1993 CHEVROLET PLYMOUTH ACCLAIM differential

COMPONENT AND SYSTEM INDEX
Name Group-page Name Group-page
BRAKES ..................................5-1
BENDIX ANTILOCK 4 BRAKE SYSTEM ...........5-12
ABS BRAKE SYSTEM DIAGNOSTIC FEATURES.......5-24
ABS SYSTEM SELF DIAGNOSIS................ 5-24
BENDIX ANTILOCK 4 BRAKE SYSTEM DIAGNOSTICS....5-25
CONTROLLER ANTILOCK BRAKE CAB............. 5-24
LATCHING VERSUS NON-LATCHING ABS FAULTS.......5-25
START-UP CYCLE........................ 5-24
ABS COMPUTER SYSTEM SERVICE PRECAUTIONS....5-23
ABS GENERAL SERVICE PRECAUTIONS........... 5-23
ABS BRAKE SYSTEM ON VEHICLE SERVICE.........5-23
TEST DRIVING ABS COMPLAINT VEHICLES.......... 5-23
WHEEL SPEED SENSOR CABLES............... 5-23
ANTILOCK BRAKE SYSTEM COMPONENTS..........5-16
BUILD/DECAY VALVES..................... 5-16
FLUID SUMPS.......................... 5-17
HYDRAULIC SPRING ACCUMULATOR.............5-17
MODULATOR ASSEMBLY.................... 5-16
PRESSURE DIFFERENTIAL SWITCH..............5-17
PROPORTIONING VALVES................... 5-17
PUMP/MOTOR ASSEMBLY...................5-17
SHUTTLE ORIFICE........................ 5-16
WHEEL SPEED SENSORS....................5-18
ANTILOCK BRAKE SYSTEM DEFINITIONS..........5-14
ANTILOCK BRAKES OPERATION AND PERFORMANCE. . . 5-15
ANTILOCK BRAKE SYSTEM OPERATION............ 5-15
PEDAL FEEL........................... 5-15
TIRE NOISE & MARKS.....................5-15
ANTILOCK SYSTEM RELAYS AND WARNING LAMPS. . . 5-19
ANTILOCK WARNING LAMP DIODE..............5-20
Antilock Warning Lamp Off................... 5-20
Antilock Warning Lamp On...................5-20
PUMP/MOTOR RELAY...................... 5-20
SYSTEM RELAY......................... 5-19
BENDIX ANTILOCK 4 BRAKE SYSTEM DIAGNOSTICS. . . 5-22
DEFINITIONS........................... 5-23
GENERAL INFORMATION....................5-22
BLEEDING BENDIX ANTILOCK 4 BRAKE SYSTEM......5-25
BENDIX ANTILOCK 4 MODULATOR ASSEMBLY BLEEDING
PROCEDURE
......................... 5-26
HYDRAULIC BRAKE TUBE ASSEMBLY (JUNCTION BLOCK
TO MODULATOR ASSEMBLY)
................ 5-34
INSTALL............................ 5-36
REMOVE............................5-34
MASTER CYLINDER AND POWER BOOSTER.........5-38
REMOVAL AND INSTALLATION................. 5-38
MODULATOR ASSEMBLY CIRCUIT BLEEDING PROCEDURE
AND SEQUENCE
....................... 5-26
1 MODULATOR PRIMARY CHECK VALVE CIRCUIT........5-26
2 MODULATOR SECONDARY CHECK VALVE CIRCUIT......5-26
3 MODULATOR ASSEMBLY PRIMARY SUMP CIRCUIT......5-27
4 MODULATOR ASSEMBLY PRIMARY ACCUMULATOR CIRCUIT. 5-27
5 MODULATOR ASSEMBLY SECONDARY SUMP CIRCUIT....5-28
6 MODULATOR ASSEMBLY SECONDARY ACCUMULATOR
CIRCUIT
........................... 5-29
MODULATOR ASSEMBLY (FIG. 1)...............5-30
INSTALL............................ 5-32
REMOVE............................5-30
PROPORTIONING VALVES (FIG. 1)...............5-38
INSTALL............................ 5-39
REMOVAL...........................5-38
PUMP/MOTOR SERVICE....................5-29
CONTROLLER ANTILOCK BRAKE CAB.............5-18
CONTROLLER ANTILOCK BRAKE (INPUTS)..........5-19
