ACURA TL 1995 Service Repair Manual

ABS Contro l Uni t Termina l Arrangemen t
ABS CONTRO L UNI T 12 P CONNECTO R
Wir e sid e o f femal e terminal s
VB: Batter y Voltag e
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Troubleshooting Precautions

ABS Indicator Light

1. If the system is OK, the ABS indicator light goes off two seconds after turning the ignition switch ON (II) without start-

ing the engine. After starting the engine, the ABS indicator light comes on again and goes off after two seconds. This

occurs because the ABS control unit is activated by the IG2 power source.

2. The ABS indicator light comes on when the ABS control unit detects a problem in the system. However, even though

the system is normal, the ABS indicator light comes on, too, under the following conditions. To determine the actual

cause of problem, question the customer about the problem, talking the following conditions into consideration.

Only drive wheels rotate

One wheel stuck of drive wheels

Vehicle spin

ABS operate condition continue for long time

Signal disturbance

3. When a problem is detected and the ABS indicator light comes on, there are cases when the indicator light stays on

until the ignition switch is turned OFF, and cases when the indicator light goes off automatically when the system

returns normal. For the DTC 61 and 62, the indicator light goes off automatically when the system returns normal. For

all other codes, the indicator light stays on until the ignition switch is turned OFF.

4. For DTCs 12, 14, 16, 18, 21, 22, 23, 24, 51, 52 and 53, the indicator light goes off when the vehicle is driven again and

the signals are OK after the ignition switch is turned from OFF to ON (II). However, if the DTC is erased, the CPU is

reset and the indicator light goes off right after the engine is started if the signals are OK.

Diagnostic Trouble Code (DTC)

1. The DTC is not memorized if the CPU cannot be activated or the CPU fails and the indicator light comes on.

2. The memory can hold any number of DTCs. However, when the same DTC is detected more than once, the later one

is written over the old one. Therefore, when the same problem is detected repeatedly, it is memorized as one DTC.

3. The DTCs are indicated in the order of ascending number, not in the order they occur.

4. The DTCs are memorized in the EEPROM (non-volatile memory). Therefore, the memorized DTCs cannot be canceled

by disconnecting the battery. Perform the specified procedures to erase the DTCs.

Self-diagnosis

1. The
self-diagnosis
can be
classified
into
two
categories.

• Initial diagnosis: Performed right after the engine starts and until the ABS indicator light goes off.

• Regular diagnosis: Performed right after the initial diagnosis until the ignition switch is turned OFF.

