ECO mode CHEVROLET DYNASTY 1993 User Guide

(6) Repeat steps 2 through 5 until a clear air free
flow of brake fluid is coming out of the Primary Ac-
cumulator bleeder screw. (7) Next select and actuate the RF Build/Decay
Valve. Again repeat steps 2 through 5 until a clean
air free flow of brake fluid is coming out of the Pri-
mary Accumulator bleeder screw.
4 SECONDARY ACCUMULATOR (1) Put a bleeder tube on the Secondary Accumu-
lator bleeder screw. (Fig. 1) (2) Use a pressure bleeder, or have an assistant,
apply light and constant pressure on the brake pedal.
Loosen the Secondary Accumulator bleeder screw
(Fig. 1). (3) Using the DRB II select the Actuate Valves
test mode. Then actuate the LF/RR Isolation Valve. (4) Bleed the Secondary Accumulator. Until a clear
air free flow of brake fluid is evident in the clear
hose and no air bubbles appear in the container, or
the brake pedal bottoms. (5) Tighten the bleeder screw and release the
brake pedal. (6) Repeat steps 2 through 5 until a clear air free
flow of brake fluid is coming out of the Secondary
Accumulator bleeder screw. (7) Next select and actuate the LF Build/Decay
Valve. Again repeat steps 2 through 5 until a clean
air free flow of brake fluid is coming out of the Pri-
mary Accumulator bleeder screw.PUMP/MOTOR SERVICE
On the Bendix Anti-Lock 6 Brake System the
Pump/Motor assembly can only be serviced as part of
Modulator Assembly.
MODULATOR ASSEMBLY (FIG. 2)
REMOVAL
(1) Center vehicle on hoist, or raise front of vehicle
on jack stands. (2) Disconnect and remove the battery, battery
tray and acid shield covering the modulator assembly
(Fig. 2). (3) Disconnect the delta (P) switch electrical con-
nector from the Modulator Assembly (Fig. 3). Re-
move the top Modulator Assembly bracket to fender
shield mounting bolt (Fig. 2). (4) Disconnect the 2 master cylinder supply tubes
at the Modulator Assembly. Loosen the 2 tubes at
the Master Cylinder so the tubes can be swung out of
the way without kinking them (Fig. 4) (5) Raise the vehicle on the hoist.
(6) From under the vehicle disconnect the Modula-
tor Assembly 10 way connector (Fig. 3). Remove the
4 remaining hydraulic brake tubes from the Modula-
tor Assembly. (7) Remove Modulator Assembly bracket mounting
bolt closest to junction block. (8) Loosen but do not fully remove bracket mount-
ing bolt nearest the radiator. (9) Lower the vehicle, the Modulator Assembly and
bracket can now be lifted out of the vehicle (Fig. 1)
Fig. 2 Modulator Assembly
5 - 128 ANTI-LOCK 6 BRAKE SYSTEM Ä

HYDRAULIC SYSTEM CONTROL VALVES INDEX
page page
General Information ....................... 10
Hydraulic System Service Procedures ......... 11 Pressure Differential Warning Light Switch
...... 10
GENERAL INFORMATION
All models equipped with a Bendix Antilock 4 Brake
System have 2 screw-in type proportioning valves.
There is 1 valve for each individual rear wheel hydrau-
lic brake line. The proportioning valves are mounted
directly into the rear brake outlet ports of the modula-
tor assembly (Fig. 1).
The proportioning valves limit brake pressure to the
rear brakes after a certain pressure (split point) is
reached. This improves front to rear brake balance
during normal braking. Screw-in proportioning valves can be identified by
numbers stamped on the body of the valve. The first
digit represents the slope, the second digit represents
the split (cut-in) point, and the arrow represents the
flow direction of the valve. Be sure numbers listed
on a replacement valve are the same as on the
valve that is being removed. See (Fig. 2) for detail of
the valve identification.
PRESSURE DIFFERENTIAL WARNING LIGHT
SWITCH
The hydraulic brake system, on vehicles equipped
with the Bendix Antilock 4 Brake System is split
diagonally. The left front and right rear brakes are on
one hydraulic system, and the right front and left
rear are on another. Both systems are routed
through, and hydraulically separated by the Pressure
Differential Switch (Fig. 3) mounted in the hydraulic brake tube junction block. The function of the Pressure
Differential Switch is to alert the driver of a malfunc-
tion in the brake hydraulic system.
