Egr DODGE RAM 1500 1998 2.G Workshop Manual

FLUID ADDITIVES
DaimlerChrysler strongly recommends against the
addition of any fluids to the transmission, other than
those automatic transmission fluids listed above.
Exceptions to this policy are the use of special dyes
to aid in detecting fluid leaks.
Various ªspecialº additives and supplements exist
that claim to improve shift feel and/or quality. These
additives and others also claim to improve converter
clutch operation and inhibit overheating, oxidation,
varnish, and sludge. These claims have not been sup-
ported to the satisfaction of DaimlerChrysler and
these additivesmust not be used.The use of trans-
mission ªsealersº should also be avoided, since they
may adversely affect the integrity of transmission
seals.
OPERATION - AUTOMATIC TRANSMISSION
FLUID
The automatic transmission fluid is selected based
upon several qualities. The fluid must provide a high
level of protection for the internal components by
providing a lubricating film between adjacent metal
components. The fluid must also be thermally stable
so that it can maintain a consistent viscosity through
a large temperature range. If the viscosity stays con-
stant through the temperature range of operation,
transmission operation and shift feel will remain con-
sistent. Transmission fluid must also be a good con-
ductor of heat. The fluid must absorb heat from the
internal transmission components and transfer that
heat to the transmission case.
FLUID CAPACITIES
SPECIFICATIONS
FLUID CAPACITIES
DESCRIPTION SPECIFICATION
FUEL TANK
Short Box (Lt. Duty) 98 L (26 gal.)*
Long Box (Lt. Duty) 132 L (35 gal.)*
ENGINE OIL WITH FILTER
3.7L 4.7 L (5.0 qts.)
4.7L 5.6 L (6.0 qts.)
5.7L 6.6 L (7.0 qts.)
5.9L DIESEL 11.4 L (12.0 qts.)
DESCRIPTION SPECIFICATION
COOLING SYSTEM
3.7L 15.4 L (16.2 qts.)**
4.7L 15.4 L (16.2 qts.)**
5.7L 15.4L (16.2 qts.)**
5.9L Diesel Engine 28L (29.5 qts.)**
POWER STEERING
Power steering fluid capacities are dependent on
engine/chassis options as well as steering gear/cooler
options. Depending on type and size of internal
cooler, length and inside diameter of cooler lines, or
use of an auxiliary cooler, these capacities may vary.
Refer to 19, Steering for proper fill and bleed
procedures.
AUTOMATIC TRANSMISSION
Service Fill - 48RE 3.8 L (4.0 qts.)
O-haul - 48RE 14-16L (29-33 pts.)L
Service Fill - 45RFE/
545RFE4X2 - 5.2 L (11.0 pts.)
4X4 - 6.2 L (13.0 pts.)
O-haul - 45RFE/545RFE 14-16 L (29-33 pts.)L
LDry fill capacity Depending on type and size of
internal cooler, length and inside diameter of cooler
lines, or use of an auxiliary cooler, these figures may
vary. (Refer to 21 - TRANSMISSION/AUTOMATIC/
FLUID - STANDARD PROCEDURE)
MANUAL TRANSMISSION
NV3500 4X2 2.27 L (4.8 pts.)
NV3500 4X4 1.99 L (4.2 pts.)
NV4500 3.79 L (8.0 pts.)
NV5600 4.50 L (9.5 pts.)
TRANSFER CASE
NV241 GENII 1.6 L (3.4 pts.)
NV243 1.6 L (3.4 pts.)
NV244 GENII 1.6 L (3.4 pts.)
NV271 1.89 L (4.0 pts.)
NV273 1.89 L (4.0 pts.)
FRONT AXLE   .03 L (1 oz)
C205F 1.66 L (3.5 pts.)
9 1/4 AA 2.25 L (4.75 pts.)
DRLUBRICATION & MAINTENANCE 0 - 5
FLUID TYPES (Continued)

A wooden crossbeam may be required for proper
connection when using the sling-type, front-end tow-
ing method.