2. When a problem is detected by self-diagnosis, the system

• Turns the ABS indicator light ON

• Memorizes the DTC

• Turns the fail-safe relay OFF

• Stops ABS controlProCarManuals.com

Troubleshooting Precaution s
Kickback
1. Th e moto r operate s whe n th e AB S is functioning , an d flui d i n th e reservoi r i s force d ou t t o th e maste r cylinde r caus -
in g kickbac k a t th e brak e pedal .
Pum p Moto r
1 . Th e pum p moto r operate s whe n th e AB S is functioning .
2 . Th e AB S contro l uni t check s th e pum p moto r operatio n durin g initia l diagnosi s an d vehicl e starts . Yo u ma y hea r th e
fain t operatio n soun d a t thi s time , bu t i t i s normal .
Brak e Flui d Replacement/Ai r Bleedin g
1 . Brak e flui d replacemen t an d ai r bleedin g procedure s ar e th e sam e a s vehicle s withou t ABS . T o cas e bleeding , star t
wit h th e fron t wheels .
Troubleshootin g
1 . Th e troubleshootin g flowchart s procedure s assum e tha t th e caus e o f th e proble m is stil l presen t an d th e AB S indica -
to r ligh t i s stil l on . Followin g th e flowchar t whe n th e AB S indicator light doe s no t com e o n ca n resul t i n incorrec t
judgment.
2. Questio n th e custome r abou t th e condition s whe n th e proble m occurred , an d tr y t o reproduc e th e sam e condition s
fo r troubleshooting .
Fin d ou t whe n th e AB S indicato r ligh t cam e on , suc h a s durin g initia l diagnosis , durin g AB S control , afte r AB S con -
trol , whe n th e vehicl e started , whe n vehicl e spee d wa s a t 1 9 mp h (3 0 km/h) , whe n th e proble m continue d fo r a fe w
second s o r a fe w minutes , etc .
3 . Whe n th e AB S indicato r ligh t doe s no t com e o n durin g th e test-drive , bu t th e troubleshootin g i s performe d base d o n
th e DTC , chec k fo r th e loos e connectors , poo r contac t o f terminals , etc , befor e troubleshooting .
4 . Afte r troubleshooting , eras e th e DT C an d test-driv e th e vehicle . B e sur e tha t th e AB S indicato r ligh t doe s no t com e on .
5 . Th e connecto r illustration s sho w th e femal e connector s wit h a singl e outlin e an d th e mal e connector s wit h a doubl e
outline .
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Diagnostic Troubl e Cod e (DTC )
Diagnosti c Troubl e Cod e (DTC ) Indicatio n (SC S Mode )
NOTE: Thi s operatio n ca n als o b e don e wit h th e Hond a PG M Tester .
1 . Connec t th e SC S servic e connecto r t o th e servic e chec k connecto r (2P ) unde r th e glov e box .
2 . Tur n th e ignitio n switc h O N (II ) withou t brak e peda l depressed .
NOTE : I f th e brak e peda l i s depresse d whe n turnin g th e ignitio n switc h O N (II) , th e syste m shift s t o ME S mode .
3 . Th e blinkin g frequenc y indicate s th e DTC .
NOTE : I f th e DT C is no t memorized , th e AB S indicato r ligh t goe s of f fo r 3. 6 second s an d the n stay s on .
4 . Tur n th e ignitio n switc h OFF , an d remov e th e SC S servic e connector .
NOTE : Th e Malfunctio n Indicato r Lam p (MIL ) wil l sta y o n afte r th e engin e i s starte d i f th e SC S servic e connecto r i s
connected .
Condition s fo r DT C indicatio n
• Th e vehicl e is a t 1 0 km/ h o r less .
• Th e SC S servic e connecto r i s connecte d befor e th e ignitio n switc h i s turne d O N (II) .
• Th e brak e peda l i s released .
SCS SERVIC E CONNECTO R07PAZ-001010 0
SERVICE CHEC KCONNECTO R (2P )
ABS INDICATO R LIGH T
• Whe n ignitio n switc h i s turne d O N (II) , th e AB S indicato r ligh t come s o n fo r tw o second s t o chec k th e bulb . D o no t
coun t thi s a s a DTC .
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Diagnostic Troubl e Cod e (DTC )
DTC Erasur e (ME S Mode )
NOTE: Thi s operatio n ca n als o b e don e wit h th e Hond a PG M Tester .
1 . Connec t th e SC S servic e connecto r t o th e servic e chec k connecto r (2P ) unde r th e glov e box .
2 . Depres s th e brak e pedal .
3 . Tur n th e ignitio n switc h O N (II ) whil e keepin g th e brak e peda l depressed .
4 . Afte r th e AB S indicator light goe s off , releas e th e brak e pedal .
5 . Afte r th e indicato r ligh t come s on , depres s th e brak e peda l again .
6 . Afte r th e indicato r ligh t goe s off , releas e th e brak e peda l again .
7 . Afte r fe w seconds , th e indicato r ligh t blink s twic e an d th e DT C is erased . I f th e indicato r ligh t doe s no t blin k twice ,
repea t step s 1 throug h 6 . I f th e indicato r ligh t stay s O N afte r th e indicato r ligh t blink s twice , chec k th e DT C becaus e a
proble m wa s detecte d durin g initia l diagnosi s befor e shiftin g t o ME S mode .
8 . Tur n th e ignitio n switc h OFF , an d remov e th e SC S servic e connector .
Condition s fo r DT C erasur e
• Vehicl e spee d i s a t 6 mp h (1 0 km/h ) o r less .
• Th e SC S servic e connecto r i s connecte d befor e th e ignitio n switc h i s turne d O N (II) .
• Th e brak e peda l i s depresse d befor e th e ignitio n switc h i s turne d O N (II) .
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Troubleshooting Inde x
NOTE : Thi s operatio n can also b e don e wit h th e Hond a PG M Tester .
19-84
19-8 6
19-87
19-88
19-89
19-9 0
19-9 3
19-9 4
19-9 5
19-98
19-10 0
19-10 2
19-103
19-10 3
is turne d fro m OF F to O N (II) , an d th e contro l uni t confirm s tha t th e syste m is O K whe n th e vehicl e starts .
