light DODGE NEON 1999 Service User Guide

DIAGNOSIS AND TESTING
BRAKE SYSTEM BASIC DIAGNOSIS GUIDE
SYMPTOMCHART 1
MISC.
COND.CHART 2
WARNING
LIGHTCHART 3
POWER
BRAKESCHART 4
BRAKE
NOISECHART 5
WHEEL
BRAKES
Brake Warning Light On X NO NO
Excessive Pedal Travel 6 X NO O
Pedal Goes To The Floor 6 X
Stop Light On Without Brakes 3
All Brakes Drag 5
Rear Brakes Drag 2 NO NO
Grabby Brakes O X
Spongy Brake Pedal X NO
Premature Rear Brake Lockup 4 NO NO O
Excessive Pedal Effort 1 O
Rough Engine Idle NO O
Brake Chatter (Rough) NO NO X
Surge During Braking NO NO X
Noise During Braking NO NO X
Rattle Or Clunking Noise NO NO X
Pedal Pulsates During Braking NO NO X
Pull To Right Or Left NO NO X
No: Not A Possible Cause X: Most Likely Cause O: Possible Cause
PLBRAKES 5 - 9

outer diameter. Care must be taken to position stem
outside the stud circle but inside the chamfer on the
hub rim (Fig. 21).Clean hub surface before
checking.
Runout should not exceed 0.08 mm (0.003 inch). If
runout exceeds this specification, hub must be
replaced. See Suspension Group 2. If hub runout
does not exceed this specification, install rotor on hub
with chalk marks two wheel studs apart (Fig. 22).
Tighten nuts in the proper sequence and torque to
specifications. Finally, check runout of rotor to see if
runout is now within specifications.If runout is not within specifications. Install a new
rotor or reface rotor, being careful to remove as little
as possible from each side of rotor. Remove equal
amounts from each side of rotor. Do not reduce thick-
ness below minimum thickness cast into the un-ma-
chined surface of the rotor.
Thickness variation measurements of rotor should
be made in conjunction with runout. Measure thick-
ness of rotor at 12 equal points with a micrometer at
a radius approximately 25 mm (1 inch) from edge of
rotor (Fig. 23). If thickness measurements vary by
more than 0.013 mm (0.0005 inch) rotor should be
removed and resurfaced, or a new rotor installed. If
cracks or burned spots are evident, rotor must be
replaced.
Light scoring and/or wear is acceptable. If heavy
scoring or warping is evident, the rotor must be
machined or replaced. See Brake Rotor Machining in
the Service Procedures Section in this group of the
service manual. Refer to front or rear brake rotor in
the Removal And Installation section in this group of
the service manual for the required brake rotor
replacement procedure.
Fig. 21 Checking Hub for Runout
Fig. 22 Index Rotor And Wheel Stud
Fig. 23 Checking Rotor For Thickness
PLBRAKES 5 - 15
DIAGNOSIS AND TESTING (Continued)

(7) With the aid of a helper, apply pressure to the
brake pedal until reading on proportioning valve
inlet gauge, is at the pressure shown on the following
chart. Then check the pressure reading on the pro-
portioning valve outlet gauge. If proportioning valve
outlet pressure does not agree with value shown on
the following chart, when inlet pressure shown on
chart is obtained, replace the proportioning valve. If
proportioning valve is within pressure specifications
do not replace proportioning valve.
(8) Check rear wheel brake shoe linings for con-
tamination or for replacement brake shoes not meet-
ing OEM brake lining material specifications. These
conditions can also be a possible cause for a prema-
ture rear wheel skid.
(9) Install proportioning valve in chassis brake
tube (Fig. 29). Tighten the proportioning valve to a
torque of 17 N´m (145 in. lbs.).
(10) Bleed the affected brake line. See Bleeding
Brake System in the Service Adjustments section of
the manual for proper bleeding procedure.
BRAKE FLUID CONTAMINATION
Indications of fluid contamination are swollen or
deteriorated rubber parts.
Swollen rubber parts indicate the presence of
petroleum in the brake fluid.
To test for contamination, put a small amount of
drained brake fluid in clear glass jar. If fluid sepa-
rates into layers, there is mineral oil or other fluid
contamination of the brake fluid.
