MITSUBISHI COLT 2006 Service Repair Manual

GROUP 35B
ANTI-SKID BRAKE SYSTEM (ABS)
CONTENTS
GENERAL INFORMATIO N . . . . . . . .35B-2CONSTRUCTION DESCRIPTION . . .35B-6
SENSORS . . . . . . . . . . . . . . . . . . . . . . . . . . 35B-6
ABS-ECU. . . . . . . . . . . . . . . . . . . . . . . . . . . 35B-6

GENERAL INFORMATION
ANTI-SKID BRAKE SYSTEM (ABS)35B-2
GENERAL INFORMATION
M2351000100409
FEATURES
The ABS ensures directional stability and controlla-
bility during hard braking.
For vehicles with this type of ABS, 4 sensors (4
channels) are installed on front and rear wheels
allowing independent left and right control.
The system has the following features:
•EBD (Electronic Brake-force Distribution system)
control has been added to provide the ideal brak
-
ing force for the rear wheels.
•Magnetic encoder for wheel speed detection has
been installed as a sensing device instead of the
rotor.
•For wiring harness saving and secure data com-
munication, CAN* bus has been adopted as a
tool of communication with another ECU.
NOTE: *: For more information about CAN (Control-
ler Area Network), refer to Group 54C, General Infor-
mation P.54C-2.
EBD CONTROL
In ABS, electronic control is used so the rear wheel
brake hydraulic pressure during braking is regulated
by rear wheel control solenoid valves in accordance
with the vehicle's rate of deceleration, and the front
and rear wheel slippage which are calculated from
the signals received from the various wheel speed
sensors. EBD control provides a high level of control
for both vehicle braking force and vehicle stability.
The system has the following features:
•Because the system provides the optimum rear
wheel braking force regardless of vehicle load
condition and the condition of the road surface,
the system reduces the required pedal depres
-
sion force, particularly when the vehicle is heavily
loaded or driven on road surfaces with high fric
-
tional coefficients.
•Because the duty placed on the front brakes is
reduced, the increase in pad temperature can be
controlled during brakes application to improve
the wear resistance characteristics of the pad.
•Control valves such as the proportioning valve
are not required.
SPECIFICATIONS
ItemSpecification
ABS control method4-sensor, 4-channel
Wheel speed
sensorMagnetic encoderFront86 (N pole:43 S pole:43)
Rear86 (N pole:43 S pole:43)
Ty p eSemiconductor

GENERAL INFORMATION
ANTI-SKID BRAKE SYSTEM (ABS)35B-3
CONSTRUCTION DIAGRAM
AC400129AB1
2
3, 7 1
4
5
6
Name of partNumberOutline of function
SensorWheel speed sensor1Sends alternating current signals at frequencies which are
proportional to the rotation speeds of each wheel to the
ABS-ECU.
Stop lamp switch2Sends a signal to the ABS-ECU to indicate whether the
brake pedal is depressed or not.
ActuatorHydraulic unit3Drives the solenoid valves according to signals from the
ABS-ECU in order to control the brake hydraulic pressure
for each wheel.
ABS warning lamp4Illuminates in response to signals from the ABS-ECU
when a problem develops in the system.
Brake warning lamp5Illuminates in response to signals from the ABS-ECU
when a problem develops in the EBD system.
Diagnosis connector6Outputs the diagnosis codes and allows communication
with the M.U.T.-III.
ABS-ECU7Controls actuators (described above) based on the signals
coming from each sensor.
Controls the self-diagnosis and fail-safe functions.
Controls the diagnostic function (M.U.T.-III compatible).

GENERAL INFORMATION
ANTI-SKID BRAKE SYSTEM (ABS)35B-4
SYSTEM CONFIGURATION DIAGRAM
AC314168
Stop lamp switch
Front-right wheel speed sensor Rear-right wheel speed sensor
Rear-left wheel speed sensor Front-left wheel speed sensor
ABS-ECU power supply Engine-CVT-ECU
Front-right solenoid valve (out)
Front-right solenoid valve (in)
Front-left solenoid valve (out)
Front-left solenoid valve (in)
Rear-right solenoid valve (out)
Rear-right solenoid valve (in)
Rear-left solenoid valve (out)
Rear-left solenoid valve (in)
ABS-ECU
Hydraulic
unit Rear-right
wheel speed
sensor
Front right
wheel speed
sensor
Front-left
wheel speed
sensor Rear-left
wheel speed
sensor
Front-right wheel (FR)
Front-left wheel (FL) Rear-right wheel (RR)
Rear-left wheel (RL)
Stop lamp switch
AB
Brake warning lamp
ABS warning lamp
Diagnosis connector
NO TE: Broken lines show CAN-bus lin e.