CONTROLLER ANTILOCK BRAKE (OUTPUTS).........5-19
DIAGNOSTIC CONNECTOR.................... 5-19
ELECTRONIC COMPONENTS..................5-41
CONTROLLER ANTILOCK BRAKE CAB.............5-41
INSTALL............................ 5-42
REMOVE............................5-41
FRONT WHEEL SPEED SENSOR (FIG. 9)...........5-43
INSTALLATION......................... 5-44
REMOVAL........................... 5-43
REAR WHEEL SPEED SENSOR (FIGS. 10 AND 11)......5-44
INSTALLATION......................... 5-44
REMOVAL........................... 5-44
REMOVAL/INSTALLATION OF SYSTEM RELAY.........5-42
INSTALL............................ 5-43
REMOVE............................5-43
REMOVE/INSTALL PUMP MOTOR RELAY...........5-43
WHEEL SPEED SENSORS.................... 5-43
INSPECTION.......................... 5-43
GENERAL INFORMATION....................5-12
HYDRAULIC CIRCUITS AND VALVE OPERATION......5-20
ABS BRAKING-BUILD PRESSURE............... 5-20
BUILD/DECAY VALVES..................... 5-20
ABS BRAKING-DECAY PRESSURE...............5-22
BUILD/DECAY VALVES..................... 5-22
NORMAL BRAKING....................... 5-20
BUILD/DECAY VALVES.....................5-20
MAJOR COMPONENTS...................... 5-14
CONTROLLER ANTILOCK BRAKE CAB.............5-14
MASTER CYLINDER AND VACUUM BOOSTER.........5-14
MODULATOR AND PUMP MOTOR/ASSEMBLY.........5-14
WHEEL SPEED SENSORS.................... 5-14
MECHANICAL DIAGNOSTICS AND SERVICE
PROCEDURES
.......................... 5-24
INTERMITTENT FAULTS.....................5-24
SPECIAL SERVICE TOOL....................5-24
DRB DIAGNOSTIC TESTER...................5-24
NORMAL BRAKE SYSTEM FUNCTION.............5-14
ON-CAR ABS BRAKE SYSTEM SERVICE...........5-25
CHECKING BRAKE FLUID LEVEL................ 5-25
GENERAL SERVICE PRECAUTIONS...............5-25
SPECIFICATIONS......................... 5-46
SYSTEM SELF-DIAGNOSTICS..................5-15
VEHICLE PERFORMANCE.................... 5-15
WARNING SYSTEMS OPERATION...............5-16
NORMAL OPERATION OF WARNING LAMP..........5-16
GENERAL INFORMATION .....................5-1
HYDRAULIC SYSTEM CONTROL VALVES .........5-10
GENERAL INFORMATION.................... 5-10
HYDRAULIC SYSTEM SERVICE PROCEDURES........5-11
BRAKE WARNING SYSTEM................... 5-11
CHECKING BRAKE WARNING SWITCH UNIT...........5-11
TESTING ANTILOCK PROPORTIONING VALVES........5-11
PRESSURE DIFFERENTIAL WARNING LIGHT SWITCH. . . 5-10
SERVICE ADJUSTMENTS .....................5-3

DRIVETRAIN INDEX
page page
Automatic Transaxle ...................... 16
Automatic Transaxle Floor Shift .............. 16
Clutch and Gearshift Linkage ............... 16
Drive Shaft Cv and Tripod Joint Boots ........ 17 Front Wheel Bearings
..................... 17
Manual Transaxle ........................ 16
Tires .................................. 17
CLUTCH AND GEARSHIFT LINKAGE
If the clutch or gearshift begins to operate with dif-
ficulty, squeak or grunt, the cables and linkage
should be lubricated before service replacement is
performed. For proper lubrication and service proce-
dures refer to Group 6, Clutch, or Group 21, Manual
Transaxle.
