brakes ACURA TL 1995 Service Repair Manual

General Info
Specifications
Maintenance
Engine
Cooling
Fuel and Emissions
2.5L
3.2L
* Transaxle
SteeringSuspension
* Brakes (Including ABS)
* Body
* Heating, Ventilation
and Air Conditioning
* Body Electrical
* Engine Electrical
* SRS2.5L
3.2L
1995±98 TL Main Menu
As sections w/ * include SRS components, special precautions are required when servicing.
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Ascending Control

When the TCM determines that the vehicle is climbing a hill in position, the system extends the engagement area of

3rd gear to prevent the transmission from frequently shifting between 3rd and 4th gears, so the vehicle can run smooth

and have more power when needed.

NOTE:

Shift schedules between 3rd and 4th gear stored in the TCM enable the TCM's fuzzy logic to automatically select the

most suitable gear according to the magnitude of a gradient.

Fuzzy logic is a form of artificial intelligence that lets computers respond to changing conditions much like a human

mind would.

Descending Control

When the TCM determines that the vehicle is going down a hill in position, the shift-up speed from 3rd to 4th gear

when the throttle is closed becomes faster than the set speed for flat road driving to widen the 3rd gear driving area.

This, in combination with engine braking from the deceleration lock-up, achieves smooth driving when the vehicle is

descending.

There are two ascending modes with different 3rd gear driving areas according to the magnitude of a gradient stored in

the
TCM.

When the vehicle is in 4th gear, and you are decelerating on a gradual hill, or when you are applying the brakes on a steep

hill, the transmission will downshift to 3rd gear. When you accelerate, the transmission will then return to 4th gear.

ASCENDING MODE
DESCENDING MODE

• Deceleration Control

When the vehicle goes around a corner, and needs to decelerate first and then accelerate, the TCM sets the data for deceleration

control to reduce the number of times the transmission shifts. When the vehicle is decelerating from speeds above 30 mph

(48 km/h), the TCM shifts the transmission from 4th to 2nd earlier than normal to cope with upcoming acceleration.ProCarManuals.com

Inspection and Adjustment

Brake System Rubber Parts and Brake Booster

Brake Booster

Check brake operation by applying the brakes.

If the brakes do not work properly, check the brake

booster. Replace the brake booster as an assembly if

it does not work properly or if there are signs of leak-

age.

Piston Cup and Pressure Cup Inspection

• Check brake operation by applying the brakes.

Visually check for damage or signs of fluid leakage.

Replace the master cylinder as an assembly if the

pedal does not work properly or if there is damage

or signs of fluid leakage.

• Check for a difference in brake pedal stroke

between quick and slow brake applications.

Replace the master cylinder if there is a difference

in pedal stroke.
Brake Hoses

Visually check for damage or signs of fluid leakage.

Replace the brake hose with a new one if it is dam-

aged or leaking.

Caliper Piston Seal and Piston Boots

Check brake operation by applying the brakes.

Visually check for damage or signs of fluid leakage.

If the pedal does not operate properly, the brakes

drag, or there is damage or signs of fluid leakage,

disassemble and inspect the brake caliper. Replace

the boots and seals with new ones whenever the

brake caliper is disassembled.ProCarManuals.com

9.
Apply Molykote M77 grease to both sides of the pad

shims and to the back of the pads. Wipe excess

grease off the shim.

PISTON

WEAR INDICATOR

Apply Molykote M77

to both sides of shims,

INNER

SHIM B

INNER PAD

('97 - 98 models)
OUTER

PAD SHIM

('95 - 96 models)

Apply Molykote M77

to both sides of shim.

10. Install the brake pads and pad shims correctly.

When reusing the pads, always reinstall the

brake pads in their original positions to prevent

loss of braking efficiency.

Contaminated brake discs or pads reduce stop-

ping ability. Keep grease off the discs and pads.

NOTE: Install the pad with the wear indicator on

the inside.
11.
Push in the piston so that the caliper will fit over the

pads. Make sure that the piston boot is in position

to prevent damaging it when pivoting the caliper

down.

CALIPER BOLT

49 N-m (5.0 kgf-m, 36 Ibf-ft)

PISTON

12. Pivot the caliper down into position, then install the

caliper bolt and tighten it.

CAUTION: Be careful not damage the pin boot

when pivoting the caliper down.

13. Depress the brake pedal several times to make sure

the brakes work, then test-drive.