SAFETY PRECAUTIONS
CAUTION: The following safety precautions must be
observed when towing a vehicle:
²Secure loose and protruding parts.
²Always use a safety chain system that is inde-
pendent of the lifting and towing equipment.
²Do not allow towing equipment to contact the
disabled vehicle's fuel tank.
²Do not allow anyone under the disabled vehicle
while it is lifted by the towing device.
²Do not allow passengers to ride in a vehicle
being towed.
²Always observe state and local laws regarding
towing regulations.
²Do not tow a vehicle in a manner that could
jeopardize the safety of the operator, pedestrians or
other motorists.
²Do not attach tow chains, T-hooks, J-hooks, or a
tow sling to a bumper, steering linkage, drive shafts
or a non-reinforced frame hole.
²Do not tow a heavily loaded vehicle. Damage to
the cab, cargo box or frame may result. Use a flatbed
device to transport a loaded vehicle.
GROUND CLEARANCE
CAUTION: If vehicle is towed with wheels removed,
install lug nuts to retain brake drums or rotors.
A towed vehicle should be raised until lifted wheels
are a minimum 100 mm (4 in) from the ground. Be
sure there is adequate ground clearance at the oppo-
site end of the vehicle, especially when towing over
rough terrain or steep rises in the road. If necessary,remove the wheels from the lifted end of the vehicle
and lower the vehicle closer to the ground, to
increase the ground clearance at the opposite end of
the vehicle. Install lug nuts on wheel attaching studs
to retain brake drums or rotors.
RAMP ANGLE
If a vehicle with flat-bed towing equipment is used,
the approach ramp angle should not exceed 15
degrees.
TOWING WHEN KEYS ARE NOT AVAILABLE
When the vehicle is locked and keys are not avail-
able, use a flat bed hauler. A Wheel-lift or Sling-type
device can be used on 4WD vehicles providedall the
wheels are lifted off the ground using tow dol-
lies.
FOUR-WHEEL-DRIVE VEHICLE TOWING
Chrysler Corporation recommends that a vehicle be
transported on a flat-bed device. A Wheel-lift or
Sling-type device can be used providedall the
wheels are lifted off the ground using tow dol-
lies.
WARNING: WHEN TOWING A DISABLED VEHICLE
AND THE DRIVE WHEELS ARE SECURED IN A
WHEEL LIFT OR TOW DOLLIES, ENSURE THE
TRANSMISSION IS IN THE PARK POSITION (AUTO-
MATIC TRANSMISSION) OR A FORWARD DRIVE
GEAR (MANUAL TRANSMISSION).
CAUTION: Many vehicles are equipped with air
dams, spoilers, and/or ground effect panels. To
avoid component damage, a wheel-lift towing vehi-
cle or a flat-bed hauling vehicle is recommended.
0 - 22 LUBRICATION & MAINTENANCEDR
TOWING (Continued)

(1) Start the engine and turn wheels both ways
before straightening the wheels. Center and Secure
the steering wheel and turn off engine.
(2) Loosen the adjustment sleeve clamp bolts.
(3) Adjust the right wheel toe position with the
drag link. Turn the sleeve until the right wheel is at
the correct TOE-IN position. Position clamp bolts to
their original position and tighten to specifications.
Make sure the toe setting does not change dur-
ing clamp tightening.
(4) Adjust left wheel toe position with tie rod at
left knuckle. Turn the sleeve until the left wheel is at
the correct TOE-IN position. Position clamp bolts to
their original position and tighten to specifications.
Make sure the toe setting does not change dur-
ing clamp tightening.
(5) Verify the right toe setting and a straight steer-
ing wheel.
(6) Road test the vehicle.
SPECIFICATIONS
ALIGNMENT
NOTE: All alignment specifications are in degrees.