MANUAL TRANSAXLE
The manual transaxle should be inspected for oil
leaks and proper oil level when other under vehicle
service is performed. To inspect the transaxle oil
level, position the vehicle on a level surface. Remove
fill plug (Fig. 1) from the transaxle side cover. The
oil level should not be below 4 mm (3/16 in) from the
bottom of the oil fill opening. The manual transaxle does not require periodic
maintenance. The oil should be changed only when
water contamination is suspected. If oil has a foamy
or milky appearance it probably is contaminated. A
circular magnet located behind the differential cover
collects metallic particles circulating in the oil. For
proper diagnostic and service procedures, refer to
Group 21, Manual Transaxle.
SELECTING MANUAL TRANSAXLE OIL
Chrysler Corporation recommends Mopar Engine
Oil, SG or SG/CD SAE 5W-30, or equivalent, be used
to fill a 5-speed transaxle.
AUTOMATIC TRANSAXLE FLOOR SHIFT
If the automatic transaxle floor shift mechanism
becomes difficult to operate or starts to make objec-
tionable noise, the mechanism should be lubricated
before service repair is performed. To lubricate the
shift mechanism, remove console as necessary. Refer
to Group 23, Body. Apply a film of Mopar Multipur-
pose Grease or equivalent, to slide surfaces and pawl
spring. For additional information, refer to Group 21,
Transaxle.
AUTOMATIC TRANSAXLE
The automatic transaxle should be inspected for
fluid leaks and proper fluid level when other under
hood service is performed.
CAUTION: To minimize fluid contamination, verify
that dipstick is seated in the fill hole or tube after
fluid level reading is taken.
TO INSPECT THE TRANSAXLE FLUID LEVEL: (1) Position the vehicle on a level surface.
(2) Start engine and allow to idle in PARK for at
least 60 seconds. The warmer the transaxle fluid, the
more accurate the reading. (3) While sitting in driver seat, apply brakes and
place gear selector in each position. Return gear se-
lector to park. (4) Raise hood and remove transaxle fluid level in-
dicator (dipstick) and wipe clean with a suitable
cloth. (5) Install dipstick and verify it is seated in fill
hole or tube (Fig. 2 or 3).
CAUTION: Do not overfill automatic transaxle, leak-
age or damage can result.
(6) Remove dipstick, with handle above tip, take
fluid level reading (Fig. 4). If the vehicle has been
driven for at least 15 minutes before inspecting fluid
level, transaxle can be considered hot and reading
should be above the WARM mark. If vehicle has run
for less than 15 minutes and more than 60 seconds
transaxle can be considered warm and reading
Fig. 1 Manual Transaxle Fill Plug
0 - 16 LUBRICATION AND MAINTENANCE Ä

FRONT SUSPENSION
FRONT SUSPENSION MAJOR COMPONENTS (FIG. 2)
STRUT SUPPORT
The system is supported by coil springs positioned
offset around the struts. The springs are contained
between an upper seat, located just below the top
strut mount assembly (Fig. 2) and a lower spring
seat on the strut lower housing. The top of each strut assembly is bolted to the up-
per fender reinforcement (shock tower) through a
rubber isolated mount. The bottom attaches to the top of the steering
knuckle with two through bolts. On some vehicles,
one bolt has an eccentric cam located below the head
of the bolt for camber adjustment. On the other ve-
hicles the camber adjustment is done by manually
moving the steering knuckle within the strut assem-
bly. Caster is a fixed setting on all vehicles and is
not adjustable.
STEERING KNUCKLE
The steering knuckle is a single casting with legs
machined for attachment to the strut damper, steer-
ing linkage, brake adaptor, and lower control arm
ball joint. The knuckle also holds the front drive hub
bearing. The hub is positioned through the bearing
and knuckle, with the constant velocity stub shaft
splined through the hub.
