1993 CHEVROLET PLYMOUTH ACCLAIM light

In addition, there is an air regeneration cycle that
is controlled by the Control Module (CM). If the
height sensor signal is in the neutral or high posi-
tion. When the ignition switch is turned to the ON
position, after a 22 to 28 second delay, the compres-
sor will run from 2 to 6 seconds. To prevent excessive cycling between the compres-
sor and the exhaust solenoid circuits during normal
ride conditions. A 12 to 18 second delay is incorpo-
rated in the microprocessor.
HEIGHT SENSOR
A magnetic switch type sensor, located in the right
air shock absorber, monitors rear vehicle height. The
sensor sends signals to the (CM) relating to vehicle
rear suspension status (low, trim, high).
AIR LINES AND FITTINGS
To release an air supply line from a rear shock ab-
sorber assembly. Push in (toward shock absorber) on
the plastic ring of the shock absorber air line fitting.
Then while holding in the plastic ring on shock ab-
sorber fitting pull the air supply line strait out of fit-
ting (Fig. 3). The fitting has a unique push-in feature. A brass
type collet locks the air line in place. One rubber
O-ring seals the air line to prevent air leakage. To
attach air line, push into fitting (Fig. 4).
COMPRESSOR RELAY
The relay is mounted to a bracket on the Control
Module (CM). When the relay is energized, it allows
the compressor to operate. This unit is controlled by
the CM.
AIR ADJUSTABLE SHOCK ABSORBERS
Air shock absorbers are essentially hydraulic shock
absorbers with a neoprene bladder sealing upper and
lower sections together. This creates an air cylinder
inside of the shock absorber.
AIR DRYER
The air dryer is attached to the compressor. This
component serves two purposes; it absorbs moisture
from the atmosphere before it enters the system. And
with the internal valves maintains a residual system
pressure of 69 to 152 kPa (10 to 22 psi).
AIR CHECK, RESIDUAL (FIG. 5).
The air dryer has a valves arrangement that main-
tains 69 to 152 kPa (10 to 22 psi) in the air shocks.
This is to improve the ride characteristics of the ve-
hicle under light load conditions. To test this func-
tion, perform the following procedure: (1) Remove the air line from the dryer and right
shock absorber. Attach a piece of bulk nylon tubing
to one side of a Pressure Gauge (0-300 psi), and to
the right shock absorber (Fig. 5). (2) Attach another piece of nylon tubing from the
dryer (compressor) to other side of the pressure
gauge.
Fig. 2 Compressor AssemblyFig. 3 Release Air Line from Fitting
Fig. 4 Push Air Line into Fitting
2 - 60 SUSPENSION AND DRIVESHAFTS Ä

