1998 NISSAN PICK-UP 4WD

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''.

Supplemental Restraint System (SRS) ``AIR
BAG'' (4WD models)
The Supplemental Restraint System ``AIR BAG'', used along with a seat belt, helps to reduce the risk or
severity of injury to the driver in a frontal collision. The Supplemental Restraint System consists of air bag
module (located in the center of the steering wheel), a diagnosis sensor unit, warning lamp, wiring harness
and spiral cable. Information necessary to service the system safely is included in theRS sectionof this
Service Manual.
WARNING:
lTo avoid rendering the SRS inoperative, which could increase the risk of personal injury or death
in the event of a collision which would result in air bag inflation, all maintenance must be per-
formed by an authorized NISSAN dealer.
lImproper maintenance, including incorrect removal and installation of the SRS, can lead to per-
sonal injury caused by unintentional activation of the system.
lDo not use electrical test equipment on any circuit related to the SRS unless instructed to in this
Service Manual. SRS wiring harnesses are covered with yellow insulation either just before the
harness connectors or for the complete harness, for easy identification.
Supplemental Restraint System (SRS) ``AIR
BAG'' (2WD models)
The Supplemental Restraint System ``AIR BAG'', used along with a seat belt, helps to reduce the risk or
severity of injury to the driver in a frontal collision. The Supplemental Restraint System consists of an air
bag module (located in the center of the steering wheel), a diagnosis sensor unit, warning lamp and spiral
cable. Information necessary to service the system safely is included in theRS sectionof this Service
Manual.
WARNING:
lTo avoid rendering the SRS inoperative, which could increase the risk of personal injury or death
in the event of a collision which would result in air bag inflation, all maintenance must be per-
formed by an authorized NISSAN dealer.
lImproper maintenance, including incorrect removal and installation of the SRS, can lead to per-
sonal injury caused by unintentional activation of the system.
lDo not use electrical test equipment on any circuit related to the SRS.
Precautions for Brake System
lUse brake fluid DOT 3 or DOT 4*1.
lNever reuse drained brake fluid.
lBe careful not to splash brake fluid on painted areas; it
may cause paint damage. If brake fluid is splashed on
painted areas, wash it away with water immediately.
lTo clean master cylinder parts, disc brake caliper parts
or wheel cylinder parts, use clean brake fluid.
lNever use mineral oils such as gasoline or kerosene.
They will ruin rubber parts of the hydraulic system.
lUse flare nut wrench when removing and installing brake
tubes.
lAlways torque brake lines when installing.
WARNING:
lClean brakes with a vacuum dust collector to minimize
the hazard of airborne materials.
*1: Refer to MA section (``Fluids and Lubricants'', ``RECOM-
MENDED FLUIDS AND LUBRICANTS'').
SBR820BA
PRECAUTIONS AND PREPARATION
BR-1

INSPECTION
1. Ensure vehicle is unladen condition*.
* Fuel, radiator coolant and engine oil full. Spare tire, jack,
hand tools and mats in designated positions.
2. Have a driver sit in the driver's seat and one person sit on
the rear of the vehicle. Then have the person on the rear of
the vehicle slowly get off. This is necessary to stabilize sus-
pension deflection.
3. Adjust length ``L'' as follows:
a. Loosen stopper bolt locknut (2WD JIDOSHA KIKI make).
b. Pull lever against stopper bolt and adjust by turning stopper
bolt.
c. Tighten stopper bolt locknut (2WD JIDOSHA KIKI make).
Length ``L'':
2WD models
Approx. 187.3 mm (7.37 in)
4WD models
Approx. 158.1 mm (6.22 in)
4. Install pressure gauge to front and rear brake air bleeder.
5. Bleed air from the Tool.
6. Raise front brake pressure to 4,904 kPa (49.0 bar, 50
kg/cm
2, 711 psi) and 9,807 kPa (98.1 bar, 100 kg/cm2, 1,422
psi) and check rear brake pressure.
Rear brake pressure:
Refer to table below.
7. Set down weight slowly over axle center so that sensor
spring length becomes the same as when in loaded condi-
tion (refer to table below). Check rear brake pressure in the
same way described in step 6.
Unit: kPa (bar, kg/cm2, psi)
Front brake
pressureRear brake pressure
2WD 4WD
Unladen
condition
L = 187.3 mm
(7.37 in)Loaded
condition
L = 204.0 mm
(8.03 in)Unladen
condition
L = 158.1 mm
(6.22 in)Loaded
condition
L = 184.0 mm
(7.24 in)
4,904
(49.0, 50, 711)1,667 - 2,648
(16.7 - 26.5, 17
- 27, 242 - 384)3,334 - 4,315
(33.3 - 43.2, 34
- 44, 483 - 626)1,863 - 2,844
(18.6 - 28.4, 19
- 29, 270 - 412)3,334 - 4,315
(33.3 - 43.2, 34
- 44, 483 - 626)
9,807
(98.1, 100,
1,422)2,844 - 3,825
(28.4 - 38.2, 29
- 39, 412 - 555)3,629 - 5,590
(36.3 - 55.9, 37
- 57, 526 - 811)2,059 - 4,021
(20.6 - 40.2, 21
- 41, 299 - 583)3,629 - 5,590
(36.3 - 55.9, 37
- 57, 526 - 811)
SBR967D
SBR968D
SBR013B
SBR014B
CONTROL VALVE
Load Sensing Valve (Cont'd)
BR-9

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

Schematic/4WD Models
HBR078
TROUBLE DIAGNOSES
BR-48

Wiring Diagram Ð ABS Ð/4WD Models
HBR074
TROUBLE DIAGNOSES
BR-49