1998 NISSAN PATROL wheel

System Components
System Description
WHEEL SENSOR
The sensor unit consists of a gear-shaped sensor rotor and a sen-
sor element. The element contains a bar magnet around which a
coil is wound. The sensor is installed on the back of the brake rotor.
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 signal
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 deactivated 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.)
SBR185E
SBR186E
ANTI-LOCK BRAKE SYSTEM
BR-34

G SENSOR
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 ®eld. 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 ®eld then diminishes and the reed switch turns off.
ABS ACTUATOR AND ELECTRIC UNIT
The ABS actuator and electric unit contains:
+An electric motor and pump
+ Two relays
+ Six solenoid valves, each inlet and outlet for
Ð LH front
Ð RH front
Ð Rear
+ ABS 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
valve Outlet solenoid
valve
Normal brake operation OFF (Open) OFF (Closed) Master cylinder brake ¯uid pressure is directly trans-
mitted to wheel cylinder via the inlet solenoid valve.
ABS operation Pressure hold ON (Closed) OFF (Closed)
Hydraulic circuit is shut off to hold the wheel cylinder
brake ¯uid pressure.
Pressure
decrease ON (Closed) ON (Open) Wheel cylinder brake ¯uid is sent to reservoir via the
outlet solenoid valve. Then it is pushed up to the
master cylinder by pump.
Pressure
increase OFF (Open) OFF (Closed) Master cylinder brake ¯uid pressure is transmitted to
wheel cylinder.
SBR189E
SBR176E
ANTI-LOCK BRAKE SYSTEM
System Description (Cont'd)
BR-35

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 assem-
bly and move it away.
FRONT WHEEL SENSOR
SBR187E
ANTI-LOCK BRAKE SYSTEM
BR-36

REAR WHEEL SENSOR
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 characteris-
tics.
SBR188E
SBR190E
ANTI-LOCK BRAKE SYSTEM
Removal and Installation (Cont'd)BR-37

MALFUNCTION CODE/SYMPTOM CHART
Code No.
(No. of warning lamp ¯ashes) Malfunctioning part Diagnostic procedure
45 Actuator front left outlet solenoid valve 2
46 Actuator front left inlet solenoid valve 2
41 Actuator front right outlet solenoid valve 2
42 Actuator front right inlet solenoid valve 2
55 Actuator rear outlet solenoid valve 2
56 Actuator rear inlet solenoid valve 2
25 .1 Front left sensor (open-circuit) 1
26 .1 Front left sensor (short-circuit) 1
21 .1 Front right sensor (open-circuit) 1
22 .1 Front right sensor (short-circuit) 1
31 .1 Rear right sensor (open-circuit) 1
32 .1 Rear right sensor (short-circuit) 1
35 .1 Rear left sensor (open-circuit) 1
36 .1 Rear left sensor (short-circuit) 1
18 .1 Sensor rotor 1
17 G sensor and circuit 5
61 .3 Actuator motor or motor relay 3
63 Solenoid valve relay 2
57 .2 Power supply (Low voltage) 4
71 Control unit 6
Warning lamp stays on when igni-
tion switch is turned on Control unit power supply circuit
Warning lamp bulb circuit
Control unit or control unit connector
Solenoid valve relay stuck
Power supply for solenoid valve relay coil
13
Warning lamp does not come on
when ignition switch is turned on Fuse, warning lamp bulb or warning lamp circuit
Control unit
12
Pedal vibration and noise Ð 11
Long stopping distance Ð 9
Unexpected pedal action Ð 8
ABS does not work Ð 10
ABS works frequently Ð 7
. 1: If one or more wheels spin on a rough or slippery road for 40 seconds or more, the ABS warning lamp will illuminate. This does
not indicate a malfunction. Only in the case of the short-circuit (Code Nos. 26, 22, 32 and 36), after repair the ABS warning lamp
also illuminates when the ignition switch is turned ``ON''. In this case, drive the vehicle at speeds greater than 30 km/h (19 MPH)
for approximately 1 minute as speci®ed in ``SELF-DIAGNOSIS PROCEDURE'', BR-47. Check to ensure that the ABS warning
lamp goes out while the vehicle is being driven.
. 2: The trouble code ``57'', which refers to a low power supply voltage, does not indicate that the ABS control unit is malfunctioning.
Do not replace the ABS control unit with a new one.
. 3: The trouble code ``61'' can sometimes appear when the ABS motor is not properly grounded. If it appears, be sure to check the
condition of the ABS motor ground circuit connection.
TROUBLE DIAGNOSES
Self-diagnosis (Cont'd)
BR-49

