble symptom.
OK
Check the following connector:
B-95NG
Repair
OK
Measure at the B-95 AYC-ECU con-
nector.
Disconnect the connector and
measure at the harness side.
Voltage across 11 and body ground
Brake pedal not depressed.
OK:1 V or lessNGCheck and repair the harness between
AYC-ECU and stop lamp switch.
Check the stop lamp switch.NG
Replace
Page 210 of 558
REAR AXLE – Troubleshooting
Code No. 65: ABS monitor systemProbable cause
This code is output when ABS is considered to remain activated (motor relay remains
ON) for a continuous 1-min.-or-more period.
It is output also when there is an open-circuit in the harness between ABS motor
relay and AYC-ECU.Defective harness or connector
Defective AYC-ECU
OK
Replace AYC-ECU.
NG
Check the harness between ABS
motor relay and AYC-ECU.NG
Repair
OK
Check the trouble symptom.
Is the ABS diagnosis code output?YESRefer to Group 35B – Troubleshooting
NO
Check the following connector:
B-95NG
Repair
Code No. 71: Proportioning valve systemProbable cause
This code is output when the proportioning valve control circuit is open- or short-circuited.Defective proportioning valve
Defective harness or connector
Defective AYC-ECU
OK
Check and repair the harness between
proportioning valve and body ground.
OK
Check the trouble symptom.
OK
Measure at F-27 proportioning valve
connector.
Disconnect the connector and
measure at the harness side.
Continuity across 2 and body
ground
OK:ConductingNGCheck the following connectors:
F-27, F-30NG
Repair
Measure at F-27 proportioning valve
connector.
Disconnect the connector and
measure at the proportioning valve.
Resistance across 2 – 3
OK:4.7 Ω or lessNGReplace the hydraulic unit.
OK
Replace AYC-ECU.
NG
Check the harness between propor-
tioning valve and AYC-ECU.NG
Repair
OK
Check the trouble symptom.
OK
Check the following connectors:
B-96, B-94, D-06, F-30, F-27NG
Repair
Page 211 of 558
REAR AXLE – Troubleshooting
Code No. 72: Directional control valve (right) systemProbable cause
This code is output when the directional control valve (right) control circuit is open-
or short-circuited.Defective directional control valve (right)
Defective harness or connector
Defective AYC-ECU
OK
Check and repair the harness between
directional control valve (right) and
body ground.
OK
Check the trouble symptom.
OK
Replace AYC-ECU.
NG
Check the harness between directional
control valve (right) and AYC-ECU.NG
Repair
OK
Check the trouble symptom.
OK
Check the following connectors:
B-96, B-94, D-06, F-30, F-29NG
Repair
OK
Measure at F-29 directional control
valve (right) connector.
Disconnect the connector and
measure at the directional control
valve side.
Continuity across 1 and body
ground
OK:ConductingNGCheck the following connectors:
F-29, F-30NG
Repair
Measure at F-29 directional control
valve (right) connector.
Disconnect the connector and
measure at the directional control
valve side.
Resistance across 1 – 2
OK:19 – 21 Ω or lessNGReplace the hydraulic unit.
Page 212 of 558
REAR AXLE – Troubleshooting
Code No. 73: Directional control valve (left) systemProbable cause
This code is output when the directional control valve (left) control circuit is open-
or short-circuited.Defective directional control valve (left)
Defective harness or connector
Defective AYC-ECU
NG
Check and repair the harness between
directional control valve (left) and body
ground.
OK
Check the trouble symptom.
OK
Replace AYC-ECU.
NG
Check the harness between directional
control valve (left) and AYC-ECU.NG
Repair
OK
Check the trouble symptom.
OK
Check the following connectors:
B-96, B-94, D-06, F-30, F-28NG
Repair
OK
Measure at F-28 directional control
valve (left) connector.
Disconnect the connector and
measure at the directional control
valve side.
Continuity across 1 and body
ground
OK:ConductingNGCheck the following connectors:
F-28, F-30NG
Repair
Measure at F-28 directional control
valve (left) connector.
Disconnect the connector and
measure at the directional control
valve side.
Resistance across 1 – 2
OK:19 – 21 Ω or lessNGReplace the hydraulic unit.
Page 213 of 558
REAR AXLE – Troubleshooting
Code No. 81: AYC relay systemProbable cause
This code is output when the coil circuit of the AYC relay is open- or short-circuited.Defective AYC relay
Defective harness or connector
Defective AYC-ECU
NG
Check and repair the harness between
AYC relay and body ground.
OK
Check the trouble symptom.
OK
Replace AYC-ECU.
NG
Check the harness between AYC relay
and AYC-ECU.NG
Repair
NG
Check the trouble symptom.
OK
Check the following connectors:
B-96, B-126NG
Repair
OK
Measure at A-126 AYC relay connec-
tor.
Disconnect the connector and
measure at the harness side.
Continuity across 1 and body
ground
OK:ConductingNGCheck the following connector:
A-126NG
Repair
Check the AYC relay.
(Refer to P.27-42.)NGReplace the AYC relay.
Page 214 of 558
REAR AXLE – Troubleshooting
Code No. 82: Electric pump systemProbable 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.Low hydraulic oil level
Oil leak
Defective fusible link
Defective AYC relay
Defective harness or connector
Defective AYC motor
Defective accumulator pressure switch
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-32NG
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-126NG
Repair
YES
Add hydraulic oil.
Is the hydraulic oil level correct in the reservoir tank?
(Refer to P.27-33.)NOIs there a hydraulic oil leak?
Measure at A-126 AYC relay connector.
Disconnect the connector and measure at the harness side.
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 heardOKMeasure at F-31 accumulator pressure switch connector.
Disconnect the connector and measure at the harness side.
Ignition switch: ON
Voltage across 2 and body ground
OK:System voltage
YES
Is diagnosis code no. 81 output?YESCheck the AYC relay system. (Refer to P.27-17.)
NG
Check the following
connectors: B-95, B-94,
D-06, F-30, F-31NG
Repair
OK
Check AYC relay for
continuity.
(Refer to P.27-42.)
Check AYC motor for
operation.NG
Repair
Page 215 of 558
REAR AXLE – Troubleshooting
Code No. 83: Electric pump systemProbable 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.Defective accumulator pressure switch
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-30NG
Repair
NO
Measure at F-31 accumulator pressure
switch connector.
Disconnect the connector and
measure at the harness side.
Ignition switch: ON
(1) Voltage across 2 and body ground
OK:System voltage
(2) Continuity across 1 and body
ground
OK:ConductingOKReplace 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?YESCheck the proportioning valve
system (code no. 71).
(Refer to P.27-14.)
Check the directional control valve
(right) system (code no. 72).
(Refer to P.27-15.)
Check the directional control valve
(left) system (code no. 73).
(Refer to P.27-16.)
(1) NGCheck the following connectors:
B-95, B-94, D-06, F-30, F-31NG
Repair
Does the AYC motor continue turning
when the ignition switch is turned ON?YESCheck the AYC relay for continuity.
(Refer to P.27-42.)NG
Repair