1998 MITSUBISHI LANCER EVOLUTION IV battery

REAR AXLE – Sensor Relay / AYC-ECU27-53
INSPECTION
1. LONGITUDINAL AND LATERAL ACCELERATION
SENSOR CHECK
Refer to GROUP 35B – Acceleration Sensor.
2. AYC RELAY CONTINUITY CHECK
Battery voltageTerminal No.
1345
When not energized
When energized
AYC-ECU
REMOVAL AND INSTALLATION
Pre-removal and Post-installation Operation
Front Floor Console Removal and Installation
Unit: Nm {kgf
m}
5 {0.5}
AYC-ECU
5 {0.5}

ABS – Troubleshooting35B-5
Code No.16: ABS-ECU power supply system (abnormal
voltage drop or rise)Probable cause
This code is output if the ABS-ECU or valve relay power supply voltage drops below
or rises above the rated values.
The valve relay power supply voltage is detected based on the voltage in the valve
relay monitor line.
Malfunction of battery

Malfunction of wiring harness or connector

Malfunction of valve relay

Malfunction of ABS-ECU
Caution
If battery voltage drops or rises during inspection, this code will be output as well, making it
impossible to obtain correct diagnostic results.
Before carrying out the following inspection, check the battery level, and refill it if necessary.
OK
Replace ABS-ECU.
OK
Replace the ABS-ECU.
OK
Check the trouble symptom.NGCheck the harness wire, and repair
if necessary.

Between ignition switch and
ABS-ECU
OK
Check the trouble symptom.NGCheck the harness wire, and repair
if necessary.

Between general-purpose fuse
No. 6 and valve relay
NG
Repair
OK
Check the harness wire for short
circuit, and repair if necessary.

Between valve relay and hydraulic
unit

Between valve relay and motor
relayNG
Repair OK
NG
Check the harness wire, and repair
if necessary.

Between valve relay and ABS-ECUNG
Repair
OK
Check the trouble symptom.
OK
Check the trouble symptom.NGCheck the harness wire, and repair
if necessary.

Between general-purpose fuse
No. 6 and valve relay
OK
Measure at the ABS-ECU connector
B-25.

Connector connected

Ignition switch: ON
(1) Voltage between 37 and body
ground
OK:Battery voltage
(2) Voltage between 48 and body
ground
OK:Battery voltage(1) NGCheck the following connectors:
A-76, B-25NG
Repair
(2) NG
Check the following connectors:
A-76, B-25NG
Repair
OK
Check the valve relay.NG
Replace
OK
Check the trouble symptom.NGCheck the harness wire, and repair
if necessary.

Between fusible link No. 8 and
valve relay
OK
Measure at the valve relay connector
A-76.

Disconnect the connector, and
measure at the harness side
connector.

Ignition switch: ON
(1) Voltage between 6 and body
ground
OK:Battery voltage
(2) Voltage between 2 and body
ground
OK:Battery voltage(1) NGCheck the following connector:
A-76NG
Repair
(2) NGCheck the following connector:
A-76NG
Repair
Measure at the ABS-ECU connector
B-24.

Disconnect the connector, and
measure at the harness side
connector.

Start the engine.

Voltage between 13 and body
ground
OK:Battery voltageNGCheck the following connectors:
B-24, B-52, B-74, B-76NG
Repair

ABS – TroubleshootingABS – Troubleshooting35B-6
Code No. 27: AYC monitor system (defective AYC)Probable cause
This code is output when the AYC monitor signal becomes faulty.
Defective AYC-ECU

Defective ABS-ECU

Defective harness or connector
OK
Replace the ABS-ECU.
OK
MUT-II data list
AYC signal
OKOFF to be displayed when the
engine runs at idle with the
vehicle stationary.NGReplace AYC-ECU.
OK
Check the harness between ABS-ECU
and AYC-ECU.NG
Repair
Check the following connectors:
B-25, B-96NG
Repair
Code No. 32: Acceleration sensor (longitudinal accelera-
tion) circuit systemProbable cause
This code is output under either of the following conditions:

The output from the acceleration sensor (longitudinal acceleration) becomes 0.5
V or less, or 4.5 V or more.