CONSULT
CONSULT APPLICATION TO ABS
EE960 program card is not applicable to ABS. Use on board diagnostic system with ABS warning lamp until
the next program card will be introduced. (Refer to ``Self-diagnosis'', BR-47.)
ITEMSELF-DIAGNOSTIC
RESULTS DATA MONITOR ACTIVE TEST
Front right wheel sensor X X Ð
Front left wheel sensor X X Ð
Rear right wheel sensor X X Ð
Rear left wheel sensor X X Ð
G switch (G sensor) X X X
Stop lamp switch Ð X Ð
Front right inlet solenoid valve X X X
Front right outlet solenoid valve X X X
Front left inlet solenoid valve X X X
Front left outlet solenoid valve X X X
Rear inlet solenoid valve X X X
Rear outlet solenoid valve X X X
Actuator solenoid valve relay X X Ð
Actuator motor relay
(ABS MOTOR is shown on the Data Monitor
screen.) XXX
ABS warning lamp Ð X Ð
Battery voltage X X Ð
X: Applicable
Ð: Not applicable
ECU (ABS control unit) part number mode
Ignore the ECU part number displayed in the ECU PART NUMBER MODE. Refer to parts catalog to order
the ECU.
TROUBLE DIAGNOSES
BR-50

SELF-DIAGNOSTIC RESULTS MODE
Diagnostic item Diagnostic item is detected when ...Diagnostic
procedure
FR RH SENSOR .1
[OPEN] +
Circuit for front right wheel sensor is open.
(An abnormally high input voltage is entered.) 1
FR LH SENSOR .1
[OPEN] +
Circuit for front left wheel sensor is open.
(An abnormally high input voltage is entered.) 1
RR RH SENSOR .1
[OPEN] +
Circuit for rear right sensor is open.
(An abnormally high input voltage is entered.) 1
RR LH SENSOR .1
[OPEN] +
Circuit for rear left sensor is open.
(An abnormally high input voltage is entered.) 1
FR RH SENSOR .1
[SHORT] +
Circuit for front right wheel sensor is shorted.
(An abnormally low input voltage is entered.) 1
FR LH SENSOR .1
[SHORT] +
Circuit for front left wheel sensor is shorted.
(An abnormally low input voltage is entered.) 1
RR RH SENSOR .1
[SHORT] +
Circuit for rear right sensor is shorted.
(An abnormally low input voltage is entered.) 1
RR LH SENSOR .1
[SHORT] +
Circuit for rear left sensor is shorted.
(An abnormally low input voltage is entered.) 1
ABS SENSOR .1
[ABNORMAL SIGNAL] +
Teeth damage on sensor rotor or improper installation of wheel sensor.
(Abnormal wheel sensor signal is entered.) 1
FR RH IN ABS SOL
[OPEN] +
Circuit for front right inlet solenoid valve is open.
(An abnormally low output voltage is entered.) 2
FR LH IN ABS SOL
[OPEN] +
Circuit for front left inlet solenoid valve is open.
(An abnormally low output voltage is entered.) 2
RR IN ABS SOL
[OPEN] +
Circuit for rear inlet solenoid valve is open.
(An abnormally low output voltage is entered.) 2
FR RH IN ABS SOL
[SHORT] +
Circuit for front right inlet solenoid valve is shorted.
(An abnormally high output voltage is entered.) 2
FR LH IN ABS SOL
[SHORT] +
Circuit for front left inlet solenoid valve is shorted.
(An abnormally high output voltage is entered.) 2
RR IN ABS SOL
[SHORT] +
Circuit for rear inlet solenoid valve is shorted.
(An abnormally high output voltage is entered.) 2
FR RH OUT ABS SOL
[OPEN] +
Circuit for front right outlet solenoid valve is open.
(An abnormally low output voltage is entered.) 2
FR LH OUT ABS SOL
[OPEN] +
Circuit for front left outlet solenoid valve is open.
(An abnormally low output voltage is entered.) 2
RR OUT ABS SOL
[OPEN] +
Circuit for rear outlet solenoid valve is open.
(An abnormally low output voltage is entered.) 2
FR RH OUT ABS SOL
[SHORT] +
Circuit for front right outlet solenoid valve is shorted.
(An abnormally high output voltage is entered.) 2
FR LH OUT ABS SOL
[SHORT] +
Circuit for front left outlet solenoid valve is shorted.
(An abnormally high output voltage is entered.) 2
RR OUT ABS SOL
[SHORT] +
Circuit for rear outlet solenoid valve is shorted.
(An abnormally high output voltage is entered.) 2
ABS ACTUATOR RELAY
[ABNORMAL] +
Actuator solenoid valve relay is ON, even if control unit sends off signal.
+ Actuator solenoid valve relay is OFF, even if control unit sends on signal. 2
ABS MOTOR RELAY
[ABNORMAL] +
Circuit for ABS motor relay is open or shorted.
+ Circuit for actuator motor is open or shorted.
+ Actuator motor relay is stuck. 3
BATTERY VOLT
[VB-LOW] +
Power source voltage supplied to ABS control unit is abnormally low. 4
CONTROL UNIT +Function of calculation in ABS control unit has failed. 6
G-SENSOR
[ABNORMAL] +
G sensor circuit is open or shorted. 5
. 1: If one or more wheels spin on a rough or slippery road for 40 seconds or more, the ABS warning lamp will illuminate. This does
not indicate a malfunction. Only in the case of the short-circuit (Code Nos. 26, 22, 32 and 36), after repair the ABS warning
lamp also illuminates when the ignition switch is turned ``ON''. In this case, drive the vehicle at speeds greater than 30 km/h (19
MPH) for approximately 1 minute as speci®ed in ``SELF-DIAGNOSIS PROCEDURE'', BR-47. Check to ensure that the ABS
warning lamp goes out while the vehicle is being driven.
TROUBLE DIAGNOSES
CONSULT Inspection Procedure (Cont'd)
BR-52

