1991 ACURA NSX relay

Anti-lock Brake System (ABS) Description

Features/Construction/Operation (cont'd)

ABS Control Unit

The ABS control unit consists of a main function section, which controls the operation of anti-lock brake system, and

sub-function, which controls the pump motor and "self-diagnosis."

1. Main Function

The main function section of the ABS control unit performs calculations on the basis of the signals from each wheel

sensor and controls the operation of the anti-lock brake system by putting into action the solenoid valves in the

modulator unit for each front and rear brake.

2. Sub-Function

The sub-function section gives driving signals to the pump motor and also gives "self-diagnosis" signals, necessary

for backing up the anti-lock brake system.

Self-Diagnostic Function

Since the anti-lock brake system modulates the braking pressure when a wheel is about to lock, regardless of the driver's

intention, the system operation and the braking power will be impaired if there is a malfunction in the system. To prevent

this possibility, at speeds above 6 mph (10 km/h), the self-diagnosis function monitors the main system functions. When

an abnormality is detected, the ABS indicator light comes on.

There is also a check mode of the self-diagnosis system itself: when the ignition switch is first turned on, the ABS in-

dicator light comes on and stays on for a few seconds after the engine starts, to signify that the self-diagnosis system is

functional.

Fail-Safe Function

If an abnormality is detected, the ABS control unit turns off the fail-safe relays and motor relay. In this condition, the

anti-lock brake system is prevented from functioning, yet the basic brake system continues to operate normally.

The ABS Indicator Light Comes On

1. When the fluid pressure pump runs more than 120 seconds.

2. When the parking brake is applied for more than 30 seconds while the vehicle is being driven.

3. When the rear wheel(s) is (are) locked more than a specified time.

4. When the wheel rotation signal is not transmitted due to faulty wire or sensor.

5. When the operation time of the solenoid valve(s) exceeds a predetermined valve, and the ABS control unit finds an

open in the solenoid circuit.

6. When the output signals from both main functions in the ABS control unit are not transmitted to the solenoid

valve(s).ProCarManuals.com

ALB Checker

Function Test (cont'd)
4. Turn the Mode Selector switch further to "2". 5. Depress the brake pedal firmly and push the Start
Test switch
The ABS indicator light should not go on while the
Test in Progress light is ON. There should bekickback on the brake pedal. If not as described, go
to troubleshooting, page 19-44 ('91-'92) ('93-'96).

NOTE: The operation sequence simulated lby
Modes 2, 3, 4 and 5:
START

About 30 seconds

END

6. Turn the Mode Selector switch to 3, 4 and 5. Perform step 5 for each of the test mode positions.
Mode 1: Sends the simulated driving signal O mph (O km/h)

– > 113 mph (180 km/h) –
>
O mph (O km/h) of each

wheel to the ABS control unit. There should be NO
kickback.
Mode 2: Sends the driving signal of each wheel, then sends
the lock signal of the rear left wheel to the ABS control unit. There should be kickback.
Mode 3: Sends the driving signal of each wheel, then sends
the lock signal of the rear right wheel to the ABS control unit. There should be kickback.
Mode 4: Sends the driving signal of each wheel, then sends
the lock signal of the front left wheel to the ABS control unit. There should be kickback. Mode 5:
Sends the driving signal of each wheel, then sends
the lock signal of the front right wheel to the ABS
control unit. There should be kickback.

NOTE: If little or no kickback is felt from the brake
pedal in modes 2 – 5, repeat the function test of
modes 1–5 several times before beginning to
troubleshoot other parts of the system.
Mode 6: Not used on this model.
Inspection points: 1. The ABS indicator light goes ON in mode 1.
Check for DTCs, and refer to the appropriate
troubleshooting.
If ABS indicator light goes on 120 seconds later
but the pump motor stops, refer to page 19-47.
2. There is no kickback in modes 2 through 5. Faulty pressure switch (remains closed)
Shorted wiresFaulty or disconnected pump motor connector
Faulty pump motor relay
3. Weak kickback in modes 2 through 5. Bleed high pressure circuits.
4. Pump motor stops in mode 1, but it does not stop
and there is no kickback in modes 2 through 5.
Brake fluid leakageBleed power unit
Clogged power unit outlet
Clogged or deteriorated power unit hoseProCarManuals.com

