1991 MITSUBISHI ECLIPSE wheel

5-8BRAKES - Troubleshooting
Symptom
Scraping or grinding
noise when brakes are
appliedProbable cause
Worn brake pad
Caliper to wheel interference
Cracked brake discRemedy
Replace
Correct or replace
Squealing, groaning orchattering noise when
brakes are appliedDisc brakes-missing or damaged brake pad
anti-
squeak shimReplace
Brake discs and pads worn or scored
Improper lining partsCorrect or replaceDisc brake-burred or rusted calipers
Dirty, greased, contaminated or glazed pad
Incorrect adjustment of brake pedal or booster
push-rodClean or deburrClean or replaceAdjust
Squealing noise when
brakes are not appliedDisc brakes-rusted, stuckLubricate or replace
Loose or extra parts in brakes
Improper positioning of pads in caliperRetighten
Improper installation of support mounting to caliperCorrect
body
Poor return of brake booster or master cylinder
Incorrect adjustment of brake pedal or booster
push-rod
ReplaceAdjust
Groaning, clicking or rat-Stones or foreign material trapped inside wheelRemove stones, etc.
tling noise when brakescovers
are not appliedDisc brakes-failure of shim
ReplaceDisc brakes-loose installation bolt
Retighten
Loose wheel nuts
Incorrect adjustment of brake pedal or booster
push-rodAdjust

BRAKES - Anti-lock Braking System Troubleshooting5-9
ANTI-LOCK BRAKING SYSTEM
-- TROUBLESHOOTINGNO!JEBAE
PARTICULAR CHARACTERISTICS OF
THE ANTI-LOCK BRAKING SYSTEMModels equipped with the anti-lock braking system
(A.B.S.) may exhibit one or more of the following
characteristics from time to time, but none of these
is abnormal.
(1) A pulsing feeling in the brake pedal, or vibration
of the body or the steering wheel, when the
anti-lock braking system is activated by sudden
braking or by braking on a slippery road surface.Actually, this phenomenon is an indication that
the anti-lock braking system is functioning nor-
mally.(2) When the vehicle speed reaches approximately
6 km/h (4 mph) after the engine is started and
the vehicle starts off (for the first time), a
whining motor noise may be heard from the
engine compartment if the vehicle is traveling in
a quiet place, but this noise is simply the result
of a self-check being made of the anti-lock
braking system operation.
TROUBLESHOOTING METHODSProblems related to the anti-lock braking system
(A.B.S.) can be classified into two general categor-
ies: problems in the electrical system and those in
the hydraulic system.For problems in the electrical system, the
self-diagnosis function is built into the electronic control
unit (E.C.U.) causing the A.B.S. warning light to
illuminate as a warning to the driver.
Problems in the hydraulic system (poor braking,
etc.) can be located in the same way as for ordinary
brakes. There is, however, the necessity to check todetermine whether the problem is related to ordin-
ary brake components or to the components relatedto the A.B.S.
HOW TO USE THE TROUBLESHOOTING
FLOW CHART(1) Using the flow chart, check the ABS warning
light light-up sequence and check the condition
of braking operation.
(2) Following the check chart listed in the remedy
column, perform the checks. There are [Explana-tion] and [Hint] in each check chart. Refer to
them when troubleshooting.
NOTEECU: Electronic control unit
HU: Hydraulic unit
MUT: Multi-use tester