REAR LEVELING DIAGNOSTIC PROCEDURES
SELF-DIAGNOSTICS
A self-diagnostic procedure is available for the ser-
vice technician to use to detect system malfunctions.
BEFORE DIAGNOSTICS TEST
Check the 20 amp fuse (position W40) and the 30
amp circuit breaker (position W5) to be assured they
are functional components. Check all connectors that link the system into the
main body wiring harness. These include compressor,
height sensor, control module, (Fig. 7) and relay.
Also check the underbody to in trunk and leveling
harness to main body harness connectors. Also, check
all air lines, connectors, and other components for
correct installation.
TEST LAMP PIN OPERATION
The monitor lamp pin output will be activated (test
lamp on) if the detection of abnormal system opera-
tion is determined by the CM.
AFTER COMPLETION OF REPAIRS
To initiate diagnostics, disconnect the test ground
wire then reconnect for repair verification.
TERMINATION OF SELF-DIAGNOSTICS
The self-diagnostic operation is terminated when
any of the following takes place:
² Disconnecting the diagnostic input from the
ground circuit.
² Turn the ignition switch to the off position.
When the self-diagnostic operation is terminated.
The control module resumes normal operation unless
it ceases operation. Due to it detecting a system mal-
function.
TEST WEIGHT
Weight between 275-300 lbs. must be added to rear
of vehicle before diagnostic testing begins.
DIAGNOSTICS (TO START PROCESS)
(1) Remove protective connector cover from diag-
nostic connector. (2) Insert wire into diagnostic ground pin. Then at-
tach to compressor ground pin, or as an alternate, in-
sert wire into diagnostic ground pin. Then ground
other end of test wire to body structure or a control
module fastener.
IGNITION
The following self diagnostic operation is initiated
by connecting the diagnostic ground pin to ground af-
ter ignition switch is turned ON. A monitor lamp
must be connected between the Test Lamp Ground
Pin and the Test Lamp Feed Pin to display the con-
trol module diagnostics status. See (Fig. 8) for diag-
nostic test pin locations.
OPERATION
(1) The compressor relay output. From the control
module (CM), is activated until the vehicle is in the
high position. The maximum relay output operation
time is 150 610 seconds. If the expected position is
not obtained, the CM ceases self-diagnostics and any
further operation. (I.e. neither operates the compres-
sor relay or exhaust outputs). The monitor lamp out-
put is continuously activated until ignition is cycled
from OFF to ON or 60 61 minutes has elapsed after
ignition was turned off. See Diagnostics Chart 1. (2) The monitor lamp output should flash to indi-
cate the position of the height sensor. The sensor
should be in the high position. A continuously
lighted monitor lamp will indicate a system failure.
Such as the compressor relay output has operated for
150 610 seconds but the height sensor did not move
to the high position within the right shock absorber).
See Diagnostic Chart 1. (3) Next the exhaust solenoid output is activated
until the vehicle is in the low position. The maxi-
mum exhaust solenoid operation time is 120 610 sec-
onds. If the expected position is not obtained, the
module ceases self-diagnostics and any further oper-
ation. The monitor lamp output is lighted continu-
ously until ignition is cycled from OFF to ON or 60
6 1 minutes has elapsed after ignition is turned off.
See Diagnostic Chart 4. (4) The monitor lamp should flash to indicate the
height sensor is in the low position. A continuouslyFig. 7 Control Module Connector
Fig. 8 Diagnostic Test Pin Location
Ä SUSPENSION AND DRIVESHAFTS 2 - 65

lighted monitor lamp will indicate a system failure.
Such as the exhaust solenoid operated for 120 610
seconds but the height sensor did not move to the
low position. See Diagnostic Chart 4. (5) The compressor relay output is activated to re-
turn the vehicle to the neutral (leveled) position. The
maximum operation time of the relay output is 150
6 10 seconds. If the expected position is not obtained.
The control module ceases self-diagnostics and any
further operation. The monitor lamp is continuously
lighted until the ignition is cycled from OFF to ON
or 60 61 minutes has elapsed after ignition is turned
off. The sensor will move to the neutral position. If not,
a continuously lighted monitor lamp will indicate a system failure. Such as the compressor relay output
operated for 150 610 seconds but the sensor did not
move to or sense the neutral position. See Diagnostic
Chart 1. (6) Completion of diagnostics, is when self diagnostic
procedure is successfully completed and control module
resumes normal operation. The diagnostic test is now
complete. Throughout the testing the vehicle load must
be maintained at a specific level. No loads are allowed
to be added/removed to/from the vehicle once the self
diagnosis tests have been initiated. The Diagnostic connector cover must be in-
stalled after completion of the test.
2 - 66 SUSPENSION AND DRIVESHAFTS Ä