If hydraulic pressure is lost in one system, the
warning light switch will activate the RED brake
warning light on the instrument panel, when the brake
pedal is depressed. At this point the brakes hydraulic
system requires immediate service. However, since the
brake systems are split diagonally the vehicle will
retain 50% of its stopping capability in the event of a
failure in either half. The warning light switch is the latching type. It
will automatically center itself after the repair is
made and the brake pedal is depressed.
Fig. 1 Rear Brake Proportioning Valve Location On Modulator Assembly
Fig. 2 ABS PROPORTIONING VALVE IDENTIFICA- TION
Fig. 3 Pressure Differential Warning Light Switch InJunction Block.
5 - 10 BRAKES Ä

ANTILOCK BRAKE SYSTEM DEFINITIONS
In this section of the manual several abbreviations
are used for the components that are in the Bendix An-
tilock 4 Brake System, they are listed below for your
reference.
² CABÐController Antilock Brake
² ABSÐAntilock Brake System
² PSIÐPounds per Square Inch (pressure)
² WSSÐWheel Speed Sensor
² ACÐAlternating Current
NORMAL BRAKE SYSTEM FUNCTION
Under normal braking conditions, the Bendix An-
tilock 4 Brake System functions the same as a stan-
dard non-Antilock brake system.
When a wheel locking tendency is detected during a
brake application, the vehicle brake system will enter
the Antilock mode. During Antilock Braking, hydraulic
pressure in the four wheel circuits is modulated to pre-
vent wheels from locking. Each wheel circuit is de-
signed with a set of electrical valves and hydraulic line
to provide modulation, although for vehicle stability,
both rear wheel valves receive the same electrical sig-
nal. The system can modulate pressure at each wheel,
depending on signals generated by the wheel speed sen-
sors (WSS) and received at the CAB.
MAJOR COMPONENTS
The following is a list of major system components.
Details of all components can be found later in this
section. See (Fig. 1) for the general location of the
components in the vehicle.
MASTER CYLINDER AND VACUUM BOOSTER
The Bendix Antilock 4 Brake System uses a vehi-
cles standard Master Cylinder/Reservoir and Vacuum
Booster (Fig. 2). The master cylinder primary and
secondary outputs (Fig. 2) go to the frame rail
mounted junction block and then directly to the mod-
ulator assembly inlet ports.
MODULATOR AND PUMP MOTOR/ASSEMBLY
The Modulator Assembly (Fig. 3) contains the elec-
tronic valves used for brake pressure modulation,
and the Pump/Motor assembly.
The Pump/Motor function, as part of the modulator
assembly, is to pump low pressure brake fluid from the
modulator sump into the ABS accumulator, as required.
WHEEL SPEED SENSORS
A Wheel Speed Sensor (Fig. 4) is located at each
wheel to transmit wheel speed information to the CAB.
CONTROLLER ANTILOCK BRAKE CAB
The CAB (Fig. 5) is a small computer which re-
ceives wheel speed information, controls Antilock op-
eration and monitors system operation.
Fig. 2 Master Cylinder And Brake Booster Assembly
Fig. 3 Modulator And Pump/Motor Assembly
Fig. 4 Wheel Speed Sensor
5 - 14 ANTILOCK 4 BRAKE SYSTEM Ä

(2) The voltage output from each of the wheel
speed sensors is verified to be within the correct op-
erating range. If a vehicle is not set in motion within 3 minutes
from the time the ignition switch is turned to the on
position. The solenoid valve test is bypassed but the
pump/motor is activated briefly to verify that it is op-
erating correctly.
WARNING SYSTEMS OPERATION
The ABS system uses an Amber Antilock Warning
Lamp, located in the instrument cluster. The purpose
of the warning lamp is discussed in detail below. The Amber Antilock Warning Light will turn on
whenever the CAB detects a condition which results
in a shutdown of the Antilock brake system. The
Amber Antilock Warning Lamp is normally on until
the CAB completes its self tests and turns the lamp
off (approximately 1-2 seconds). When the Amber
Antilock Warning Light is on, only the Antilock
brake function of the brake system if affected. The
standard brake system and the ability to stop the car
will not be affected when only the Amber Antilock
Warning Light is on.