BRAKES - Anti-lock Braking System Troubleshooting5-14
./
No.Trouble conditionMajor causesRemedyAfter the ignition key is turned to the
l Break in harness for ECU warningCheck, usinflow
“ON” position, it blinks once and then
light drive circuit
chart D. (Re er to9illuminates when it is turned to the
l Malfunction of ECUP.5-18.)“START” position. When the key is
4returned 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.)
ABSwarninglighto:-
Ignition
keyACC. LCi+-
14*0593CONTINUED FROM PREVIOUS PAGE
Does the ABS warning light illuminate
when starting to drive the car?
Yes~ Trouble with the motor re-lay, solenoid valve [due toL Check, following trouble
source check charts E-l -self test when driving above
E-6.6 km/h (4 mph)] or malfunc-
NoIs there one-sided braking, insufficient
braking force or malfunction of ABS
operation?
YesTrouble condition
Major causes
One-sided braking
Insufficient braking forcel Mechanical lock of HU solenoid valve
l Hydraulic line in HU is clogged.
Decline in ABS function
(Wheels easily lock when there is sud-
den braking.)
ABS sometimes functions even when
there is no sudden braking. (ABS opera-
tion vibration is transmitted.)
1 tion of wheel speed sensor 1
NoNormall Malfunction in HU solenoid valve op-
erationl Hydraulic line in HU is clogged.
l Insufficient wheel speed sensor out-
put voltage (sensor malfunction, too
large a gap between sensor rotor,
missing rotor teeth or temporarily
broken wire in sensor harness)
l Malfunction of ABS ECU
RemedyCheck HU operation and, if
necessary, replace HU.
If HU is normal, check
structural parts for normal
braking. (Refer to
P.5-7.)Check wheel speed sensor
(Refer to
P.5-82.) and, ifnecessary,replace sensor,
adjust gap or replace rotor.
If tests indicate that there are
no mechanical or electrical
failures, replace the ECU.

BRAKES - Anti-lock Braking System Troubleshooting549
E-lInput abnormality of wheel speed sensorI-[Explanation][Hint]The ABS ECU detects breaks in the wheel speed
In addition to a broken wire/short circuit in the wheelsensor wire. The warning light lights up if the wheel
speed sensor, also check whether the sensor gap isspeed sensor signal is not input (or short circuited)
too large, rotor teeth are missing, sensor harness
or if its output is low when starting to drive or while
wire is temporarily broken, or sensor harness and
driving.body connector are not properly inserted.
I IE-2Output abnormality of wheel speed sensorI
[Explanation]The warning light lights up when there is an
abnormality (other than broken wire or short circuit)
in the wheel speed sensor output signal while
driving.
[Hint]
The following can be considered as the cause of thewheel 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 signall When the sensor output signal is below the
standard value or when amplitude modulation is
over the standard value, using an oscilloscope tomeasure 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
If contact is poor, check the sensor cable by bendingand lightly stretching it.
SPEED SENSOR
FRONTREAR(LEFT SIDE) (RIGHT SIDE) (LEFT SIDE) (RIGHT SIDE)
Km
I-.IIGND
III24I
FRONT SIDE
I
ABSECU
REVERSE SIDE
SELF-DIAGNOSIS
CHECK CONNECTOR
14AO601

5-20 _BRAKES - Anti-lock Braking System TroubleshootingCheck flow connected with wheel speed
sensorNOTE:When checking with an oscilloscope, first measure voltage
variations in the wheel speed sensor output. (Refer to
P.5-51.)
Is the resistance value of the wheelNo c Malfunction of wheel speedReplace wheel speed
speed sensor part, which the displayedsensor
sensor.trouble code indicates, normal?
Standard value:
0.8-l .2 kQ
I YesIs the resistance value with the ECU
No c Harness wire for wheel -Repair harness.connector normal?
speed
sensorcircuit is
Ibroken.
II1
1
Is the standard value for the
gap between the wheel
speed sensor and rotor,
which the output trouble
code indicates, within the
range?
Standard value:
h
%Z~Pf!;!~~~e~no missing or damaged
teeth?
1 Yes
1Check the output of each
wheel speed sensor with an
oscilloscope, including the
waveform. (Refer to
measurement ofwheel
speed sensor output voltage
variations on
P.5-51 .I Is the
output voltage for each
wheel speed sensor over
the standard value and is thewave form normal?
Yes
Canthe abnormality beNoRepair harness.foundeven if the sensorIharness and connection be-
tween sensor harness and
body harness are bent and
estretched?
Yes