The acceleration sensor (longitudinal acceleration) harness is open- or
short-circuited.
Defective acceleration sensor (longitudinal accelera-
tion)

Defective harness or connector

Defective ABS-ECU
OK
Check the trouble symptom.NGReplace ABS-ECU.
OK
Check the trouble symptom.NGCheck and repair the harness between
acceleration sensor (longitudinal
acceleration) and ABS-ECU.
OK
Check the trouble symptom.NGCheck and repair the harness between
general-purpose fuse No. 6 and
acceleration sensor (longitudinal
acceleration).
OK
Replace ABS-ECU.
OK
Check the following connector:
B-24NG
Repair
OK
Measure at B-24 ABS-ECU connector.

Connect the connector.

Ignition switch: ON

Voltage across 4 and 17
OK:2.4 – 2.6 V
(horizontal position)NGCheck the following connectors:
B-24, D-20, B-52NG
Repair
NG
Check the harness between accelera-
tion sensor (longitudinal acceleration)
and ABS-ECU.NG
Repair
OK
Check the trouble symptom.
OK
Check the valve relay.NG
Replace
(1) NGCheck the following connectors:
D-20, B-49, B-75NG
Repair
Check the following connector:
D-20, B-49, B-75NG
Repair
(2) NG
Measure at D-20 acceleration sensor
(longitudinal acceleration) connector.

Disconnect the connector and
measure at the harness side.

Ignition switch: ON
(1) Voltage across 1 and body ground
OK:Battery voltage
(2) Continuity across 3 and body
ground
OK:Conducting

ABS – Troubleshooting35B-7
Code No.33: Stop lamp switch system (open circuit or
stop lamp stays ON)Probable cause
This code is output, if the stop lamp switch is continuously on for 15 minutes or
more.
Malfunction of stop lamp switch

Malfunction of wiring harness or connector

Malfunction of ABS-ECU
OK
Check the trouble symptom.NGCheck the harness wire, and repair
if necessary.

Between dedicated fuse No. 11
and ABS-ECU
OK
Check the trouble symptom.NGReplace the ABS-ECU.
OK
Check the trouble symptom.NGCheck the harness wire, and repair
if necessary.

Between stop lamp switch and
ABS-ECU
OK
Check the following connectors:
B-15, B-21, B-25, B-32, B-65NG
Repair
OK
Check the following connector:
B-25NG
Repair
YES
Measure at the ABS-ECU connector
B-25.

Disconnect the connector, and
measure at the harness side
connector.

Stop lamp switch: ON

Voltage between 34 and body
ground
OK:Battery voltageNG
Check the following connectors:
B-25, B-32, B-65NG
Repair
OK
Stop lamp switch checkNG
Repair
Does the stop lamp turn on and off
normally?NOStop lamp switch installation checkNG
Repair
Code No. 41, 42, 43, 44: Solenoid valve systemProbable cause
ABS-ECU monitors the solenoid valve energization circuit at all times. This code is
output when no current flows through the solenoid even when ABS-ECU energizes
it or when current continues flowing through the solenoid even when ABS-ECU
deenergizes it, which is considered to be attributable to an open- or short-circuited
solenoid coil or open- or short-circuited harness.
Defective hydraulic unit

Defective harness or connector

Defective ABS-ECU
OK
Replace the ABS-ECU.
OK
Check the trouble symptom.NGCheck the harness between hydraulic
unit (solenoid valve) and ABS-ECU.NG
Repair
OK
Check the trouble symptom.NGCheck and repair the harness between
hydraulic unit and valve relay.
OK
Check the following connectors:
A-21, B-24, B-25NG
Repair
OK
Measure at A-22 hydraulic unit connec-
tor and A-76 valve relay connector.

Disconnect the connector and
measure at the harness side.

Continuity across the following
terminals
Hydraulic Valve relay
unit side side
11–3
OK:Battery voltageNGCheck the following connectors:
A-22, A-76NG
Repair
Check the solenoid valve.NGReplace the hydraulic unit.