NORMAL OPERATION OF WARNING LAMP
With ignition key turned to the Crank position, the
Red Brake Warning Lamp and Amber Antilock
Warning Lamp will turn on as a bulb check. The
Amber Antilock Warning Lamp will stay on for 1-2
seconds then turn off, once verification of Antilock
Brake System self diagnosis is completed.
ANTILOCK BRAKE SYSTEM COMPONENTS
The following is a detailed description of the Ben-
dix Antilock 4 Brake System components. For infor-
mation on servicing the Four Wheel Disc Brake
System, see the standard Brake section in the Front
Wheel Drive Car, chassis service manual.
MODULATOR ASSEMBLY
WARNING: THE ONLY COMPONENTS OF THE
MODULATOR ASSSEMBLY THAT ARE SERVICE-
ABLE, ARE THE 2 PROPORTIONING VALVES,
BLEED SCREWS AND THREAD SAVERS. THE RE-
MAINING COMPONENTS OF THE MODULATOR AS-
SEMBLY ARE NOT INTENDED TO BE
SERVICEABLE ITEMS. NO ATTEMPT SHOULD BE
MADE TO REMOVE OR SERVICE ANY OTHER COM-
PONENTS OF THE MODEULATOR ASSEMBLY.
The Modulator Assembly (Fig. 1) is located under
the battery tray and is covered with an acid shield.
The Modulator Assembly contains the following com-
ponents for controlling the Antilock brake system. 4
Build/Decay Valves, 4 Shuttle Orifices, 2 Fluid
Sumps, 2 Accumulators, and a Pump/Motor assem- bly. Also attached to the Modulator Assembly are 6
brake tubes which are connected to a 12 way junc-
tion block. The junction block (Fig. 2) is mounted to
the left frame rail below the master cylinder in the
same location as the non ABS equipped combination
valve. The wheel brake lines are attached to the sys-
tem via the connector block.BUILD/DECAY VALVES
There are 4 Build/Decay valves, one for each
wheel. In the released position they provide a fluid
path direct to the wheel brakes. In the actuated (de-
cay) position, they provide a fluid path from the
wheel brakes to the sump. The Build/Decay valves
are spring loaded in the released (build) position.
SHUTTLE ORIFICE
There are 4 Shuttle Orifice Valves, one for each
wheel. The Shuttle Orifice Valve is a hydraulically
actuated valve which shuttles when the Build/Decay
valve is actuated. Actuating of the Build/Decay valve
causes a pressure differential to be created across the
Shuttle Orifice Valve. This acts like placing an ori-
Fig. 1 Modulator Assembly
Fig. 2 Antilock Brake Junction Block
5 - 16 ANTILOCK 4 BRAKE SYSTEM Ä

WHEEL SPEED SENSORS
One Wheel Speed Sensor (WSS), is located at each
wheel (Fig. 5 and 6), and sends a small AC signal to the
control module CAB. This signal is generated by mag-
netic induction. The magnetic induction is created,
when a toothed sensor ring (Tone Wheel) (Fig. 7) passes
a stationary magnetic Wheel Speed Sensor. The CAB
converts the AC signal generated at each wheel into a
digital signal. If a wheel locking tendency is detected,
the CAB will then modulate hydraulic pressure to pre-
vent the wheel or wheels from locking.
The front Wheel Speed Sensor is attached to a boss
in the steering knuckle (Fig. 5). The tone wheel is
part of the outboard constant velocity joint (Fig. 5). The rear Wheel Speed Sensor is mounted to the cal-
iper adapter (Fig. 6) and the rear tone wheel is an
integral part of the rear wheel hub (Fig. 7). The
speed sensor air gap is NOT adjustable.
The four Wheel Speed Sensors are serviced individ-
ually. The front Tone Wheels are serviced as an as-
sembly with the outboard constant velocity joint. The
rear Tone Wheels are serviced as an assembly with
the rear brake hub. Correct Antilock system operation is dependent on
the vehicle's wheel speed signals, that are generated
by the Wheel Speed Sensors. The vehicle's wheels
and tires must all be the same size and type to gen-
erate accurate signals. In addition, the tires must be
inflated to the recommended pressures for optimum
system operation. Variations in wheel and tire size
or significant variations in inflation pressure can
produce inaccurate wheel speed signals.
