1989 MITSUBISHI GALANT Service Repair Manual

SERVICE BRAKES - Anti-lock Braking System Troubleshooting
W
ith the ignition key in the “ON” posi- No
Check fuse No. 9. If it is
tion, do other warning lights illuminate? blown, correct the cause of
-T-
Yesthe blown fuse and then
replace the fuse.I
Remove the combination
meter, and check with
the ignition key “ON”.
I
Does voltage between har-NoThe harness between the ness
connector terminal
No. 8 and ground indicate
-combination meter from
fuse No. 9 is broken.
battery voltage?
I
Yes Repair harness.
Circuit in combination meter
is broken.
L Repair or replace com-
bination meter.
Turn the ignition switch OFF an
check.
I
Is the ABS warning light normal? (CheckNo
for burned bulb.)c A$Eedyrning light bulb
,
c Replace ABS warning
light bulb.
Yes
Is there continuity between terminals No. No -
8 and 4” or 17’2 on the combinationI Malfunction of combinatio
n
meter
I Repair or replace combi-
meter side? nation meter
Are instrument panel wiring harness, No
-~
engine compartment wiring harness, . Connect connectors firmly.
body wiring harness and ABS wiring
(Check for pins pulled out or
harness connectors connected properly? bent, repair as needed.)
I
1 Yes
I
Broken wire in ECU, valve relay or both
drive circuits. Check and repair both
circuits.
I
NOTE‘1: Non-Turbo . Turbol *:Non-Turbo
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35-42
SERVICE BRAKES - Anti-lock Braking System Troubleshooting
BABS warning light illuminated after the engine is started and remains on\
.
[Explanation]
This is the symptom when the ABS ECU does not
power up due to broken ECU power circuit, etc.,
when the fail safe function operates and isolates the
system or when the warning light drive circuit is
short circuited.
[Hint]
Check the on-board diagnostic output and if there is
no output voltage or if the scan tool and ABS ECU
cannot communicate, there is a good possibility
that power is not flowing to the ECU.
Caution
l
If there is no output of diagnostic trouble
codes, there is a good possibility that the
fail safe is functioning.
MAINFUSIBLELINK @
IGNITION
SWITCH
(IG1)
ILOIE;NATION
+10
3
@izJ”,HUZ8 p:r12 /e-,
xx
I
I
I*I
; 16 4=
9
II
d
+qfimamq!2 a
I -LQ-7 ABS ECUm1
: Non-Turbo . Turbo: Non-Turbo Is there on-board diagnosticNocCONTINUE TO
output? (Is there communi- NEXT PAGE
cation with scan tool?)
I
Yes
Does diagnostic troublecode output display normalcodes?
No . Check, using the diagnos-tic trouble code checkchart. (Refer to P.35-38.)IIILI
Short in harness betweenrgl;r ECU and ABS warning) Repair harness or replacecombination meter.
II
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SERVICE BRAKES - Anti-lock Braking System Troubleshooting35-41
1 Check ABS ECU.I
W

ith the ignition key in the “ON”
position, remove the ECU connector
(nd check. ,)
Does the voltage between ECU harnessNo- Broken wire between ABS
connector terminal No.25
and ground
warning light and ECU
indicate battery voltage?
Yes Replace ABS ECU.
Check ABS valve relay.

Is valve relaynormalReplace valve relay.
I
rgnrtron key in the “ON” position,
Does voltage between the HU harness
No- Broken harness wire be- -Repair harness. connetor
terminal No. 8 and ground indi-
tween ABS warning lightcate battery voltage?
and HU
I
Yes
Is there continuity between HU harness
No - Broken harness wire be-
Repair harness.
connector terminal No.9
and ground?
tween HU and ground
I
’ N
o
Is there continuity between terminals No.
8 and No. 9 on the HU side connector?
- Repair harness or replaceHU.
Yes
* Connector connection mal- function
NOTEWhen inspecting the parts marked with l ,take care to the diode polarity. (Refer to the circuit diagram on R.S5-39.)
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SERVICE BRAKES - Anti-lock Braking System Troubleshooting35-43
MAINFUSIBLELINK @
IGNITION
KgCHm

l
CONTINUED FROM
PREVIOUS PAGE
CONNECTOR
t ,
Is there continuity betweenNo FHarness wire between
body harness connector
ter-data link connector and minals

No.23 and No.24, andABS ECU is broken.
data link connectors No.4 &No.1 O?I
Repair harness.
Yes
I
1 Malfunction of ABS ECUI1-4 Replace ABS ECU.III1
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1 Yes
No - Correct cause of blown fuse and replace fuse.
r
L
W
ith the ignition key
in theNo ~ Is power relay normal?
“ON” position, does the (Refer to P.35-74.)power relay make a “click”noise?
YesNoYes
tI ,
Disconnect ECU connector
and check harness connec-
tor.t
Replace power relay.1
W
ith the ignition key in the
NoHarness wire between
“ON” position, does voltage- power relay and ECU is
between ECU connector ter-
broken.
minal No. 18 and ground in-
dicate the battery voltage?
4
Repair harness.
Yes
tp
Is there continuity betweenNoECU ground line broken
body harness terminal
s
No.9
and No. 34, and
c
ground?Repair harness.I
Yes

