1996 ACURA RL KA9 turn signal

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.

Main Control BlockProCarManuals.com

System Descriptio n
Fail-Safe Functio n
I f th e contro l uni t detect s a n abnormality , i t shut s th e
tractio n contro l syste m of f an d cause s th e TC S indicato r
light t o com e on . Howeve r i f th e abnormalit y is detecte d
while th e TC S is activated , th e contro l uni t firs t estab -
lishe s th e appropriat e whee l spi n velocity , the n shut s
the syste m down , thu s preventin g excessiv e whee l spin .
Self-Diagnosi s Functio n
If th e contro l uni t detect s a n abnormality , i t record s a
Diagnosti c Troubl e Cod e (DTC ) whic h ca n b e use d t o
diagnos e th e problem . Th e DT C is show n a t th e TC S
indicato r ligh t whe n th e Servic e Chec k connecto r termi -
nal s ar e connecte d wit h th e SC S servic e connector .
Steerin g Angl e Detectio n
Steerin g angl e is detecte d b y th e steerin g angl e sensor .
A dis c wit h a regula r patter n o f slit s is positione d betwee n
th e facin g part s o f a ligh t emittin g par t (LED) , an d a ligh t
receivin g par t (phot o transistor) . As the dis c rotates , i t
interrupt s th e ligh t fro m th e LED . Th e ligh t whic h passe s
throug h a sli t i s converte d int o th e electri c curren t b y th e
phot o transistor , an d th e wavefor m o f thi s electri c cur -
ren t i s shape d b y th e comparato r t o outpu t th e dis c rota -
tio n a s a rectangula r signal .
Th e analysi s performanc e o f th e syste m is improve d b y
providin g th e fixe d sli t i n fron t o f th e LED , an d thereb y
identifyin g th e brightnes s an d darknes s o f th e ligh t whic h
i s receive d a t th e phot o transistor .
Th e outpu t signa l i s a 2-phas e outpu t (A-phas e an d Bi -
phase) , an d th e steerin g whee l turnin g angl e an d th e
turnin g directio n ar e calculate d b y th e TC S contro l unit .
Vehicl e Spee d Detectio n
Whee l rotatio n spee d i s detecte d b y th e whee l sensors ,
locate d a t eac h wheel . Th e signal s ar e sen t t o th e con -
trol unit , whic h compare s eac h wheel' s spee d an d deter -
mines whethe r tractio n contro l i s required .
FIXED SLI T
LIGH T EMITTIN G PAR T (LED )
TCS INDICATO R LIGH T
LIGHT RECEIVIN G PAR T(PHOT O TRANSISTOR )
SLIT
Steerin g whee l i s
turne d to right .
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Engine Output Control

When the TCS is activated, the TCS control unit signals the TCS control valve actuator and PCM. The actuator is linked to

the TCS control valve which is normally returned to the fully open position by the two return springs. Although the throttle

valve is still within the driver's control, the engine output is relaxed by the TCS control valve and PCM to achieve optimum

traction.

TCS CONTROL VALVE SENSOR

TCS CONTROL VALVE
TCS CONTROL VALVE

RETURN SPRINGS

TCS CONTROL VALVE

ACTUATOR (DC MOTOR)

DURING NORMAL DRIVING:
DURING TCS ACTUATION:

