light MITSUBISHI ECLIPSE 1991 Owner's Manual

BRAKES - Anti-lock Braking System Troubleshooting5-25
TROUBLESHOOTING (ABS-AWD)Confirm condition in the following way and diagnosis accordingly.
C
F
>oes the ABS warning light illuminate as described
relow up to the time the engine starts?
1) When the ignition key is turned to the “ON”
position, the ABS warning light illuminates for
approximately 1 second due to the ABS ECU (asa self check of the valve relays is performed),
then it blinks four times and goes out and stays
out.power to the ABS ECU is interrupted and the
ABS warning light remains lit because the valve
relay is OFF.
t:2) With the ignition key in the “START” position,(3) When the ignition key is turned from the
“START” position to the “ON” position, the
ABS warning light illuminates for approximately
1 second (during this time a recheck of the valverelays is performed), then it blinks four times
and then goes out and stays out.IO1
-1 sec. 1 sec.1
sec.1 sec.
14AO594
YesCONTINUE TO NEXT PAGE
No
No.
1
2
3
Trouble condition
ABS warning light does not light up at all.
ABSwarninglightOFFIgnitionkey
ACC.
LO;-+
14AOSSOWhen the ignition key is turned to the
“ON” position, it remains lighted.
4BSNamingight
0:7gnition
wACC.
LO:+14A0591Does not illuminate when ignition key is
in “START” position.
4BSNamingightONOFF
14A0595
Major causes
l ABS warning light bulb is burnt out.
l Open in ABS warning light electrical
circuit (check for blown fuse)
l Fail safe is functioning due to ECU self
diagnosis
l Short in ECU warning light drive circuitl Malfunction of ECU
l Malfunction of valve relay
l Break in harness between ABS warn-
ing light and HU
l Break in harness between HU and
body groundRemedy
Check, using flow
chart A. (Refer to
P.5-27.)
Check, using flow
chart B. (Refer to P.5-30.)
Check, using flow
chart C. (Refer to
P.5-
32.)

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.

BRAKES - Anti-lock Braking System Troubleshooting5-27
AABS warning light does not light at all.I-. [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.
MAIN FUSIBLE
LINK
@
2
c-4
I 1~0~0~fWW-i
m2 ac
HU&,52&8--1
III
IA x A ,c
VALVE "I
RELAYI
1 IRELAY /--+I1 &-I I
\, J,. \ ,I L-1
I-----------A
I I
[Hint]If other warning lights do not light up either, fuse is
probably blown.
IGNITIONIGNITIONSWITCH (IG2)SWITCH (IGI)
10A10A p,
*2\I6-IM"
7,,14112131415161718I 9 I
iE4~oWERI.0(1111211311915116117
#$II;NATION
58
ABS ECU125
GNDGNDT7”

5-28BRAKES -Anti-lock Braking System Troubleshooting
With the ignition key in the “ON”
posi-NoCheck fuse No.ll. If it is
tion, do other warning lights illuminate?blown, correct the cause of
the blown fuse and then
replace the fuse.
YesTurn the ignition switch OFF and
Does voltage between
har-NOThe harness between the
nessNo. 14 and ground indicate
battery voltage?) fuse No.1 1 is broken.
YesCircuit in combination meter
is broken.
tRepair or replace com-
bination meter.II
IIIs the ABS warning light normal? (CheckNO) ABS warning light bulbReplace ABS warning
for burned bulb.)
burned.* light bulb.
I
Yes
- No
Are instrument panel wiring harness,
engine compartment wiring harness,
body wiring harness and ABS wiring
harness connectors connected properly?
c Connect connectors firmly.
(Check for pins pulled out or
bent, repair as needed.)
YesBroken wire in ECU, valve relay or both
drive circuits. Check and repair both
circuits.