NOTE: Engagement of the brake may require a

greater pedal stroke immediately after the brake

pads have been replaced as a set. Several applica-

tions of the brake pedal will restore the normal

pedal stroke.

14. After installation, check for leaks at hose and line

joints or connections, and retighten if necessary.
INNER

SHIM A

OUTER PADProCarManuals.com

Rear Brake Pads

Inspection and Replacement

(cont'd)

15. After installation, check for leaks at hose and line

joints and connections, and retighten if necessary.

16. Depress the brake pedal several times to make sure

the brakes work, then test-drive.

NOTE: Engagement of the brake may require a

greater pedal stroke immediately after the brake

pads have been replaced as a set. Several applica-

tions of the brake pedal will restore the normal

pedal stroke.ProCarManuals.com

Piston/valve:

The piston/valve assembly consists of the piston, cut valve, and sleeve. There are four piston/valve assemblies in the mod-

ulator unit to control the brake fluid pressure to each caliper. The piston/valve assemblies for the rear brakes also serve as

proportioning control valves to prevent the rear wheels from locking if the ABS malfunctions or when the ABS is not acti-

vated.

Solenoid valves:

The modulator unit opens and closes the inlet and outlet solenoid valves, and shifts the ABS high-pressure passage

according to the signals from the ABS control unit. There are three solenoid valve assemblies, each containing an inlet

and outlet valve, in the modulator unit; one for each front wheel, and one for both rear wheels. The inlet valves are nor-

mally open (open when the coil is not energized), while the outlet valves are normally closed.

MODULATOR UNIT

RESERVOIR

To ABS CONTROL

UNIT

To RIGHT-FRONT

WHEEL

To LEFT-FRONT

WHEEL

PUMP MOTOR RELAY
From MASTER

CYLINDER

PRIMARY PISTON

From MASTER

CYLINDER

SECONDARY

PISTON

To LEFT-REAR

WHEEL

To RIGHT-

REAR WHEEL
MOTOR
PUMP

PISTON/VALVE
CUT

VALVE
PISTON
SLEEVE
SOLENOID VALVES (3 SETS)

RELIEF

VALVE

ACCUMULATOR

PRESSURE

SWITCHProCarManuals.com

Anti-lock Brake System (ABS)

Features/Construction (cont'd)

Wheel sensor:

The wheel sensor is a contactless type that detects the rotating speed of a wheel. It consists of a permanent magnet and

coil. When the gear pulsers attached to the rotating parts of each wheel turn, the magnetic flux around the coil in the

wheel sensor alternates, generating voltages with frequency in proportion to wheel rotating speed. These pulses are sent

to the ABS control unit, and the ABS control unit identifies the wheel speed.

WHEEL SENSOR

COIL PERMANENT MAGNET

at HIGH SPEED

at LOW SPEED

GEAR PULSER

GEAR PULSER

ABS control unit:

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

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

For safety, the main function consists of two systems, and the ABS control unit activates the solenoid valve only when the

outputs of the two systems agree with each other.

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 activating the solenoid valves in the modulator unit

for each front brake and for the two rear brakes. The ABS has individual control of the front wheels and common con-

trol ("Select low") for the rear wheels. "Select low" means that the rear wheel that would lock first (the one with the

lowest resistance to lock-up) determines the ABS activation for both rear wheels.

The sub-function section has the fail-safe function that monitors the system operation by inputting the brake switch,

parking brake switch and pressure switch signals, and stops the anti-lock brake system when it detects an abnormality

in the system. It also has a self-diagnosis function and the pump motor control function.

WHEEL SENSORS
ABS CONTROL UNIT

RIGHT-FRONT WHEEL

LEFT-FRONT WHEEL

RIGHT-REAR WHEEL

LEFT-REAR WHEEL

BRAKE SWITCH

PARKING BRAKE SWITCH
MAIN FUNCTION

• BASIC ABS

FUNCTION CONTROL

SUB-FUNCTION

• SELF-DIAGNOSIS FUNCTION

• FAIL-SAFE FUNCTION

• PUMP MOTOR CONTROL

PRESSURE SWITCH

PUMP MOTOR RELAY
MODULATOR UNIT

SOLENOID

SOLENOID

SOLENOID

FRONT FAIL - SAFE RELAY

REAR FAIL - SAFE RELAY

PUMP MOTORProCarManuals.com

Anti-lock Brake System (ABS)

Operation (cont'd)

Proportioning Control Valve Function:

The modulators for the rear brakes serve as proportioning

control valves to prevent the rear wheels from locking if

the ABS malfunctions or when the ABS is not activated.