CONTROLLER ANTILOCK BRAKE CAB
The Antilock Brake Controller is a small micropro-
cessor based device which monitors the brake system
and controls the system while it functions in the An-
tilock mode. The CAB is mounted on the top of the
right front frame rail and uses a 60-way system con-
nector (Fig. 8). The power source for the CAB is
through the ignition switch in the Run or On posi-
tion. THE CONTROLLER ANTILOCK BRAKE
CAB IS NOT ON THE CCD BUS The primary functions of the CAB are:
(1) Detect wheel locking tendencies.
(2) Control fluid modulation to the brakes while in
Antilock mode. (3) Monitor the system for proper operation.
Fig. 5 Front Wheel Speed Sensor
Fig. 6 Rear Wheel Speed Sensor
Fig. 7 Rear Tone Wheel (Typical)
5 - 18 ANTILOCK 4 BRAKE SYSTEM Ä

ANTILOCK WARNING LAMP DIODE
The Warning Lamp Relay on the Bendix Antilock
4 Brake System has been replaced with a diode. The
diode is used to control the function of the warning
lamp and is located inside the CAB module wiring
harness. The diode is a replaceable component of the
wiring harness, and will not require replacement of
the entire wiring harness if only the diode is diag-
nosed to have failed. When the system relay is de-energized, the Anti-
lock warning lamp will be lit. This will occur because
a ground path exists for the Antilock warning lamp
through the Antilock warning lamp diode and the
system relay armature. When the system relay is en-
ergized by the CAB, the system relay armature will
no longer provide a ground and the lamp will turn
off. Thus, the lamp will be lit if either the CAB is
disconnected or a system fault causes the Antilock to
be turned off.
PUMP/MOTOR RELAY
Pump/Motor power is supplied by the Pump/Motor
Relay. The Pump/Motor Relay is either mounted on
the left front inner fender shield, or the front of the
left shock tower. The mounting location is dependent
on whether the vehicle is or is not equipped with a
power distribution center. See (Fig. 11 and 12) for
specific mounting locations.
ANTILOCK WARNING LAMP OFF
System Relay Energized
From pin 57, the CAB energizes the Antilock sys-
tem relay coil, thus the electrical current flow in the
coil closes the system relay. Then electrical current
is provided to pins 47 and 41 of the CAB to provide
power to the modulator valves. The CAB turns off the Amber Antilock Warning
Lamp by breaking the ground path through pin 15 of
the CAB.
ANTILOCK WARNING LAMP ON
System Relay De-Energized.
When the Amber Antilock Warning Lamp is on,
there is no electrical current flow from the CAB at
pin 57 and the System Relay coil is NOT energized.
No electrical current flows to pin 47 and 41 (modula-
tor valve power), or to the Antilock Warning Lamp
diode. Thus, the Amber Antilock Warning Lamp is
not energized. The Amber Antilock Warning Lamp is
now grounded through the Antilock Warning Lamp
diode and pin 15 of the CAB turning on the Amber
Antilock Warning Lamp.
HYDRAULIC CIRCUITS AND VALVE OPERATION
Through the following operation descriptions and
diagrams. The function of the various hydraulic con-
trol valves in the ABS system will be described. The
fluid control valves mentioned below, control the flow
of pressurized brake fluid to the wheel brakes during
the different modes of Antilock braking. For explanation purposes we will assume all speed
sensors are sending the same wheel speed informa-
tion, requiring the same hydraulic fluid modulation
at the same rate.
NORMAL BRAKING
BUILD/DECAY VALVES
Closed (Fig. 1)
The brake pedal is applied. The travel of the brake
pedal closes primary and secondary circuits from the
master cylinder fluid supply. Brake fluid from the
master cylinder primary and secondary circuits flows
through the build/decay valves to the wheel brakes.
ABS BRAKING-BUILD PRESSURE
BUILD/DECAY VALVES
Open (Fig. 2)
Fig. 11 Pump Motor Relay Location On AA Body W/O Power Distribution Center
Fig. 12 Pump Motor Relay Location On AJ BodyWith Power Distribution Center
5 - 20 ANTILOCK 4 BRAKE SYSTEM Ä

(4) After brake pedal bottoms, close and tighten
bleed screw and release brake pedal. Do not release
brake pedal prior to closing and tightening bleed
screw. (5) Continue bleeding secondary check valve circuit,
repeating steps 2 through 4, until a clear, bubble free
flow of brake fluid is evident. (6) When air is bled from primary check valve cir-
cuit, tighten bleed screw and remove bleed hose from
bleed screw. Do not remove bleed hose before
tightening bleed screw, air may re-enter modula-
tor. (7) Torque modulator assembly primary bleed screw
to9N Im (80 in. lbs.).