If brake fluid is contaminated, drain and thor-
oughly flush system. Replace master cylinder, propor-
tioning valve, caliper seals, wheel cylinder seals,
Antilock Brakes hydraulic unit and all hydraulic
fluid hoses.
RED BRAKE WARNING LAMP TEST
For diagnosis of specific problems with the red
brake warning lamp system, refer to Brake System
Diagnostics Chart 2, located in the Diagnosis And
Testing section in this group of the service manual.
STOP LAMP SWITCH TEST PROCEDURE
The required procedure for testing the stop lamp
switch is covered in Group 8H, Vehicle Speed Control
System in this service manual. The electrical circuit
tests for stop lamps is covered in Group 8W Rear
Lighting in this service manual.
SERVICE PROCEDURES
BRAKE FLUID LEVEL CHECK
Check master cylinder reservoir brake fluid level a
minimum of twice a year.
Master cylinder reservoirs are marked with the
wordsFULL AND MINindicating proper range of
the master cylinder fluid level (Fig. 34).
Fig. 33 Pressure Gauges Installed On Pressure Test
Fittings
BRAKE PROPORTIONING VALVE APPLICATIONS AND PRESSURE SPECIFICATIONS
Sales CodeBrake
System
TypeSplit
PointSlopeIdentifi-
cationInlet
PressureOutlet
Pressure
BRA 149
Disc/Drum400 psi 0.43 Black
Band1000 psi 600-700
psi
BRD 149
Disc/Disc300 psi 0.34 Bar Code
Band1000 psi 550-650
psi
BRF 149
Disc/Disc
W/ABS300 psi 0.34 Bar Code
Band1000 psi 550-650
psi
PLBRAKES 5 - 19
DIAGNOSIS AND TESTING (Continued)

(7) Remove both rear park brake cables from the
park brake cable equalizer (Fig. 131).
(8) Remove wiring harness electrical connector for
brake warning light ground from the park brake
lever (Fig. 132).
(9) Remove the 2 nuts (Fig. 133) attaching the
park brake lever to the console bracket. Remove park
brake lever mechanism from vehicle.
INSTALL
(1) Place park brake lever on console bracket.
Install and securely tighten the 2 attaching nuts
(Fig. 133).
(2) Install both rear park brake cables into equal-
izer on park brake lever output cable (Fig. 131).
(3) Ensure that park brake cable is correctly
installed and aligned with cable track on park brake
lever.
(4) Firmly grasp park brake lever locking pin (Fig.
134) and quickly remove it from the park brake levermechanism. This will allow the park brake lever
mechanism to correctly adjust the park brake cables.
(5) Connect electrical connector for brake warning
lamp onto terminal on park brake lever assembly
(Fig. 132).
(6) Cycle park brake lever once to position park
brake cables. Then return the park brake lever its
released position. Check the rear wheels of the vehi-
cle. They should rotate freely without dragging.
(7) Raise park brake lever to its fully engaged
position. This is necessary to allow installation of the
center console.
(8) Install center console assembly.
(9) Install the 4 center console assembly attaching
screws (Fig. 127), (Fig. 128) and (Fig. 129).
PARK BRAKE LEVER OUTPUT CABLE
On this vehicle, the park brake lever output cable
(Fig. 135), is not replaceable as a separate component
Fig. 130 Locking Pin Installed In Park Brake
Mechanism
Fig. 131 Park Brake Cables At Equalizer
Fig. 132 Brake Warning Lamp Connection To Park
Brake Lever
Fig. 133 Park Brake Lever Attachment To Console
Bracket
PLBRAKES 5 - 49
REMOVAL AND INSTALLATION (Continued)

from rotor, so hydraulic fluid cannot get on rotor.
Place a small piece of wood between the piston and
caliper fingers.
(2)Carefullydepress brake pedal to hydraulically
push piston out of bore. Then apply and hold down
the brake pedal to any position beyond the first inch
of pedal travel. This will prevent loss of brake fluid
from the master cylinder.
(3) If both front caliper pistons are to be removed,
disconnect brake tube at flexible brake hose at frame
rail. Plug brake tube and remove piston from oppo-
site caliper using the same process as above for the
first piston removal.
(4) Disconnect the brake fluid flex hose from the
caliper assembly.
CAUTION: Do not use excessive force when clamp-
ing caliper in vise. Excessive vise pressure will
cause bore distortion and binding of piston.
