1989 MITSUBISHI GALANT Service Repair Manual

35-16SERVICE BRAKES - Anti-lock Braking System Troubleshooting
TROUBLESHOOTING (ABS-FWD)
Confirm condition in the following way and diagnose accordingly.
Ioes the ABS warning light illuminate as describedpower to the ABS ECU is interrupted and the
lelow up to the time the engine starts?ABS warning light remains lit because the valve
1) When the ignition key is turned to the “ON” relay is OFF.
position, the ABS warning light blinks twice for (3) When the ignition key is turned from the “START’
approximately 1 second due to the ABS ECU (as position to the “ON” position, the ABS warning
a self check of the valve relays is performed), light blinks twice for approximately 1 second
and goes out and stays out. (during this time a recheck of the valve relays is
2) With the ignition key in the “START” position, performed), and then goes out and stays out.
ABS warning
,,lseq (se+
lightII
OFF -I
Ignitionkey
ABS warnmg/;,ght68A009314A0589
YAS rICONTINUE TO NEXT PAGENo
No.
Trouble condition
ABS warning light does not light up at all.
ABSwarnina
ON
OFF
1light -
lgnltionkey
I14 A0590
When the ignition key is turned to the l Fail safe is functioning due to ECU on-
“ON” position, it remains lighted. board diagnostic
ABSwarning
2lightOZ7
l Short in ECU warning light drive circuit
l Malfunction of ECU
lgnitlonkev
ACC. LOi+14A0591
Does not illuminate when ignition key is
in “START” position.
ABSwarning
3light
Ignition
key ACC. LO:+14AO592
Major causes
l ABS warning light bulb is burnt out.
l Open in ABS warning light electrical circuit (check for blown fuse)
l Malfunction of valve relay
l Break in harness between ABS warn- ing light and HU
l Break in harness between HU and body ground Remedy
Check, using flow
chart A (Refer to
P.35-21.)
Check, using flowchart B (Refer toP.35-24.)
Check, using flow:hart C (Refer to ‘.35-26.)
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SERVICE BRAKES - Anti-lock Braking System Troubleshooting35-I 7
No.
4
Trouble condition
After the ignition key is turned to the “ON” position, it blinks once and then
illuminates when it is turned to the “START” position. When the key is
returned to the “ON” position, the light
blinks again. (Blinking with the ignition
key in the “ON” position is synchronized
with operation noise of the valve relay.)
ABSwarning
ighto:=
gnition:eyACC. LCFY-
14AO593
Major causes
l Break in harness for ECU warning light drive circuit
l Malfunction of ECU
CONTINUED FROM PREVIOUS PAGE
Does the ABS warning light illuminate
_Yes Trouble with the motor re-
when starting to drive the car?
c lay, solenoid valve [due to self test when driving above
6 km/h (4 mph)] or malfunc-
Notion of wheel speed sensor
I
Is there one-sided braking, insufficientNo
L
braking force or malfunction of ABS
operation?
I
Yes
t
Trouble condition
One-sided braking Insufficient braking force
Decline in ABS function
I
Major causes
l Mechanical lock of HU solenoid valve
l Hydraulic line in HU is clogged.
l Malfunction in HU solenoid valve
op-
(Wheels easily lock when there is sud-
eration
den braking.) l Hydraulic line in HU is clogged.
ABS sometimes functions even when l Insufficient wheel speed sensor out-
there is no sudden braking. (ABS opera-
put voltage (sensor malfunction,
to0
tion vibration is transmitted.)
large a gap between sensor rotor or
missing rotor teeth or temporarily
broken wire in sensor harness)
l Malfunction of ABS ECU Remedy
Check, using flow
chart D. (Refer to
P.35-27.)
Remedy
Check HU operation (Refer to
P.35-20.) and, if necessary,
replace HU. If HU is normal, check
structural parts for normal
braking. (Refer to
P.35-12.)
Check wheel speed sensor
(Refer to P.35-126.) and, if
necessary. replace sensor,
adjust gap or replace rotor. If tests indicate that there are
no mechanical or electrical
failures, replace the ECU.
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35-18SERVICE BRAKES - Anti-lock Braking System Troubleshooting
CONTINUED FROM PREVIOUS PAGEAfter a test drive*, use on-board diag-
ostic
to check.
(Refer to
P.35-19.)
No diagnostic trouble codes output and
normal codes are displayed? No on-board diagnostic
No outpu
t
No Diagnostic trouble codes are output
D Check and repair the har-
ness between the ABS
ECU serial/on-board di-
agnostic output terminals
and the data link connec-
tor. (Refer to
P.35-25.)
Yes
All ABS functions are normal. (Nor are there stored memory of past di-
agnostic trouble code.)t
There was trouble in the
past.
NOTE
Store diagnostic trouble
codes in the memory. Referring to the
diagnos-tic trouble code checkc chart E-l-E-6, make the
diagnostic trouble code
reoccur to discover the
main cause of intermit-
tent or other trouble.
If diagnostic trouble does
not reappear, watch ve-
hicle movements until it
reappears.
l :Run for over 30 sets. at a speed exceeding 30 km/h (18.6 mph).
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SERVICE BRAKES - Anti-lock Braking System Troubleshooting35-19
(1) With the ignition switch OFF, connect the adapter harness
and scan tool, turn the ignition ON and select the ABS sys-
tem. (The ABS warning light lights up, it goes into the scan
tool mode.
In the scan tool mode, ABS does not func-
tion.)
If it does not go into the scan tool mode, check the ECU
power circuit and
the harness between the ECU and data
link connector.
(2) Read the on-board diagnostic output codes from the ECU
(3) ?a\?zl’ythe diagnostic trouble codes once from memory.
(Refer to P.35-20.)
If the memory can not be canceled, the ECU is currently
detecting the trouble. If it can be cleared, the trouble is
either temporary or appears only when driving.
(4) When the diagnostic trouble codes are cleared, or when
the ABS system goes into fail safe during another test drive
and diagnostic trouble codes are outputed, check accord-
ing to diagnostic trouble code check charts (E-l -E-6).
DIAGNOSTIC TROUBLE CODE CHART
Diagnostic trouble code CheckReferenceDiagnostic trouble codeCheckReference
chart name
pawchart namepawNo. Scan tool display letters or remedy No. Scan tool display letters or remedy
11FL SPD SENSOR41SOL V FRONT L
12FR SPD SENSOR42SOL V FRONT RE-4P.35-31
E-lP.35-2813RL SPD SENSOR
43SOL V REAR
14RR SPD SENSOR51VALVE RLYE-5P.35-32
15 SENSOR FAULTE-2P.35-28 52MOTOR RLYE-6P.35-33
22 STOP SWE-3P.35-30 55ECU ECUreplacement -
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35-20SERVICE BRAKES - Anti-lock Braking System Troubleshooting
METHOD OF CLEARING DIAGNOSTIC
TROUBLE CODE MEMORY
Caution
l When servicing is finished, clear the diag-
nostic trouble code memory.
Diagnostic trouble codes cannot be cleared from
memory when the ABS ECU system in fail safe.
Proceed to diagnosis and repair.
(1) Clear memory using scan tool.
(For details, refer to the scan tool instruction
manual.)
(2) After clearing, recheck the diagnostic trouble
codes, and check that memory is cleared.
Actuator test specifications ACTUATOR TEST FUNCTION
The actuator can be forcibly driven in the following
way by using the scan tool.
NOTE
lThe actuator test cannot be carried out when
the ABS ECU system is fail safe.
lWhen using forced drive using the scan tool, the
vehicle must be stopped.
lDuring forced drive using the scan tool, forced
drive operation is stopped when any wheel
speed reaches 10 km/h (6 mph).
No.ScGc;r$ol displayDrive solenoidvalve and motor
01
02
FR VALVE A
FL VALVE ASolenoid valve andpump motor foreach HU corres-ponding channel.
I
03REAR VALVE A
Solenoid valve and
04FR VALVE Mpump motor foreach HU corres-ponding channel.
05FL VALVE M
I
06REAR VALVE M
Drive pattern
Not used
Pressure
increaseI I
Solenoid Pressurevalve
Pump ONIms! 3s I 3sImotorOFFIStart of forced drive
I
End of forced drive

