GENERAL – Precautions Before Service00-15
PRECAUTIONS BEFORE SERVICE
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
1. Items to follow when servicing SRS
(1) Be sure to read GROUP 52B – Supplemental Restraint System (SRS).
For safe operations, please follow the directions and heed all warnings.
(2) Always use the designated special tools and test equipment.
(3) Wait at least 60 seconds after disconnecting the battery cable before doing any further work.
The SRS system is designed to retain enough voltage to deploy the air bag even after the battery
has been disconnected. Serious injury may result from unintended air bag deployment if work
is done on the SRS system immediately after the battery cable is disconnected.
(4) Never attempt to disassemble or repair the SRS components. (SRS air bag control unit, air bag
module and clock spring.) If faulty, replace it.
(5) Warnings labels must be needed when servicing and handling SRS components. Warning labels
are located in the following locations.
Sun visor
Glove box
SRS air bag control unit
Steering wheel
Steering gear and linkage
Air bag module
Clock spring
(6) Store components removed from the SRS in a clean and dry place.
The air bag module should be stored on a flat surface and placed so that the pad surface is
facing upwards.
(7) Be sure to deploy the air bag before disposing of air bag module or disposing of a vehicle equipped
with an air bag. (Refer to GROUP 52B – Air Bag Module Disposal Procedures.)
(8) Whenever you finish servicing the SRS, check the SRS warning lamp operation to make sure
that the system functions properly.
2. Observe the following when carrying out operations on place where SRS components are installed,
including operations not directly related to the SRS air bag.
(1) When removing or installing parts do not allow any impact or shock to the SRS components.
(2) SRS components should not be subjected to heat over 93C, so remove the SRS components
before drying or baking the vehicle after painting.
After re-installing them, check the SRS warning lamp operation to make sure that the system
functions properly.
MPI – Troubleshooting
Vehicle
speedInitial accel-
erator pedal
depression
NormalHesitation
Sag
Time
(Figure 1)(Figure 2)
Normal
Initial accel-
erator pedal
depression
IdlingStumble
TimeVehicle
speed
13-19
PROBLEM SYMPTOMS TABLE (FOR YOUR INFORMATION)
ItemsSymptom
StartingWon’t startThe starter is used to crank the engine, but there is no combustion within the
cylinders, and the engine won’t start.
Fires up and diesThere is combustion within the cylinders, but then the engine soon stalls.
Hard startingEngine starts after cranking a while.
Idling
stability
HuntingEngine speed doesn’t remain constant; changes at idle.
stability
Rough idleUsually, a judgement can be based upon the movement of the tachometer
pointer, and the vibration transmitted to the steering wheel, shift lever, body, etc.
This is called rough idle.
Incorrect idle speedThe engine doesn’t idle at the usual correct speed.
Engine stall
(Die out)The engine stalls when the foot is taken from the accelerator pedal, regardless
of whether the vehicles is moving or not.
Engine stall
(Pass out)The engine stalls when the accelerator pedal is depressed or while it is being
used.
DrivingHesitation, Sag“Hesitation” is the delay in response of the vehicle speed (engine speed) that
occurs when the accelerator is depressed in order to accelerate from the speed
at which the vehicle is now traveling, or a temporary drop in vehicle speed
(engine speed) during such acceleration. Serious hesitation is called “sag”.
(Refer to Figure 1.)
Poor accelerationPoor acceleration is inability to obtain an acceleration corresponding to the
degree of throttle opening, even though acceleration is smooth, or the inability
to reach maximum speed.
StumbleEngine speed increase is delayed when the accelerator pedal is initially
depressed for acceleration. (Refer to Figure 2.)
ShockThe feeling of a comparatively large impact or vibration when the engine is
accelerated or decelerated.
SurgeThis is repeated surging ahead during constant speed travel or during variable
speed travel.
KnockingA sharp sound like a hammer striking the cylinder walls during driving and which
adversely affects driving.
StoppingRun on
(“Dieseling”)The condition in which the engine continues to run after the ignition switch is
turned to OFF. Also called “Dieseling”.
MPI – Troubleshooting13-58
Item
No.Reference
page Inspection
procedure
No. Normal condition Inspection contents Inspection
item
22Crank angle
sensorEngine: Cranking
Tachometer:
ConnectedCompare the engine
speed readings on
the tachometer and
the MUT-II.Accord––
Engine: Idling
Idle position
switch: ONWhen engine
coolant temperature
is –20C1,300 – 1,500 rpm
When engine
coolant temperature
is 0C1,300 – 1,500 rpm
When engine
coolant temperature
is 20C1,300 – 1,500 rpm
When engine
coolant temperature
is 40C1,150 – 1,350 rpm
When engine
coolant temperature
is 80C750 – 950 rpm
25Barometric
pressure
Ignition switch: ONAt altitude of 0 m101 kPaCode No.
25
13-14
pressure
sensor
At altitude of 600 m95 kPa
25
At altitude of 1,200 m88 kPa
At altitude of 1,800 m81 kPa
26Idle position
switchIgnition switch: ON
Check by operating
accelerator pedal
Throttle valve:
Set to idle positionONProcedure
No. 2613-38
accelerator pedal
repeatedly.)Throttle valve:
Slightly openOFF*
27Power
steering fluid
pressure
Engine: IdlingSteering wheel
stationaryOFFProcedure
No. 2813-39
pressure
switchSteering wheel
turningON
28A/C switchEngine: Idling
(when A/C switch isA/C switch: OFFOFFProcedure
No. 2913-39
(Ctc
ON, A/C compressor
should be operating.)A/C switch: ONON
NOTE
*: The idle position switch normally turns off when the voltage of the throttle position sensor is 50 –
100 mV higher than the voltage at the idle position. If the throttle position switch turns back on
after the throttle valve has opened, the idle position switch and the throttle position sensor need
to be adjusted.
