ISUZU TROOPER 1995 Workshop Manual

4-WHEEL ANTILOCK BRAKE SYSTEM (ABS) 5A4-31
MODE F6: WHEEL SENSORS
When conducting the wheel sensor test, note the following:
1) Accelerate vehicle only slightly above 20 km/h (12 mph).
2) When this speed is attained, put transmission into neutral and allow vehicle to coast to a halt. (Parking
brake may be engaged slightly.)
3) When vehicle is at a standstill, actuate either foot brake or parking brake.
When the
wheel speed sensor test is being performed, the output or speed value of all four sensors is
monitored
by TECH 1. When the output of wheel sensors becomes too low to convert into speed value, the
last known vehicle speed is displayed and the values are fixed. If wheel sensors are normal, it is at the
vehicle speed
of 5 km/h (3 mph) or less that their output is lost. Therefore, if all the fixed speed values are
less than 5 km/h (3 mph), the wheel sensors are normal. If one or more of the four speed values is more
than 5 km/h
(3 mph), it suggests that the following abnormalities have occurred to the sensor(s):
1. Excess gap between the sensor and sensor rotor.
2. Broken or damaged sensor rotor teeth.
3. Momentary open in sensor harness.

5A4-32 4-WHEEL ANTI LOCK BRAKE SYSTEM (ABS)
TECH 1 Display Key Operation
INSTRUCT I ON: This explains MODE F6.
DRIVE VE-Drive vehicle at 20 km/h (12 mph).
HICLE AT 20km/h Press the YES key for the next display.
AND THEN (YES)
RELEASE GAS Release accelerator pedal while driving, and put transmission into neutral.
PEDAL, DISENGAGE Press the YES key for the next display.
TRANSMISSION
AND (YES)
AS SOON AS THE After coasting to a halt with transmission in neutral, apply brakes
VEHICLE HAS immediately.
STOPPED APPLY Press the YES key for the next display.
BRAKES (YES) This completes instructions as to F6.
The test will be started with the next display.
BEGIN TEST Let's begin the test.
DRIVE VE-Carry out the test according to the display.
HICLE AT 20km/h ** indicates the wheel speed value into which the output of each sensor ** ** ** ** has been converted.
Decelerate vehicle by coasting until it comes to a halt. (Parking brake may
DECREASE VEHICLE be slightly engaged.)
SPEED TO Okm/h
** ** ** **
MEASURED WHEEL Make sure that there is no significant difference among the wheel speed
SPEED THRESHOLDS values.
** **
** ** The
data indicate 3-5 km/h (2-3 mph).
SEE CHART 6 (YES) See CHART 6 .. Refer to CHART C-2 for check procedure.
To obtain mph in
MODE: F6, display mph in MODE: FO once and thereafter, change to MODE:F6.

4-WHEEL ANTILOCK BRAKE SYSTEM (ABS) 5A4-33
PIN-OUT CHECKS
Connect Pinout Box J-35592 to 35-Pin Electronic Brake Control Module connector as described in this section.
~ Perform checks with high impedance digital multimeter J-39200 or equivalent.
Ignition
Multi meter Measure
No. Circuit to be Tested
Switch Scale/Range between Nominal Value Note Position
Pin Number
1 Ignition enable OFF 20DCV 1 (+), 10 (-) OV to 0.1V
ON 20DCV
1 (+), 10 (-) 11.5Vto 14.5V
2
Valve relay OFF n 32, 10 continuity: OK
no continuity: NG
OFF 200.Q 17,27 75 to 120n
3 Motor relay OFF n 14, 10 continuity: OK
no continuity: NG
OFF 200Q 17,28 70 to 90n
4
Diode ON n 29 (+), 32 (-) Replace(+) and
(-)with each
29 (-), 32 (+) other and check
to see a variation
of continuity/
no continuity.
5
Stop light switch OFF 20DCV 25, 10 11.5V to 14.5V Press brake pedal
6 Ground connection OFF 200Q 32, 10 Less than 2.Q Valve relay
32,20
32,34
7 FL solenoid valve OFF 200Q 2,32 0.6 to 1.8Q
8 FR solenoid valve OFF 200Q 35,32 0.6 to 1.8n
9 Rr solenoid valve OFF 200Q 18,32 0.6 to 1.8n
10 FL speed sensor OFF 2k.Q 22,4 0.8k to 1.3kn Internal Resistance
OFF 200k.Q 22, 10 more than 100kn Insulation Resistance
OFF 200mACV 22,4 more than 200mV Turn wheel at 1RPS
11 FR speed
sensor OFF 2k.Q 23,21 0.8k to 1.3k.Q Internal Resistance
OFF 200k.Q 23, 10 more than 100k.Q Insulation Resistance
OFF 200mACV 23,21 more than 200mV Turn wheel at 1RPS
12 RL speed sensor OFF 2k.Q 8,9 0.8k to 1.3k.Q Internal Resistance
OFF 200k.Q 8, 10 more than 100k.Q Insulation Resistance
OFF 200mACV 8,9 more than 200mV Turn wheel at 1RPS
13 RR speed sensor OFF 2k.Q 24,26 0.8k to 1.3k.Q Internal Resistance
OFF 200k.Q 24, 10 more than 100k.Q Insulation Resistance
OFF 200mACV 24,26 more than 200mV Turn wheel at 1RPS
14 G-sensor OFF 200.Q 13, 1 less than 100n
15 Transmission-Input ON n 16,20 continuity A/T
(L, R shift lever
position)
no
continuity
(other shift
position)
20DCV 16 (+), 20 (-) 11.5V to 14.5V
(M/T-1, 2, R)
ov
(other shift
position)
16 Transfer-Input ON 20DCV 15 (+), 20 (-) 11.5-14.5V (2H)
OV (4H, 4L)