3 MODULATOR ASSEMBLY PRIMARY SUMP CIRCUIT (1) Move clear bleed tube to primary sump bleed
screw (Fig. 3). Then install bleed tube into a con-
tainer partially filled with fresh clean brake fluid (Fig.
3). (2) Pump brake pedal several times, then apply and
hold a constant medium to heavy force on brake pedal. (3) Open modulator assembly primary sump circuit
bleed screw (Fig. 3) at least 1 full turn. This will ensure
an adequate flow of brake fluid from the primary sump
circuit. (4) Using the DRB, select the bleed ABS hydraulic
unit mode. Then select the primary circuit. (The RF
and LR solenoids will alternately fire for five se-
conds). Using the DRB, continue to select the primary
circuit until an air-free flow of brake fluid from pri-
mary sump bleed screw is maintained or brake pedal bottoms. If an air-free flow of brake fluid is not main-
tained before brake pedal bottoms, close bleed screw
and repeat steps 2 through 4, until an air free flow is
maintained.
(5) After an air-free flow of brake fluid is maintained
from primary sump bleed screw, close and lightly
tighten bleeder screw. Then release brake pedal. Do
not release brake pedal prior to closing and
tightening bleeder screw. (6) After primary sump bleed screw is closed, remove
bleed hose from primary sump bleed screw. (7) Torque modulator assembly primary sump bleed
screw to 9 N Im (18 in. lbs.).
4 MODULATOR ASSEMBLY PRIMARY ACCUMULATOR CIR-
CUIT
(8) Transfer clear bleed tube to primary accumulator
bleed screw (Fig. 4). Then install bleed tube into a
container partially filled with fresh clean brake fluid
(Fig. 4). (9) Pump brake pedal several times, then apply a
constant medium to heavy force on the brake pedal.
Using the DRB, select the bleed ABS hydraulic unit
mode. Then select the primary circuit valves. (The RF
and LR modulator assembly solenoids will fire for 5
seconds). (10) Open the modulator assembly primary accu-
mulator circuit bleed screw (Fig. 4) at least one full
turn. This will ensure an adequate flow of brake
fluid from the primary accumulator circuit. Continue
bleeding primary accumulator circuit until an air-
free flow of brake fluid from bleed screw is main-
tained or the brake pedal bottoms. If an air-free flow
Fig. 3 Bleeding Modulator Assembly Primary Sump CircuitFig. 2 Bleeding Modulator Assembly SecondaryCheck Valve Circuit
Ä ANTILOCK 4 BRAKE SYSTEM 5 - 27

of brake fluid is not maintained before brake pedal
bottoms, close bleed screw and repeat steps 8 and 9
until an air free flow is maintained.(11) After an air-free flow of brake fluid is main-
tained from the primary accumulator bleed screw, close
and lightly tighten bleed screw. Then release pressure
from brake pedal. Do not release force from brake
pedal prior to closing and tightening bleed
screw. Note: For the next modulator assembly bleed-
ing procedure, use of the DRB is not required.
This step of the bleed procedure does not require
modulator solenoids to be operated for bleeding
to be performed. (12) Pump brake pedal several times, then apply
and hold a constant medium to heavy force on the
brake pedal. (13) Again without firing modulator solenoids, open
primary accumulator circuit bleed screw (Fig. 4) 1 full
turn. This will ensure an adequate flow of brake fluid
from the primary accumulator circuit. (14) Bleed primary accumulator circuit until a clear,
air-free flow of brake fluid is maintained from the
accumulator bleed screw or the brake pedal bottoms. If
an air-free flow of brake fluid is not maintained from
the bleed screw before the brake pedal bottoms. First,
close bleed screw and then repeat steps 11 and 12 of
this bleeding procedure until an air-free flow is main-
tained. (15) After an air-free flow of brake fluid is main-
tained from the primary accumulator circuit bleed
screw, close and lightly tighten bleed screw. Then re- lease force from brake pedal.