Solenoid Flushin g
1. Remov e th e moto r rela y fro m th e under-hoo d
fuse/rela y box . (Location : se e pag e 19-40 )
2 . Instal l th e specia l too l int o th e tw o moto r rela y cavi -
tie s i n th e rela y box .
AUXILIAR Y
WINDO W SWITC H
07KAZ-001000 A
MOTOR RELA Y
UNDER-HOO DFUSE/RELAYBOX
3. Disconnec t th e fou r modulato r solenoi d connec -
tors .
4 . Blee d an y high-pressur e flui d fro m th e maintenanc e
bleeder wit h th e specia l tool , the n retighte n th e
bleeder .
SOLENOI D UNI T
BLEEDE R T-WRENC H07HAA - SG0010 1or 07HA A-SG0010 0
ACCUMULATOR /
PRESSUR E SWITC HPOWERUNIT
MAINTENANC EBLEEDER8 x 1.2 5 mm9 N- m (0. 9 kg-m ,6.5 Ib-ft )
5. Connec t th e RE D termina l fro m on e solenoi d con -
necto r t o th e batter y positiv e (+ ) termina l wit h a
remot e starte r switch . Connec t th e BL K termina l
fro m th e sam e solenoi d t o th e batter y negativ e (- )
termina l wit h a jumpe r lea d a s shown .
SOLENOI D CONNECTOR S
FRONT-RIGH T REAR-LEF T REAR-RIGH T
FRONT-RIGHT
REMOT ESTARTE RSWITCH
6. Pres s th e auxiliar y windo w switc h t o ru n th e pump .
Afte r th e pum p ha s ru n fo r abou t fiv e seconds ,
pres s an d releas e th e remot e starte r switc h thre e o r
fou r time s t o ope n an d clos e th e solenoid . Continu e
runnin g th e pum p fo r abou t 3 0 seconds , the n
releas e th e auxiliar y windo w switc h an d ope n an d
clos e th e solenoi d anothe r thre e o r fou r times .
7. Repea t step s 4- 6 fo r th e othe r thre e solenoids .
8 . Reconnec t th e solenoid s an d th e pum p relay .
9 . Connec t th e AL B Checke r an d tur n th e Mod e Selec -
to r t o "1" . Star t th e engin e an d releas e th e parkin g
brake . Pus h th e Star t Tes t butto n o n th e AL B
Checker .
10. Whil e th e pum p i s running , plac e you r finge r ove r
th e to p o f th e solenoi d retur n tub e in th e modulato r
reservoi r an d chec k fo r leaks .
• I f a solenoi d i s stil l leaking , replac e th e
modulator/solenoi d
unit.
ProCarManuals.com

Fail-Safe Relays/Moto r Rela y
Inspectio n
1. Chec k fo r continuit y betwee n terminal s an d
There shoul d b e n o continuity .
2. Connec t a 1 2 V batter y acros s terminal s an d
There shoul d b e continuit y betwee n terminal s
and
Pulsers/Sensor s
Inspection
1. Chec k th e pulse r fo r chippe d o r damage d teeth .
2 . Measur e ai r ga p betwee n th e senso r an d pulse r al l
th e wa y aroun d whil e rotatin g th e driveshaf t b y
hand .
(A) - (B) = Standard: 0.4-1.0 mm
(0.02-0.04 in.)
NOTE: I f th e ga p exceed s 1. 0 m m (0.0 4 in) , th e
probabilit y i s a distorte d knuckl e whic h shoul d b e
replaced .
KNUCKL E
SENSOR
PULSER
ABS Control Unit
ProCarManuals.com

Headliner/lnterior Trim

Replacement

To remove the headliner, first remove the: Sunvisors
Center pillar trim panels

Front pillar trim panels

Seats (see page 20-39('93-'96)

Ceiling light (see section 23)

NOTE:
When installing the headliner, be careful not to fold
or bend it. Also, be careful not to scratch the body.
Check that both sides of the headliner are securely

attached to the trim.

Disassemble in numbered sequence.
NOTE: When removing the rear trim panels, take care not to

damage the control units and relays.

Take care not to scratch the trim panels.

Clip Locations
CENTER PILLAR

TRIM PANEL

FRONT PILLAR
TRIM PANEL
DOOR TRIM
SIDE SILL

PAD

SIDE SILL

TRIM

REAR SIDE TRIM PANEL
CENTER ARMREST
Replacement, see page

20-49

OPENER
KNOB
SIDE SILL

TRIM

UNDER-DASH FUSE BOX LID

Installation is the reverse of the removal procedure.
NOTE: If necessary, replace any damaged clips.
RELEASE

HANDLE

Replacement,

see page 20-68
REAR SIDE TRIM PANEL CLIP
SIDE SILL

PAD
LEFT REAR TRIM PANEL

CLIP

REAR UPPER TRIM PANEL REAR CENTER
TRIM PANEL

GUIDE PIN

RIGHT REAR TRIM
PANEL LEFT SUNVISOR
CENTER SUNVISOR

RIGHT SUNVISOR

HEADLINERProCarManuals.com

SRS components are located in this area. Review the SRS component locations, precautions, and procedures in the SRS

section 24 before performing repairs or service.