DATA MONITOR MODE
MONITOR ITEM CONDITION SPECIFICATION
FR RH SENSOR
FR LH SENSOR
RR SENSOR
RR RH SENSOR
RR LH SENSORDrive vehicle.
(Each wheel is rotating.)
Wheel speed signal
(Almost the same speed as speedometer.)
STOP LAMP SW Brake is depressed. Depress the pedal: ON
Release the pedal: OFF
G-SWITCH Vehicle is driven.
Vehicle is stopped.
Brake is applied.During sudden braking while driving on high  roads (asphalt
roads, etc.): OFF
While vehicle is stopped or during constant-speed driving: ON
FR RH IN SOL
FR RH OUT SOL
FR LH IN SOL
FR LH OUT SOL
RR IN SOL
RR OUT SOL 1. Drive vehicle at speeds over
30 km/h (19 MPH) for at
least one minute.
2. Engine is running. Operating conditions for each solenoid valve are indicated.
ABS is not operating: OFF
MOTOR RELAY ABS is not operating: OFF
ABS is operating: ON
ACTUATOR RELAY Ignition switch is ON or
engine is running.Ignition switch ON (Engine stops): OFF
Engine running: ON
WARNING LAMP ABS warning lamp is turned on: ON
ABS warning lamp is turned off: OFF
BATTERY VOLT Power supply voltage for control unit
ACTIVE TEST MODE
TEST ITEM CONDITION JUDGEMENT
FR RH SOLENOID
FR LH SOLENOID
REAR SOLENOID Engine is running.Brake ¯uid pressure control operation
IN SOL OUT SOL
UP (Increase):
KEEP (Hold):
DOWN (Decrease): OFF
ON
ONOFF
OFF
ON
ABS MOTOR ABS actuator motor
ON: Motor runs (ABS motor relay ON)
OFF: Motor stops (ABS motor relay OFF)
G SWITCH Ignition switch is ON. G SWITCH (G SENSOR),
ON: Set G SWITCH MONITOR ``ON''
(G switch circuit is closed.)
OFF: Set G SWITCH MONITOR ``OFF'' (G switch circuit is open.)
Note: Active test will automatically stop ten seconds after the test starts. (LIMIT SIGNAL monitor shows ON.)
TROUBLE DIAGNOSES
CONSULT Inspection Procedure (Cont'd)
BR-55