5A4-34 4-WHEEL ANTILOCK BRAKE SYSTEM (ABS)
CIRCUIT DIAGRAM
FENDER -LH
BODY· FRT
FENDER -LH
+ o-----J----'8:..:8:..:/R~
B
EJ
~~B BODY ENG. FRAME
II
11~5
II C-16
E 8 C M
Fig. 5A4-11
o.sw 8BI6
.. -d ~
DATA LINK CONNECTOR
C-4 lOA ELEC. IGN. O.Sl/W
C-10 lOA METER, GAUGE
H-24
IM/TI ------~
H-10
I I I 10
I H;lo I
4WDS1111
•

4-WHEEL ANTILOCK BRAKE SYSTEM (ABS) 5A4-35
0.85 G/W
0.5 L/W
~ ..
"' i 0 ..
~ .. ~ iii ..
H-25
l!'/jc;_R_Uli!_E_<;_q_N_T!I9~1-___ , ' ~ ' ~ '
DJ
"' 0 ..
"' ~ 5l z ~ Ul " ..
18 3 H-24 ' 4 ~~~ '
-----------------l ;:~ "'" ~~ 0
" ... U>:::> ~ "' iii !!!1] 0 .. ~~ 0.85 G/Y
~ 3 "' CD 0 CD
BOO~ffiT llr---------------------------~~------------------------------------------~--------------~

5A4-36 4-WHEEL ANTILOCK BRAKE SYSTEM (ABS)
+ o--1---=8..:8:.:.111~
B
B
~IP-1oiB BODY ENG. FRAME
EBCM(16i
0.5G/B
~1-"T=-''---'-'-'~
~ :::>
~1-L-.--.-~
FENDER-RH II C-39 1----------------------------------
Fig. 5A4-12
UPSHIFT INDICATOR (METER I
•

!! co U1 )> "" I .... w
(
EBCM
RR
ABS SPEED SENSOR
(RHl
.
RELAY:
UPSHIFT-2
""·,'-....."
M-11_
. ·r·---
..
C-39
M-12"-~.·
··..
> .. , ,·
~'
...
,
~~~~~
~.-· RELAY
& FUSE
BOX
· ••.
(FL-1,
FL-2, FL-6,
F-9~
'•
BATTERY HYDRAULIC
--+1--.-.
UNIT
C-33
--~----
C-34.
H-41
H-42
TRANSMISSION
(


~·~ rl r
( STARTER
SW
RR
ABS SPEED SENSOR
(LH)
\~· \'
-.
.
B-46
' G SENSOR
\
FUSE
BOX (C-3, C-4, C-10, C-14)
BRAKE
SW
(W/CRUISE CONTROL)
STOPLIGHT SW
(W/0
CRUISE CONTROL)
BRAKE PEDAL FRT
ABS
SPEED SENSOR
(LH)
(
"V )> ~ r-0 s 5 2
.... :e ::I: m
m r-l> 2 ~ r-0 0 ~ CCI ~ ~ m ~ Cl) -t m s: ~ ~ c.n t I w .....

5A4-38 4-WHEEL ANTI LOCK BRAKE SYSTEM (ABS)
SYMPTOM DIAGNOSIS
The symptoms that cannot be indicated by warning light can be divided in the following five categories:
1) ABS works frequently but vehicle does not decelerate.
2) Uneven braking occurs while ABS works.
3) The wheels lock during braking.
4) Brake pedal feel is abnormal.
5) Braking sound (from hydraulic unit) is heard while not braking.
These are
all attributable to problems which cannot be detected by EBCM's self-diagnosis. Use the
customer complaint and a test to determine which symptom is present. Then follow the appropriate flow
chart listed below.
Diagnostic Flow Charts
No. Symptom Without TECH 1 With TECH 1
1
ABS works frequently but vehicles does not Chart A-1 Chart TA-1
decelerate.
2
Uneven braking occurs while ABS works. Chart A-2 Chart
TA-2
3 The
wheels are locked. Chart A-3 Chart
TA-3
4 Brake
pedal feel is abnormal. Chart A-4 -
5 Braking
sound (from hydraulic unit) is heard while Chart A-5 Chart
TA-5 not braking.
•

4-WHEEL ANTILOCK BRAKE SYSTEM (ABS) 5A4-39
CHART A-1 [):Eeft:j]
1) ABS WORKS FREOUENTL V BUT VEHICLE DOES NOT DECELERATE
PUT KEY OFF AND CONNECT PINOUT BOX.
WITH G SENSOR CONNECTOR DISCONNECTED,
CHECK CONTINUITY BETWEEN THE TERMINALS 1 AND 13
CHECK G SENSOR SINGLY (REFER TO CHART C-1)
IS THERE DAMAGE, OR POWDERED IRON STICKING
TO EACH WHEEL SPEED SENSOR/SENSOR RING?
IS
THE OUTPUT OF EACH WHEEL SPEED SENSOR
NORMAL?
(REFER TO CHART C-2)
• HARNESS BB04, BB16, BB17 ARE SHORTED
• REPAIR THE HARNESSES
REPLACE WHEEL SPEED
SENSOR OR REPAIR HARNESS

5A4-40 4-WHEEL ANTILOCK BRAKE SYSTEM (ABS)
CHART TA-1 I TECH 1 I
1) ABS WORKS FREOUENTL Y BUT VEHICLE DOES NOT DECELERATE ~
CONNECT TECH 1 I
I
MODE F6: WHEEL SENSORS MAKES SURE OF THE OUTPUT CONDITIONS OF EACH SENSOR
I
RETURN TO CHART A-1 I I REPLACE WHEEL SPEED SENSOR I
•