(5) To disassemble caliper, mount in a vise
equipped with protective jaws.
(6) Remove guide pin sleeves and guide pin bush-
ings. See Removing Guide Pin Bushings in the cali-
per disassembly section of this manual.
(7) Remove the piston dust boot from the caliper
and discard (Fig. 177).
(8) Using a soft tool, such as a plastic trim stick,
work piston seal out of its groove in caliper piston
bore (Fig. 178). Discard old seal.Do not use a
screw driver or other metal tool for this opera-
tion, because of the possibility of scratching
piston bore or burring edges of seal groove.(9) Clean all parts using alcohol or a suitable sol-
vent and wipe dryusing only a lint free cloth.No
lint residue can remain in caliper bore. Clean out all
drilled passages and bores.Whenever a caliper
has been disassembled, a new boot and seal
must be installed at assembly.
(10) Inspect the piston bore for scoring or pitting.
Bores that show light scratches or corrosion can usu-
ally be cleared of the light scratches or corrosion
using crocus cloth. Bores that have deep scratches or
scoring should be honed. Use Caliper Hone, Special
Tool C-4095, or equivalent providing the diameter of
the bore is not increased more than 0.0254 mm
(0.001 inch) (Fig. 179).
(11) If the bore does not clean up within this spec-
ification, a new caliper housing should be installed.
Install a new piston if the old one is pitted or scored.
NOTE: When using Caliper Honing Tool, Special
Tool C-4095, coat the stones and bore with brake
fluid. After honing the bore, carefully clean the seal
and boot grooves with a stiff non-metallic rotary
brush.
NOTE: Use extreme care in cleaning the caliper
after honing. Remove all dirt and grit by flushing
the caliper with brake fluid; wipe dry with a clean,
lint free cloth and then clean a second time.
CAUTION: When inspecting caliper piston, do not
use anything but solvents to clean piston surface. If
surface of piston cannot be cleaned using only sol-
vents, piston must be replaced.
Fig. 177 Removing Caliper/Piston Dust Boot
Fig. 178 Removing Piston Seal From Caliper
PLBRAKES 5 - 61
DISASSEMBLY AND ASSEMBLY (Continued)

MUST always be used when installing brake
hose to caliper.
(12) Bleed the brake system (see Bleeding Brake
System).
WHEEL CYLINDER (REAR DRUM BRAKE)
DISASSEMBLE
To disassemble the wheel cylinders, proceed as fol-
lows:
(1) Pry boots away from cylinders and remove (Fig.
183).
(2) PressINon one piston to force out opposite
piston, cup and spring (Fig. 183). 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 (Fig.
183) in clean brake fluid or alcohol;(DO NOT USE
ANY PETROLEUM BASE SOLVENTS)clean thor-
oughly and blow dry with compressed air. Inspect cyl-
inder bore and piston for scoring and pitting. (Do not
use a rag as lint from the rag will stick to bore sur-
faces.)
(4) Wheel cylinder bores and pistons that are
badly scored or pitted should be replaced. Cylinder
walls that have light scratches, or show signs of cor-
rosion, can usually be cleaned with crocus cloth,
using a circular motion. Black stains on the cylinder
walls are caused by piston cups and will not impair
operation of cylinder.
ASSEMBLE
Before assembling the pistons and new cups in the
wheel cylinders, dip them in clean brake fluid. If theboots 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) Lightly coat the sealing lip and outer surfaces
of the wheel cylinder cups with Mopar Protect-A-Cup
Lubricant.
(3) Install expansion spring with cup expanders in
cylinder. Install cups in each end of cylinder with
open end of cups facing each other (Fig. 183).
(4) Install piston in each end of cylinder having
the flat face of each piston contacting the flat face of
each cup, already installed (Fig. 183).
(5) Coat the interior surfaces of the push on boots
(Fig. 183) with the Mopar Protect-A-Cup Lubricant
(6) Install a boot over each end of cylinder (Fig.
183).Be careful not to damage boot during
installation.
CLEANING AND INSPECTION
FRONT DISC BRAKES
BRAKE PAD LINING WEAR
If a visual inspection does not adequately deter-
mine the condition of the lining, a physical check will
be necessary. To check the amount of lining wear,
remove the wheel and tire assemblies, and the cali-
pers.
Remove the front disc brake shoes. Refer to Front
Disc Brake Shoe Removal in the Removal And Instal-
lation section in this group of the service manual for
the required procedure.