TCS CONTROL VALVE

TCS CONTROL VALVE

ACTUATOR (DC MOTOR)
TCS CONTROL VALVE

RETURN SPRINGS

TCS ACTUATION SIGNAL

FROM TCS CONTROL UNITProCarManuals.com

Troubleshooting
Steering Angl e Senso r
Diagnosti c Troubl e Cod e (DTC ) 2-1 : Steerin g Angl e Senso r Diagnosi s
The TC S contro l uni t perform s th e self-diagnosi s fo r th e steerin g angl e senso r whe n th e spee d o f th e fou r wheel s exceed s
6 mp h (1 0 km/h ) o n a smoot h road . Th e TC S indicato r ligh t come s o n if a ya w rat e is generated , th e correspondin g steer -
ing angl e signa l i s no t inpu t whe n th e steerin g whee l i s turned , an d ther e is n o inpu t fro m th e STO P (brak e peda l positio n
switch signal ) an d PAR K (parkin g brak e switc h signal) .
With engin e running , TC S indi -
cato r ligh t i s ON .
Th e tir e pressur e i s correct ,
an d tire s wit h a correc t diame -
te r ar e installed .
Wit h th e SC S servic e connec -
to r connecte d (se e pag e
19-159 ), DT C 2- 1 is indicated .
Chec k fo r a shor t t o bod y groun d
i n th e wire s betwee n th e TC S con -
tro l uni t an d steerin g angl e sensor :
1 . Disconnec t th e TC S contro l uni t
14P an d 20 P connector s an dsteerin g angl e senso r connec -tor.2. Chec k fo r continuit y betwee n
bod y groun d an d TC S contro l
unit 14 P connecto r terminal sNo. 9 an d No . 1 3 individuall yand betwee n th e 20 P connec -
to r termina l No . 4 an d No . 1 6
individually .
Is ther e continuity ?
Chec k th e STR-VC C circui t insid e
th e TC S contro l unit :
1 . Connec t th e TC S contro l uni t
14 P an d 20 P connectors .
2 . Tur n th e ignitio n switc h O N (II) .
3. Measur e th e voltag e betwee nthe TC S contro l uni t 20 P con -necto r termina l No . 1 6 an dbod y ground .
Is ther e abou t 5 V ?
Chec k th e STR-GN D circui t insid e
th e TC S contro l unit :
Measur e th e voltag e betwee n th e
TC S contro l uni t 20 P connecto r ter -
mina l No . 4 an d No . 16 .
Is ther e abou t 5 V ?
T o pag e 19-16 9 TC
S CONTRO L UNI T 14 P CONNECTO R
Wir e sid e o f femal e terminal s
TC S CONTRO L UNI T 20 P CONNECTO R
Repair shor t t o bod y groun d in th ewire(s ) betwee n th e TC S contro l
uni t an d steerin g angl e sensor . Wir
e sid e o f femal e terminal s
Replac e th e TC S contro l unit .
Replac e th e TC S contro l unit .
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PGM-FI DTC: 36 [TC-FC signal (High-Low check)]

Check for a short to body ground

in the TC-FC circuit:

1. Disconnect the PCM connec-

tor C (12P) and TCS control

unit 20P connectors.

2. Check for continuity between

the TCS control unit 20P con-

nector terminal No. 14 and

body ground.
TCS CONTROL UNIT 20P CONNECTOR

Is there continuity?
Repair short to body ground in

the wire between the PCM and

TCS control unit.
Wire side of female terminals

TCS IS NOT TCS IS

FUNCTIONING FUNCTIONING

NOTE: Use the 10 V range or a similar

range in an analog tester.

Is there about 4.5 V when TCS is

not functioning?
Check for loose TCS control unit

connector. If necessary, substi-

tute a known-good TCS control

unit and recheck.

Check for an open in the TC-FC

circuit:

Measure the voltage between the

PCM connector C (12P) terminal

No. 10 and body ground.
NOTE: Use the 10 V range or a similar

range in an analog tester.
TCS IS NOT TCS IS

FUNCTIONING FUNCTIONING

PCM CONNECTOR C (12P)

Is there about 4.5 V when TCS is

not functioning?
Repair open in the wire between

the TCS control unit and PCM.

Wire side of female terminals

Check for loose PCM connectors.

If necessary, substitute a known-

good PCM and recheck.
Check the TCS control unit:

1. Connect the TCS control unit

20P connector.

2. Turn the ignition switch ON

(II).

