1998 NISSAN PATROL brake

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

ABS ACTUATOR AND ELECTRIC UNIT
Removal
1. Disconnect battery cable.
2. Drain brake ¯uid. Refer to ``Changing Brake Fluid'', BR-3.
3. Remove mounting bracket ®xing bolts and nuts.
4. Disconnect connector, brake pipes and remove ®xing nuts.
Installation
CAUTION:
After installation, re®ll brake ¯uid. Then bleed air. Refer to
Bleeding Brake System'', BR-4.
1. Connect brake pipes temporarily.
2. Tighten ®xing bolts and nuts.
3. Tighten brake pipes.
4. Connect connector and battery cable.
SBR191E
ANTI-LOCK BRAKE SYSTEM
Removal and Installation (Cont'd)BR-38

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
instantly drives the actuators. It is essential that both kinds of sig-
nals are proper and stable. It is also important to check for conven-
tional problems: such as air leaks in booster lines, lack of brake
¯uid, or other problems with the brake system.
It is much more difficult to diagnose a problem that occurs intermit-
tently rather than continuously. 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 only may not ®nd the cause of the problems, so a
road test should be performed.
Before undertaking actual checks, take a few minutes to talk with
a customer who approaches with a ABS complaint. The customer
is a very good source of information on such problems; especially
intermittent ones. Through the talks with the customer, ®nd out what
symptoms are present and under what conditions they occur.
Start your diagnosis by looking for ``conventional'' problems ®rst.
This is one of the best ways to troubleshoot brake problems on an
ABS controlled vehicle.
SEF233G
SEF234G
TROUBLE DIAGNOSES
BR-39

Preliminary Check
Check brake ¯uid level in reservoir
tank.
- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Low ¯uid level may indicate brake pad
wear or leakage from brake line.
Check brake line for leakage.
OKcNG Repair.
b
Check brake booster for operation and air
tightness. Refer to BR-15.
OK
cNGReplace.
b
Check brake pads and rotor. Refer to
BR-21, 25.
OK
cNGReplace.
Check brake ¯uid level in reservoir tank
again.
OK
cNGFill up brake ¯uid.
Check warning lamp activation.
When ignition switch is turned on, warning
lamp turns on.
OK
cNG
Check fuse, warning lamp
bulb and warning lamp cir-
cuit.
Check warning lamp for deactivation after
engine is started.
OK
cNGGo to Self-diagnosis,
BR-46, 50.
Drive vehicle at speeds over 30 km/h (19
MPH) for at least 1 minute.
Ensure warning lamp remains off while
driving.
OK
cNGGo to Self-diagnosis,
BR-46, 50.
END
SBR451D
SBR389C
SBR058C
SBR059C
SBR186E
.
.
.
.
.
.
.
.
.
TROUBLE DIAGNOSES
BR-40

Self-diagnosis
FUNCTION
+When a problem occurs in the ABS, the warning lamp on the
instrument panel comes on. To start the self-diagnostic results
mode, ground the self-diagnostic (check) terminal located on
``Data Link Connector for CONSULT''. The location of the mal-
function is indicated by the warning lamp ¯ashing.
+ While DIFF-LOCK is on, anti-lock warning light ¯ashes.
SELF-DIAGNOSIS PROCEDURE
Turn off DIFF-LOCK switch.
Drive vehicle over 30 km/h (19 MPH) for
at least one minute.
Turn ignition switch ``OFF''.
Ground terminal ``4'' of ``Data link con-
nector for CONSULT'' with a suitable har-
ness.
Turn ignition switch ``ON'' while ground-
ing terminal ``4''.
Do not depress brake pedal.
After 3.0 seconds, the warning lamp
starts ¯ashing to indicate the malfunction
code No. (See NOTE.)
Verify the location of the malfunction with
the malfunction code chart. Refer to
BR-48. Then make the necessary repairs
following the diagnostic procedures.
After the malfunctions are repaired, erase
the malfunction codes stored in the con-
trol unit. Refer to BR-47.
Rerun the self-diagnostic results mode to
verify that the malfunction codes have
been erased.
Disconnect the check terminal from the
ground. The self-diagnostic results mode
is now complete.NOTE: The indication terminates
after ®ve minutes.
However, when the ignition
switch is turned from
``OFF'' to ``ON'', the indica-
tion starts ¯ashing again.
j
A
SBR193E
SBR186E
SBR194E
.
.
.
.
.
.
.
.
.
TROUBLE DIAGNOSES
BR-47

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

Diagnostic Procedure 7 (ABS works
frequently.)
CHECK BRAKE FLUID PRESSURE.
- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Check brake ¯uid pressure distribution.
Refer to proportioning valve inspection.
OK
cNG Perform Preliminary
Check, refer to BR-40.
CHECK WHEEL SENSOR.
- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1. Check wheel sensor connector for ter- minal damage or loose connections.
2. Perform wheel sensor mechanical check.
Refer to Diagnostic Procedure 1,
BR-57.
OK
cNG Repair.
CHECK FRONT AXLES.
- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Check front axles for excessive loose-
ness. Refer to FA section (``Front Wheel
Bearing'', ``ON-VEHICLE SERVICE'').
OK
cNG Repair.
Go toin Diagnostic Procedure 8,
BR-66.
.
.
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TROUBLE DIAGNOSES FOR SYMPTOMS
BR-66

Diagnostic Procedure 8 (Unexpected pedal
action)
CHECK BRAKE PEDAL STROKE.
- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Check brake pedal stroke. Is stroke
excessively large?
No
cYe s Perform Preliminary
Check, refer to BR-40.
CHECK BRAKE PERFORMANCE.
- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Disconnect ABS actuator and electric unit
connector and check whether brake is
effective.
Ye s
cNo Perform Preliminary
Check, refer to BR-40.
CHECK WARNING LAMP ACTIVATE.
- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Ensure warning lamp remains off while
driving.
OK
cNG Carry out self-diagnosis.
Refer to BR-47, 51.
CHECK WHEEL SENSOR.
- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1. Check wheel sensor connector for ter- minal damage or loose connection.
2. Perform wheel sensor mechanical check.
Refer to Diagnostic Procedure 1,
BR-57.
OK
cNG Repair.
CHECK HARNESS CONNECTOR.
- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Check ABS actuator and electric unit pin
terminals for damage or the connection of
ABS actuator and electric unit harness
connector.
Reconnect ABS actuator and electric unit
harness connector. Then retest.
Diagnostic Procedure 9 (Long stopping
distance)
CHECK ABS PERFORMANCE.
- ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Disconnect ABS actuator and electric unit
connector and check whether stopping
distance is still long.
Ye s
cNo Go toin Diagnostic
Procedure 8, BR-67.
Perform Preliminary Check and air bleed-
ing.
Note: Stopping distance may be larger than vehicles without ABS when road condition is slippery.
SBR540A
SBR186E
.
.
.
.
.
TROUBLE DIAGNOSES FOR SYMPTOMS
BR-67