SPECIFICATIONS
DESCRIP-
TIONSPECIFICATION
VEHICLE
1500WHEEL
BASECASTER
(4.0É
Min,
+.75É
Max)CAMBER
(  .50É)TOTAL
TOE-IN
(  .10É)
4X2 120.5 in 4.0É .0É .10É
4X2 140.5 in 4.2É .0É .10É
4X2 160.5 in 4.4É .0É .10É
VEHICLE
1500WHEEL
BASECASTER
(4.0É
Min,
+.75É
Min)CAMBER
( .50É)TOTAL
TOE-IN
( .10É)
4X4 120.5 in 4.2É .0É .10É
4X4 140.5 in 4.4É .0É .10É
4X4 160.5 in 4.6É .0É .10É
MAX
RT/LT
DIF-
FERENCE
4X2
1500Ð .40É .50É 0.06É
DESCRIP-
TIONSPECIFICATION
MAX
RT/LT
DIF-
FERENCE
4X4
1500Ð .40É .60É 0.06É
VEHICLE
4X2
2500 &
3500WHEEL
BASECASTER
(3.55É
Min,
+.75É
Max)CAMBER
( .50É)TOTAL
TOE-IN
(0.20É
 .10É)
4X2
2500&3500140 4.0É 0.0É .10É  
.05É
4X2
2500&3500160 4.3É 0.0É .10É  
.05É
MAX
RT/LT
DIF-
FERENCE
4X2
2500&3500Ð  0.4É  0.6É 0.1É
VEHICLE
4X4
2500&3500WHEEL
BASECASTER
(4.0É
Min,
+.75É
Max)CAMBER
(.25É
 .5É)TOTAL
TOE-IN
(0.20É
 .10É)
4X4
2500&3500140 4.5É .25É .10É  
.05É
4X4
2500&3500160 4.7É .25É .10É  
.05É
MAX
RT/LT
DIF-
FERENCE
4X4
2500&3500Ð  .5É  .5É 0.1É
DESCRIP-
TIONREAR SPECIFICATION
CAMBER
(-.10É   0.35É)TOTAL TOE-IN
(0.30É   0.35É)
THRUST ANGLE 0É   0.4É
4X2
4X4
1500
THRUST ANGLE -0.2É   0.2É
4X2
4X4
2500&3500
2 - 6 WHEEL ALIGNMENTDR
WHEEL ALIGNMENT (Continued)

INSTALLATION
CAUTION: The left and right side torsion bars are
NOT interchangeable. The bars are identified and
stamped R or L, for right or left. The bars do not
have a front or rear end and can be installed with
either end facing forward.
(1) Insert torsion bar ends into anchor and suspen-
sion arm.
(2) Position the anchor in the frame crossmember.
(3) Install Special Tool - 8686 to the anchor and
the crossmember (Fig. 30).
(4) Increase the tension on the anchor in order to
load the torsion bar.
(5) Install the adjustment bolt and the adjuster
nut.
(6) Turn adjustment bolt clockwise the recorded
amount of turns.
(7) Remove tool - 8686 from the torsion bar cross-
member (Fig. 30).
(8) Install the transfer case skid plate (Refer to 13
- FRAME & BUMPERS/FRAME/TRANSFER CASE
SKID PLATE - INSTALLATION).
(9) Lower vehicle and adjust the front suspension
height (Refer to 2 - SUSPENSION/WHEEL ALIGN-
MENT - STANDARD PROCEDURE).
(10) Perform a wheel alignment (Refer to 2 - SUS-
PENSION/WHEEL ALIGNMENT - STANDARD
PROCEDURE).
UPPER BALL JOINT
DIAGNOSIS AND TESTING - UPPER BALL
JOINT
NOTE: If the ball joint is equipped with a lubrication
fitting, grease the joint then road test the vehicle
before performing test.
(1) Raise the front of the vehicle. Place safety floor
stands under both lower control arms as far outboard
as possible. Lower the vehicle to allow the stands to
support some or all of the vehicle weight.
(2) Remove the front tires.(3) Mount a dial indicator solidly to the frame and
then zero the dial indicator.
(4) Position dial indicator plunger on the topside of
the upper ball joint (Fig. 32).