The combined brake shoe and lining material
thickness should be measured at the thinnest part of
the assembly.
When a set of brake shoes are worn to a total
thickness of approximately 7.95 mm (5/16 inch) they
should be replaced.
Replacebothbrake shoe assemblies (inboard and
outboard). It is necessary thatbothfront wheel sets
be replaced whenever brake shoe assemblies on
either side are replaced.
If the brake shoe assemblies do not require
replacement, reinstall, the assemblies making sure
each brake shoe is returned to the original position.
Refer to Front Disc Brake Shoe Installation in the
Removal And Installation section in this group of the
service manual for the required procedure.
CALIPER INSPECTION
Check for brake fluid leaks in and around boot
area and inboard lining, and for any ruptures, brit-
tleness or damage to the piston dust boot. If the boot
Fig. 182 Installing Dust Boot In Caliper Counterbore
PLBRAKES 5 - 63
DISASSEMBLY AND ASSEMBLY (Continued)

(3)Be sure parking brake lever is fully
released.
(4) Insert Brake Adjuster, Special Tool C-3784,
(Fig. 187) or equivalent, through the adjusting hole
in support plate and against star wheel of adjusting
screw. Move handle of tool downward 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. 187). Push adjust-
ing lever out of engagement with star wheel.Care
should be taken so as not to bend adjusting
lever or distort lever spring.While holding
adjusting lever out of engagement with star wheel,
back off star wheel to ensure a free wheel with no
brake shoe drag.
(6) Repeat above adjustment at the other rear
wheel. Install adjusting hole rubber plugs (Fig. 186)
in rear brake supports.
(7) Apply and release the park brake lever one
timeafterwheel brake adjustment.
PARK BRAKE ADJUSTMENT
VEHICLE EQUIPPED REAR DRUM BRAKES
Due to the auto adjust feature of the park brake
lever, no manual adjustment of the operating cables
for the park brake system is required. On vehicles
equipped with rear drum brakes, proper operation of
the park brake relies on proper adjustment of the
rear drum brake shoes. See Rear Brake Adjustment
in the Service Adjustments Section in this group of
the service manual.
VEHICLE EQUIPPED REAR DISC BRAKES
Due to the auto adjust feature of the park brake
lever, no manual adjustment of the operating cables
for the park brake system is required. On vehicles
equipped with rear disc brakes, proper operation of
the park brake relies on the proper adjustment of the
drum-in-hat park brake shoes. Refer to the following
procedure to correctly adjust the drum-in-hat park
brake shoes.
NOTE: The park brake shoes used in the drum-in-
hat park brake system do not automatically adjust
to compensate for brake shoe lining wear. There-
fore, it is necessary to manually adjust the park
brake shoes. Manual adjustment of the park brake
shoes is required whenever any of the following
occurs. Excessive travel of the of the park brake
lever, new park brake shoes are installed, or any
service is performed that effects the location of the
park brake shoes like: replacing hold down clips,
return springs, adjuster mechanism etc.
(1) Fully release the park brake hand lever.
(2) Raise vehicle. See Hoisting Recommendations
in the Lubrication And Maintenance Section of this
service manual.
Fig. 185 Stop Light Switch Location In Vehicle
Fig. 186 Rear Brake Adjusting Hole Plug
Fig. 187 Brake Drum Adjustment With Tool C-3784
5 - 66 BRAKESPL
ADJUSTMENTS (Continued)

(3) Remove the rubber plug from the adjusting
hole in the brake shoe backing plate on both sides of
the vehicle.
(4)Driver (left) side park brake shoe adjust-
ment procedure.Insert a medium size screwdriver
through adjustment hole in backing plate. Position
the srewdriver against the starwheel on the park
brake shoe adjuster mechanism. Using the screw-
driver rotate the starwheeldownwarduntil a slight
drag is felt when turning the rear tire and wheel.
Then, using the screwdriver rotate the starwheel
upwardjust until the rear tire and wheel can be
rotated with no park brake shoe drag. From the
point where there is no more park brake drag rotate
the starwheelupwarda maximum of two additional
clicks. The park brake shoe to drum clearance is
know properly adjusted.