POWER TRANSISTORBLOWER MOTOR

RECIRCULATION

CONTROL
MOTOR

CONDENSER
FAN MOTOR UNDER-HOOD RELAY BOX A
(CONDENSER FAN RELAY, COMPRESSOR CLUTCH RELAY,
BLOWER MOTOR HIGH RELAY, BLOWER MOTOR RELAY)
UNDER-HOOD

FUSE/RELAY

BOX

HEATER CORE TEMPERATURE SENSOR
CLIMATE CONTROL UNIT VENT DOOR
CONTROL MOTOR
OUTSIDE AIR
TEMPERATURE SENSOR ENGINE COMPARTMENT

FUSE/RELAY BOX
A/C TRIPLE PRESSURE SWITCH
FAN CONTROL UNIT (Fan radiator and con-

denser fans inside car,

behind seats)
EVAPORATOR

TEMPERATURE

SENSOR

IN-CAR

TEMPERATURE
SENSOR
MODE CONTROL

MOTOR

AIR MIX CONTROL MOTOR
SUNLIGHT

SENSORProCarManuals.com

Blower Unit

Replacement

1. Remove the spare tire (refer to Owner's manual).

2. Remove the spare tire holder.

CORROSION RESISTANT BOLT

6 x 1.0 mm

10 N-m (1.0 kg-m, 7 Ib-ft)

SPARE TIRE

HOLDER

3. Disconnect the cables from the battery, loosen the

hold-down bracket nuts, and remove the hold-

down bracket. Then, remove the battery.

BATTERY

HOLD-DOWN

BRACKET
4. Remove the under-hood relay box A and the water

drain duct. Disconnect the connectors from the

blower motor, power transistor and recirculation

control motor.

CORROSION RESISTANT BOLT

6 x 1.0 mm

10 N-m (1.0 kg-m, 7 Ib-ft)

WATER

DRAIN

DUCT

BLOWER MOTOR,

POWER TRANSISTOR,

and RECIRCULATION CONTROL

MOTOR CONNECTORS 6 x 1.0 mm

10 N-m (1.0 kg-m, 7 Ib-ft)

5. Remove the mounting bolts, then remove the blower

unit.

CORROSION RESISTANT BOLT

BLOWER

UNIT

6 x 1.0 mm

10 N-m (1.0 kg-m, 7 Ib-ft)

6. Install the blower unit in the reverse order of

removal, then make sure it runs and doesn't leak

any
air.
UNDER-HOOD

RELAY

BOX AProCarManuals.com

Relay and Control Unit Locations

Front Compartment

HORN RELAY

A/C COMPRESSOR CLUTCH

RELAY

RADIATOR FAN

LOW RELAY

RADIATOR FAN

HIGH RELAY

CONDENSER FAN RELAY

UNDER-HOOD RELAY BOX A
LEFT HEADLIGHT RETRACTOR

CUT RELAY
WINDSHIELD WIPER

LOW RELAY

WINDSHIELD WIPER

INTERMITTENT RELAY

POWER AMPLIFIER

RELAY
ABS

REAR FAIL-SAFE RELAY

ABS FRONT

FAIL-SAFE RELAY

HEADLIGHT RELAY
RIGHT HEADLIGHT RETRACTOR RELAY

Wire colors: BLU/GRN,

BRN/WHT, BLU/RED,

GRN/YEL, and BLK

LEFT HEADLIGHT RETRACTOR RELAY

Wire colors: BLU/BLK,

WHT/BLK, GRN/RED,

BLU,
and BLK
RIGHT HEADLIGHT RETRACTOR

CUT RELAY

BLOWER RELAY

BLOWER HIGH RELAY

WINDSHIELD WIPER

HIGH RELAY

WINDSHIELD

WASHER RELAY

UNDER-HOOD

RELAY BOX B

DIMMER RELAY

POWER WINDOW

RELAY

TAILLIGHT RELAY

ABS MOTOR RELAY

UNDER-HOOD FUSE/RELAY BOXProCarManuals.com