Do not release force
from brake pedal prior to closing and tightening
bleeder screw. (16) After primary accumulator bleed screw is
closed, remove bleed hose from bleed screw. (17) Torque secondary accumulator bleed screw to 9
N Im (80 in. lbs.).
5 MODULATOR ASSEMBLY SECONDARY SUMP CIRCUIT (1) Transfer clear bleed tube to secondary sump
bleed screw on modulator assembly (Fig. 5). Then
install bleed tube into a container partially filled with
fresh clean brake fluid (Fig. 5).
(2) Pump brake pedal several times, then apply and
hold a constant medium to heavy force on brake pedal. (3) Open the secondary sump circuit bleed screw
(Fig. 5) at least 1 full turn. This will ensure an
adequate flow of brake fluid is expelled from the
secondary sump circuit. (4) Using the DRB, select the bleed ABS hydraulic
unit mode. Then select the secondary circuit valves.
(The LF and RR solenoids will alternately fire for five
seconds). Continue bleeding secondary sump circuit
until an air-free flow of brake fluid from secondary
sump bleed screw is maintained or brake pedal bot-
toms. If an air-free flow of brake fluid is not maintained
before brake pedal bottoms, close bleed screw and
repeat steps 2 through 4 until an air-free flow is
maintained. (5) After an air-free flow of brake fluid is maintained
from secondary sump bleed screw, close and lightly
tighten bleed screw. Then release force from
Fig. 4 Bleeding Modulator Assembly Primary Accu- mulator Circuit
Fig. 5 Bleeding Modulator Assembly SecondarySump Circuit
5 - 28 ANTILOCK 4 BRAKE SYSTEM Ä

brake pedal. Do not release brake pedal prior to
closing and tightening bleeder screw. (6) After secondary sump bleed screw is closed, re-
move bleed hose from bleed screw. (7) Torque secondary sump bleed screw to 9 N Im (80
in. lbs.).
6 MODULATOR ASSEMBLY SECONDARY ACCUMULATOR
CIRCUIT
(8) Transfer bleed tube to secondary accumulator
bleed screw (Fig. 6). Then install bleed tube into a
container partially filled with fresh clean brake fluid
(Fig. 6).
(9) Apply constant, medium to heavy force on brake
pedal. Then using the DRB, select the bleed ABS
hydraulic unit mode, and then select the secondary
circuit valves. (The LF and RR modulator assembly
solenoids will fire for 5 seconds). (10) Open the secondary accumulator circuit bleed
screw (Fig. 6) at least one full turn. This will ensure an
adequate flow of brake fluid is expelled from the
secondary accumulator circuit. Continue to bleed pri- mary accumulator circuit, until an air-free flow of
brake fluid from the bleed screw is maintained or brake
pedal bottoms. If an air-free flow of brake fluid is not
maintained from bleed screw before brake pedal bot-
toms, close bleed screw and then repeat steps 8 and 9
until an air free flow is maintained. (11) After an air-free flow of brake fluid is main-
tained from the bleed screw, close and lightly tighten
the bleed screw. Then release force from brake pedal.
Do not release force from brake pedal prior to
closing and tightening bleeder screw. Note: For the next modulator assembly bleed-
ing procedure, use of the DRB is not required.
This step of the bleeding procedure does not
require the modulator solenoids to be operated
for bleeding to be performed. (12) Pump brake pedal several times, then apply
and hold constant medium to heavy force on brake
pedal. (13) Again without firing modulator assembly sole-
noids, open secondary accumulator circuit bleed screw
(Fig. 6) at least 1 full turn. This will ensure an
adequate flow of brake fluid is expelled from the
secondary accumulator circuit. (14) Bleed secondary accumulator circuit until a
clear, air-free flow of brake fluid is maintained from the
secondary accumulator bleed screw or the brake pedal
bottoms. If an air- free flow of brake fluid is not
maintained from secondary accumulator bleed screw
before brake pedal bottoms, repeat steps 12 and 13 of
this bleeding procedure until an air-free flow is main-
tained. (15) After an air free flow of brake fluid is main-
tained from secondary accumulator circuit bleed screw,
close and lightly tighten bleed screw. Then release
force from brake pedal. Do not release force from
brake pedal prior to closing and tightening bleed
screw. (16) After secondary accumulator bleed screw is
closed, remove bleed hose from bleed screw. (17) Torque secondary accumulator bleed screw to 9
N Im (80 in. lbs.).