(5)Passenger (right) side park brake shoe
adjustment procedure.Insert a medium size
screwdriver through adjustment hole in backing
plate. Position the srewdriver against the starwheel
on the park brake shoe adjuster mechanism. Using
the screwdriver rotate the starwheelupwarduntil a
slight drag is felt when turning the rear tire and
wheel. Then, using the screwdriver rotate the star-
wheeldownwardjust until the rear tire and wheel
can be rotated with no park brake shoe drag. From
the point where there is no more park brake drag
rotate the starwheeldownwarda maximum of two
additional clicks. The park brake shoe to drum clear-
ance is know properly adjusted.
(6) Install the rubber plug in the adjusting hole on
the brake shoe backing plate on both sides of the
vehicle.
(7) Lower vehicle far enough to allow access the
park brake lever. The rear tires must not be on the
ground.
(8) Fully apply and release the park brakes two
times after adjusting the park brake shoes. Then
rotate both rear wheels to ensure that the park
brake shoes do not drag on the brake drum following
the application and release of the park brakes.
SPECIFICATIONS
BRAKE FLUID
The brake fluid used in this vehicle must conform
to DOT 3 specifications and SAE J1703 standards.
No other type of brake fluid is recommended or
approved for usage in the vehicle brake system. Use
only Mopar brake fluid or an equivalent from a
tightly sealed container.
CAUTION: Never use reclaimed brake fluid or fluid
from an container which has been left open. Anopen container will absorb moisture from the air
and contaminate the fluid.
CAUTION: Never use any type of a petroleum-
based fluid in the brake hydraulic system. Use of
such type fluids will result in seal damage of the
vehicle brake hydraulic system causing a failure of
the vehicle brake system. Petroleum based fluids
would be items such as engine oil, transmission
fluid, power steering fluid ect.
BRAKE ACTUATION SYSTEM
ACTUATION:
Vacuum Operated Power Brakes.........Standard
Hydraulic System...........Dual-Diagonally Split
MASTER CYLINDER ASSEMBLY:
Type ...........................Dual Tandem
Body Material...............Anodized Aluminum
Reservoir Material................Polypropelene
MASTER CYLINDER BORE / STROKE
AND SPLIT:
NonABS ....21mmx32.6 mm (.875 in. x 1.28 in.)
ABS........21mmx32.7 mm (.874 in. x 1.29 in.)
Displacement Split.....................50/50
MASTER CYLINDER FLUID OUTLET PORTS:
ABS ..........Primary 3/8±24 Secondary 7/16±24
Non ABS . . .Primary Inboard And Outboard 7/16±24
Non ABS . . .Secondary Inboard And Outboard 3/8±23
Outlet Fitting Type.......SAE 45 É Inverted Flare
ABS HYDRAULIC CONTROL UNIT:
Hydraulic Tube Fitting Type.SAE 45 É Inverted Flare
BOOSTER:
Make/Type.........Bendix Vacuum W/&W/O ABS
Mounting Studs.....................M8x1.25
Type ..........................230 mm Single
Boost At 20 inches Of Manifold Vacuum. . . .4690 All
PROPORTIONING VALVE:
Material...........................Aluminum
Function........Hydraulic Pressure Proportioning
BRAKE PEDAL
Pedal Ratio.............................3.28
BRAKE FASTENER TORQUE SPECIFICATIONS
DESCRIPTION TORQUE
BRAKE TUBES:
Tube Nuts To Fittings And
Components Except HCU. . . . 17 N´m (145 in. lbs.)
From Master Cylinder To
HCU At HCU Ports........21N´m(185 in. lbs.)
BRAKE HOSE:
To Caliper Banjo Bolt..........48N´m(35ft.lbs.)
Intermediate Bracket.........12N´m(105 in. lbs.)
PLBRAKES 5 - 67
ADJUSTMENTS (Continued)

This is accomplished by a sophisticated system of
electrical and hydraulic components. As a result,
there are a few performance characteristics that may
at first seem different but should be considered nor-
mal. These characteristics are discussed below.
NORMAL BRAKING SYSTEM FUNCTION
Under normal braking conditions, the ABS System
functions the same as a standard brake system with
a diagonally split master cylinder and conventional
vacuum assist.
ABS SYSTEM OPERATION
If a wheel locking tendency is detected during a
brake application, the brake system will enter the
ABS mode. During ABS braking, hydraulic pressure
in the four wheel circuits is modulated to prevent
any wheel from locking. Each wheel circuit is
designed with a set of electric solenoids to allow mod-
ulation, although for vehicle stability, both rear
wheel solenoids receive the same electrical signal.