ABS – Troubleshooting35B-8
Code No. 51: Valve relay systemProbable cause
This code is output under any of the following conditions:

The solenoid valve power is not supplied when ABS-ECU attempts to turn ON
the valve relay as part of the initial check when the ignition switch is turned ON.

The solenoid valve power remains supplied when ABS-ECU attempts to turn OFF
the valve relay as part of the initial check when the ignition switch is turned ON.

The solenoid valve power is not supplied while the valve relay remains ON under
normal conditions.
Defective ABS valve relay

Defective harness or connector

Defective ABS-ECU
NOTE
In the diagnosis code reading by means of the ABS warning lamp, this code is output in addition to
the actual diagnosis code since the valve relay connector is disconnected.
If the ABS warning lamp turns ON even when the spot represented by the diagnosis code output in
addition to this code has been repaired, and if no diagnosis code other than No. 51 is output, then
the valve relay system is probably defective. Make the following checks.
OK
Check the trouble symptom.NGCheck and repair the harness between
general-purpose fuse No. 6 and valve
relay.
NG
Replace the ABS-ECU.
OK
Check the trouble symptom.
OK
Check the trouble symptom.NGCheck and repair the harness between
valve relay and ABS-ECU.
OK
Check the following connectors:
A-76, B-25NG
Repair
OK
Measure at A-76 valve relay connector
and B-25 ABS-ECU connector.

Disconnect the connector and
measure at the harness side.

Continuity across the following
terminals
OK:Conducting
Valve relay ABS-ECU
side side
3–48
5–37NGCheck the following connectors:
A-76, B-25NG
Repair
OK
Check the trouble symptom.NGCheck and repair the harness between
fusible link No. 8 and valve relay.
OK
Measure at A-76 valve relay connector.

Disconnect the connector and
measure at the harness side.

Ignition switch: ON
(1) Voltage across 6 and body ground
(2) Voltage across 2 and body ground
OK:Battery voltage(1) NGCheck the following connector:
A-76NG
Repair
(2) NG
Check the following connector:
A-76NG
Repair
Check the valve relay.NG
Replace

ABS – Troubleshooting35B-9
Code No. 53: Motor relay systemProbable cause
This code is output under any of the following conditions:

No signals are input to the motor monitor when the motor relay is ON (motor
does not run, etc.).

A signal is being input to the motor monitor for 3 sec. or more when the motor
relay is OFF (motor continues running, etc.).

The motor relay is inoperative.
Defective motor relay

Defective harness or connector

Defective hydraulic unit

Defective ABS-ECU
Caution
(1) If the motor relay contacts fuse, the motor continues running even when the ignition switch
is turned OFF. In this case, immediately remove fusible link No. 8 (60 A) or disconnect the
A-22 connector or A-77 motor relay connector of the hydraulic unit. Overloading the motor
results in a rundown battery.
(2) Driving the motor through actuator test runs down the battery. After the test, run the engine
for some while.
OK
Check the trouble symptom.NGCheck and repair the harness between
fusible link No. 8 and motor relay.
OK
Check the trouble symptom.NGCheck and repair the harness between
motor relay and hydraulic unit.
OK
Check the trouble symptom.NGCheck and repair the harness between
motor relay and ABS-ECU motor
monitor terminal No. 49.
OK
Check the motor for operation.NGReplace ABS-ECU.
OK
Check the following connectors:
A-22, A-77, B-25NG
Repair
OK
Check the motor for operation.NGReplace the hydraulic unit.
OK
Measure at A-77 motor relay connector
and B-25 ABS-ECU connector.

Disconnect the connector and
measure at the harness side.

Continuity across the following
terminals
Motor relay ABS-ECU
side side
4–49
OK:ConductingNGCheck the following connectors:
A-77, B-25NG
Repair
OK
Measure at A-77 motor relay connector
and A-22 hydraulic unit connector.

Disconnect the connector and
measure at the harness side.

Continuity across the following
terminals
Motor relay Hydraulic
side unit side
4–12
OK:ConductingNGCheck the following connectors:
A-22, A-77NG
Repair
OK
Measure at A-77 motor relay connec-
tor.