When this function is not provided, the hydraulic pressure

from the master cylinder and the hydraulic pressure to

the rear brake system are equal.

If the fluid pressure is transmitted to the rear brakes at

the same rate as the front brakes, the rear wheels will

lock first because the rear axle load becomes lighter

when the brakes are applied.

To prevent the rear wheels from locking, the proportion-

ing control valve function changes the distribution rate

of the fluid pressure to the rear wheels when the pres-

sure in the rear brake system exceeds the given value of

the fluid pressure from the master cylinder. The fluid

pressure point where the distribution rate changes is

called the turning point.
FLUID PRESSURE WITHOUT PCV

FLUID PRESSURE WITH PCV

TURNING POINT

MASTER CYLINDER FLUID PRESSURE

The cut valve seat in the rear brake system has a shoulder between sections A and B. Section A, where pressure from the

master cylinder is applied, has a smaller diameter than section B, where pressure from the rear brake caliper is applied.

This design provides the proportioning control valve function as follows.

1. When the fluid pressure from the master cylinder is below the turning point, the cut valve seat is pushed by the

spring force and the cut valve is open. Therefore, the fluid pressure from the master cylinder is transmitted to the

rear brake caliper side. Under these conditions, fluid pressure from the master cylinder is equal to the pressure to the

rear brake caliper, but because of the diameter difference between sections A and B, the force on the cut valve over-

comes the spring force, moving the cut valve seat toward the cut valve slowly.

2. When the fluid pressure to the rear brake caliper reaches the turning point, the cut valve is closed by the cut valve

seat, blocking the fluid passage between the master cylinder side and rear wheel cylinder side.

3. When the fluid from the master cylinder exceeds the turning point, the fluid pressure from the master cylinder rises,

while the pressure to the rear brake caliper remains at the turning point value. As a result, the cut valve seat moves

away from the cut valve and the cut valve opens. The passage between the master cylinder and caliper opens

momentarily, but it is blocked again because the fluid pressure to the brake caliper rises, and the cut valve seat

moves to close the cut valve. As described above, when the pressure in the master cylinder is above the turning

point, the cut valve seat reduces the pressure in the rear brake caliper to the prescribed amount by repeating this pro-

cess.

From MASTER CYLINDER

To REAR BRAKE CALIPER

SPRING FORCE

SECTION WHERE PRESSURE FROM REAR CALIPER IS APPLIED.

SECTION WHERE PRESSURE FROM MASTER CYLINDER IS APPLIED.
CUT VALVE SEATProCarManuals.com

Modulator Uni t
Reservoi r Replacemen t
1. Drai n th e brak e flui d completel y fro m th e reservoi r
(see pag e 19-11 5 fo r th e brak e flui d replacement) .
2 . Remov e th e modulato r uni t fro m th e ca r (se e pag e
19-117 ).
3 . Remov e th e reservoi r fro m th e modulato r unit .
RESERVOI RReplace.
MODULATO RUNIT
JOIN TReplace .
4. Instal l th e reservoi r i n th e revers e orde r o f removal .
5 . Fil l th e reservoi r t o th e MA X (upper ) leve l wit h fres h
brak e fluid .
6. Befor e installin g th e modulato r uni t o n th e car , b e
sur e to blee d th e ai r fro m th e suctio n por t i n th e mod -
ulator uni t (se e pag e 19-118 ).
NOTE : Afte r installin g th e modulato r uni t an d
bleedin g th e brakes , star t th e engin e an d mak e sur e
that th e AB S indicato r ligh t goe s off .
ProCarManuals.com

3. Remov e th e modulato r uni t fro m th e ca r (se e pag e
19-117 ).
4 . Remov e th e accumulato r fro m th e modulato r unit .
MODULATO R UNI TRELIE F PLU G
ACCUMULATO RReplace.
9.8 N- m (1. 0 kgf-m , 7 Ibf-ft )
5. Remov e th e relie f plu g completely , an d dispos e o f
the accumulator .
6. Instal l th e ne w accumulato r o n th e modulato r unit .
7. Instal l th e modulato r uni t (se e pag e 19-118 ).
NOTE : Afte r installin g th e modulato r uni t an d bleed -
in g th e brakes , star t th e engine and mak e sur e tha t
th e AB S indicato r ligh t goe s off .
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