5-30BRAKES - 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 thesystem or when the warning light drive circuit is
short circuited.
MAINIGNITIONFUSIBLELINK
@SWITCH(IGl)
ABS ECU
JCheck, using check chart
E-l -E-7.with the ECU connector
dis-
YesDoes the ABS warning light
NoShort in HU harness or
remainilluminated even
with the ECU connector dis-m sticking of valve relay
contact
connected?I
YesReplace HU or replace
valve relay.
ItShort in harness between
IT$Uhx ECU and ABS warningc Repair harness or replace
combination meter.

5-32BRAKES -Anti-lock Braking System Troubleshooting
CABS warning light does not illuminate when ignition key is in “START” position.
[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 ABSwarning light does not illuminate at this time, there
warning light uses the
IGI power source which isis 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
MAINIGNITIONFUSIBLESWITCHLINK @I(IGl)J/B
“62
I .1411213141516l7l61911112113114115U6i,79
@COMBINATIONAL METER
“58ABS ECU
1410000
hydraulicunit (HU) connector and
>\/I
1With the ignition key in the
“ON” position, does voltage
between body connector
terminal No.8 and ground
indicate the battery voltage?
Is there continuity between
No~Broken line between HU
body connector terminaland body groundNo.9 and ground?
I
YesIs there continuity between
HU connector terminal No. 8and terminal
No.9?
YesRemove the valve relay. Is
there continuity between
terminal No. 87a and No. 30?
I
Yes1 Replace valve relay.
HU harness malfunction
I
1 Replace HU.

BRAKES - Anti-lock Braking System Troubleshooting5-33
DABS warning light blinks once after the ignition key is turned to the “ON” position. It
illuminates in the “START” position and blinks once again when turned to the “ON” position.*-_
[Explanation ]When power flows, the ABS ECU turns on the
harness between the ECU and the warning light, thewarning 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 the
the valve relay test, etc.
Y
x %l4
9
4
n. 58
ABS ECU
14A0597
EC
4connector and check with
he harness connector. /\/
IIn the ignition key “ON”
position, does voltage be-
tween terminal
No.25 andground indicate battery vol-
tage?
Replace ABS ECU.I

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

5-36BRAKES - Anti-lock Braking System Troubleshooting
E-3Abnormality of G sensor circuit
[Explanation]The ABS ECU turns on the warning light in the
following cases.
lOFF trouble turning G sensor OFF (It is judged
that the
G sensor continues to be OFF for more
than approximately 13 seconds except when the
lWhen there is a broken wire or short circuit in
the harness for the
G sensor system.
PlUN; F;SIBLEIGNITIONSWITCH (IG2)J/B
G-SENSOR
E-lABSECU
14AO609
Is G sensor normal? (ReferNoto
P.5-86.)Replace G sensor.
I YesWith the ignition key “ON”
_ No m The harness between the
does the voltage betweenG sensor and the ABS
terminal No.6 and groundECU is broken.
indicate battery voltage?
IG sensor circuit is normal.I

BRAKES - Anti-lock Braking System Troubleshooting5-37
E-4Abnormality of stop light switch circuitI
- [Explanation][Hint]The ABS ECU turns on the warning light in theIf the stop light operates normal, the ABS harness
following cases.
wire for the stop light switch input circuit to the ECU
lStop light switch may remain on for more thanis broken or there is a malfunction in the ABS ECU.
15 minutes without the ABS functions.
lThe harness wire for the stop light switch may
be open.
AUTO-CRUISE
STOP
--I0.85-G
’LIGHT
w
STOPLIGHTSWITCHABSECURESIS-
TOR
14AO610
Do the stop lights light up _ No c Check the stop light re-and go out normally?lated circuit and repair
problem spots.
Yes
isconnect the ABS ECconnector and inspect at
the harness side
connec-
tor.When the brake pedal is
NoHarness wire between
pressed forcefully, does the
* stop light switch and ABS
voltage between connectorECU is broken.
terminal No. 29 and ground
indicate battery voltage?
c
Repair harness.
Yes.
;gSJ;ght switch circuit is