5-24BRAKES - Anti-lock Braking System Troubleshooting
E-6 Abnormality of motor drive circuit
[Explanation]The ABS ECU illuminates the warning light for the
motor relay and motor in the following cases.
l When the motor relay does not function
lWhen there is trouble with the motor itself and it
does not revolve
lWhen the motor ground line is disconnected and
[Hint]If there is motor operation noise when wheel speed
exceeds
Gkm/h (4mph) when starting up after the
engine is started, there is a broken or short circuitedmotor monitor wire.
the motor does not revolve
l When the motor continues to revolve
14A0605Does the motor make a
YesBroken wire or short cir-noise when wheel speedcuit in motor monitor line
exceeds 6 km/h (4 mph)?
1Repair the harness be-
tween HU and ECU.
, NoRemove the motor relay.
Remove the motor relay andcheck resistance values.
No. 85-No. 86:resistancevalue
30-60 52No.30-No.87: no continui-
ty
Battery voltage is applied onterminals No. 86 and No.85
grounded.No.30-No.87: continuity
IYesIs pump motor ground con-
NoConnect ground wire.
netted normally?
IlYes
motor relay and re-
move HU connector.>Does voltage between body
connector terminal 51 and
No c Broken wire in pump
motor power circuit
ground indicate battery vol-
tage?4Repair the harness.
YesIs resistance between body
NoMalfunction of harnessconnector terminal No. 2 andbetween HU and ECUNo.26 30-60 ohms?iII1Repair harness.

5-26BRAKES - Anti-lock Braking System Troubleshooting
No.Trouble conditionMajor causesRemedyAfter the ignition key is turned to the
l Break in harness for ECU warningCheck, using flow“ON” position, it blinks once and thenlight drive circuitchart D. (Refer to P.5-illuminates when it is turned to the
l Malfunction of ECU33.)“START” position. When the key is
returned to the “ON” position, the light
4blinks again. (Blinking with the ignition
key in the “ON” position is synchronized
with operation noise of the valve relay.)
ABSwarning
light
0:~
Ignition
keyACC. iv-
14A0593CONTINUED FROM
PREVIOU? PAGE
I ,
Does the ABS warning light illuminateYes* Check, following trouble
when starting to drive the car?L Trouble with the motor re-lay, solenoid valve [due to
self test when driving above
6 km/h (4 mph)] or malfunc-source check charts E-l -E-7.
Notion of wheel speed sensor
Normal
YesTrouble condition
Major causes
RemedyOne-sided brakingl Mechanical lock of HU solenoid valveCheck HU operation and, if
Insufficient braking forcel Hydraulic line in HU is clogged.
necessary, replace HU.
If HU is normal, check
Decline in ABS functionl Malfunction in HU solenoid valve op- structural parts for normal
(Wheels easily lock when there is
sud-
erationbraking. (Refer to P.5-2.)den braking.)l Hydraulic line in HU is clogged.
ABS sometimes functions even whenl Insufficient wheel speed sensor
out-Check wheel speed sensor
there is no sudden braking. (ABS opera-put voltage (sensor malfunction, too (Refer to P.5-82.) and, if
tion vibration is transmitted.)
large a gap between sensor rotor, necessary, replace sensor,
missing rotor teeth or temporarily adjust gap or replace rotor.
broken wire in sensor harness)
If tests indicate that there are
l Malfunction of ABS ECU
no mechanical or electrical
failures, replace the ECU.

5-34BRAKES -Anti-lock Braking System Troubleshooting
E-lInput abnormality of wheel speed sensorI.
[Explanation][Hint]s”rThe ABS ECU detects breaks in the wheel speed
In addition to a broken wire/short circuit in the wheel--sensor wire. The warning light lights up if the wheel
speed sensor, also check whether the sensor gap isspeed sensor signal RL is not input (or shorttoo large, rotor teeth are missing, sensor- harness
circuited) or if its output is low when starting to drivewire is temporarily broken, or sensor harness and
or while driving.body connector are not properly inserted.
E-2Output abnormality of wheel speed sensor
[Explanation]The warning light lights up when there is an
abnormality (other than broken wire or short circuit)
in the wheel speed sensor output signal while
driving.
[Hinti
The following can be considered as the cause of thewheel 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 signall When the sensor output signal is below the
standard value or when amplitude modulation is
over the standard value, using an oscilloscope tomeasure 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
If contact is poor, check the sensor cable by bendingand lightly stretching it.
SPEED SENSOR
FRONTREARP%(LEFT SIDE)
(RIGHT SIDE)(LEFT SIDE)(RIGHT SIDE),’
1
FRONT SIDE
SELF-DIAGNOSISCHECK CONNECTOR14AO608