3. Measure the voltage between

the TCS control unit 20P con-

nector terminal No. 14 and

body ground.ProCarManuals.com

Description
Fan Contro l Uni t
The fa n contro l uni t make s calculation s base d o n signal s fro m th e radiato r fa n contro l sensor . I t the n control s th e opera -
tio n o f th e radiato r fan , condense r fa n an d A/ C system .
ON
OF F
172° F (78°C )
183°F (84°C )Whe
n engin e coolan t temperatur e is abov e 183° F (84°C) ,
th e fa n contro l uni t turn s Tr 1 ON , an d th e radiato r fa n
(Low ) an d condense r fa n run s (Low) .
ON
OF F
183° F (84°C )
When engin e coolan t temperatur e is abov e 194° F (90°C) ,
th e fa n contro l uni t turn s Tr 2 ON , an d th e radiato r fa n
(High ) runs , an d th e condense r fa n (High ) goe s on .
194° F (90°C )
ON
OF F
225° F (107°C )When engin e coolan t temperatur e is abov e 228° F (109°C) ,
the fa n contro l uni t turn s Tr 3 OFF , an d stop s th e A/ C com -
pressor .
228°F (109°C )
*1: CONDENSE R FA N RELA Y*2: RADIATO R FA N RELA Y*3: RADIATO R FA N MAI N RELA Y
RED/WH T
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Relay an d Contro l Uni t Location s
Dashboar d
IMMOBILIZE R PGM-F I MAI N CRUIS E CONTRO L
CONTRO L UNI T RELA Y STEERIN G COLUM N CONTRO L UNI T UNI T
MULTIPLE X
CONTROL UNI T(DRIVER'S )
UNDER-DAS H
FUSE/RELA Y BO X
STARTE R CU T RELA Y
SRS UNI T
POWE R WINDO WRELAY
TURN SIGNAL /HAZARD RELA Y
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*: Yo u ca n als o tes t th e switc h b y usin g th e self-diagnosi s functio n (mod e 2) . (Se e pag e 23-252 .)
UNDER-DAS HFUSE/RELAY BO X
TUR N SIGNAL/HAZAR D RELA Y
Inpu t Test , pag e 23-13 4
COMBINATIO
N LIGH T SWITCH *
Test , pag e 23-12 1
DAS
H LIGHT S BRIGHTNES S
CONTROLLER *Controller Test ,
pag e 23-25 6
Lightin g Syste m
Componen t Locatio n Inde x
Automati c Lightin g System : Whe n th e combinatio n ligh t switc h i s i n th e "AUTO " position , th e automati c lightin g contro l
uni t turn s o n th e headlights , al l othe r exterio r lights , an d th e instrumen t pane l light s whe n th e ambien t ligh t i s low . Th e
contro l uni t receive s signal s fro m th e automati c lightin g sensor , whic h sense s th e lu x (illumination ) leve l outsid e th e vehi -
cle , an d it control s th e light s b y mean s o f th e lightin g rela y an d tailligh t relay .
NOTE : Th e exterio r light s (othe r tha n th e headlights ) circui t i s include d wit h th e fo g light s circuit . Whil e i n th e "AUTO "
mode , whe n th e exterio r light s ar e turne d off , th e fo g light s ar e turne d of f automatically .
Whil e in th e "AUTO " mode , th e ligh t wil l remai n o n whe n th e ignitio n switc h i s turne d off .
The y wil l tur n of f automaticall y whe n th e driver' s doo r i s opened .
• FO G LIGH T SWITC H
Test , pag e 23-12 6
HIGH BEA M INDICATO R LIGH T
Bul b Locations , pag e 23-7 6
TUR
N SIGNA L INDICATO R LIGH T
Bul b Locations , pag e 23-7 6
DR L INDICATO R LIGH T (Canada )
Bul b Locations , pag e 23-7 6
HAZAR D WARNIN G SWITC H
Test , pag e 23-13 5
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