1991 ACURA NSX Service Repair Manual

Troubleshooting

Anti-lock Brake System Indicator Light

Temporary Driving Conditions:
1. The anti-lock brake system indicator light will come
on and the control unit memorizes the problem
under certain conditions.
NOTE: Problem codes are explained on pages
19 - 46.
The tire(s) adhesion is lost due to excessive cor-
nering speed.
Problem codes: 5, 5-4, 5-8. The vehicle loses traction when starting from a
stuck condition on a muddy, snowy, or sandy

road.
Problem code: 4-1, 4-2, 4-4, 4-8. When the parking brake is applied for more than
30 seconds while the vehicle is being driven.
Problem code: 2. The vehicle is driven on extremely rough road.
The anti-lock brake system is OK, if the anti-lock brake system indicator light goes off after the
engine is restarted.
ANTI-LOCK BRAKE SYSTEM INDICATOR LIGHT
2. If you receive a customer's report that the anti-lock brake system indicator light sometimes comes on,
check the system using the ALB checker to confirm
whether there is any trouble in the system.

See page 19 - 41.

3. The anti-lock brake system indicator light will come on and the control unit will store a problem codewhen there is insufficient battery voltage to the
control unit. An example would be when the bat-
tery is so weak that the car must be jump-started. After the battery is sufficiently recharged, the anti-lock brake system indicator light will work normally
after the engine is stopped and restarted.
However, after recharging the battery, the problem
code must be cleared from the control unit's
memory by disconnecting the ALB 2,3 (No. 32)
fuse for at least 3 seconds. Anti-lock Brake System Indicator Light Circuit:
CAUTION: Use only the digital multimeter to

check the system.

1. The indicator light does not go on when the ignition switch is turned on.
Check the following items. If they are OK, check
the control unit connectors. If not loose or disconnected, install a new control
unit and recheck:
Blown anti-lock brake system indicator light
bulb.
Open circuit in YEL wire between No. 5 (10 A)
fuse and gauge assembly. Open circuit in BLU/WHT wire between gauge
assembly and control unit. Loose component grounding of the control unit
to the body.
2. The anti-lock brake system indicator light remains ON after the engine is started, however the anti-lock brake system indicator light does not blink any
code or sub-code. Check the following items:
Loose or poor connection of the wire harness at

the control unit.

Faulty ALB 2,3 (No. 32) fuse.
Open circuit in WHT/BLK wire between ALB 2,3(No. 32) fuse and control unit.
Open circuit in YEL/BLK wire between fuse No.

4 (1 5 A) and control unit.

Short circuit in BLU/WHT wire between gauge
assembly and control unit. Open circuit in WHT/BLU wire between alter-

nator and control unit.

If the problem is not found substitute a known-good
control unit and recheck whether the warning light re-
mains ON.ProCarManuals.com

Comes on and remains on while running:
1. Stop the engine.
2. Turn the ignition switch on and make sure that the anti-lock brake system indicator light comes on.
3. Restart the engine and check the anti-lock brake system indicator light.
There is no problem in the anti-lock brake system, if the anti-lock brake system indicator light goes off. Go to step 4, if the anti-lock brake system indicator light remains on.

4. Stop the engine.
5. Disconnect the service check connector from the connector cover located under the glove box.
Connect the two terminals of the service check connector with a jumper wire.
6. Turn the ignition switch on, but do not start the engine. 7. Record the blinking frequency of the anti-lock brake system indicator light.
The blinking frequency indicates the problem code.
CAUTION: Before starting the engine, disconnect the jumper wire from the service check connector, or else the
Check Engine light will stay on with the engine running.

Turn the ignition

switch on
PROBLEM CODE:

4– 2

Main Code: 4

Sub-Code: 2
PROBLEM

CODE: 1

Main Code: 1

Sub-Code: none
PROBLEM CODE

7–2

Main Code: 7

Sub-Code: 2

Indicator

light on

Indicator

light off
Connect the

jumper wire
2

Second

pause
1

Second

pause
5 second

pause

5 second

pause

1

Second

pause

1 Second

NOTE:
The control unit can indicate three problem codes (one, two or three problems). If the anti-lock brake system indicator light does not light, see Troubleshooting of Anti-lock Brake System
Indicator Light Circuit page 19-44.
If you miscount the blinking frequency, turn the ignition switch off, then turn on to blink the anti-lock brake
system indicator light again. After the repair is completed, disconnect the ALB 2,3 (No. 32) fuse for at least 3 seconds to erase the control

unit's memory. Then turn the ignition key on again and recheck.
The memory is erased if the connector is disconnected from the control unit or the control unit is removed from
the body. After recording the main and sub-code (if applicable), refer to the Symptom-to-System Chart.