NOTE: The dial indicator plunger must be perpen-
dicular to the machined surface of the ball joint
(Fig. 32).
NOTE: Use care not to pry or tear the ball joint
boot, when checking the free play.
(5) Position a pry bar between the steering
knuckle and the upper control arm. Pry upwards on
the upper control arm (Fig. 32).
(6) If the travel exceeds 0.5 mm (0.020 in.), replace
the upper control arm since the upper ball joint is
integral to the arm (Refer to 2 - SUSPENSION/
FRONT/UPPER CONTROL ARM - REMOVAL).
(7) If the upper ball joint is within specs reinstall
the front tires (Refer to 22 - TIRES/WHEELS/
WHEELS - STANDARD PROCEDURE).
Fig. 32 UPPER BALL JOINT PLAY
1 - DIAL INDICATOR
2 - UPPER CONTROL ARM
3-PRYBAR
4 - KNUCKLE
5 - BALL JOINT BOOT
DRFRONT - INDEPENDENT FRONT SUSPENSION 2 - 27
TORSION BAR (Continued)

This measurement will give you the transmis-
sion yoke Output Angle (A).
(6) Rotate propeller shaft 90 degrees and place
Inclinometer on yoke bearing parallel to the shaft
(Fig. 5). Center bubble in sight glass and record mea-
surement. This measurement can also be taken at
the rear end of the shaft.
This measurement will give you the Propeller
Shaft Angle (C).(7) Rotate propeller shaft 90 degrees and place
inclinometer on companion flange yoke bearing par-
allel to the shaft (Fig. 6). Center bubble in sight glass
and record measurement.
This measurement will give you the pinion
Companion Flange Input Angle (B).
(8) Subtract smaller figure from larger (C minus
A) to obtain Transmission/Transfer CaseOutput
Operating Angle.
(9) Subtract smaller figure from larger (C minus
B) to obtain axleInput Operating Angle.
Refer to rules and example in (Fig. 7) for addi-
tional information.
RULES
²Good cancellation of U-joint operating angles
should be within 1 degree.
²Operating angles should be less than 3 degrees.
²Operating angles less than 10 degrees for double
cardan U-joint.
²At least 1/2 of one degree continuous operating
propeller shaft angle.
TWO-PIECE PROPELLER SHAFT
Two-piece propeller shaft angles measurement (Fig.
8) is the same as a one-piece propeller shaft.
Fig. 4 OUTPUT ANGLE (A)
Fig. 5 PROPELLER SHAFT ANGLE (C)
Fig. 6 INPUT ANGLE (B)
3 - 4 PROPELLER SHAFTDR
PROPELLER SHAFT (Continued)

(1) Through the axle tube use Wrench C-4164 to
adjust each threaded adjuster inward until the differ-
ential bearing free-play is eliminated. Allow some
ring gear backlash approximately 0.25 mm (0.01 in.)
between the ring and pinion gear. Seat the bearing
cups with the procedure described above.
(2) Install dial indicator and position the plunger
against the drive side of a ring gear tooth (Fig. 9).
Measure the backlash at 4 positions, 90 degrees
apart around the ring gear. Locate and mark the
area of minimum backlash.
(3) Rotate the ring gear to the position of the least
backlash. Mark the gear so that all future backlash
measurements will be taken with the same gear
teeth meshed.
(4) Loosen the right-side, tighten the left-side
threaded adjuster. Obtain backlash of 0.076 to 0.102
mm (0.003-0.004 in.) with each adjuster tightened to
14 N´m (10 ft. lbs.). Seat the bearing cups with the
procedure described above.
(5) Tighten the differential bearing cap bolts 136
N´m (100 ft. lbs.).
(6) Tighten the right-side threaded adjuster to 102
N´m (75 ft. lbs.). Seat the bearing cups with the pro-
cedure described above. Continue to tighten the
right-side adjuster and seat bearing cups until the
torque remains constant at 102 N´m (75 ft. lbs.)