SERVICE BRAKES - Anti-lock Braking System Troubleshooting35-21
A ABS warning light does not light at all.
[Explanation]
When it does not light up at all, there is a strong
possibility that there is trouble with ABS warning
light or with power to the light.
[Hint]
If other warning lights do not light up either, fuse is
probably blown.
MAIN FUSIBLE
LINK @IGNITIONSWITCH (IG2)IGNITIONSWITCH (IGl)
Ea
1
0 U
, ,8--1I
CL
, VALVE
fI*I1 RELAY 1 Ii 1,
M
i 10
z 13-
--3z2-&
rc11_ 3
t”71
_----
a-II
2
dt II
zz
c:
35 126J.27ABS ECU
1
GND GND GNDv v v
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14A0085

35-22SERVICE BRAKES- Anti-lock Braking System Troubleshooting
- N

o
With the ignition key in the “ON” posi-
Check fuse No. 9. If it is
tion. do other warning lights illuminate?
* blown, correct the cause of
the blown fuse and thenreplace the fuse.
I
Yes
Turn the ignition switch OFF and check.
4II., III,
Is the ABS warning light normal? (CheckNo cABS warning light bulb Replace ABS warning
for burned bulb.)burned.* light bulb.
I
Yes
NoThe harness between the
combination meter from
* fuse No. 9 is broken.
1
Repair harness.I
Circuit in combination metercRepair or replace com-
is broken. bination meter.
Yes
Is there continuity between terminals No.NoMalfunction of combination Repair or replace combi-
;,d”,l” No. 17 on the combination meter -meter
nation meter
Yes
Are instrument panel wiring harness, _
Noc Connect connectors firmly.
engine compartment wiring harness,
body wiring harness and ABS wiring
harness connectors connected properly? (Check for pins pulled out or
bent, repair as needed.)
Yes
Broken wire in ECU, valve relay or both
drive circuits. Check and repair both
circuits.
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SERVICE BRAKES - Anti-lock Braking System Troubleshooting35-23
the ignition key in the
position, remove the ECU connector
Does the voltage between ECU harness
No r Broken wire between ABS .
connector terminal No.25
and ground
indicate battery voltage? warning light and ECU.Repair harness.
Yes Replace ABS ECU.
(Remove valve relay and check.
>
Valve relay malfunction Replace valve relay.I
Yes
/Install
the valve relay and,
\
ignition key in the “ON
”
remove the HU connector and
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Does voltage between the HU harnessNo * Broken harness wire be- -Repair harness.
connetor terminal No.8 and ground indi-
tween ABS warning lightIcate
battery voltage? and HU
I
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?
I
- Repair harness or replaceHU.
YesConnector connection mal-
function
NOTEWhen inspecting the parts marked with l ,take care to the diode polarity. (Refer to the circuit diagram on P.35-21.)