ANTI-LOCK BRAKE SYSTEM INDICATOR LIGHT
SERVICE CHECK CONNECTOR

JUMPER WIREProCarManuals.com

Hydraulic System

Hydraulic Connections

CAUTION: Do not spill brake fluid on the car; it may damage the paint; if brake fluid does contact the paint, wash it off

immediately with water.

BRAKE BOOSTER
MASTER CYLINDER

RESERVOIR TANK

To right rear brake

To left rear brake

To left front brake

MASTER CYLINDER

To right front brake

POWER UNIT
MODULATOR/

SOLENOID UNIT
MODULATOR

RESERVOIRProCarManuals.com

Hydraulic System

Relieving Accumulator/Line Pressure

Use the Bleeder T-Wrench before disassembling the parts shaded in the illustration.

1. Drain the brake fluid from the master cylinder and modulator reservoir thoroughly.

2. Remove the red cap from the bleeder on the top of the power unit.

3. Install the special tool on the bleeder screw and turn it out slowly 90° to collect high pressure fluid into reservoir.

Turn the special tool out one complete turn to drain the brake fluid thoroughly.

4. Retighten the bleeder screw and discard the fluid.

5. Reinstall the red cap.

MODULATOR RESERVOIR

HIGH PRESSURE

HOSE
BLEEDER T-WRENCH

07HAA-SG00100

or

07HAA-SG00101

SOLENOID HEAD

ACCUMULATOR/

PRESSURE SWITCH

RED CAP

MAINTENANCE

BLEEDER

5.5 N·m

(0.55 kg-m. 4.0 Ib-ft)
POWER UNITProCarManuals.com

Modulator/Solenoid Unit
Index/Torque

CAUTION:
Do not damage the brake pipes when removing the spare tire and modulator/solenoid unit.
Do not spill brake fluid on the car; it may damage the paint; if brake fluid does contact the paint, wash it off immediate-
ly with water.

CORROSION RESISTANT BOLT 19 N·m (1.9 kg-m. 14 Ib-ft)

MODULATOR/SOLENOID UNIT
Do not disassemble.

Solenoid leak test,
page 19 - 64
Solenoid flushing,
page
19-65

19 N·m
(1.9 kg-m,

14 Ib-ft)

8 x
1.25
mm
15 N·m (1.5 kg-m, 11 Ib-ft)
12 x
1.25
mm

12 x 1.0 mm

19 N·m (1.9 kg-m, 14 Ib-ft)
OIL BOLT
35 N·m (3.5 kg-m, 14 Ib-ft)
10 x 1.0 mm

19 N·m
(1.9 kg-m.

14 Ib-ft)ProCarManuals.com

Modulator/Solenoid Unit

Solenoid Leak Test

1. Disconnect the 6-P inspection connector (PNK) from the connector cover located under the glovebox and connect the inspection connector to the
ALB checker.

ANTI-LOCK BRAKE SYSTEM
INDICATOR LIGHT

CONNECTOR

COVER

ALB CHECKER

07HAJ - SG00100 or
07HAJ - SG0010B (US)

07HAJ - SG00200 (Canada)
6-P INSPECTION

CONNECTOR

CAUTION: Place the vehicle on level ground with
the wheels blocked. Put the transmission in neutral
for manual transmission models, and in P for automatic transmission models.
2. Remove the modulator reservoir filter, then fill the modulator reservoir to the MAX level.
NOTE: Do not reuse aerated brake fluid that has
been bled from the power unit.
3. Bleed high pressure fluid from the maintenance bleeder with the special tool.
BLEEDER T-WRENCH

07HAA-SG00100
or

07HAA-SG00101

SOLENOID HEAD
MAINTENANCE
BLEEDER

8 x
1.25
mm
5.5 N·m
(0.55 kg-m,

4.0 Ib-ft)

POWER

UNIT

ACCUMULATOR/
PRESSURE SWITCH
If you can feel back fluid coming from the return
tube, one of the solenoids is leaking. Go to Solenoid Flushing.If you can feel brake fluid coming from the return
tube, one of the solenoids is leaking. Go to step
7.

