1996 ACURA RL KA9 engine

System Description

Outline

Role of System

The traction control is a variable system designed to enhance traction during acceleration and cornering. It does so by

determining the optimum amount of wheel spin for any given driving situation, then suppressing surplus engine power

accordingly.

Construction and Function

The TCS control unit gets signals about the vehicle's speed, direction, and road conditions from sensors at the wheels and

the steering column. Based on these signals, the control unit will determine the optimum amount of wheel spin. Because

the system is variable, the control unit may determine, depending on the driving conditions, that some wheel spin is bene-

ficial (thus enhancing straight-line acceleration), or that no wheel spin is beneficial (thus enhancing cornering). For any

given driving situation, the control unit will determine the amount of wheel spin best suited to the driver's needs and, if

necessary, will then signal the TCS control valve actuator and Powertrain Control Module (PCM) to reduce engine power.

The system is automatically "ready" whenever the engine is started, but can be manually canceled with the TCS switch.

However, once activated, the system cannot be canceled until it is once again in the ready state.

Components:

Wheel sensors: The TCS "shares" the wheel sensors with the ABS. The wheel sensors transmit wheel speed signals to

the TCS through the ABS control unit.

Steering angle sensor: The steering angle sensor signals the TCS control unit about the amount of steering angle.

TCS control valve sensor: The TCS control valve sensor signals the TCS control unit about the amount of TCS control

valve angle.

TCS control valve actuator: The actuator gets signals from the TCS control unit and closes the TCS control valve

accordingly.

TCS control unit: The TCS control unit detects the driving condition signals from the sensors and, if necessary, signals

the Powertrain Control Module (PCM).ProCarManuals.com

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

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

TCS CONTROL UNIT 20P CONNECTOR

Wire side of female terminals

VB: Battery Voltage

Terminal

number

1

2

4

5

6

9

10

11

12

13

14

15

16

17

20
Wire

color

BLK/YEL

GRN/RED

BLU

PNK/BLU

BLK/WHT

BLK

BRN/WHT

GRN/WHT

BLU

GRN/ORN

BLK/ORN

BRN/BLK

WHT/BLU

BLU/GRY

GRN

BRN
Terminal sign

(Terminal name)

IG1

(Ignition 1)

PARK

(Parking)

SCS

(Service check

signal)

STR-GND

(Steering ground)

AT-SHIFT

(AT shift)

FSR

(Fail-safe relay)

PMG

(Power motor

Ground)

VPM

(Voltage power

motor)

STOP

(Stop)

NEP (Engine

speed pulse)

BARO

(Barometric)

TC-FC

(Traction control

fuel cut)

LG2

(Logic ground 2)

STR-VCC (Steer-

ing power supply)

WARN2

(Warning 2)

SH-MOT

(Shield motor)

MOT +

(Motor +)

MOT-

(Motor -)
Description

Detects ignition switch

IG1 signal

Detects parking brake

switch signal

Detects service check

connector signal

(Diagnostic trouble

code indication)

Ground for the steering

angle sensor

Detects A/T shift posi-

tion signal

Drives fail-safe relay

Power ground for the

TCS control valve

actuator motor

Power source for the

TCS control valve

actuator motor

Detects brake pedal

position switch signal

Detects engine speed

signal

Detects barometric

sensor signal

TCS Fl, Fuel cut

(torque down) signal

Ground for the logic

circuit

Power source for the

steering angle sensor

Drives TCS indicator light

(The indicator light comes

on by the self-bias)

Shield for the TCS con-

trol valve actuator motor

Drives TCS control

valve actuator motor

Drives TCS control

valve actuator motor
Measurement

terminals

1-GND

2

3-GND

4-GND

5-GND

6-GND

9-GND

10-GND

11-GND

12-GND

13-GND

14-GND

15-GND

16-GND

17-GND

19-20

20-19
Voltage

Conditions

(Ignition Switch ON (II))

Depress the parking

brake pedal.

Release the parking

brake pedal.

SCS service connector

connected.

SCS service connector

disconnected.

Shift the transmission

to position, then

start the engine.

Start the engine.

Start the engine.

Brake pedal depressed.

Brake pedal released.

Engine idling

TCS is functioning,

(maximum fuel cut)

TCS is not functioning.

Indicator light ON

Indicator light OFF

TCS is functioning.

TCS is not functioning.

TCS is functioning.

TCS is not functioning.
Output

voltage

VB

Below 0.6 V

VB

0V

5V

Below 0.3V

About 4V

(5V 0V)

VB

1.5V

Below 0.3 V

0V

VB

VB

0V

About 6V

(12V
0V)

About 3 V

About 1.5V

About 4.5 V

(5 V,
PWM)

Below 0.3V

About 5 V

About 2 V

VB

VB

0V

VB

0VProCarManuals.com

Diagnostic Troubl e Cod e (DTC )
Diagnosti c Troubl e Cod e (DTC ) Indicatio n
1. Connec t th e SC S servic e connecto r t o th e servic e chec k connecto r unde r th e glov e box .
2 . Tur n th e ignitio n switc h O N (II) , bu t d o no t star t th e engine .
3 . Recor d th e blinkin g frequenc y o f th e TC S indicato r light . Th e blinkin g frequenc y indicate s th e diagnosti c troubl e cod e
(DTC) .
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 is starte d if th e SC S servic e connecto r i s con -
nected .
5 . Perfor m th e DT C erasure .
SERVIC E CHEC KCONNECTO R (2P )
SC S SERVIC E CONNECTO R
07PAZ-001010 0
DTC Indicatio n Patter n
TCS INDICATO R LIGH T
Turn th e ignitio n switc h O N (II) . Th e TC S indicato r ligh t come s o n to chec k th e bulb . D o no t coun t i t a s DTC .
Th e TC S contro l uni t ca n memoriz e u p to 3 DTCs .
A ne w DT C is no t memorize d whe n th e TC S contro l uni t ha s alread y memorize d th e sam e DTC .
Th e TC S contro l uni t indicate s th e DT C repeatedl y a t interval s o f 3. 3 seconds .
I f yo u miscoun t th e blinkin g frequenc y o r i f yo u rechec k th e blinkin g frequency , tur n th e ignitio n switc h OFF , the n tur n
i t O N (II ) t o cycl e th e TC S indicato r ligh t again .
ProCarManuals.com

