1998 DODGE RAM 1500 fig

Inspect the adjuster screw assembly. Replace the
assembly if the star wheel or threads are damaged,
or the components are severely rusted or corroded
(Fig. 77).
Discard the brake springs and retainer components
if worn, distorted or collapsed. Also replace the
springs if a brake drag condition had occurred. Over-
heating will distort and weaken the springs.
Inspect the brake shoe contact pads on the support
plate, replace the support plate if any of the pads are
worn or rusted through. Also replace the plate if it is
bent or distorted (Fig. 77).
INSTALLATION
NOTE: On a new vehicle or after parking brake lin-
ing replacement, it is recommended that the park-
ing brake system be conditioned prior to use. This
is done by making one stop from 25 mph on dry
pavement or concrete using light to moderate force
on the parking brake foot pedal.
(1) Reassemble the rear park brake shoes (Fig. 67)
or (Fig. 78).
(2) Install the axleshaft (Fig. 76) (Refer to 3 - DIF-
FERENTIAL & DRIVELINE/REAR AXLE - 9 1/4/
AXLE SHAFTS - INSTALLATION) or (Refer to 3 -
DIFFERENTIAL & DRIVELINE/REAR AXLE - 11
1/2 AA/10 1/2 AA/AXLE SHAFTS - INSTALLATION).
(3) Install the park brake cable to the lever behind
the support plate.
(4) Unlock the park brake cable.
(5) Install the disc brake rotor (Refer to 5 -
BRAKES/HYDRAULIC/MECHANICAL/ROTORS -
INSTALLATION).(6) Install the disc brake caliper (Refer to 5 -
BRAKES/HYDRAULIC/MECHANICAL/DISC
BRAKE CALIPERS - INSTALLATION).
(7) Adjust the rear brake shoes (Refer to 5 -
BRAKES/PARKING BRAKE/SHOES - ADJUST-
MENTS).
Fig. 76 AXLE SHAFT
1 - AXLE SHAFT
2 - SUPPORT PLATE
3 - CALIPER
4 - PARK BRAKE SHOE ASSEMBLY
Fig. 77 PARK BRAKE SHOES
1 - SUPPORT PLATE
2 - SHOES
3 - RETURN SPRINGS
4 - RETAINER CLIPS
5 - ADJUSTER
Fig. 78 SHOE ASSEMBLY
1 - Park Brake Shoes
2 - Hold Downs
3 - Return Springs
5 - 40 BRAKES - BASEDR
SHOES (Continued)

(8) Install the tire and wheel assembly (Refer to 22
- TIRES/WHEELS/WHEELS - STANDARD PROCE-
DURE).
(9) Lower the vehicle.
ADJUSTMENTS
ADJUSTMENT - PARKING BRAKE SHOES
CAUTION: Before adjusting the park brake shoes be
sure that the park brake pedal is in the fully
released position. If park brake pedal is not in the
fully released position, the park brake shoes can
not be accurately adjusted.
(1) Raise vehicle.
(2) Remove tire and wheel.
(3) Remove disc brake caliper from caliper adapter
(Refer to 5 - BRAKES/HYDRAULIC/MECHANICAL/
DISC BRAKE CALIPERS - REMOVAL).
(4) Remove rotor from the axleshaft (Refer to 5 -
BRAKES/HYDRAULIC/MECHANICAL/ROTORS -
REMOVAL).
NOTE: When measuring the brake drum diameter,
the diameter should be measured in the center of
the area in which the park brake shoes contact the
surface of the brake drum.
(5) Using Brake Shoe Gauge, Special Tool C-3919,
or equivalent,accuratelymeasure the inside diam-
eter of the park brake drum portion of the rotor (Fig.
79).
(6) Using a ruler that reads in 64th of an inch,
accurately read the measurement of the inside diam-
eter of the park brake drum from the special tool
(Fig. 80).
