1998 NISSAN PICK-UP ABS

BRAKE SYSTEM
SECTIONBR
CONTENTS
PRECAUTIONS AND PREPARATION..................... 1
Supplemental Restraint System (SRS) ``AIR
BAG'' (4WD models).............................................. 1
Supplemental Restraint System (SRS) ``AIR
BAG'' (2WD models).............................................. 1
Precautions for Brake System ............................... 1
Special Service Tools ............................................ 2
Commercial Service Tools ..................................... 2
CHECK AND ADJUSTMENT.................................... 3
Checking Brake Fluid Level ................................... 3
Checking Brake Line.............................................. 3
Changing Brake Fluid ............................................ 3
Bleeding Brake System ......................................... 4
BRAKE HYDRAULIC LINE....................................... 5
CONTROL VALVE..................................................... 7
Load Sensing Valve ............................................... 7
BRAKE PEDAL AND BRACKET............................ 10
Removal and Installation ..................................... 10
Inspection ............................................................. 11
Adjustment ........................................................... 11
MASTER CYLINDER............................................... 12
Removal ............................................................... 12
Disassembly ......................................................... 13
Inspection ............................................................. 13
Assembly.............................................................. 13
Installation ............................................................ 14
BRAKE BOOSTER.................................................. 15
On-vehicle Service ............................................... 15
Removal ............................................................... 15
Inspection ............................................................. 15
Installation ............................................................ 16
VACUUM HOSE...................................................... 17
Removal and Installation ..................................... 17Inspection ............................................................. 17
VACUUM PUMP...................................................... 19
Removal and Installation ..................................... 19
Inspection ............................................................. 19
FRONT DISC BRAKE............................................. 21
Pad Replacement ................................................ 21
Removal ............................................................... 22
Disassembly ......................................................... 23
Inspection - Caliper .............................................. 23
Inspection - Rotor ................................................ 23
Assembly.............................................................. 24
Installation ............................................................ 24
Brake Burnishing Procedure ................................ 24
REAR DRUM BRAKE............................................. 26
Removal ............................................................... 27
Inspection - Wheel Cylinder................................. 28
Wheel Cylinder Overhaul ..................................... 28
Inspection - Drum ................................................ 28
Inspection - Lining................................................ 28
Installation ............................................................ 28
PARKING BRAKE CONTROL................................ 30
Removal and Installation ..................................... 31
Inspection ............................................................. 31
Adjustment ........................................................... 31
ANTI-LOCK BRAKE SYSTEM................................ 32
Purpose ................................................................ 32
Operation ............................................................. 32
ABS Hydraulic Circuit .......................................... 32
System Components............................................ 33
System Description .............................................. 33
Removal and Installation ..................................... 35
TROUBLE DIAGNOSES......................................... 38
BR

How to Perform Trouble Diagnoses for Quick
and Accurate Repair ............................................ 38
Preliminary Check ................................................ 39
Component Parts and Harness Connector
Location................................................................ 40
Schematic/2WD Models....................................... 41
Wiring Diagram - ABS -/2WD LHD Models ......... 42
Wiring Diagram - ABS -/2WD RHD Models ........ 45
Schematic/4WD Models....................................... 48
Wiring Diagram - ABS -/4WD Models ................. 49
Self-diagnosis....................................................... 53
CONSULT ............................................................ 56
CONSULT Inspection Procedure......................... 57
Ground Circuit Check .......................................... 62
TROUBLE DIAGNOSES FOR
SELF-DIAGNOSTIC ITEMS.................................... 63
Diagnostic Procedure 1
(Wheel sensor or rotor)........................................ 63
Diagnostic Procedure 2 (ABS actuator
solenoid valve and solenoid valve relay)............. 65
Diagnostic Procedure 3 (Motor relay or motor) ... 67
Diagnostic Procedure 4 (Low voltage) ................ 69Diagnostic Procedure 5 (G sensor) ..................... 70
Diagnostic Procedure 6 (Control unit) ................. 71
TROUBLE DIAGNOSES FOR SYMPTOMS........... 72
Diagnostic Procedure 7
(ABS works frequently.) ....................................... 72
Diagnostic Procedure 8
(Unexpected pedal action) ................................... 73
Diagnostic Procedure 9
(Long stopping distance) ..................................... 73
Diagnostic Procedure 10
(ABS does not work.)........................................... 74
Diagnostic Procedure 11
(Pedal vibration and noise) .................................. 74
Diagnostic Procedure 12 (Warning lamp does
not come on when ignition switch is turned
ON.)...................................................................... 75
Diagnostic Procedure 13 (Warning lamp stays
on when ignition switch is turned ON.)................ 77
SERVICE DATA AND SPECIFICATIONS (SDS)... 78
General Specifications ......................................... 78
Inspection and Adjustment .................................. 80
When you read wiring diagrams:
lRead GI section, ``HOW TO READ WIRING DIAGRAMS''.
lSee EL section, ``POWER SUPPLY ROUTING'' for power distribution circuit.
When you perform trouble diagnoses, read GI section, ``HOW TO FOLLOW FLOW
CHART IN TROUBLE DIAGNOSES'' and ``HOW TO PERFORM EFFICIENT DIAGNOSIS
FOR AN ELECTRICAL INCIDENT''.