PUMP/MOTOR SERVICE
On the Bendix Antilock 4 Brake System the
Pump/Motor assembly can only be serviced as part of
Modulator Assembly.
Fig. 6 Bleeding Modulator Assembly Secondary Ac- cumulator Circuit
Ä ANTILOCK 4 BRAKE SYSTEM 5 - 29

MANUAL TRANSAXLE CLUTCH
CONTENTS
page page
CLEANING PRECAUTIONS ................. 6
CLUTCH CABLE MECHANISM .............. 1
CLUTCH CABLE REPLACEMENT ............ 2
CLUTCH CHATTER COMPLAINTS ........... 1
CLUTCH DISC REPLACEMENT ............. 5
CLUTCH PEDAL NOISE/POP ............... 2 CLUTCH PEDAL POSITION SWITCH
......... 4
EXCESSIVE CLUTCH SPIN TIME/CLASH INTO REVERSE COMPLAINTS ............ 1
GENERAL INFORMATION .................. 1
RELEASE BEARING AND FORK ............. 6
GENERAL INFORMATION
Throughout this group, references may be made to
a particular vehicle by letter or number designation.
A chart showing the breakdown of these designations
is included in the Introduction Section at the front of
this service manual. The clutch used in all models are a single, dry disc
type with no adjustment for wear being provided in
the clutch itself. The clutch pedal is connected to the release shaft
through a cable and lever. The upper end of the clutch pedal pivots in the
pedal bracket on two nylon bushings. These bushings
do not require periodic lubrication.
CLUTCH CHATTER COMPLAINTS
For all clutch chatter complaints, do the following:
(1) Check for loose, misaligned, or broken engine
and transmission mounts. If present, they should be
corrected at this time. Test vehicle for chatter. If
chatter is gone, there is no need to go any further. If
chatter persists: (2) Check to see if clutch cable routing is correct
and operates smoothly. (3) Check for loose connections in drive train. Cor-
rect any problems and determine if clutch chatter
complaints has been satisfied. If not, (4) Remove transaxle. See Group 21, Manual Tran-
saxle, for procedure. (5) Check to see if the release bearing is sticky or
binding. Replace bearing, if needed. (6) Check linkage for excessive wear on bushings.
Replace all worn parts. A small amount of bearing
grease between the release shaft bushings and the
shaft is beneficial, but not required. (7) Check flywheel and clutch pressure plate for
contamination (dirt, oil) or scored. Replace flywheel
and/or pressure plate, if required. (8) Check to see if the clutch disc hub splines are
damaged. Replace with new disc. (9) Check input shaft splines for damage. Replace
if necessary. (10) Check for uneven wear on clutch fingers.
EXCESSIVE CLUTCH SPIN TIME/CLASH INTO
REVERSE COMPLAINTS
For all excessive clutch spin time/clash into reverse
complaints, do the following: (1) Depress clutch pedal to floor and hold. After
three seconds, shift to reverse. If clash is present,
clutch has excessive spin time. (2) Remove transaxle. See Group 21, Manual Tran-
saxle, for procedure. (3) Check the input shaft spline, clutch disc splines
and release bearing for dry rust. If present, clean
rust off and apply a light coat of bearing grease to
the input shaft splines. Apply grease on the input
shaft splines only where the clutch disc slides. (4) Check to see if the clutch disc hub splines are
damaged, replace with new disc if required. (5) Check the input shaft for damaged splines. Re-
place as necessary. (6) Check for excessive clutch disc runout or
warpage. (7) Install clutch assembly and transaxle.
CLUTCH CABLE MECHANISM
The manual transaxle clutch release system has a
unique self-adjusting mechanism to compensate for
clutch disc wear. This adjuster mechanism is located
within the clutch pedal. The preload spring main-
tains tension on the cable. This tension keeps the
clutch release bearing continuously loaded against
the fingers of the clutch cover assembly. When the pedal is depressed, teeth on the adjuster
and the positioner engage and pull the release cable.
A spring located behind the adjuster ensures proper
tooth engagement. When the pedal is released, the adjuster contacts
the bumper. This separates the adjuster and posi-
tioner teeth, allowing the preload spring to function.
Ä MANUAL TRANSAXLE CLUTCH 6 - 1