(7) Reduce the inside diameter measurement of
the brake drum that was taken using Special ToolC-3919 by 1/64 of an inch. Reset Gauge, Brake Shoe,
Special Tool C-3919 or the equivalent used, so that
the outside measurement jaws are set to the reduced
measurement (Fig. 81).
(8) Place Gauge, Brake Shoe, Special Tool C-3919,
or equivalent over the park brake shoes. The special
tool must be located diagonally across at the top of
one shoe and bottom of opposite shoe (widest point)
of the park brake shoes.
(9) Using the star wheel adjuster, adjust the park
brake shoes until the lining on the park brake shoes
just touches the jaws on the special tool.
(10) Repeat step 8 above and measure shoes in
both directions.
(11) Install brake rotor on the axleshaft (Refer to 5
- BRAKES/HYDRAULIC/MECHANICAL/ROTORS -
INSTALLATION).
Fig. 79 Measuring Park Brake Drum Diameter
Fig. 80 Reading Park Brake Drum Diameter
1 - SPECIAL TOOL C-3919
2 - RULER
Fig. 81 Setting Gauge To Park Brake Shoe
Measurement
1 - RULER
2 - SPECIAL TOOL C-3919
DRBRAKES - BASE 5 - 41
SHOES (Continued)

(12) Rotate rotor to verify that the park brake
shoes are not dragging on the brake drum. If park
brake shoes are dragging, remove rotor and back off
star wheel adjuster one notch and recheck for brake
shoe drag against drum. Continue with the previous
step until brake shoes are not dragging on brake
drum.
(13) Install disc brake caliper on caliper adapter
(Refer to 5 - BRAKES/HYDRAULIC/MECHANICAL/
DISC BRAKE CALIPERS - INSTALLATION).
(14) Install wheel and tire.
(15) Tighten the wheel mounting nuts in the
proper sequence until all nuts are torqued to half the
specified torque. Then repeat the tightening sequence
to the full specified torque of 180 N´m (135 ft. lbs.)
1500 & 2500 Series or 195 N´m (145 ft. lbs.) 3500
Series.
(16) Lower vehicle.
(17) Apply and release the park brake pedal one
time. This will seat and correctly adjust the park
brake cables.
CAUTION: Before moving vehicle, pump brake
pedal several times to ensure the vehicle has a firm
enough pedal to stop the vehicle.
NOTE: On a new vehicle or after parking brake lin-
ing replacement, it is recommended that the park-
ing brake system be conditioned prior to use. This
is done by making one stop from 25 mph on dry
pavement or concrete using light to moderate force
on the parking brake foot pedal.
(18) Road test the vehicle to ensure proper func-
tion of the vehicle's brake system.
ADJUSTMENT - WITH ADJUSTING TOOL
Adjustment can be made with a standard brake
gauge or with adjusting tool. Adjustment is per-
formed with the complete brake assembly installed
on the backing plate.
(1) Be sure parking brake lever is fully released.
(2) Raise vehicle so rear wheels can be rotated
freely.
(3) Remove plug from each access hole in brake
support plates.
(4) Loosen parking brake cable adjustment nut
until there is slack in front cable.
(5) Insert adjusting tool through support plate
access hole and engage tool in teeth of adjusting
screw star wheel (Fig. 82).
(6) Rotate adjuster screw star wheel (move tool
handle upward) until slight drag can be felt when
wheel is rotated.
(7) Back off adjuster screw star wheel until brake
drag is eliminated.(8) Repeat adjustment at opposite wheel. Be sure
adjustment is equal at both wheels.
(9) Install support plate access hole plugs.
(10) Adjust parking brake cable and lower vehicle.
(11) Depress park brake pedal and make sure park
brakes hold the vehicle staionary.
(12) Release park brake pedal.
PEDAL
REMOVAL
(1) Release the parking brake.
(2) Raise the vehicle.
(3) Loosen the cable tensioner nut at the equalizer
to create slack in the front cable.
(4) Lower the vehicle.
(5) Remove the knee bolster, (Refer to 23 - BODY/
INSTRUMENT PANEL/STEERING COLUMN
OPENING COVER - REMOVAL).