During an ABS stop, the brakes hydraulic system
is still diagonally split. However, the brake system
pressure is further split into four control channels.
During antilock operation of the vehicle's brake sys-
tem the front wheels are controlled independently
and are on two separate control channels and the
rear wheels of the vehicle are controlled together.
The system can build and release pressure at each
wheel, depending on signals generated by the wheel
speed sensors (WSS) at each wheel and received at
the Controller Antilock Brake (CAB).
ABS operation is available at all vehicle speeds
above 3 to 5 mph. Wheel lockup may be perceived at
the very end of an ABS stop and is considered nor-
mal.
VEHICLE HANDLING PERFORMANCE DURING
ABS BRAKING
It is important to remember that an antilock brake
system does not shorten a vehicle's stopping distance
under all driving conditions, but does provide
improved control of the vehicle while stopping. Vehi-
cle stopping distance is still dependent on vehicle
speed, weight, tires, road surfaces and other factors.
Though ABS provides the driver with some steer-
ing control during hard braking, there are conditions
however, where the system does not provide any ben-
efit. In particular, hydroplaning is still possible when
the tires ride on a film of water. This results in the
vehicles tires leaving the road surface rendering the
vehicle virtually uncontrollable. In addition, extreme
steering maneuvers at high speed or high speed cor-
nering beyond the limits of tire adhesion to the road
surface may cause vehicle skidding, independent of
vehicle braking. For this reason, the ABS system is
termed Antilock instead of Anti-Skid.
NOISE AND BRAKE PEDAL FEEL
During ABS braking, some brake pedal movement
may be felt. In addition, ABS braking will create
ticking, popping and/or groaning noises heard by the
driver. This is normal due to pressurized fluid being
transferred between the master cylinder and the
brakes. If ABS operation occurs during hard braking,
some pulsation may be felt in the vehicle body due to
fore and aft movement of the suspension as brake
pressures are modulated.
At the end of an ABS stop, ABS will be turned off
when the vehicle is slowed to a speed of 3±4 mph.
There may be a slight brake pedal drop anytime that
the ABS is deactivated, such as at the end of the stop
when the vehicle speed is less then 3 mph or during
an ABS stop where ABS is no longer required. These
conditions will exist when a vehicle is being stopped
on a road surface with patches of ice, loose gravel or
sand on it. Also stopping a vehicle on a bumpy road
surface will activate ABS because of the wheel hop
caused by the bumps.
TIRE NOISE AND MARKS
Although the ABS system prevents complete wheel
lock-up, some wheel slip is desired in order to
achieve optimum braking performance. Wheel slip is
defined as follows, 0 percent slip means the wheel is
rolling freely and 100 percent slip means the wheel is
fully locked. During brake pressure modulation,
wheel slip is allowed to reach up to 25 to30%. This
means that the wheel rolling velocity is 25 to 30%
less than that of a free rolling wheel at a given vehi-
cle speed. This slip may result in some tire chirping,
depending on the road surface. This sound should not
be interpreted as total wheel lock-up.
Complete wheel lock up normally leaves black tire
marks on dry pavement. The ABS System will not
leave dark black tire marks since the wheel never
reaches a fully locked condition. Tire marks may
however be noticeable as light patched marks.
START UP CYCLE
When the ignition is turned on, a popping sound
and a slight brake pedal movement may be noticed.
Additionally, when the vehicle is first driven off a
humming may be heard and/or felt by the driver at
approximately 20 to 40 kph (12 to 25 mph). The ABS
warning lamp will also be on for up to 5 seconds
after the ignition is turned on. All of these conditions
are a normal function of ABS as the system is per-
forming a diagnosis check.
5 - 70 BRAKESPL
DESCRIPTION AND OPERATION (Continued)

cally cleared from the CAB memory after the identi-
cal fault has not been seen during the next 255 key
cycles of vehicle operation.
CONTROLLER ANTILOCK BRAKE INPUTS
²Four wheel speed sensors.
²Stop lamp switch.
²Ignition switch.
²System relay voltage.
²Ground.
²Diagnostics Communications (CCD)
CONTROLLER ANTILOCK BRAKE OUTPUTS
²ABS warning lamp actuation.