(7) Measure the ring gear backlash. The range of
backlash is 0.15 to 0.203 mm (0.006 to 0.008 in.).(8) Continue increasing the torque at the right-
side threaded adjuster until the specified backlash is
obtained.
NOTE: The left-side threaded adjuster torque
should have approximately 102 N´m (75 ft. lbs.). If
the torque is considerably less, the complete
adjustment procedure must be repeated.
(9) Tighten the left-side threaded adjuster until
102 N´m (75 ft. lbs.) torque is indicated. Seat the
bearing rollers with the procedure described above.
Do this until the torque remains constant.
(10) Install the threaded adjuster locks and
tighten the lock screws to 10 N´m (90 in. lbs.).
GEAR CONTACT PATTERN
Gear tooth contact pattern is used to verify the cor-
rect running position of the ring and pinion gears.
This will produce low noise and long gear life. Gears
which are not positioned properly may be noisy and
have shorten gear life.
(1) Wipe clean each tooth of the ring gear.
(2) Apply gear marking compound to all of the ring
gear teeth.
(3) Verify bearing cap bolts are torque specifica-
tion.
(4) Apply parking brakes lightly to create at 14
N´m (10 ft. lbs.) pinion rotating torque.
(5) Rotate the pinion/pinion yoke 4 full revolutions
in each directions.
(6) Read gear tooth contact pattern:
²Gear contact pattern is correct (Fig. 10). Back-
lash and pinion depth is correct.
Fig. 9 RING GEAR BACKLASH
1 - DIAL INDICATOR
2 - RING GEAR
3 - EXCITER RING
Fig. 10 CORRECT CONTACT PATTERN
DRREAR AXLE - 9 1/4 3 - 87
REAR AXLE - 9 1/4 (Continued)

INSTALLATION
INSTALLATION - ALL EXCEPT HYDROBOOST
NOTE: If master cylinder is replaced bleed cylinder
before installation.
NOTE: Make sure the output rod of the brake
booster is in position and retained by a output rod
retaining ring, by looking into the boosters master
cylinder mounting hole. This position will enable
the output rod to enter inside of the master cylinder
plunger sleeve during installation. Proper position
is obtained when the output rod is centered perpen-
dicular to the master cylinder mounting hole (Fig.
49).
NOTE: Prior to installing the master cylinder assem-
bly check that there is a vacuum seal present at the
shoulder of the master cylinder flange and it's neck.
A square seal must be present to ensure vacuum
integrity with the booster.
(1) Gently install the master cylinder on the
booster mounting studs.
NOTE: Take precautions to locate the master cylin-
der plunger over the booster output rod, before
installing the master cylinder. If correctly fitted the
master cylinder should slide easily onto the booster
output rod before the mounting studs are engaged
in the flange holes of the master cylinder.(2) Install new mounting nuts and tighten to 25
N´m (221 in. lbs.)
(3) Install the brake lines and tighten to 19 N´m
(170 in. lbs.)
(4) Reconnect the electrical connector for the low
fluid level switch.
(5) Fill and bleed the base brake system. (Refer to
5 - BRAKES - STANDARD PROCEDURE).
INSTALLATION - HYDROBOOST
NOTE: If master cylinder is replaced bleed cylinder
before installation.
(1) Install the master cylinder on the booster
mounting studs (Fig. 48).
(2) Install new mounting nuts and tighten to 25
N´m (221 in. lbs.)
(3) Install the brake lines and tighten to 19 N´m
(170 in. lbs.)
(4) Reconnect the elctrical connector for the low
fluid level switch.
(5) Fill and bleed the base brake system. (Refer to
5 - BRAKES - STANDARD PROCEDURE).