(6) Disconnect the brake lamp wire from the
switch on the pedal assembly.
(7) Roll the carpet back, loosen the front cable
grommet from the floorpan and the cable retainer.
(8) Disengage the release rod (Fig. 83) from the
arm on the pedal assembly.
(9) Remove the bolts/nuts from the pedal assembly
and remove the assembly.
INSTALLATION
(1) Position the replacement pedal assembly on the
dash and cowl.
Fig. 82 Brake Adjustment
1 - STAR WHEEL
2 - LEVER
3 - BRAKE SHOE WEB
4 - SCREWDRIVER
5 - ADJUSTING TOOL
6 - ADJUSTER SPRING
5 - 42 BRAKES - BASEDR
SHOES (Continued)

(2) Install the bolts/nuts and tighten to 28 N´m (21
ft. lbs.) (Fig. 84).
(3) Install the park brake release rod.
(4) Connect the front cable to the arm on the pedal
assembly.
(5) Install the front cable grommet into the floor-
pan and the cable retainer, roll the carpet back.
(6) Connect the wires to the brake lamp switch.
(7) Install the knee bolster, (Refer to 23 - BODY/
INSTRUMENT PANEL/STEERING COLUMN
OPENING COVER - INSTALLATION).
(8) Raise the vehicle.
(9) Adjust the parking brake cable tensioner (Refer
to 5 - BRAKES/PARKING BRAKE/CABLE TEN-
SIONER - ADJUSTMENTS).
CABLE TENSIONER
ADJUSTMENTS
ADJUSTMENT
NOTE: Tensioner adjustment is only necessary
when the tensioner, or a cable has been replaced or
disconnected for service. When adjustment is nec-
essary, perform adjustment only as described in the
following procedure. This is necessary to avoid
faulty park brake operation.
(1) Raise the vehicle.
(2) Back off the cable tensioner adjusting nut to
create slack in the cables.
(3) Remove the rear wheel/tire assemblies. Then
remove the brake rotors (Refer to 5 - BRAKES/HY-
DRAULIC/MECHANICAL/ROTORS - REMOVAL).
(4) Verify the brakes are in good condition and
operating properly.
(5) Verify the park brake cables operate freely and
are not binding, or seized.
(6) Check the rear brake shoe adjustment with
standard brake gauge (Refer to 5 - BRAKES/PARK-
ING BRAKE/SHOES - ADJUSTMENTS).
(7) Install the rotors (Refer to 5 - BRAKES/HY-
DRAULIC/MECHANICAL/ROTORS - INSTALLA-
TION) and verify that the rotors rotate freely
without drag.
(8) Install the wheel/tire assemblies, (Refer to 22 -
TIRES/WHEELS/WHEELS - STANDARD PROCE-
DURE).
(9) Lower the vehicle enough for access to the park
brake foot pedal. Then fully apply the park brakes.
NOTE: Leave park brakes applied until adjustment
is complete.
(10) Raise the vehicle again.
(11) Mark the tensioner rod 6.35 mm (1/4 in.) from
edge of the tensioner (Fig. 85).
(12) Tighten the adjusting nut on the tensioner rod
until the mark is no longer visible.
CAUTION: Do not loosen, or tighten the tensioner
adjusting nut for any reason after completing
adjustment.
(13) Lower the vehicle until the rear wheels are
15-20 cm (6-8 in.) off the shop floor.
(14) Release the park brake foot pedal and verify
that rear wheels rotate freely without drag. Then
lower the vehicle.
Fig. 83 PARKING BRAKE PEDAL
1 - RELEASE ROD
2 - PEDAL ASSEMBLY
Fig. 84 PARKING BRAKE ASSEMBLY
1 - PEDAL ASSEMBLY
2 - MOUNTING NUT
DRBRAKES - BASE 5 - 43
PEDAL (Continued)

RELEASE HANDLE
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Reach under the driver side outboard end of
the instrument panel to access and unsnap the plas-
tic retainer clip that secures the park brake release
linkage rod to the park brake mechanism on the left
cowl side inner panel.