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

SERVICE ADJUSTMENTS INDEX
page page
Adjusting Rear Service Brakes ............... 4
Bleeding Brake System ..................... 6
Brake Hose and Tubing ................... 11
Master Cylinder Fluid Level .................. 4 Stop Lamp Switch Adjustment (All Vehicles)
.... 13
Test for Fluid Contamination ................. 7
Testing Application Adjuster Operation ......... 6
Wheel Stud Nut Tightening .................. 7
MASTER CYLINDER FLUID LEVEL
ALL EXCEPT AC/AY BODY WITH ABS
Check master cylinder reservoir brake fluid level a
minimum of twice a year. Master cylinder reservoirs are marked with the
words fill to bottom of rings indicating proper fluid
level (Fig. 1). If necessary, add fluid to bring the level to the bot-
tom of the primary reservoir split ring. Use only Mopar tbrake fluid or an equivalent from
a sealed container. Brake fluid must conform to DOT
3, specifications. DO NOT use brake fluid with a lower boiling
point, as brake failure could result during prolonged
hard braking. Use only brake fluid that was stored in a tightly-
sealed container. DO NOT use petroleum-based fluid because seal
damage in the brake system will result.
AC AND AY BODY WITH ANTI-LOCK BRAKES
The hydraulic assembly is equipped with a plastic
fluid reservoir with a filter/strainer in the filler neck
of the reservoir. The Anti-Lock brake system requires that the hy-
draulic accumulator be de-pressurized whenever
checking the brake fluid level. To check the brake
fluid level, the following procedure should be used: (1) With the ignition switch turned to the off position
and key removed. De-pressurize hydraulic accumula-
tor by applying brake pedal approximately 40 times,
using a pedal force of approximately 220 N (50 lbs.). A
noticeable change in pedal feel will occur when accu-
mulator is de-pressurized. Continue to apply brake
pedal several times after this change in pedal feel
occurs to insure that brake system is fully de-
pressurized. (2) Thoroughly clean both reservoir caps and sur-
rounding area of reservoir, (Fig. 2) before removing
caps. This is to avoid getting dirt into the reservoir and
contaminating the brake fluid. (3) Inspect the brake fluid to see if it is at the proper
level, see instructions on top of reservoir. (FILL TO
TOP OF WHITE SCREEN ON FRONT
FILTER/STRAINER.) (4) Fill reservoir with brake fluid to top of screen
(Fig. 3) on the filter/strainer located in brake fluid
reservoir. Only use brake fluid conforming to DOT 3
specifications such as Mopar tor equivalent.
(5) Replace brake fluid reservoir caps.
ADJUSTING REAR SERVICE BRAKES
Normally, self adjusting drum brakes will not
require manual brake shoe adjustment. Al-
though in the event of a brake reline it is advis-
able to make the initial adjustment manually to
speed up the adjusting time. (1) Raise the vehicle so all wheels are free to turn.
See Hoisting Recommendations in the Lubrication And
Maintenance Section, at the front of this service
manual. (2) Remove rear brake adjusting hole rubber plug
(Fig. 4), from the rear brake shoe support plate. (3) Be sure parking brake lever is fully re-
leased. Then back off parking brake cable adjust-
ment so there is slack in the cable. (4) Insert Brake Adjuster, Special Tool C-3784, (Fig.
5) or equivalent through the adjusting hole in support
plate and against star wheel of adjusting screw. Move
handle of tool upward until a slight drag is felt when
the road wheel is rotated. (5) Insert a thin screwdriver or piece of welding rod
into brake adjusting hole (Fig. 5). Push adjusting lever
out of engagement with star wheel. Care
Fig. 1 Master Cylinder Fluid Level (All Except AC/AY
Body W/ABS)
5 - 4 BRAKES Ä

(3) Position the tubing in the jaws of the Flaring
Tool so that it is flush with the top surface of the
flaring tool bar assembly. (See Fig. 17). (4) Install the correct size adaptor for the brake
tubing being flared, on the feed screw of the yoke as-
sembly. Center the yoke and adapter over the end of
the tubing. Apply lubricant to the adapter area that
contacts brake tubing. Making sure the adapter pilot
is fully inserted in the end of the brake tubing.
Screw in the feed screw of the yoke assembly until
the adaptor has seated squarely on the surface of the
bar assembly (Fig. 17). This process has created the
(metric) ISO tubing flare.STOP LAMP SWITCH ADJUSTMENT (ALL
VEHICLES)
The stop lamp switch incorporates a self adjusting
feature. If adjustment or replacement is required,
proceed as follows: Install the switch in the retaining
bracket and push the switch forward as far as it will
go. The brake pedal will move forward slightly (Fig.
18). Gently pull back on the brake pedal bringing the
striker back toward the switch until the brake pedal
will go back no further. This will cause the switch to
ratchet backward to the correct position. Very little
movement is required, and no further adjustment is
necessary.
Fig. 17 ISO Tubing Flare ProcessFig. 18 Stop Lamp Switch
BASIC DIAGNOSIS GUIDE
Ä BRAKES 5 - 13