Fig. 48 HYDROBOOST MASTER CYLINDER
1 - HYDROBOOST UNIT
2 - MASTER CYLINDER RESERVOIR
3 - MASTER CYLINDER
4 - MOUNTING NUTS
Fig. 49 OUTPUT ROD ORIENTATION
1 - MASTER CYLINDER RESERVOIR
2 - CHECK VALVE
3 - VACUUM BOOST UNIT
4 - BOOSTER MOUNTING STUDS
5 - INPUT ROD
6 - OUTPUT ROD
7 - MASTER CYLINDER MOUNTING STUDS
8 - MASTER CYLINDER PLUNGER SLEEVE
9- MASTER CYLINDER
10 - ELECTRICAL CONNECTOR
DRBRAKES - BASE 5 - 27
MASTER CYLINDER (Continued)

Brake fluid apply pressure is modulated according
to wheel speed, degree of slip and rate of decelera-
tion. Sensors at each front wheel convert wheel speed
into electrical signals. These signals are transmitted
to the CAB for processing and determination of
wheel slip and deceleration rate.
The ABS system has three fluid pressure control
channels. The front brakes are controlled separately
and the rear brakes in tandem. A speed sensor input
signal indicating a wheel slip condition activates the
CAB antilock program.
There are Two solenoid valves (Isolation and Dump
valve) which are used in each antilock control chan-
nel. The valves are all located within the HCU valve
body and work in pairs to either increase, hold, or
decrease apply pressure as needed in the individual
control channels.
During an ABS stop the ISO valve is energized
which acts to prevent further pressure build-up to
the calipers. Then the Dump valve dumps off pres-
sure until the wheel unlocks. This will continue until
the wheels quit slipping altogether.STANDARD PROCEDURE - ABS BRAKE
BLEEDING
ABS system bleeding requires conventional bleed-
ing methods plus use of the DRB scan tool. The pro-
cedure involves performing a base brake bleeding,
followed by use of the scan tool to cycle and bleed the
HCU pump and solenoids. A second base brake bleed-
ing procedure is then required to remove any air
remaining in the system.
(1) Perform base brake bleeding,(Refer to 5 -
BRAKES - STANDARD PROCEDURE) OR (Refer to
5 - BRAKES - STANDARD PROCEDURE).
(2) Connect scan tool to the Data Link Connector.
(3) Select ANTILOCK BRAKES, followed by MIS-
CELLANEOUS, then ABS BRAKES. Follow the
instructions displayed. When scan tool displays TEST
COMPLETE, disconnect scan tool and proceed.
(4) Perform base brake bleeding a second time,(Re-
fer to 5 - BRAKES - STANDARD PROCEDURE) OR
(Refer to 5 - BRAKES - STANDARD PROCEDURE).
(5) Top off master cylinder fluid level and verify
proper brake operation before moving vehicle.
SPECIFICATIONS
TORQUE CHART
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
ABS Assembly
Mounting Bolts15 11 Ð
ABS Assembly
CAB Screws3.5 Ð 31
ABS Assembly
Brake Line Fittings19 Ð 170
Wheel Speed Sensors
Front Sensor Bolt21 Ð 190
Wheel Speed Sensors
Bracket To Knuckle6.7 Ð 60
Wheel Speed Sensors
Rear Sensor Stud22.5 Ð 200
Controller
Mounting Screws6Ð53
RWAL Module
Mounting Bolts15 11 Ð
RWAL Valve
Brake Line Fittings19 Ð 170
Rear Wheel Speed
Sensor
Mounting Bolt24 Ð 200
5 - 46 BRAKES - ABSDR
BRAKES - ABS (Continued)

TONE WHEEL
DIAGNOSIS AND TESTING - REAR WHEEL
SPEED SENSOR
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 Antilock 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 Antilock Brake system. For test proce-
dures refer to the Chassis Diagnostic Manual.
HYDRAULIC/MECHANICAL
DESCRIPTION - ELECTRONIC VARIABLE
BRAKE PROPORTIONING
Vehicles equipped with ABS use electronic variable
brake proportioning (EVBP) to balance front-to-rear
braking. The EVBP is used in place of a rear propor-
tioning valve. The EVBP system uses the ABS sys-
tem to control the slip of the rear wheels in partial
braking range. The braking force of the rear wheels
is controlled electronically by using the inlet and out-
let valves located in the integrated control unit
(ICU).