²Diagnostic communication. (CCD)
ABS WARNING LAMP (YELLOW)
The ABS system uses a yellow colored ABS Warn-
ing Lamp. The ABS warning lamp is located on the
lower left side of the instrument pane. The purpose
of the warning lamp is discussed in detail below.
The ABS warning lamp will turn on when the CAB
detects a condition which results in a shutdown of
ABS function. When the ignition key is turned to the
on position, the ABS Warning Lamp is on until the
CAB completes its self tests and turns the lamp off
(approximately 4 seconds after the ignition switch is
turned on). Under most conditions, when the ABS
warning lamp is on, only the ABS function of the
brake system is affected. The standard brake system
and the ability to stop the car will not be affected
when only the ABS warning lamp is on.
The ABS warning lamp is controlled by the CAB.
The CAB turns on the yellow ABS warning lamp by
grounding the circuit.
HYDRAULIC CIRCUITS AND VALVE OPERATION
Through the following operation descriptions the
function of the various hydraulic control valves in the
ABS will be described. The fluid control valves men-
tioned below, control the flow of pressurized brake
fluid to the wheel brakes during the different modes
of ABS braking.
For explanation purposes, all wheel speed sensors
except the right front are sending the same wheel
speed information. The following diagrams show only
the right front wheel in a antilock braking condition.
NORMAL BRAKING HYDRAULIC CIRCUIT AND
SOLENOID VALVE FUNCTION
This condition is the normal operation of the vehi-
cles base brake hydraulic system. The hydraulic sys-
tem circuit diagram (Fig. 11) shows a situation where
no wheel spin or slip is occurring relative to the
speed of the vehicle. The driver is applying the brake
pedal to build pressure in the brake hydraulic system
to apply the brakes and stop the vehicle.
TEVES MARK 20 ABS CIRCUIT AND
SOLENOID VALVE FUNCTION
This hydraulic circuit diagram (Fig. 12) shows the
vehicle in the ABS braking mode. This hydraulic cir-
cuit (Fig. 12) shows a situation where one wheel is
slipping because the driver is attempting to stop the
vehicle at a faster rate than the surface the vehicle's
tires are on will allow. The normally open and nor-
mally closed valves modulate the brake hydraulic
pressure as required. The pump/motor is switched on
so that the brake fluid from the low pressure accu-
mulators is returned to the master cylinder circuits.
The brake fluid will then be routed to either the mas-
ter cylinder or the wheel brake depending on the
position of the normally open valve.
TEVES MARK 20 SECONDARY ABS CIRCUIT
AND SOLENOID VALVE FUNCTION
This hydraulic circuit diagram (Fig. 13) shows the
vehicle in the ABS braking mode. This hydraulic cir-
cuit (Fig. 13) shows a situation where one wheel is
slipping because the driver is attempting to stop the
vehicle at a faster rate than the surface the vehicle's
tires are on will allow. The normally open and nor-
mally closed valves modulate the brake hydraulic
pressure as required. The pump/motor is switched on
so that the brake fluid from the low pressure accu-
mulators is returned to the master cylinder circuits.
The brake fluid will then be routed to either the mas-
ter cylinder or the wheel brake depending on the
position of the normally open valve. A volume of 1.2
cc's of brake fluid is taken in by the lip seal saver
(Fig. 13) to protect the lip seals on the piston of the
master cylinder.
DIAGNOSIS AND TESTING
ABS GENERAL DIAGNOSTICS INFORMATION
This section contains the information necessary to
diagnose the ITT Teves Mark 20 ABS Brake System.
Specifically, this section should be used to help diag-
nose conditions which result in any of the following:
(1) ABS Warning Lamp turned on.
(2) Brakes Lock-up on hard application
Diagnosis of base brake conditions which are obvi-
ously mechanical in nature should be directed to
Group 5 Brakes in this service manual. This includes
brake noise, brake pulsation, lack of power assist,
parking brake, Red BRAKE Warning Lamp lighting,
or vehicle vibration during normal braking.
Many conditions that generate customer com-
plaints may be normal operating conditions, but are
judged to be a problem due to not being familiar with
the ABS system. These conditions can be recognized
without performing extensive diagnostic work, given
adequate understanding of the operating principles
PLBRAKES 5 - 75
DESCRIPTION AND OPERATION (Continued)