(3) Disengage the park brake release linkage rod
end from the park brake mechanism.
(4) Lift the park brake release handle to access
and unsnap the plastic retainer clip that secures the
park brake release linkage rod to the lever on the
back of the park brake release handle.
(5) Lower the park brake release handle and reach
under the driver side outboard end of the instrument
panel to disengage the park brake release linkage
rod end from the lever on the back of the park brake
release handle.
(6) Lift the park brake release handle to access the
handle mounting bracket.
(7) Using a trim stick or another suitable wide
flat-bladed tool, gently pry each of the park brake
release handle mounting bracket latch tabs away
from the retaining notches in the instrument panel
receptacle (Fig. 86).
(8) With both of the park brake release handle
mounting bracket latches released, slide the handle
and bracket assembly down and out of the instru-
ment panel receptacle.
INSTALLATION
(1) Position the park brake release handle to the
instrument panel.
(2) Slide the handle and bracket assembly up into
the instrument panel receptacle until both of the
park brake release handle mounting bracket latches
are engaged with the notches in the instrument
panel receptacle.
(3) Lower the park brake release handle and reach
under the driver side outboard end of the instrument
panel to engage the park brake release linkage rod
end with the lever on the back of the park brake
release handle.
(4) Lift the park brake release handle to access
and snap the plastic retainer clip that secures the
park brake release linkage rod to the lever on the
back of the park brake release handle over the link-
age rod.
(5) Reach under the driver side outboard end of
the instrument panel to access and engage the park
brake release linkage rod end to the park brake
mechanism.
(6) Snap the plastic retainer clip that secures the
park brake release linkage rod to the park brake
mechanism on the left cowl side inner panel over the
linkage rod.
(7) Reconnect the battery negative cable.
Fig. 85 Adjustment Mark
1 - TENSIONER CABLE BRACKET
2 - TENSIONER
3 - CABLE CONNECTOR
4 - 6.35mm
(1/4 IN.)
5 - ADJUSTER NUT
Fig. 86 Park Brake Release Handle Remove/Install
1 - CLIP
2 - ROD
3 - MOUNTING BRACKET
4 - TRIM STICK
5 - LATCH TABS
6 - PARK BRAKE RELEASE HANDLE
5 - 44 BRAKES - BASEDR
CABLE TENSIONER (Continued)

FRONT WHEEL SPEED
SENSOR
DESCRIPTION
The ABS brake system uses 3 wheel speed sensors.
A sensor is mounted to each front hub/bearings. The
third sensor is mounted on top of the rear axle dif-
ferential housing.
OPERATION
The Wheel Speed Sensor consists of a magnet sur-
rounded by windings from a single strand of wire.
The sensor sends a small AC signal to the CAB. This
signal is generated by magnetic induction. The mag-
netic induction is created when a toothed sensor ring
(exciter ring or tone wheel) passes the stationary
magnetic WSS.
When the ring gear is rotated, the exciter ring
passes the tip of the WSS. As the exciter ring tooth
approaches the tip of the WSS, the magnetic lines of
force expand, causing the magnetic field to cut across
the sensor's windings. This, in turn causes current to
flow through the WSS circuit (Fig. 1) in one direc-
tion. When the exciter ring tooth moves away from
the sensor tip, the magnetic lines of force collapse
cutting the winding in the opposite direction. This
causes the current to flow in the opposite direction.
Every time a tooth of the exciter ring passes the tip
of the WSS, an AC signal is generated. Each AC sig-
nal (positive to negative signal or sinewave) is inter-
preted by the CAB. It then compares the frequency of
the sinewave to a time value to calculate vehicle
speed. The CAB continues to monitor the frequency
to determine a deceleration rate that would indicate
a possible wheel-locking tendency.