If you can't feel brake fluid coming from the return tube, the solenoids are OK.
Reinstall the modulator reservoir filter and refill
the reservoir to the MAX level.
7. Bleed high-pressure fluid from the maintenance
bleeder with the special tool, then run through

modes 3 and 6 with the ALB checker. Repeat this

three or four times.

8. Repeat steps 5 and 6. If the solenoid leakage has stopped, reinstall the
modulator reservoir filter and refill the reservoir
to the MAX level. If one of the solenoids is still leaking, replace the
modulator/solenoid
unit.
SOLENOID

RETURN

TUBE
PUMP

SUPPLY

BRAKE

FLUID
SOLENOID RETURN

TUBE
Feel for brake

fluid here.

4. Start the engine and release the parking brake.
5. Turn the Mode Selector to 1 and press the Start Test button.
6. While the pump is running, place your finger over the top of the solenoid return tube in the modulator
reservoir.ProCarManuals.com

Solenoid Flushing
1. Remove the motor relay from the under-hood fuse/relay box. (Location: page 19 - 40)
2. Install the auxiliary window switch (07KAZ — 001000A) into the two motor relay cavities in the
relay box.

MOTOR RELAY

WINDOW SWITCH

07KAZ-001000A

UNDER-HOOD
FUSE/RELAY

BOX

3. Disconnect the four modulator solenoid connec- tors.
4. Bleed any high-pressure fluid from the maintenance bleeder with the Bleeder T-Wrench, then retighten
the bleeder.

BLEEDER T-WRENCH

07HAA - SG00100

or 07HAA - SG00101

SOLENOID HEAD

MAINTENANCE
BLEEDER

8 x
1.25
mm
5.5 N·m
(0.55 kg-m,

4.0 Ib-ft)

POWER

UNIT

ACCUMULATOR/

PRESSURE SWITCH
6. Press the auxiliary switch to run the pump. After
the pump has run for about five seconds, press andrelease the remote starter switch three or four
times to open and close the solenoid. Continue run- ning the pump for about 30 seconds, then release
the auxiliary switch and open and close the solenoid another three or four times.
7. Repeat steps 4-6 for the other two solenoids.
8. Reconnect the solenoids and the pump relay. 9. Connect the ALB Checker and turn the Mode Selec- tor to "1". Start the engine and release the parkingbrake. Push the Start Test button on the ALB

Checker.

10. While the pump is running, place your finger over the top of the solenoid return tube in the modulatorresorvoir and check for leaks. If a solenoid is still leaking, replace the
modulator/solenoid
unit.
REMOTE

STARTER

SWITCH

TO BLK

TERMINAL

TO RED

TERMINAL
FRONT-

RIGHT

FRONT-RIGHT

REAR-LEFT
REAR-RIGHT

5. Connect the RED terminal from one solenoid to the
battery positive (+) terminal with a remote starter
switch. Connect the BLK terminal from the same
solenoid to the battery negative (-) terminal with a
jumper lead as shown.ProCarManuals.com

Bleeding

Air Bleeding with ALB Checker
1. Disconnect the 6-P inspection connecotor (PNK) from the connector cover located under the glovebox and connect the inspection connector to the
ALB checker.
ANTI-LOCK BRAKE SYSTEM
INDICATOR LIGHT

CONNECTOR

COVER

ALB CHECKER

07HAJ - SG00100 or

07HAJ - SG0010B (US)

or

07HAJ-SG00200 (Canada)
6-P INSPECTION

CONNECTOR

CAUTION: Place the vehicle on level ground with
the wheels blocked. Put the transmission in neutral
for manual transmission models, and in P for automatic transmission models.
2. Fill the modulator reservoir to the MAX level.
NOTE: Do not reuse aerated brake fluid that has
been bled from the power unit.
3. Bleed high pressure fluid from the maintenance bleeder with the special tool.
BLEEDER T-WRENCH

07HAA-SG00100

or

07HAA-SG00101

SOLENOID HEAD

ACCUMULATOR/
PRESSURE SWITCH
POWER

UNIT
MAINTENANCE

BLEEDER

8 x
1.25
mm
5.5 N·m
(0.55 kg-m,
4.0 Ib-ft) 7. Install the reservoir cap.

8. Check the anti-lock brake system function in all

modes by using the ALB checker.
MAX

RESERVOIR

CAP

4. Start the engine and release the parking brake.
NOTE: Depress the brake pedal firmly while test in pro-

gress light in ON.

5. There should be at least two strong kickbacks. If not, repeat steps 2 through 5, as necessary.
6. Fill the modulator reservoir up to the MAX level.ProCarManuals.com