GENERAL INFORMATION
ANTI-SKID BRAKE SYSTEM (ABS)35B-5
ABS ELECTRICAL CIRCUIT DIAGRAM
AC314169
Engine-CVT-ECU
Front wheel speed
sensor Rear wheel speed
sensor
Motor power
supply
Solenoid valve
power supply
ABS-ECU
Motor power
supply
Solenoid valve
Hydraulic unit
Stop lamp
switch J/B
(Fuse)
No.42
15A No.40
7.5A
Fusible
link No.1
Ignition
switch (IG1) Fusible
link No.5 Fusible
link No.3
J/B
(Fuse)
No.33
15A Fusible
link No.6
J/C
(CAN2)
J/C
(CAN1) Diagnosis connector
Combination meter
(ABS warning lamp and
brake warning lamp)
AB
(rear, right)
(front, right)
(front, left)
(rear, left)
On
Off

CONSTRUCTION DESCRIPTION
ANTI-SKID BRAKE SYSTEM (ABS)35B-6
CONSTRUCTION DESCRIPTION
SENSORSM2351001000427
WHEEL SPEED SENSORS AND MAG-
NETIC ENCODER FOR WHEEL SPEED
DETECTION
AC601358
Rear wheel speed sensor
Front wheel speed sensor
Front Rear Rear
Encoder for wheel
speed detection Encoder for wheel
speed detectionRear wheel speed sensor
Encoder for wheel
speed detection
AB
Wheel spee d se nsor is a kin d of a pulse gen erator
consisted of
a mag netic encoder (a pla t e on which
north an
d so uth po le sides of th e mag net are
arrange
d alte rnately) for wh eel speed detection
which rot
a tes at the same speed of the wheels, and a
spee
d sen s or (semicon duct o r se nsor), send s fre
-
quency pulse sig nals in proportion to wh eel spee d.
Front wheel sp eed sensor co nsist s of a front whe e l
spee
d sen s or secu red on the knuckle, and a mag
-
netic encoder for wheel spee d dete c tio n fitt ed to th e
inside o
f the fro n t wheel bearing. Rear wh eel speed
sensor consist
s o f a rear wh eel speed sensor
secured on
the re ar hub, and a magn etic encoder fo r
whe
e l speed detection press fit t ed to the rear hub
inner ring.
ABS-ECU
M23510030 0025 2
•By integrating ABS-ECU into the hydraulic unit ,
no
more wiring h a rnesses for sending signal that
ope
rates the solen o id valve an d pump mo tor is
requ
ired, assuring high er reliability .
•Self-diag nostic p r ograms an d memory functions
are
integrated into ABS-ECU. If any malfunction
is dete
c ted by th e se lf-diagnostic function,
ABS-ECU activates
a fail-s afe function and illumi
-
nates ABS warning lamp and brake warning
la
mp
*.
NO TE: *: ABS-E CU illuminates the brake warning
l
a
m
p as EBD c o nt ro l wa rn in g la m p .
•ABS-ECU detects vehicle speed from the wheel
speed sensor signal, reco
gnizes the whee l rot a
-
tion, estimates the wheel slip condition based on
the
preprog rammed algorithm, a nd the n co ntrols
th
e soleno id valve in the hydr aulic u n it so th at the
wheels d
o not lock.
ABS FLUID PRESSURE CONTROL
FOUR-WHEEL CONTROL
ABS fluid pressure is controlled indep enden tly for
four whee
ls.

