1998 MITSUBISHI LANCER EVOLUTION IV warning light

MPI – Troubleshooting13-23
Terminal
No.Normal condition Check condition (Engine condition) Check item
21Fan motor relay (LOW)Fan not operating (coolant temperature: 90C or
below)Battery voltage
Fan at low speed (coolant temperature: 90 – 100C)0 – 3 V
22A/C relayEngine: Idling
A/C switch: OFF to ON (Compressor is being
driven.)Battery voltage, or 6 V
or more instanta-
neously to 0 – 3 V
33Alternator G terminalEngine: Warm, idle (radiator fan: OFF)
Headlamp: OFF to ON
Brake lamp: OFF to ON
Rear defogger switch: OFF to ONVoltage rises by 0.2 –
3.5 V.
36Engine warning lampIgnition switch: OFF → ON0 – 3 V → Battery
voltage (After several
seconds have
elapsed)
37Power steering fluid
pressure switchEngine: Idling after
warming upWhen steering wheel is
stationaryBattery voltage
When steering wheel is
turned0 – 3 V
38Control relayIgnition switch: OFFBattery voltage
Ignition switch: ON0 – 3 V
39Fuel pump relay No.2While engine is idling, suddenly depress the
accelerator pedal.Momentarily rises
slightly from 0 to 3 V.
40Exhaust temperature
warning lampIgnition switch: OFF to ON0 – 3 V to battery
voltage (After several
seconds have
elapsed)
41Alternator FR terminalEngine: Warm, idle (radiator fan: OFF)
Headlamp: OFF to ON
Brake lamp: OFF to ON
Rear defogger switch: OFF to ONVoltage drops by 0.2 –
3.5 V.
45A/C switchEngine: Idle speedTurn the A/C switch OFF0 – 3 V
Turn the A/C switch ON
(A/C compressor is oper-
ating)Battery voltage
60Oxygen sensor heater
(Evolution V only)
Engine: Idling0 – 3 V
(Evolution-V only)
Engine speed: 5,000 r/minBattery voltage
71Ignition switch-STEngine: Cranking8 V or more

REAR AXLE – Troubleshooting 27-9
Code No. 25: Wrong-diameter tireProbable cause
This code is output if the speed of any one of the four wheels exceeds a specified
level with respect to the average of the four wheel speed sensor outputs when the
steering wheel is in the straight-ahead position and the vehicle speed exceeds 20
km/h. At this time, the warning lamp does not light up.
Defective harness or connector

Defective AYC-ECU

Defective ABS-ECU

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: OK

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)OKCheck the following connector:
B-95
YES
Is ABS diagnosis code No. 15 output?YESTroubleshooting
Are correct tires mounted on all four
wheels?NO
Repair
NG
Repair

NG
Check and repair the harness between
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 speed sensor output voltage.
(Refer to p. 27-31.)NGCheck speed sensor and rotor.
YES
Check speed sensor for installation.NG
Repair
Are correct tires mounted on all four
wheels?NO
Repair
NG
Replace

REAR AXLE – Troubleshooting 27-21
5. INSPECTION CHART FOR TROUBLE SYMPTOMS
Trouble symptomInspection
procedure No.Ref. page
AYC warning lamp does not light up when the ignition key is turned to “ON” (engine
stationary).127-21
AYC warning lamp remains lit up after the engine has started.227-22
AYC is inoperative.
Unable to start or accelerate on slippery road surfaces.327-22
Rear tires are noisy during low-speed cornering.
Vehicle skews.427-23
6. INSPECTION PROCEDURE FOR TROUBLE SYMPTOMS
INSPECTION PROCEDURE 1
AYC warning lamp does not light up when the ignition key
is turned to “ON” (engine stationary).
Probable cause
The lamp power supply circuit is probably open-circuited, lamp bulb is out, or the
circuit between AYC warning lamp and AYC-ECU or AYC-ECU itself is defective.
Blown fuse

AYC warning lamp out

Defective harness or connector

Defective AYC-ECU
NG
Check and repair the harness between
ignition switch (IG
2) and AYC warning
lamp.
OK
Check the trouble symptom.
OK
Replace combination meter.
NG
Check the harness between AYC
warning lamp and AYC-ECU.NG
Repair
OK
Check the trouble symptom.OK
Replace AYC-ECU.
OK
Check the following connectors:
B-96, B-94, B-08NG
Repair
OK
Measure at B-96 AYC-ECU connector.