35-44SERVICE BRAKES - Anti-lock Braking System Troubleshooting
CABS warning light does not illuminate when ignition key is in “START”\
position.I
[Explanation]
The ABS ECU uses the IG2 power source which isand the ECU turns the valve relay OFF. If the
turned off in the “START” position. The ABS
warning light does not illuminate at this time, there
warning light uses the IGl power source which is is trouble in the warning light circuit on the valve
not turned off even in the “START” position.
relay side.
Consequently, in the “START” position, power is off
KLlh-0u
:LEIGNITIONSWITCH0(IGl) 0
Es10
1
7IIIIIII
I
I!
: Non-Turbo
.
TurboI: Non-Turbo 1
Remove the fuse fo
power source of the
ABS power relay in the
junction block and switch off ABS-ECU.
l Remove and inspect
10 pin connectors ofthe hydraulic unit.
“ON” position, does voltage
between body connector
terminal
No.8 and around1indicate the battery vcltage?
b!$%iii&Broken line between HUand body groundI
Yest
Remove the valve relay. Is - Nothere continuity between Valve relay malfunction
terminal No. 87a and No. 30?I
Yes[Replace-relay
HU harness malfunction
IReplace HU.I
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SERVICE BRAKES - Anti-lock Braking System Troubleshooting35-45
DABS warning light blinks once after the ignition key is turned to the “\
ON” positi??. It
illuminates in the “START” position and blinks once again when tur\
ned to the “ON” posItron.
[Explanation]
When power flows, the ABS ECU turns on theharness between the ECU and the warning light, the
warning light for approximately 1 sec. while itlight illuminates only when the valve relay is off in
performs a valve relay test. If there is a break in thethe valve relay test, etc.
El
ABS ECU
11 ,* (3 14
1 5 j 6 1 ,I 8 I 9)10111112113114115l161171~8)[19~0p1l22~3lz4125126127129l29l,ol31l32l33l~l35l
‘1. Non-Turbo . Turbo‘2: Non-Turbo 14AO662
Removehydraulic unitconnector andABS-ECUconnector and inspect atthe ABS-ECUharness \side
connect:/
-.
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Yes
Replace ABS ECU.I

35-46SERVICE BRAKES - Anti-lock Braking System TroubleshootingE-l
When the following diagnostic trouble codes are displayed “11 FL SPD \
SENSOR” “12
FR SPD SENSOR” “13 RL SPD SENSOR” “14 RR SPD SENSOR”
[Explanation] [Hint]
The ABS ECU detects breaks in the wheel speedIn addition to a broken wire/short circuit in the wheel
sensor wire. This diagnostic trouble code is output
if the wheel speed sensor signal is not input (or
speed sensor, also check whether the sensor gap is
too large, rotor teeth are missing, sensor harness
short circuited) or if its output is low when starting wire is temporarily broken, or sensor harness and
to drive or while driving.
body connector are not properly inserted.
E-2When diagnostic trouble code "15 SENSOR FAULT” is displayed
[Explanation]
This diagnostic trouble code is output when there is
an abnormality (other than broken wire or short cir-
cuit) in the wheel speed sensor output signal while
driving.
[Hint]
The following can be considered as the cause of the
wheel speed sensor output abnormality. l Distortion of rotor, teeth missing
lLow frequency noise interference when sensor
harness wire is broken
l Noise interference in sensor signal
0 When the sensor output signal is below the
standard value or when amplitude modulation is
over the standard value., using an oscilloscope to
measure the wave shape of the wheel speed
sensor output signal is very effective.
l Loose wheel bearing l Temporarily broken wire in sensor harness
l Sensor harness and body connector are not
properly inserted.
NOTE
(1) If contact is poor, check the sensor cable by
bending and lightly stretching it.
(2) If there is currently no trouble and if abnormality
in the displayed sensor circuit cannot be dis-
covered since values are normal even when
checked, turn the ignition switch OFF and
re-execute the driving test. Try replacing the
ABS ECU only if the same diagnostic trouble
code is output at this time.
(If it is difficult to recreate the trouble, there is a
possibility of speed sensor trouble recurring even if
the ECU is replaced.)
SPEED SENSOR
FRONT
REAR(LEFT SIDE) (RIGHT SIDE) (LEFT SIDE) (RIGHT SIDE)
ABS
ECU
GNDG!D
r23 )‘24 ;34Y9
FRONT SIDE
REVERSE SIDE DATA LlNK
CONNECTOR
14A0690
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SERVICE BRAKES - Anti-lock Braking System Troubleshooting35-47
Check flow connected with wheel speed
sensorNOTE:When checking with an oscilloscope, first measure voltage
variations in the wheel speed sensor output. (Refer to
P.35-69.)
Is the resistance value of the wheel speedNoMalfunction of wheel speed . Replace wheel speed
sensor part, which the displayed diag-
sensor sensor.nostic
trouble code indicates, normal?
Standard value:
0.8-I .2 kSZ
Yes
Is the resistance value with the ECU No* Harness wire for wheel
connector normal? speedsensor circuitis
Standard value: 0.8- 1.2 k0broken.
I
Repair harness.
t
Is the standard value for the
gap between the whee
l
speed sensor and rotor,
which the output diagnostic
trouble codeindicates,
within the range?
stendllrd value:!I$0.9 mm (.012- .035
) YesI
1 Yes.
Check the output of each
wheel speed sensor with an
oscilloscope, including the
wave form. (Refer to mea-
surement of wheel speed
sensor output voltage varia-
tions on
P.35-69.) Is the out-
put voltage for each wheel
speed sensor over
thestandard value and is the
wave form normal?
Yes
Can the abnormality b
e
found even if the sensor
harness and connection be-
tween sensor harness and body harness are bent and
stretched? No
-Recheck if below th
e
standard value or if the
sensor has a poor wave
form. Replace sensor or
rotor.
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