LOWER CONTROL ARM
The lower control arm is a steel casting with 2
large spool type rubber pivot bushings. The lower
control arm is bolted to the crossmember with pivot
bolts through the center of the rubber pivot bush-
ings. The ball joint is pressed into the control arm and
has a non-tapered stud with a notch for clamp bolt
clearance. The stud is clamped and locked into the
steering knuckle leg with a clamp bolt. The lower control arms are inter-connected through
a rubber isolated sway bar (Fig. 2).
DRIVESHAFTS
A left and right driveshaft is attached inboard to
the transaxle differential side gears, and outboard to
the driven wheel hub. To deliver driving force from the transaxle to the
front wheels during turning maneuvers and suspen-
sion movement. Both shafts are constructed with con-
stant velocity universal joints at both ends. Both shafts have a Tripod (sliding) joint at the
transaxle end and Rzeppa joints (with splined stub
shafts) on the hub ends. Due to the transaxle loca-
tion the connecting shafts between the C/V joints are
of different length and construction. The right shaft
is longer and of tubular construction. The left shaft
is solid.
2 - 2 SUSPENSION AND DRIVESHAFTS Ä

DRIVESHAFT IDENTIFICATION
Driveshafts are identified by the manufacturer. Vehi-
cles can be equipped with any of these driveshaft as-
semblies. Each assembly can be identified as shown in
(Fig. 2).
SERVICE PROCEDURES
Procedures for the removal and installation of the
driveshafts are essentially the same for all front
wheel drive vehicles. Each driveshaft has a spring
within the inboard Tripod C/V joint that maintains
constant engagement with the transaxle. This allows
the drive shaft to be removed without dismantling
part of the transaxle.
CAUTION: Boot sealing is vital to retain special lu-
bricants and to prevent foreign contaminants from
entering the C/V joint. Mishandling, such as allow-
ing the assemblies to dangle unsupported, pulling
or pushing the ends can cut boots or damage C/V
joints. During removal and installation procedures
always support both ends of the driveshaft to pre-
vent damage.
DRIVESHAFTS, REMOVE INSTALL
HUB NUT REMOVAL
Hub nut removal and installation is the same for
all front wheel drive vehicles. For installation see
Hub Nut Assemblies Install. (1) Remove cotter pin, lock and spring washer (Fig.
3).
(2) Loosen hub nut and wheel nuts while vehicle is
on floor and brakes applied (Fig. 4). (3) Raise vehicle, see Hoisting in Lubrication and
Maintenance, Group 0 of this service manual. (4) Remove hub nut, washer, wheel and tire as-
sembly (Fig. 5).
DRIVESHAFT ASSEMBLIES REMOVE
Inboard C/V joints have stub shafts splined into the
differential side gears, or splined into the intermedi-
ate shaft on the right side of an equal length system.
Driveshafts are retained in the side gears by a con-
stant spring force provided by a spring contained
within the inboard C/V joints. (1) For removal of right driveshaft, the speedome-
ter pinion must be removed BEFORE shaft removal
(Fig. 6). (2) Remove clamp bolt securing ball joint stud into
steering knuckle (Fig. 7). (3) Separate ball joint stud from steering knuckle
by prying against knuckle leg and control arm.
CAUTION: Do not damage ball joint or C/V joint
boots (Fig. 8). (4) Separate outer C/V joint splined shaft from hub
by holding C/V housing while moving knuckle(hub)
assembly away (Fig. 9).
Fig. 3 Remove Cotter Pin, Nut Lock, & Spring Washer
Fig. 4 Loosen Hub Nut & Wheel Nuts
Fig. 5 Remove Hub Nut & Washer Loosen Shaft
Ä SUSPENSION AND DRIVESHAFTS 2 - 27

(1) Hold inner joint assembly at housing (Figs. 11
and 12) while aligning and guiding the inner joint
spline into the transaxle or intermediate shaft assem-
bly. On Equal Length System vehicles only, be
sure that the rubber washer seal is in place on
the right inner C/V joint (Fig. 1).