The signal strength of any magnetic induction sen-
sor is directly affected by:
²Magnetic field strength; the stronger the mag-
netic field, the stronger the signal
²Number of windings in the sensor; more wind-
ings provide a stronger signal
²Exciter ring speed; the faster the exciter ring/
tone wheel rotates, the stronger the signal will be
²Distance between the exciter ring teeth and
WSS; the closer the WSS is to the exciter ring/tone
wheel, the stronger the signal will be
The rear WSS is not adjustable. A clearance speci-
fication has been established for manufacturing toler-
ances. If the clearance is not within these
specifications, then either the WSS or other compo-
nents may be damaged. The clearance between the
WSS and the exciter ring is 0.005 ± 0.050 in.
The assembly plant performs a ªRolls Testº on
every vehicle that leaves the assembly plant. One of
the test performed is a test of the WSS. To properlytest the sensor, the assembly plant connects test
equipment to the Data Link Connector (DLC). This
connector is located to the right of the steering col-
umn and attached to the lower portion of the instru-
ment panel (Fig. 2). The rolls test terminal is spliced
to the WSS circuit. The vehicle is then driven on a
set of rollers and the WSS output is monitored for
proper operation.
Fig. 1 Operation of the Wheel Speed Sensor
1 - MAGNETIC CORE
2 - CAB
3 - AIR GAP
4 - EXCITER RING
5 - COIL
Fig. 2 Data Link Connector - Typical
1 - 16±WAY DATA LINK CONNECTOR
DRBRAKES - ABS 5 - 47

REMOVAL
(1) Remove the front rotor (Refer to 5 - BRAKES/
HYDRAULIC/MECHANICAL/ROTORS -
REMOVAL).
(2) Remove the wheel speed sensor mounting bolt
from the hub. (Fig. 3)
(3) Remove the wheel speed sensor from the hub.
(4) Remove the wiring from the clips and discon-
nect the electrical connector.
INSTALLATION
(1) Install the wiring to the clips and Reconnect
the electrical connector.
(2) Install the wheel speed sensor to the hub.
(3) Install the wheel speed sensor mounting bolt to
the hub. Tighten the bolt to 21 N´m (190 in. lbs.).
(4) Install the front rotor and brake caliper assem-
bly (Refer to 5 - BRAKES/HYDRAULIC/MECHANI-
CAL/ROTORS - INSTALLATION).
REAR WHEEL SPEED SENSOR
DIAGNOSIS AND TESTING - REAR WHEEL
ANTILOCK
Diagnosis of base brake conditions which are
mechanical in nature should be performed first. This
includes brake noise, lack of power assist, parking
brake, or vehicle vibration during normal braking.
The RWAL brake system performs several self-
tests every time the ignition switch is turned on and
the vehicle is driven. The CAB monitors the system
inputs and outputs circuits to verify the system is
operating properly. If the CAB senses a malfunction
in the system it will set a DTC into memory and trig-
ger the warning lamp.NOTE: The MDS or DRB III scan tool is used to
diagnose the RWAL system. For test procedures
refer to the Chassis Diagnostic Manual.
REMOVAL
(1) Raise the vehicle on a hoist.
(2) Remove the brake line mounting nut and
remove the brake line from the sensor stud.
(3) Remove the mounting stud from the sensor and
shield (Fig. 4).
(4) Remove the sensor and shield from the differ-
ential housing.
(5) Disconnect the sensor wire harness and remove
the sensor.
INSTALLATION
(1) Connect the harness to the sensor.Be sure
the seal is securely in place between the sensor
and the wiring connector.
(2) Install the O-ring on the sensor (if removed).
(3) Insert the sensor in the differential housing.
(4) Install the sensor shield.
(5) Install the sensor mounting stud and tighten to
24 N´m (200 in. lbs.).
(6) Install the brake line on the sensor stud and
install the nut.
(7) Lower the vehicle.