Bleeding Brake System
CAUTION:
lCarefully monitor brake fluid level at master cylinder
during bleeding operation.
lIf master cylinder is suspected to have air inside, bleed
air from master cylinder first. Refer to ``Installation'',
``MASTER CYLINDER'', BR-14.
lFill reservoir with new brake fluid DOT 3 or DOT 4*1.
Make sure it is full at all times while bleeding air out of
system.
lPlace a container under master cylinder to avoid spillage
of brake fluid.
lFor models with ABS, turn ignition switch OFF and dis-
connect ABS actuator connector or battery cable.
lBleed air in the following order.
a. LSV air bleeder
b. Left rear brake
c. Right rear brake
d. Left front brake
e. Right front brake
*1: Refer to MA section (``Fluids and Lubricants'', ``RECOM-
MENDED FLUIDS AND LUBRICANTS'').
1. Connect a transparent vinyl tube to air bleeder valve.
2. Fully depress brake pedal several times.
3. With brake pedal depressed, open air bleeder valve to
release air.
4. Close air bleeder valve.
5. Release brake pedal slowly.
6. Repeat steps 2 through 5 until clear brake fluid comes out of
air bleeder valve.
7. Tighten air bleeder to the specified torque.
:7-9N´m(0.7 - 0.9 kg-m, 61 - 78 in-lb)
SBR995
SBR419C
CHECK AND ADJUSTMENT
BR-4

Purpose
The Anti-Lock Brake System (ABS) consists of electronic and hydraulic components. It allows for control of
braking force so locking of the wheels can be avoided.
The ABS:
1) Improves proper tracking performance through steering wheel operation.
2) Eases obstacle avoidance through steering wheel operation.
3) Improves vehicle stability.
Operation
lWhen the vehicle speed is less than 10 km/h (6 MPH) this system does not work.
lThe Anti-Lock Brake System (ABS) has a self-test function. The system turns on the ABS warning lamp
for 1 second each time the ignition switch is turned ``ON''. After the engine is started, the ABS warning
lamp turns off. The system performs a test the first time the vehicle reaches 6 km/h (4 MPH). A
mechanical noise may be heard as the ABS performs this self-test. This is a normal part of the self-test
feature. If a malfunction is found during this check, the ABS warning lamp will stay on.
lWhile driving, a mechanical noise may be heard during ABS operation. This is a normal condition.
ABS Hydraulic Circuit
V1Inlet solenoid valve
V2Outlet solenoid valve
V3Pump
V4Motor
V5Inlet valve
V6Outlet valve
V7Bypass check valve
V8Damper
SBR316E
ANTI-LOCK BRAKE SYSTEM
BR-32

System Components
System Description
WHEEL SENSOR
The sensor unit consists of a gear-shaped sensor rotor and a
sensor element. The element contains a bar magnet around
which a coil is wound. The sensor is installed on the back of the
brake rotor and the front of the differential (2WD) or the back of
the rear brake drum (4WD). As the wheel rotates, the sensor
generates a sine-wave pattern. The frequency and voltage
increase(s) as the rotating speed increases.
CONTROL UNIT (built in ABS actuator and electric
unit)
The control unit computes the wheel rotating speed by the sig-
nal current sent from the sensor. Then it supplies a DC current
to the actuator solenoid valve. It also controls ON-OFF operation
of the valve relay and motor relay. If any electrical malfunction
should be detected in the system, the control unit causes the
warning lamp to light up. In this condition, the ABS will be deac-
tivated by the control unit, and the vehicle's brake system reverts
to normal operation. (For control unit layout, refer to ABS
ACTUATOR AND ELECTRIC UNIT, BR-34.)
SBR068E
SBR069E
ANTI-LOCK BRAKE SYSTEM
BR-33

G SENSOR (4WD models only)
The G sensor senses deceleration during braking to determine whether the vehicle is being driven on a high
 road (asphalt road, etc.) or a low  road (snow-covered road, etc.). It then sends a signal to the ABS con-
trol unit.
The reed switch turns on when it is affected by a magnetic field. During sudden deceleration (braking on a
high  road), the weight moves and the magnet in the weight moves away from the reed switch. The mag-
netic field then diminishes and the reed switch turns off.
ABS ACTUATOR AND ELECTRIC UNIT
The ABS actuator and electric unit contains:
lAn electric motor and pump
lTwo relays
lSix solenoid valves, each inlet and outlet for
Ð LH front
Ð RH front
Ð Rear
lABS control unit
This component controls the hydraulic circuit and increases,
holds or decreases hydraulic pressure to all or individual wheels.
The ABS actuator and electric unit are not disassemble.
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 wheel cylinder via the inlet solenoid valve.
ABS operationPressure hold ON (Closed) OFF (Closed)Hydraulic circuit is shut off to hold the wheel cylinder
brake fluid pressure.
Pressure
decreaseON (Closed) ON (Open)Wheel cylinder 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
wheel cylinder.
SBR070E
SBR071E
ANTI-LOCK BRAKE SYSTEM
System Description (Cont'd)
BR-34

Removal and Installation
CAUTION:
Be careful not to damage sensor edge and sensor rotor
teeth.
When removing the front wheel hub or rear axle shaft
assembly, disconnect the ABS wheel sensor from the
assembly and move it away.
FRONT WHEEL SENSOR
SBR311E
ANTI-LOCK BRAKE SYSTEM
BR-35

G SENSOR
Always replace G sensor if bumped or dropped. Otherwise,
performance characteristics of G sensor will be changed,
which in turn changes ABS control performance character-
istics.
ABS ACTUATOR AND ELECTRIC UNIT
Removal
1. Disconnect battery cable.
2. Drain brake fluid. Refer to ``Changing Brake Fluid'', BR-3.
3. Remove mounting bracket fixing bolts and nuts.
4. Disconnect connector, brake pipes and remove fixing nuts.
Installation
CAUTION:
After installation, refill brake fluid. Then bleed air. Refer to
``Bleeding Brake System'', BR-4.
1. Connect brake pipes temporarily.
2. Tighten fixing bolts and nuts.
3. Tighten brake pipes.
4. Connect connector and battery cable.
SBR074E
SBR075E
ANTI-LOCK BRAKE SYSTEM
Removal and Installation (Cont'd)
BR-37