CAUTION: Seal/Wear Sleeve Lubrication During any
service procedures where knuckle and driveshaft are
separated. Thoroughly clean seal and wear sleeve
with suitable solvent (solvent must not touch boot)
and lubricate both components prior to installing
driveshaft. Lubricate wear sleeve and seal with Mopar
Multi-Purpose Lubricant, or equivalent.
Apply on the full circumference of the Wear Sleeve a
bead of lubricant that is 6 mm (1/4 in.) wide to seal
contact area (Fig. 13). Fill the seal lip to housing cavity
on bearing seal with lubricant. Lubricant is to be
applied around complete circumference of the seal, and
seal lip should be wet with lubricant (Fig. 13). Use
Mopar Multi-Purpose Lubricant or equivalent for lu-
brication of the Wear Sleeve and Bearing Seal. (2) Push knuckle (hub) assembly out and install
splined outer C/V joint shaft in hub (Fig. 14). CAUTION: Steering knuckle clamp bolt shown in
(Figs. 14 and 15) is Prevailing Torque Type, original
or equivalent bolt must be installed during assem-
bly.
(3) Install knuckle assembly on ball joint stud
(Fig. 15). (4) Install and tighten clamp bolt to 95 N Im (70 ft.
lbs.) torque (Fig. 16). (5) Install speedometer pinion (Fig. 17).
(6) Fill differential with proper lubricant (see Lu-
brication and Maintenance Group 0). (7) Install hub nut assembly.
(8) If after installing the driveshaft assembly,the
inboard boot appears collapsed or deformed. Vent
the inner boot by inserting, a round tipped small di-
ameter rod between the boot and shaft. If necessary,
massage the boot to remove all puckers being careful
Fig. 13 Seal & Wear Sleeve Lubrication
Fig. 14 Install Outer Shaft into Hub
Fig. 11 Removing Driveshaft Assembly Equal Length
Fig. 12 Installing Inner Shaft into Transaxle
Ä SUSPENSION AND DRIVESHAFTS 2 - 29

BRAKES
CONTENTS
page page
ANTI-LOCK BRAKE SYSTEMÐBENDIX ANTI-LOCK 10 AC/Y BODY ............. 72
ANTI-LOCK BRAKE SYSTEMÐBENDIX ANTI-LOCK 6 AA,AG,AJ,AP BODY ....... 113
BRAKE DISC (ROTOR) ................... 53
BRAKE SUPPORT ASSEMBLY ............. 25
FRONT DISC BRAKES ................... 31
GENERAL INFORMATION .................. 1
HYDRAULIC SYSTEM CONTROL VALVES . . . 26
KELSEY HAYES DOUBLE PIN FAMILY CALIPER ............................ 35 KELSEY HAYES DOUBLE PIN NON-FAMILY
CALIPER ............................ 38
MASTER CYLINDER ..................... 66
PARKING BRAKES ...................... 57
POWER BRAKES ....................... 68
REAR DISC BRAKES .................... 45
REAR WHEEL DRUM BRAKES ............ 18
SERVICE ADJUSTMENTS .................. 4
WHEEL BEARINGS ...................... 70
WHEEL CYLINDERS ..................... 23
GENERAL INFORMATION
Throughout this group, references may be made to
a particular vehicle by letter or number designation.
A chart showing the break down of these designa-
tions is included in the Introduction Section at the
front of this service manual. Standard brake equipment consists of:
² Double pin floating caliper disc front brakes.
² Rear automatic adjusting drum brakes.
² Differential valve with a brake warning switch.
² Master cylinder.
² Vacuum power booster.
² Double pin floating caliper rear disc brakes are
available on some models. The Bendix Anti-Lock 10 braking system, uses the
standard power brake system caliper assemblies,
braking discs, pedal assembly, brake lines and hoses.
