NISSAN TERRANO 2002 Service Repair Manual

G SENSOR
The G sensor analyses deceleration during braking to determine whether the vehicle is being driven on a road
with low surface resistance () (snow-covered road, etc.). The ABS control unit uses the signal from the
deceleration sensor to compensate for road surface conditions when controlling the braking operation.
NBR136
ANTI-LOCK BRAKE SYSTEM
System Description (Cont'd)
BR-39

ACTUATOR AND ELECTRIC UNIT
The actuator and electric unit contains:
IAn electric motor and pump
ITwo relays
ISix solenoid valves, each inlet and outlet for
Ð LH front
Ð RH front
Ð Rear
IABS control unit
These components control the hydraulic circuit. The ABS control
unit directs the actuator to increase, hold or decrease hydraulic
pressure to all or individual wheels. The ABS actuator and electric
unit cannot be disassembled and has to be serviced as an assem-
bly.
YBR299
ANTI-LOCK BRAKE SYSTEM
System Description (Cont'd)
BR-40

ABS actuator operation
Inlet solenoid
valveOutlet solenoid
valve
Normal brake operation OFF (Open) OFF (Closed)Master cylinder brake fluid pressure is directly trans-
mitted to caliper via the inlet solenoid valve.
ABS operationPressure hold ON (Closed) OFF (Closed)Hydraulic circuit is shut off to hold the caliper brake
fluid pressure.
Pressure
decreaseON (Closed) ON (Open)Caliper brake fluid is sent to reservoir via the outlet
solenoid valve. Then it is pushed up to the master
cylinder by pump.
Pressure
increaseOFF (Open) OFF (Closed)Master cylinder brake fluid pressure is transmitted to
caliper.
ANTI-LOCK BRAKE SYSTEM
System Description (Cont'd)
BR-41

Removal and Installation
CAUTION:
Be careful not to damage sensor edge and sensor rotor teeth.
When removing the front or rear wheel hub assembly, discon-
nect the ABS wheel sensor from the assembly and move it
away.
FRONT WHEEL SENSOR
REAR WHEEL SENSOR
NBR122
SBR399D
ANTI-LOCK BRAKE SYSTEM
BR-42

FRONT SENSOR ROTOR
Removal
1. Remove the drive shaft and rear wheel hub. Refer to ªFront axle
Ð drive shaftº in FA section and ªRear axleº in RA section.
2. Remove the sensor rotor using suitable puller, drift and bear-
ing replacer.
Installation
Install the sensor rotor. For front sensor rotor, use hammer and
wooden block. For rear sensor rotor, use suitable drift and press.
IAlways replace sensor rotor with new one.
YBR295
YBR296
ANTI-LOCK BRAKE SYSTEM
Removal and Installation (Cont'd)
BR-43

REAR SENSOR ROTOR
Removal
IRemove the sensor rotor using Tool.
Installation
Install the sensor rotor using suitable drift and press.
IAlways replace sensor rotor with new one.
IPay attention to the direction of front sensor rotor as shown in
figure.
CONTROL UNIT
Location: Built-in ABS actuator.
When disconnecting the harness connector, pull the lever as
shown in figure.
G SENSOR
Always replace G sensor if bumped or dropped. Otherwise,
performance characteristics of G sensor will be changed,
which in turn alters ABS control performance characteristics.
SBR401D
SBR402D
NBR212
NBR127
ANTI-LOCK BRAKE SYSTEM
Removal and Installation (Cont'd)
BR-44

ACTUATOR
Removal
1. Disconnect battery cable.
2. Drain brake fluid. Refer to BR-5.
3. Unlock the slider then disconnect the electrical harness con-
nectors from ABS control unit.
4. Identify each brake pipe with corresponding actuator port hole
and mark them accordingly.
5. Disconnect brake pipes and move them away from actuator. Do
not force brake pipes so as to kink them or bend them exces-
sively.
Ensure that brake fluid does not come into contact with
any parts.
YBR299
ANTI-LOCK BRAKE SYSTEM
Removal and Installation (Cont'd)
BR-45

6. Loosen/remove mounting nuts between actuator and bracket.
Installation
CAUTION:
After installation, pay attention to the following points:
IRefill brake fluid and bleed air. Refer to ªCHECK AND
ADJUSTMENTº, BR-5 and ªBleeding Brake Systemº,
ªBRAKE HYDRAULIC LINEº, BR-8, respectively.
1. Install actuator on bracket without tightening fixings.
2. Assemble brake tubes to actuator without tightening tube nuts.
Ensure that correct tubes are connected to each port.
3. Fully tighten actuator and bracket fixings to specified torque.
4. Fully tighten flare nuts to specified torque, BR-9.
5. Secure ABS control unit harness connector and battery cable.
ANTI-LOCK BRAKE SYSTEM
Removal and Installation (Cont'd)
BR-46

How to Perform Trouble Diagnoses for Quick
and Accurate Repair
INTRODUCTION
The ABS system has an electronic control unit to control major
functions. The control unit accepts input signals from sensors and
uses this data to compute control characteristics to instantly drive
the actuators. It is essential that both kinds of signal are accurate
and stable. It is also important to check for conventional brake
system problems: such as air leaks in booster lines, lack of brake
fluid, or other problems with the brake system.
It is much more difficult to diagnose a problem that occurs intermit-
tently rather than catastrophically. Most intermittent problems are
caused by poor electric connections or faulty wiring. In this case,
careful checking of suspicious circuits may help prevent the
replacement of good parts.
A visual check may not be sufficient to determine the cause of the
problems, so a road test should also be conducted.
Before undertaking actual checks, take a few minutes to talk with
a customer who approaches with an ABS complaint. The customer
is a very good source of information on such problems; especially
intermittent ones. Through the talks with the customer, find out what
symptoms are present and under what conditions they occur.
Start your diagnosis by looking for ªconventionalº problems first.
This is one of the best ways to troubleshoot brake problems on an
ABS controlled vehicle.
SEF233G
SEF234G
TROUBLE DIAGNOSES
BR-47

Component Parts and Harness Connector
Location
YBR264
TROUBLE DIAGNOSES
BR-48