*2 : Whe n voltag e return s normal , th e AB S indicato r ligh t goe s off .
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Special Tool s
Ref. No.Too l Numbe r DescriptionQtyPag e Referenc e
07PAZ-001010 0 SC
S Servic e Connecto r 19-11
7, 19-81, 19-10
1
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Component Location s
ABS CONTRO L UNI TSERVIC E CHEC K CONNECTO R (2P )
STEERIN G ANGL E SENSO R RIGHT-REA
R WHEE L SENSO R
TCS CONTRO L UNI T
UNDER-DAS H RELA Y BO X
POWERTRAI N
CONTRO L MODUL E (PCM )
EC T SENSO R
TC S CONTRO L VALV E
SENSO R
RIGHT-FRON T
WHEE L SENSO R
LEFT-REA RWHEEL SENSO R
TC S SWITC H
UNDER-DAS H FUSE/RELA Y BO X
UNDER-DAS H FUSE/RELA Y BO X
GAUG E ASSEMBL Y
TC S INDICATO R LIGH T
UNDER-HOO D FUSE/RELA Y BO X BACK-U
P LIGHTS /
METE R LIGHT S
(1 0 A ) FUS E EC
U (PCM)/CRUIS E
CONTRO L
(1 5 A ) FUS E
BATTER Y (120A ) FUS E
UNDER-DASH RELA Y BO X
I G S W (5 0 A ) FUS E
FAIL-SAF E RELA Y
TCS CONTRO L
VALV E ACTUATO R
UNDER-HOO D FUSE/RELA Y BO X
LEFT-FRON
T WHEE L SENSO R
TCS/RUNNIN GLIGHT (1 5 A ) FUS ESTOP/HOR N(20 A ) FUS E
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System Descriptio n
Outline
Role o f Syste m
Th e tractio n contro l i s a variabl e syste m designe d t o enhanc e tractio n durin g acceleratio n an d cornering . I t doe s s o b y
determinin g th e optimu m amoun t o f whee l spi n fo r an y give n drivin g situation , the n suppressin g surplu s engin e powe r
accordingly .
Constructio n an d Functio n
The TC S contro l uni t get s signal s abou t th e vehicle' s speed , direction , an d roa d condition s fro m sensor s a t th e wheel s an d
the steerin g column . Base d o n thes e signals , th e contro l uni t wil l determin e th e optimu m amoun t o f whee l spin . Becaus e
th e syste m is variable , th e contro l uni t ma y determine , dependin g o n th e drivin g conditions , tha t som e whee l spi n i s bene -
ficia l (thu s enhancin g straight-lin e acceleration) , o r tha t n o whee l spi n i s beneficia l (thu s enhancin g cornering) . Fo r an y
give n drivin g situation , th e contro l uni t wil l determin e th e amoun t o f whee l spi n bes t suite d t o th e driver' s need s and , i f
necessary , wil l the n signa l th e TC S contro l valv e actuato r an d Powertrai n Contro l Modul e (PCM ) t o reduc e engin e power .
Th e syste m is automaticall y "ready " wheneve r th e engine is started , bu t ca n b e manuall y cancele d wit h th e TC S switch .
However , onc e activated , th e syste m canno t b e cancele d unti l i t i s onc e agai n i n th e read y state .
SERVIC E CHEC K CONNECTO R (2P )ABS CONTRO L UNI TTCS CONTRO L UNI TUNDER-DAS H RELA Y BO X
POWERTRAI N
CONTRO L MODUL E (PCM )
EC T SENSO R
TC S CONTRO L VALV E
ANGL E SENSO R STEERIN
G ANGL E SENSO R
RIGHT-REA R WHEE L SENSO R
RIGHT-FRON T
WHEE L SENSO R
Components :
• Whee l sensors : Th e TC S "shares " th e whee l sensor s wit h th e ABS . Th e whee l sensor s transmi t whee l spee d signal s t o
th e TC S throug h th e AB S contro l unit .
• Steerin g angl e sensor : Th e steerin g angl e senso r signal s th e TC S contro l uni t abou t th e amoun t o f steerin g angle .
• TC S contro l valv e sensor : Th e TC S contro l valv e senso r signal s th e TC S contro l uni t abou t th e amoun t o f TC S contro l
valv e angle .
• TC S contro l valv e actuator : Th e actuato r get s signal s fro m th e TC S contro l uni t an d close s th e TC S contro l valv e
accordingly .
• TC S contro l unit : Th e TC S contro l uni t detect s th e drivin g conditio n signal s fro m th e sensor s and , i f necessary , signal s
th e Powertrai n Contro l Modul e (PCM) .
LEFT-REA RWHEEL SENSO R
UNDER-HOO D FUSE/RELA Y BO X
LEFT-FRON
T WHEE L SENSO R
TC
S CONTRO L
VALV E ACTUATO R UNDER-DAS
H FUSE/RELA Y BO X
TC
S SWITC H
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Construction and Function

TCS Control unit

Driving Control

When the drive wheel speed exceeds the vehicle speed by a given amount, the TCS control unit judges that the drive

wheels are slipping, and it outputs the traction control signal to reduce engine power.

Handling Control

Based on signals about right and left driven wheel rotational speeds, the control unit calculates the vehicle's "yaw" rate

(the turn rate of the vehicle's body). Based on signals from the steering angle sensor, the control unit also calculates the

yaw rate expected by the driver. If the difference between actual and expected yaw rates is substantial — that is, if the

direction of the vehicle's body will exceed the driver's expected line — the control unit signals the TCS control valve actu-

ator and PCM, thus reducing engine power and maintaining the expected line.

Rough Road Control

Based on signals from the wheel sensors, the control unit detects a rough road based on frequency of wheel rotational

vibration. The control unit then signals the TCS control valve actuator and PCM to relax engine power, thus improving

acceleration efficiency.

Grip Control

Based on signals about wheel speed and yaw rate, the control unit determines the efficiency of the grip of the tires on the

road and signals the TCS control valve actuator and PCM to relax engine power, if necessary, thus improving grip.

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