CONSTRUCTION DESCRIPTION
ANTI-SKID BRAKE SYSTEM (ABS)35B-7
EBD FLUID PRESSURE CONTROL
AC208548AB
Ideal distribution curve when
seated by fixed personsEBD operating conceptual design
Rear braking force
Ideal distribution curve when seated by one persons Braking force distribution curve
by the existing proportioning valveBraking force distribution
by EBD control
Front braking force
Braking Force
Improved
EBD control is
activate d within the lower slip ratio
area where
ABS is disab l ed. ABS-ECU calculates
vehicle
decelera t ion a nd slip amou nt of th e four
whe
e ls based on the wheel sp eed senso r signal. If
the rear
wh eel speed dif f ers f r om th e ve hicle speed
by a
cert ain level or more, ABS-ECU boost, holds,
and de
pressurises the rea r wh eel contro l so leno id
valve in the h
y drau lic unit, and then a d just s rear
whe
e l b r ake fluid pressure fa ir ly close to an ideal dis
-
tribution curve.
INITIAL CHECK
ABS-ECU inter nally activates the self-d iagno stic
function. ABS-ECU illuminates
ABS warning l a mp for
3 seconds (in
c lu ding the in itia l check)
* after th e ign i-
tion switch is turned ON. If a n y malf unction is
detected, ABS-ECU cont
inues illuminating ABS
war
n ing lamp and disables ABS cont rol.
NOTE: *: ABS warning lamp may st ay ON af ter the
ignition
switch is turned ON un til t he st artu p ve hicle
spee
d reaches approximately 10km/h . As far as
ABS-ECU memorizes any d i agn osis code related t o
the
whee l speed sen s or malfunct i on record ed d u ring
previous ignition ON st atus, ABS-ECU continues illu
-
mina ting ABS warn ing lamp until it verif i es that th e
malfunct
i on for tha t co de is resolved (S t a rtup che ck).
STARTUP CHECK
When th e st artup veh i cle sp eed re ache s app roxi-
mately 10 km/h, ABS-ECU performs the following
checks.
•Motor, solen o id valve check (onl y i n ini t ial st ar-
tup*)
Operat es the motor relay in ECU and checks the
pump motor op eratio n. At the same time,
ABS-ECU sequentially e nergizes each solenoid
valve in a ve ry sh ort perio d and ch ecks the valve
ope ration .
NOTE: *: Initia l st artu p ind i ca tes a first st artup af ter
the
system has st arted .
•Whee l speed sensor check
ABS-ECU che cks for a n y whee ls that ha ve no t
received whee l sp eed sens or signal from the
st artu p.
CONSTANT CHECK
ABS-ECU con s t antly ch ecks th e following item.
•ABS-ECU
Performs se lf-diagnosis in ECU.
•ECU power supply
Checks if ECU po we r sup p ly volt ag e reaches within
the operat ional range .
•Whee l speed sensor
•Monitors the ou tput volt age of the sensor sig-
nal wiring ha rness an d che c ks for a bnormal
output
volt ag e (ope n/sho r t circuit).
•Checks fo r any wheels tha t do n o t send pu lse
sig
nal while th e ve hicle is in motion.
•Checks if wheel spee d which is abno rmally
high
er or lo we r than the vehicle speed is
inpu
t.
•Pump mo tor and solenoid valve
Checks tha t ABS-ECU outp u t signal and t he ope rat-
ing co ndition of the pump motor an d so leno id
valve agree
with ea ch ot her .