Disconnect the connector and
measure at the harness side.

Voltage across 5 and body ground
OK:Battery voltageNGCheck the following connector:
A-77NG
Repair
Check the motor relay.NGReplace the motor relay.

ABS – Troubleshooting35B-10
Code No. 71: Acceleration sensor (lateral acceleration)
systemProbable cause
This code is output under either of the following conditions:

The output from the acceleration sensor (lateral acceleration) becomes 0.5 V or
less, or 4.5 V or more.

The acceleration sensor (lateral acceleration) harness is open- or short-circuited.
Defective acceleration sensor (lateral acceleration)

Defective harness or connector

Defective ABS-ECU
OK
Check the trouble symptom.NGReplace ABS-ECU.
OK
Check the trouble symptom.NGCheck and repair the harness between
acceleration sensor (lateral accelera-
tion) and ABS-ECU.
OK
Check the trouble symptom.NGCheck and repair the harness between
general-purpose fuse No. 6 and
acceleration sensor (lateral accelera-
tion).
OK
Replace ABS-ECU.
OK
Check the following connector:
B-24NG
Repair
OK
Measure at B-24 ABS-ECU connector.

Connect the connector.

Ignition switch: ON

Voltage across 17 and 18
OK:2.4 – 2.6 V
(horizontal position)NGCheck the following connectors:
B-24, D-32, B-52NG
Repair
NG
Check the harness between accelera-
tion sensor (lateral acceleration) and
ABS-ECU.NG
Repair
OK
Check the trouble symptom.
OK
Check the acceleration sensor (lateral
acceleration). (Refer to P.35B-17.)NG
Replace
(1) NGCheck the following connectors:
D-32, B-49, B-75NG
Repair
Check the following connector:
D-32, B-49, B-75NG
Repair
(2) NG
Measure at D-32 acceleration sensor
(lateral acceleration) connector.

Disconnect the connector and
measure at the harness side.

Ignition switch: ON
(1) Voltage across 1 and body ground
OK:Battery voltage
(2) Continuity across 3 and body
ground
OK:Conducting

ABS – Troubleshooting35B-12
4. INSPECTION PROCEDURE FOR TROUBLE SYMPTOMS
INSPECTION PROCEDURE 1
When the ignition key is turned to “ON” (engine stopped),
the ABS warning lamp does not illuminate.
Probable cause
The ABS-ECU turns the valve relay ON → OFF → ON for initial checking when
it is powered ON. Accordingly, the ABS warning lamp illuminates twice even if the
circuit between the ABS warning lamp and ABS-ECU is faulty.
The cause may be an open circuit in the lamp power supply circuit, a blown lamp,
an open circuit between the ABS warning lamp and ABS-ECU or between the ABS
warning lamp and the valve relay.
Blown fuse

Burn out ABS warning lamp bulb

Malfunction of wiring harness or connector
OK
Check the trouble symptom.NGReplace the combination meter.
OK
Check the following connectors:
B-08, B-09NG
Repair
OK
Check the trouble symptom.NGCheck the harness wire, and repair
if necessary.

Between ignition switch and ABS
warning lamp
OK
Check the motor for operation.NGCheck the harness wire, and repair
if necessary.

Between ABS warning lamp and
ABS-ECU

Between ABS warning lamp and
valve relay
OK
Check the following connectors:
A-76, B-09, B-52NG
Repair
OK
Measure at the combination meter con-
nector B-09.

Disconnect the connector, and
measure at the combination meter
side connector.

Ignition switch: ON

ABS warning lamp condition when
terminal 12 is grounded.
OK:IlluminatesNGCheck whether the ABS warning lamp
bulb is burnt out.NG
OK
Measure at the combination meter con-
nector B-08.

Disconnect the connector and
measure at the harness side
connector.

Ignition switch: ON

Voltage between 42 and body
ground
OK:Battery voltageNGCheck the following connectors:
B-08, B-75, B-76NG
Repair
Fuse check
General-purpose fuse No.4NGReplace fuse after eliminating the
cause.
Replace the ABS warning lamp bulb.