Disconnect the connector and
measure at the harness side.

Ignition switch: ON

Warning lamp when 36 is grounded
to body
OK:Lit upNGCheck the lamp bulb.NG
Replace
Measure at B-08 combination meter
connector.

Disconnect the connector and
measure at the harness side.

Ignition switch: ON

Voltage across 48 and body ground
OK:Battery voltageNGCheck the following connectors:
B-08, B-74, B-76NG
Repair

REAR AXLE – On-vehicle Service 27-32
Waveform Observation Points
SymptomProbable causeAction
Waveform amplitude is too small, or no
waveform.Defective speed sensorReplace sensor.
Waveform amplitude varies greatly. (No
problem ifthe smallest amplitude is 100
Excessive axle hub lateral and radial runoutReplace hub.
problem if the smallest amplitude is 100
mV or more)Poor AYC-ECU groundingRepair.
Noise on waveform or disturbed
waveform
Open-circuited sensorReplace sensor.
waveform
Open-circuited harnessRepair harness.
Improperly mounted speed sensorCorrect sensor installation.
Missing or collapsed rotor toothReplace rotor.
Caution
Since the speed sensor cable follows the movement of the front or rear suspension, it may be
open-circuited only when the vehicle is run on rough roads and not on ordinary road. The speed
sensor output voltage waveform should therefore be checked also by rocking the sensor harness
so that driving on rough roads may be simulated.
8. ACTION WHEN BATTERY RUNS OUT
When the engine is started using a booster cable where the
battery has completely run down and you attempt to start
the vehicle without waiting for the battery to recover a certain
charge, the engine can misfire and you just cannot start to
move it. In such cases, charge the battery sufficiently; or,
remove the AYC fusible link from the engine compartment
relay box to make AYC inactive before attempting to start
the vehicle. When the fusible link is removed, the AYC warning
lamp lights up. After the battery has been recharged, fit the
fusible link back again and start the engine to ensure that
the AYC warning lamp is off.AYC fusible link

CHASSIS ELECTRICAL – Headlamp54-33
TROUBLESHOOTING
DIAGNOSIS FUNCTION
INPUT SIGNAL INSPECTION POINTS
Refer to Group 00 – How to Use Troubleshooting / Inspection Service Points.
The lighting monitor buzzer does not sound even when
the ignition key is removed with the tail lamps or
headlamps ON and the driver’s side door open. [However,
the key reminder warning buzzer sounds when inserting
the key into the ignition key cylinder.
Probable cause
The cause is probably a malfunction of the lighting switch input circuit system or
a malfunction of ETACS-ECU or buzzer ECU. When the key reminder warning buzzer
is sounding, the lighting monitor warning buzzer does not sound even if the tail lamps
or headlamps are lit.
Malfunction of harness or connector

Malfunction of ETACS-ECU

Malfunction of buzzer ECU

MUT-II Pulse check
OK:MUT-II buzzer sounds once
when the lighting switch is
turned from OFF to TAIL or
HEAD.NG
Check the following connectors.
B-79Repair
OK
Check trouble symptom.NGOK
Replace the ETACS-ECU.

NG
Check the harness in the junction block.NG
Replace the ETACS-ECU or the buzzer
ECU.OKRepair NG

CHASSIS ELECTRICAL – Rear Combination Lamp54-42
REAR COMBINATION LAMP
TROUBLESHOOTING
For the troubleshooting of the lighting monitor warning buzzer, refer to P.54-33.
REAR COMBINATION LAMP
REMOVAL AND INSTALLATION
Caution: SRS
Before removal of air bag module and clock spring, refer to GROUP 52B – SRS Service Precautions and Air Bag
Module and Clock Spring.
2
1
3
1. Column switchRear combination lamp removal
steps
2. Rear end trim
3. Rear combination lamp
INSPECTION
LIGHTING SWITCH CONTINUITY CHECK
Switch positionTerminal No.
Connector BConnector A
5671
LIGHTING
SWITCH
OFF
SWITCHTAIL
HEAD
Connector A Connector B