Troubleshooting
Steering Angl e Senso r (cont'd )
From pag e 19-16 9
Chec k fo r a n ope n i n th e STR- Acircuit:Measur e th e voltag e betwee n th e
TC S contro l uni t 14 P connecto r
termina l No . 1 3 an d bod y groun d
whe n turnin g th e steerin g whee l
slowly.
Is ther e 5 V 0 V?
Chec k fo r a n ope n in th e STR- B cir -
cuit :Measur e th e voltag e betwee n th e
TC S contro l uni t 14 P connecto r
termina l No . 9 an d bod y groun d
when turnin g th e steerin g whee lslowly .
Is ther e 5 V 0 V? Repai
r ope n in th e wir e betwee n
th e TC S contro l uni t an d steerin g
angl e sensor .
Wire sid e o f femal e terminal s
Repai r ope n in th e wir e betwee n
th e TC S contro l uni t an d steerin gangle sensor .
Erase th e DTC , an d tur n th e steer -
in g whee l slowl y afte r startin g
th e engine . I f TC S indicato r ligh t
come s o n an d DT C 2- 1 is indicated ,
replac e th e TC S contro l unit . TC
S CONTRO L UNI T 14 P CONNECTO R
ProCarManuals.com

Troubleshooting

TC-INH Signal (No PGM-FI DTC is indicated)

Check for a short to body ground

in the TC-INH circuit:

1. Disconnect the PCM connec-

tor C (12P) and TCS control

unit 14P connectors.

2. Check for continuity between

the PCM connector C (12P) ter-

minal No. 9 and body ground.

Is there continuity?

Check the PCM:

1. Connect the PCM connector C

(12P).

2. Start the engine.

3. Measure the voltage between

the PCM connector C (12P) ter-

minal No. 9 and body ground.

Does the tester needle swing

to about 2.5 V?

Check for an open in the TC-INH

circuit:

Measure the voltage between the

TCS control unit 14P connector

terminal No. 8 and body ground.

Does the tester needle swing

to about 2.5 V?

Check for loose TCS control unit

connectors. If necessary, substi-

tute a known-good TCS control

unit and recheck.
PCM CONNECTOR C (12P)

Repair short to body ground in

the wire between the PCM and

TCS control unit.
Wire side of female terminals

NOTE: Check under the following condi-

tions.

The coolant temperature is above 32°F

(0°C).

The MIL does not come on.

NOTE: Use the 10 V range or a similar

range in an analog tester.

Check for loose PCM connectors.

If necessary, substitute a known-

good PCM and recheck.

NOTE: Check under the following condi-

tions.

The coolant temperature is above 32°F

(0°C).

The MIL does not come on.

NOTE: Use the 10 V range or a similar

range in an analog tester.
TCS CONTROL UNIT UP CONNECTOR

Repair open in the wire between

the PCM and TCS control unit.

Wire side of female terminalsProCarManuals.com

PGM-FI DTC : 3 5 (TC-ST B signa l doe s no t matc h TC-F C signal )
Check fo r a shor t t o bod y groun d
i n th e TC-ST B circuit :
1 . Disconnec t th e PC M connec -
to r C (12P ) an d TC S contro l
uni t 14 P connectors .
2 . Chec k fo r continuit y betwee n
th e TC S contro l uni t U P con -
necto r termina l No . 1 0 an d
bod y ground . TC
S CONTRO L UNI T 14 P CONNECTO R
Wir e sid e o f femal e terminal s
I s ther e continuity ? Repai
r shor t t o bod y groun d in
th e wir e betwee n th e PC M an d
TC S contro l unit .
TCS CONTRO L UNI T 20 P CONNECTO R
Chec k fo r a shor t t o bod y groun d
i n th e TC-F C circuit :
1 . Disconnec t th e TC S contro l
uni t 20 P connector .
2 . Chec k fo r continuit y betwee n
termina l No . 1 4 an d bod y
ground .
Is ther e continuity ?Repair shor t t o bod y groun d in
th e wir e betwee n th e PC M an d
TC S contro l unit . Wir
e sid e o f femal e terminal s
Chec k th e TC S contro l uni t (TC -
STB) :1. Connec t th e TC S contro l uni t
14 P an d 20 P connector s an d
PC M connecto r C (12P) .
2 . Rais e th e fron t o f th e vehicle ,
and suppor t i t wit h safet ystands.
3 . Star t th e engine .
4 . Measur e th e voltag e betwee n
th e TC S contro l uni t 14 P con -
necto r termina l No . 1 0 an d
bod y ground . TC
S CONTRO L UNI T U P CONNECTO R
Wir e sid e o f femal e terminal s
I s th e voltag e a s specified ?
TCS is functioning :about 0 V
TC S is no t functioning :
abou t 5 V Chec
k fo r loos e TC S contro l uni t
connectors . I f necessary , substi -
tut e a known-goo d TC S contro l
uni t an d recheck .
To pag e 19-17 4
NOTE : Sto p th e wheel s b y depressin g
th e brak e peda l lightly .
ProCarManuals.com