NISSAN PATROL 1998 Y61 / 5.G Brake System Service Manual

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

Component Parts and Harness Connector
Location
SBR192E
TROUBLE DIAGNOSES
BR-41

Circuit Diagram for Quick Pinpoint Check
TBR098
TROUBLE DIAGNOSES
BR-42

Wiring Diagram Ð ABS Ð
TBR099
TROUBLE DIAGNOSES
BR-43

TBR100
TROUBLE DIAGNOSES
Wiring Diagram Ð ABS Ð (Cont'd)BR-44

TBR101
TROUBLE DIAGNOSES
Wiring Diagram Ð ABS Ð (Cont'd)BR-45

TBR102
TROUBLE DIAGNOSES
Wiring Diagram Ð ABS Ð (Cont'd)BR-46

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

jA
Check warning lamp for deactivation after
driving vehicle over 30 km/h (19 MPH)
for at least one minute.
After making certain that warning lamp
does not come on, test the ABS in a safe
area to verify that it functions properly.
HOW TO READ SELF-DIAGNOSTIC RESULTS (Malfunction codes)
+Determine the code No. by counting the number of times the warning lamp ¯ashes on and off.
+ When several malfunctions occur at one time, up to three code numbers can be stored; the latest mal-
function will be indicated ®rst.
+ The indication begins with the start code 12. After that a maximum of three code numbers appear in the
order of the latest one ®rst. The indication then returns to the start code 12 to repeat (the indication will
stay on for ®ve minutes at the most).
+ The malfunction code chart is given on the next page.
HOW TO ERASE SELF-DIAGNOSTIC RESULTS
(Malfunction codes)
1. Disconnect the check terminal from ground (ABS warning lamp
will stay lit).
2. Within 12.5 seconds, ground the check terminal 3 times. Each terminal ground must last more than 1 second. The ABS warn-
ing lamp goes out after the erase operation has been com-
pleted.
3. Perform self-diagnosis again. Refer to BR-47. Only the start- code should appear, no malfunction codes.
SBR457D
ABR256
.
.
TROUBLE DIAGNOSES
Self-diagnosis (Cont'd)
BR-48