CONSTRUCTION DESCRIPTION
ANTI-SKID BRAKE SYSTEM (ABS)35B-8
CAN COMMUNICATION
ABS-ECU outputs ABS warning lamp and EBD
warning lamp
* illumination request signals to the
combination meter through CAN communication.
NOTE: *: ABS-ECU illuminates the brake warning
lamp as EBD control warning lamp.
FAIL - SAFE FUNCTION
If any malfunction is detected by the self-diagnostic
function, ABS-ECU illuminates ABS warning lamp
and brake warning lamp
*, and it controls ABS and
EBD as shown in the following table.
NOTE: *: ABS-ECU illuminates the brake warning
lamp as EBD control warning lamp.
Diagnosis
code No.ItemAction during fail-safe operation
ABS controlEBD controlCAN outputBrake
warning
lampABS
warning
lamp
C1200Open or short
circuit in wheel
speed sensor (FR)Prohibits
control of
malfunctioning
wheel.
Prohibits all
wheel control
after control is
completed.Two or less
wheel
Abnormal:
Enabled
Three or
more wheels
Abnormal:
Prohibits
Output
permittedTw o o r l es s
wheel
Abnormal:
OFF
Three or
more
wheels
Abnormal:
ON
ON
C1201Wheel speed
sensor (FR) system
C1205Open or short
circuit in wheel
speed sensor (FL)
C1206Wheel speed
sensor (FL) system
C1210Open or short
circuit in wheel
speed sensor (RR)
C1211Wheel speed
sensor (RR)
system
C1215Open or short
circuit in wheel
speed sensor (RL)
C1216Wheel speed
sensor (RL) system
C1225Wheel speed
sensor malfunctionSystem
shut-downSystem
shut-downOutput
permittedONON

CONSTRUCTION DESCRIPTION
ANTI-SKID BRAKE SYSTEM (ABS)35B-9
C1226Control solenoid
valve (FR) pressure
holding system ProhibitedProhibitedOutput
permittedONON
C1231Control solenoid
valve (FR)
decompressing
system
C1236Control solenoid
valve (FL) pressure
holding system
C1241Control solenoid
valve (FL) pressure
reducing system
C1246Control solenoid
valve (RR)
pressure holding
system
C1251Control solenoid
valve (RR)
pressure reducing
system
C1256Control solenoid
valve (RL) pressure
holding system
C1261Control solenoid
valve (RL)
decompressing
system
C1266Motor system
(stuck)ProhibitedEnabledOutput
permittedOFFON
C1273Motor relay stuck
off
C1274Motor relay stuck
on
C1276Valve relay systemSystem
shut-downSystem
shut-downOutput
permittedONON
C1278Valve relay system
stuck offSystem
shut-downSystem
shut-downOutput
permittedONON
C1279Valve relay system
stuck onProhibitedEnabledOutput
permittedOFFON
Diagnosis
code No.Item Action during fail-safe operation
ABS control EBD control CAN output Brake
warning
lampABS
warning
lamp

CONSTRUCTION DESCRIPTION
ANTI-SKID BRAKE SYSTEM (ABS)35B-10
NOTE: .
•*: If any trouble occurs in CAN communication,
the brake warning lamp and ABS warning lamp
on the combination meter turns ON.
•Prohibit: Any controls are not performed until the
ignition switch is turned OFF.
•System shut-down: Control will be disabled until
valve power supply is turned off, and then ignition
switch is turned to the OFF position.
•Wait: ABS control is restarted when the normal
condition is resumed even though the ignition
switch is not turned OFF.
DIAGNOSTIC FUNCTION
ABS-ECU has the following functions for easier sys-
tem checks. The following items can be diagnosed
using the M.U.T.-III (ABS warning lamp illuminates
and ABS control is prohibited while the ABS-ECU
communicates with the M.U.T.-III).
•Diagnosis code set
•Service data output
•Actuator test
DIAGNOSIS CODE SET
There are 28 diagnostic items. Since all the diagnos-
tic results are recorded in volatile memory (EEP-
ROM*), they are stored in the memory even though
the battery terminals are disconnected.
NOTE: .
•*EEPROM (Electrical Erasable &;Programmable
ROM): Special type of memory that can be pro
-
grammed or erased electrically
•For each diagnostic item, refer to Fail-safe Func-
tion.
C1607Trouble in
ABS-ECUSystem
shut-downSystem
shut-downOutput
permitted
(Output may
be
impossible).ONON
Trouble in
ABS-ECU (CAN
Initialisation
malfunction)EnabledEnabledOutput
impossibleON *ON *
C1860High voltage at
ABS-ECU power
supplyWaitWaitOutput
permittedONON
C1861Low voltage at
ABS-ECU power
supplyWaitWaitOutput
permittedONON
U1073Trouble in CAN bus
systemEnabledEnabledOutput
impossibleON *ON *
Diagnosis
code No.Item Action during fail-safe operation
ABS control EBD control CAN output Brake
warning
lampABS
warning
lamp