1991 MITSUBISHI ECLIPSE ECU

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

BRAKES - Anti-lock Braking System Troubleshooting5-35Check flow connected with wheel speed
NOTE:
sensorWhen checking with an oscilloscope, first measure voltagefl-variations in the wheel speed sensor output. (Refer to P.5-51.)Is the resistance value of the wheel
speed sensor part, which the displayed
No cMalfunction of wheel speed _~ Replacewheel speedsensor
sensor.trouble code indicates, normal?
Standard value:
0.8-l .2 kQIs the resistance value with the ECU
No* Harness
wireforwheelRepair harness.connector normal?
speedI
broken.Is the standard value tor the
gap between the wheel
speed sensor and rotor,
which the output trouble
code indicates, within the
range?Standard value:
h;ti;j3-0.9 mm (.012-Rear
Nb adjustment
- No
the wheel speed sensor. Replace rotor that has
rotor that the trouble code
missingor damaged
indicates, normal and withteeth.
missing or damaged
Check the output of each
wheel speed sensor with an
oscilloscope, including the
wave form.
(Refewhekqmeasurement of
speed sensor output voltage
variations on
P.5-51.) Is the
output voltage for each
wheel speed sensor over
the standard value and is thewave form normal?I
YesCan the abnormality be
found even if the sensor
harness and connection be-
tween sensor harness and
body harness are bent and
stretched?
No
Repair harness.

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

5-38BRAKES - Anti-lock Braking System Troubleshooting
E-5Abnormality of solenoid valve drive circuit
[Explanation]*>The ABS ECU normally monitors the solenoid valve
when turned OFF, the ECU determines the solenoid%’ -’drive circuit.coil wire is broken/short circuited or the harness is
If no current flows in the solenoid even if the ECUbroken/short circuited and then the warning light
turns the solenoid ON or if it continues to flow evenlights up.
IGNITIONSWITCH(IGI)
7JIB------_-_tor and check with the
side connector.
Connect HU
1OP connec-
disconnect ECU con-
>Is the solenoid valve resis-
tance value within the range
of the standard values when
measured at the ECU con-
nector?Standard value:
3.0-3.2 Q
Yes1
II
I
Solenoid valve drive circuit isnormal.I
NoReplace HU.I
NoIs the resistance value for
the solenoid valve within the
range ofthe standard
values?Standard value:
3.0-3.2 Q, IYes ,
1
JThe harness wire for the
solenoidvalvecircuit
whose resistance value is
outside the range of the
standard value is broken
or short circuited.,-‘he-
-Repair

BRAKES - Anti-lock Braking System Troubleshooting5-39
E-6Abnormality of valve relay drive circuitI
j-a [Explanation]When the ignition switch is turned ON, the ABSnormal. In addition, normally it monitors whether or
ECU switches the valve relay OFF and ON for annot there is power in the valve power monitor line
initial check, compares the voltage of the signal tosince the valve relay is normally ON. Then, if the
the valve relay and valve power monitor line voltagesupply of power to the valve power monitor line is
to check whether the valve relay operation is
interrupted, the warning light illuminates.
IGNITIONMAIN FUSIBLESWITCHLINK @W-31)When the valve relay is
checked, are the followingconditions found?No.85-No.86:resistancevalue 60-120 Q
No.30-No.87a: continuityNo.30-No.87: No continui-
When battery voltage is ap-plied between terminals
No.86 and No. 85 grounded.
No. 30-No. 87: continuity
No.
30-No. 87a: no continui-
tyremove the HU connec-
NoValve relay malfunction
Replace valve relay.
IConnect the HU
remove the ECU con-
I Yes
IValve relay drive circuit isnormal.I

5-40BRAKES - Anti-lock Braking System Troubleshooting
E-7Abnormality 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
[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.
lWhen the motor ground line is disconnected andthe motor does not revolve
l When the motor continues to revolve
Does the motor make a
YesBroken wire or short cir-noise when wheel speed
-cuit in motor monitor line
exceeds 6 km/h (4 mph)?
b
NoRepair the harness between HU and ECU.
emove the motor rela
ABS ECU
14A0105
Remove the motor relav and
check resistance values.
No.
85-No. 86:resistancevalue 30-60 QNo.30-No.87: no continui-
ty
Battery voltage is applied on
terminals No. 86 and No. 85
grounded
No. 30-No. 87: continuity
Yes
q Motor relay malfunction 1
Replace motor relay.I
Is pump motor ground con-netted normally?Connect ground wire.I
b
Does voltage between bodyNo
connector terminal 51 andIBroken wire in pumpmotor power circuit
ground indicate battery vol-
tage?1Repair the harness.
YesIs resistance between body
- No L Malfunction of harness
connector terminal No. 2 andbetween HU and ECU
No.26 30-60 ohms?b
YesRepair harness.
Motor drive circuit is normal.