Fig. 3 WHEEL SPEED SENSOR
1 - WHEEL SPEED SENSOR MOUNTING BOLT
2 - WHEEL SPEED SENSOR
3 - HUB/BEARINGFig. 4 REAR WHEEL SPEED SENSOR
1 - WHEEL SPEED SENSOR
2 - MOUNTING BOLT
3 - AXLE HOUSING
5 - 48 BRAKES - ABSDR
FRONT WHEEL SPEED SENSOR (Continued)

PRESSURE INCREASE
The inlet valve is open and the outlet valve is
closed during the pressure increase cycle. The pres-
sure increase cycle is used to reapply thew brakes.
This cycle controls re-application of fluid apply pres-
sure.
REMOVAL
(1) Install a prop rod on the brake pedal to keep
pressure on the brake system.
(2) Disconnect the battery cables from the battery.
(3) Remove the battery.
(4) Disconnect the two electrical harness connec-
tors (Fig. 5).
(5) Remove the five brake lines from the HCU
(Fig. 5).
(6) Remove HCU/CAB mounting bolts and remove
the HCU/CAB (Fig. 5).
INSTALLATION
NOTE: If the CAB is being replaced with a new CAB
is must be reprogrammed with the use of a DRB III.
(1) Install HCU/CAB on the mounts and Tighten
the bolts to 15N´m (11 ft. lbs.) (Fig. 5).
(2) Install the five brake lines to the HCU and
tighten to 19 N´m (170 in. lbs.) (Fig. 5).
(3) Install the two electrical harness connectors to
the HCU/CAB and push down on the release to
secure the connectors.
(4) Install the battery.
(5) Install the battery cables to the battery.
(6) Remove the prop rod on the brake pedal.
(7) Bleed ABS brake system (Refer to 5 - BRAKES
- STANDARD PROCEDURE).
RWAL VALVE
DESCRIPTION
Rear Wheel Antilock (RWAL) brake system is stan-
dard equipment on 1500 series vehicles. The RWAL
brake system is designed to prevent rear wheel
lock-up on virtually all types of road surfaces. RWAL
braking is desirable because a vehicle which is
stopped without locking the rear wheels will retain
directional stability. This allows the driver to retain
greater control of the vehicle during braking.
The valve is located on the drivers side inner
fender under the hood. The valve modulates hydrau-
lic pressure to the rear brakes.
The RWAL components include:
²RWAL Valve
²Controller Antilock brake (CAB)
²Rear Wheel Speed Sensor (WSS)
OPERATION
When the brakes are applied, hydraulic fluid is
routed from the master cylinder's secondary circuit to
the RWAL valve. From there hydraulic fluid is routed
to the rear brakes. The Controller Antilock Brake
(CAB) contains an Electronic Variable Brake Propor-
tioning (EVBP) control algorithm, which proportions
the applied braking force to the rear wheels during
braking. The EVBP function of the RWAL system
takes the place of a conventional hydraulic propor-
tioning valve. The CAB monitors the rear wheel
speed through the rear wheel speed sensor and cal-
culates an estimated vehicle deceleration. When an
established deceleration threshold is exceeded, an
isolation valve is closed to hold the applied brake
pressure to the rear brakes constant. Upon further
increases in the estimated vehicle deceleration, the
isolation valve is selectively opened to increase rear
brake pressure in proportion to the front brake pres-
sure. If impending rear wheel lock-up is sensed, the
CAB signals the RWAL valve to modulate hydraulic
brake pressure to the rear wheels to prevent lock-up.
NORMAL BRAKING Since the RWAL valve also
performs the EVBP or proportioning function, vehicle
deceleration under normal braking may be sufficient
to trigger the EVBP function of the RWAL system
without full RWAL activity as would normally occur
during an impending rear wheel lock-up. As previ-
ously mentioned, the isolation valve is selectively
closed and opened to increase rear brake pressure in
proportion to the front brake pressure under EVBP
control. Slight brake pedal pulsations may be noticed
as the isolation valve is opened.
Fig. 5 HYDRAULIC CONTROL UNIT
1 - HYDRAULIC CONTROL UNIT
2 - MOUNTING BOLTS
5 - 50 BRAKES - ABSDR
HCU (HYDRAULIC CONTROL UNIT) (Continued)