The unique parts of the Bendix Anti-Lock 10 braking
system consists of the following components. Propor-
tioning valves, wheel speed sensors, tone wheels,
electronic control unit, modulator assembly and hy-
draulic assembly. These components replace the con-
ventional master cylinder and power booster. The
components will be described in detail in the Bendix
Anti-Lock 10 brake section in this group of the ser-
vice manual. The Bendix Anti-Lock 6 braking system, uses the
following standard brake system components. Master
cylinder, power booster, caliper assemblies, braking
discs, pedal assembly, brake lines and hoses. The
unique parts of the Bendix Anti-Lock 6 braking sys-
tem consists of the following components. Modulator
assembly, unique proportioning valves, wheel speed
sensors, tone wheels, and electronic control unit.
These components will be described in detail in the
Bendix Anti-Lock 6 brake section in this group of the
service manual. The front disc brake shoes have semi-metallic lin-
ings. The hydraulic brake system (Fig .123and4)is
diagonally split on both the Non-ABS and ABS brak-
ing system. With the left front and right rear brakes
on one hydraulic system and the right front and left
rear on the other. The Non-ABS and ABS brake system may use dif-
ferent types of brake line fittings and tubing flares.
The Non-ABS brake system uses double wall tubing
flares and fittings at all tubing joint locations. Some
ABS brake systems use both ISO style tubing flares
and double wall tubing flares and corresponding fit-
tings at different joint locations. See (Figs . 2 3 and 4)
for specific joint locations and type of tubing flare. The front disc brakes consist of two different types
of caliper assemblies. A double pin Kelsey-Hayes cal-
iper (family caliper) with a bolt-on adapter attached
to the steering knuckle. Or a double pin Kelsey-
Hayes caliper (non-family caliper) which mounts di-
rectly to rails on the steering knuckle. The non-
family caliper is only used on the AY Body
(Imperials).
CAUTION: Caliper pistons, boots and seals for the
different caliper assemblies used on the front and
rear disc brake assemblies are not interchangeable.
Misusage could result in a complete brake system
failure. Be sure that the parts are replaced with the
correct replacement parts, refer to the parts book
for the type and model year of the vehicle being
worked on.
The master cylinder is anodized, lightweight alu-
minum, with a bore size of 24.0mm, 21.0mm or 7/8
inch.
Ä BRAKES 5 - 1

HYDRAULIC SYSTEM CONTROL VALVES INDEX
page page
ABS Brake Proportioning Valve Operation ...... 27
General Information ....................... 26
Hydraulic System Service Procedures ......... 27 Non-ABS Proportioning Unit Operation
........ 26
Pressure Differential Warning Light Switch ...... 26
Testing ABS Proportioning Valves ............ 29
GENERAL INFORMATION
Most models not equipped with an Anti-Lock brak-
ing system have a combination hydraulic system con-
trol valve in the brake hydraulic system (Fig. 1). The
valve is attached to the frame rail below the master
cylinder.
The control valve assembly combines a warning
switch with a dual proportioning valve (Fig. 2) Proportioning valves balance front to rear braking
by controlling at a given ratio, the increase in rear
system hydraulic pressure above a preset level. Un-
der light pedal application, the valve allows full hy-
draulic pressure to the rear brakes. There is only one valve assembly in each vehicle,
see Valve Application Chart. During any service pro-
cedures identify valve assemblies by part number as
well as split point (PSI) and slope.
PRESSURE DIFFERENTIAL WARNING LIGHT
SWITCH
The hydraulic brake system, on non-ABS vehicles,
is split diagonally. The left front and right rear
brakes are part of one system. And the right front and left rear are part of another. Both systems are
routed through, but hydraulically separated by a Pres-
sure Differential Switch. The function of the Pressure
Differential Switch is to alert the driver of a malfunc-
tion in the brake system. If hydraulic pressure is lost in one system, the
warning light switch will activate a red light on the
instrument panel, when the brake pedal is depressed.