MPI – Troubleshooting13-64
Terminal
No.Normal condition Check condition (Engine condition) Check item
20Radiator fan motor
relay (HI)
Radiator fan not operating (coolant temperature:
95C or below)System voltage
105C or above)0 – 3 V
21Fan motor relay (LOW)
below)System voltage
Fan at low speed (coolant temperature: 95 – 100C)0 – 3 V
21Radiator fan motor
relay (LOW)
Radiator fan not operating (coolant temperature:
95C or below)System voltage
– 105C)0 – 3 V
22A/C relayEngine: Idling
A/C switch: OFF to ON (Compressor is being
driven.)System voltage, or 6
V or more instanta-
neously to 0 – 3 V
32A/C condenser fan
motor relay (HI)
A/C condenser fan not operating (A/C switch: ON,
coolant temperature: 105C or below)System voltage
coolant temperature: 105C or above)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.
34A/C condenser fan
motor relay (LOW)
A/C condenser fan not operating (A/C switch: OFF,
coolant temperature: 105C or below)System voltage
coolant temperature: 105C or above)0 – 3 V
36Engine warning lampIgnition switch: OFF → ON0 – 3 V → System
voltage (After several
seconds have
elapsed)
37Power steering fluid
pressure switchEngine: Idling after
warming upWhen steering wheel is
stationarySystem voltage
When steering wheel is
turned0 – 3 V
38Control relayIgnition switch: OFFSystem 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 system
voltage (After several
seconds have
elapsed)
REAR AXLE – Special Tools / Troubleshooting
MB990925
Brass bar
Bar (one-touch type)Toolbox
Installer adapter
Tool number (MB990925)O.D. mmTool number (MB990925)O.D. mm
AMB99092639.0AMB99093363.5
MB99092745.0MB99093467.5
MB99092849.5MB99093571.5
MB99092951.0MB99093675.5
MB99093054.0MB99093779.0
MB99093157.0BMB990938–
MB99093261.0CMB990939–
TROUBLESHOOTING
BASIC TROUBLESHOOTING CONDITIONS
Refer to Group 00 – How to Use Troubleshooting / Inspection Service Points.
NOTE
Before starting the troubleshooting procedure, make sure that the following items have been checked
okay.
The correct steering wheel has been properly installed in the neutral position of the steering column
shaft.
Tire and wheel sizes are correct with correct specifications. Inflation pressure, balance, and wear
conditions are okay.
Wheel alignment is correct.
The engine, suspension, and other parts have not been remodeled so as to affect the AYC system.
DIAGNOSIS FUNCTION
READING THE DIAGNOSIS CODE
Read the diagnosis code using an MUT-II tester or the AYC warning lamp.
(Refer to Group 00 – How to Use Troubleshooting / Inspection Service Points.)
ERASING THE DIAGNOSIS CODE
Refer to Group 00 – How to Use Troubleshooting / Inspection Service Points.
REAR AXLE – Troubleshooting
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: ON
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?YESGroup 35* – Refer to Troubleshooting
Are correct tires mounted on all four
wheels?NO
Repair
NG
Repair
NO
Repair
NOCheck and repair the harness between
wheel 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 wheel speed sensor output volt-
age. (Refer to p. 27-37.)NGCheck wheel speed sensor and ABS
rotor. (Refer to Group 35B.)
YES
Check Wheel speed sensor for instal-
lation.NG
Repair
Are correct tires mounted on all four
wheels?
NG
Replace
REAR AXLE – Troubleshooting
Code No. 31: Steer sensor (ST-1, ST-2, ST-N) systemProbable 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.Defective steer sensor
Defective harness or connector
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-98NG
Repair
NG: Voltage remains
at 4 V or more.
Measure at B-98 steer sensor connec-
tor.
Disconnect the connector and
measure at the harness side.
Continuity across 3 and body
ground
OK:ConductingNGCheck the following connectors:
B-98, B-50NG
Repair
NG
Replace AYC-ECU.
OK
Check the trouble symptom.
Measure at B-95 AYC-ECU connector.
Connector connected.
Ignition switch: ON
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.OKCheck the following connector:
B-95NG
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) systemProbable 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).Defective steer sensor
Defective harness or connector
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.
Disconnect the connector and
measure at the harness side.
Ignition switch: ON
Turn steering wheel about 90 in
either direction from the straight-
ahead position.
Voltage across 17 and body
ground.
OK:No continuityNGCheck the following connectors:
B-95, B-65, B-98NG
Repair
Measure at B-95 AYC-ECU connector.
Connector connected.
Ignition switch: ON
Turn steering wheel about 90 in
either direction from the straight-
ahead position.
Voltage across 17 and body
ground.
OK:The voltage increases from
about 0.5 V or less to about
3 V.OKCheck the following connector:
B-95NG
Repair
REAR AXLE – Troubleshooting
Code No. 33: Steer sensor (ST-N) systemProbable cause
This code is output when the steering wheel is turned 400 or more in the same
direction with ST-N OFF (HIGH voltage).Defective steer sensor
Defective harness or connector
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.
Connector connected.
Ignition switch: ON
Turn steering wheel about 90 in
either direction from the straight-
ahead position.
Voltage across 17 and body
ground.
OK:The voltage increases from
about 0.5 V or less to about
3 V.NGCheck the following connectors:
B-95, B-65, B-98NG
Repair
Code No. 34: Steer sensor (ST-1, ST-2) systemProbable 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.Defective steer sensor
Defective harness or connector
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.
Connector connected.
Ignition switch: ON
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.NGCheck the following connectors:
B-95, B-65, B-98NG
Repair