WHEEL CYLINDERS INDEX
page page
General Information ....................... 23
Installing Wheel Cylinders .................. 24 Service Procedures
....................... 23
GENERAL INFORMATION
The piston boots are of the push-on type and pre-
vent moisture from entering the wheel cylinder. To perform service operations or inspections of the
rear wheel brake cylinders. It will be necessary to re-
move the cylinders from the support plate and disas-
semble on the bench.
CAUTION: Wheel cylinders with cup expanders
must have cup expanders after any service proce-
dures (reconditioning or replacement).
SERVICE PROCEDURES
REMOVING WHEEL CYLINDERS FROM BRAKE SUPPORT PLATES
With brake drums removed, inspect the wheel cyl-
inder boots for evidence of a brake fluid leak. Then
block the brake pedal in the stroke position, and vi-
sually check the boots for cuts, tears, or heat cracks.
If any of these conditions exist, the wheel cylinders
should be completely cleaned, inspected and new
parts installed. (A slight amount of fluid on the boot
may not be a leak, but may be preservative fluid
used at assembly.) (1) In case of a leak, remove brake shoes, (replace
if soaked with grease or brake fluid.) (2) Thoroughly clean area of wheel cylinder, where
hydraulic brake line connects to wheel cylinder. Dis-
connect hydraulic brake tube from wheel cylinder
(Fig. 1). (3) Remove the rear wheel cylinder attaching bolts
(Fig. 1). Then pull wheel cylinder assembly off the
brake support plate (Fig. 2). (4) Clean the surface sealant off the support plate
and wheel cylinder surfaces.
DISASSEMBLING WHEEL CYLINDERS
To disassemble the wheel cylinders, (Fig. 3) pro-
ceed as follows: (1) Pry boots away from cylinders and remove.
(2) Press INon one piston to force out opposite pis-
ton, cup and spring (with cup expanders). Then using
a soft tool such as a dowel rod, press out the cup and
piston that remain in the wheel cylinder. (3) Wash wheel cylinder, pistons, and spring in
clean brake fluid or alcohol; (DO NOT USE ANY
PETROLEUM BASE SOLVENTS) clean thor- oughly and blow dry with compressed air. Inspect
Fig. 1 Brake Tube Disconnected
Fig. 2 Remove or Install Wheel Cylinder
Ä
BRAKES 5 - 23

cylinder bore and piston for scoring and pitting. (Do
not use a rag as lint from the rag will stick to bore
surfaces.) Wheel cylinder bores and pistons that are scored or
pitted in any way should be replaced. Cylinder walls
that have light scratches, or show signs of corrosion,
can usually be cleaned with crocus cloth, using a cir-
cular motion. Black stains on the cylinder walls are
caused by piston cups and will not impair operation
of cylinder.
ASSEMBLING WHEEL CYLINDERS
Before assembling the pistons and new cups in the
wheel cylinders, dip them in clean brake fluid. If the
boots are deteriorated, cracked or do not fit tightly
on the pistons or the cylinder casting, install new
boots. (1) Coat cylinder bore with clean brake fluid.
(2) Install expansion spring with cup expanders in
cylinder. Install cups in each end of cylinder with
open end of cups facing each other (Fig. 3). (3) Install piston in each end of cylinder having
the flat face of each piston contacting the flat face of
each cup, already installed (Fig. 3). (4) Install a boot over each end of cylinder. Be
careful not to damage boot during installation.
INSTALLING WHEEL CYLINDERS
(1) Apply Mopar tGasket In-A-Tube or equivalent
sealant around wheel cylinder mounting surface (Fig.
4). (2) Install wheel cylinder onto brake support, and
tighten the wheel cylinder to brake support plate at-
taching bolts to 8 N Im (75 in. lbs.). (3) Attach hydraulic brake tube to wheel cylinder,
and tighten tube to wheel cylinder fitting to 17 N Im
(145 in. lbs.). (4) Install brake shoes on support plate.
(5) Install rear brake drum onto rear hub. Install
rear wheel and tire assembly, tighten wheel stud
nuts to 115 N Im (85 ft. lbs.).
(6) Adjust the rear brakes, (See Adjusting Service
Brakes) in Service Adjustments section in this group
of the service manual. (7) Bleed the entire brake system. See (Bleeding
Brake System) in Service Adjustments section in this
group of the service manual.
Fig. 3 Rear Wheel Cylinder
Fig. 4 Apply Sealant on Support Plate
5 - 24 BRAKES Ä