At this point the brakes require 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. The instrument panel bulb can be checked each time
the ignition switch is turned to the start position or the
parking brake is set.
NON-ABS PROPORTIONING UNIT OPERATION
The proportioning valve section operates by trans-
mitting full input pressure to the rear brakes up to a
certain point. This is called the split point. Beyond this
point it reduces the amount of pressure increase to the
rear brakes according to a certain ratio. On light pedal applications equal brake pressure will
be transmitted to the front and rear brakes. On heavier
pedal applications the pressure transmitted
Fig. 1 Brake Combination Valve And Warning Switch Location
Fig. 2 Switch and Valve Assembly
5 - 26 BRAKES Ä

to the rear will be lower than the front brakes. This will
prevent premature rear wheel lock-up and skid. If
hydraulic pressure is lost in one half of the diagonally
split system, the operation of the proportioning valve
in the remaining half is not effected.
ABS BRAKE PROPORTIONING VALVE OPERATION
On vehicles using the ABS braking system, screw in
proportioning valves are used in place of the conven-
tional differential pressure/proportioning valve. Each rear brake circuit has its own screw-in propor-
tioning valve which is attached to the rear brake outlet
ports of the hydraulic assembly. These valves limit
brake pressure to the rear brakes after a certain
pressure is reached. This improves front to rear brake
balance during normal braking.
Screw in proportioning valves can be identified by
the numbers stamped on the body of the valve. The
first digit represents the slope, the second digit repre-
sents the split (cut-in) point, and the arrow represents
the flow direction of the valve. Be sure that the
numbers listed on the replacement valve are the
same as on the valve that is being removed. See
(Fig. 3) for detail of the valve identification.
HYDRAULIC SYSTEM SERVICE PROCEDURES
BRAKE WARNING SYSTEM
CHECKING BRAKE WARNING SWITCH UNIT
The Red Brake Warning light will come on when
the parking brake is applied with the ignition key
turned ON. The same light will also illuminate
should one of the two service brake hydraulic sys-
tems fail.
CAUTION:Make sure air does not enter the hydrau-
lic system during this test procedure. See bleeding
without a pressure bleeder at the beginning of this
section for master cylinder fluid level checking pro-
cedures.
To test the service brake warning system lamp.
Raise the vehicle on a hoist and open a wheel cylin-
der bleeder while a helper depresses the brake pedal
and observes the warning light. If the light fails to light, inspect for a burned out
bulb, disconnected socket, or a broken or discon-
nected wire at the switch. If the bulb is not burned
out and the wire continuity is uninterrupted. Check
the service brake warning switch operation with a
test lamp between the switch terminal and a known
good ground. Be sure to fill master cylinder and
bleed brake system after correction has been made, if
necessary.
PROPORTIONING VALVES
TESTING PROPORTIONING VALVE UNIT
If premature rear wheel skid occurs on hard brake
application, it could be an indication that a malfunc-
tion has occurred with the proportioning valve unit. The proportioning valve is designed with two sep-
arate systems. One half controls the right rear
brake, and the other half controls the left rear brake.
Therefore, a road test to determine which rear brake
slides first is essential.
RIGHT REAR WHEEL SLIDES FIRST To test the proportioning valve when the right rear
wheel slides first, leave the front brakes connected to
the valve, proceed as follows: (1) Install one gauge and (TEE) of set C-4007-A
between the brake line from the master cylinder sec-
ondary port and the brake valve assembly. (2) Install the second gauge of set C-4007-A to the
right rear brake outlet port (Fig. 4). Using an
adapter tube, made from a short piece of brake tube
and (2) 3/8 x 24 tube nuts. Connect the hose to the
valve. Bleed the hose and gauge. (3) Have a helper exert pressure on the brake
pedal (holding pressure) to get a reading on the valve
inlet gauge and check the reading on the outlet
Fig. 3 ABS PROPORTIONING VALVE IDENTIFICA- TION
Ä BRAKES 5 - 27