OPERATION - ELECTRONIC VARIABLE BRAKE
PROPORTIONING
EVBP is able to decrease, hold and increase rear
brake pressure without activating full ABS control.
Upon entry into EVBP the inlet valve for the rear
brake circuit is switched on so that the fluid supply
from the master cylinder is shut off. In order to
decrease the rear brake pressure, the outlet valve for
the rear brake circuit is pulsed. This allows fluid to
enter the low pressure accumulator (LPA) in the
hydraulic control unit (HCU) resulting in a drop in
fluid pressure to the rear brakes. In order to increase
the rear brake pressure, the outlet valve is switched
off and the inlet valve is pulsed. This increases the
pressure to the rear brakes.
The EVBP will remain functional during many
ABS fault modes. If both the red BRAKE and amber
ABS warning indicators are illuminated, the EVBP
may not be functioning.
HCU (HYDRAULIC CONTROL
UNIT)
DESCRIPTION
The HCU consists of a valve body, pump motor, low
pressure accumulators, inlet valves, outlet valves and
noise attenuators.
OPERATION
Accumulators in the valve body store extra fluid
released to the system for ABS mode operation. The
pump provides the fluid volume needed and is oper-
ated by a DC type motor. The motor is controlled by
the CAB.
The valves modulate brake pressure during
antilock braking and are controlled by the CAB.
The HCU provides three channel pressure control
to the front and rear brakes. One channel controls
the rear wheel brakes in tandem. The two remaining
channels control the front wheel brakes individually.
During antilock braking, the solenoid valves are
opened and closed as needed.
During normal braking, the HCU solenoid valves
and pump are not activated. The master cylinder and
power booster operate the same as a vehicle without
an ABS brake system.
NOTE: The three modes mentioned below do occur
but not necessarily in the order listed everytime.
During antilock braking, solenoid valve pressure
modulation occurs in three stages, pressure increase,
pressure hold, and pressure decrease. The valves are
all contained in the valve body portion of the HCU.
PRESSURE DECREASE
The outlet valve is opened and the inlet valve is
closed during the pressure decrease cycle.
A pressure decrease cycle is initiated when speed
sensor signals indicate high wheel slip at one or
more wheels. At this point, the CAB closes the inlet
then opens the outlet valve, which also opens the
return circuit to the accumulators. Fluid pressure is
allowed to bleed off (decrease) as needed to prevent
wheel lock.
Once the period of high wheel slip has ended, the
CAB closes the outlet valve and begins a pressure
increase or hold cycle as needed.
PRESSURE HOLD
Both solenoid valves are closed in the pressure
hold cycle but only the inlet valve is energized. Fluid
apply pressure in the control channel is maintained
at a constant rate. The CAB maintains the hold cycle
until sensor inputs indicate a pressure change is nec-
essary.
DRBRAKES - ABS 5 - 49

(2) Apply a light coating of grease to the inside
diameter of the master cylinder push rod eye.
(3) Install clutch master cylinder on dash panel
and tighten clutch master cylinder nuts to 28 N´m
(21 ft. lbs.).
(4) Install clutch master cylinder push rod pin.
(5) Connect clutch pedal position interlock switch
wires.
(6) Install plastic clip securing hydraulic line to
the dash panel into the lower dash panel flange.
(7) Install plastic clip securing hydraulic line to
the dash panel onto the upper dash panel stud.
(8) Raise vehicle.
(9) Install slave cylinder and verify cylinder rod is
properly seated in release lever.
(10) Install and tighten slave cylinder nuts to 23
N´m (17 ft. lbs.).
(11) Ifnewclutch linkage is being installed, con-
nect the clutch hydraulic line to the clutch slave cyl-
inder.
CAUTION: Once the clutch hydraulic line is con-
nected to the slave cylinder, it should never be dis-
connected.
(12) Lower vehicle.
(13) Operate linkage several times to verify proper
operation.
CLUTCH PEDAL POSITION
SWITCH
DESCRIPTION
A clutch pedal position switch (CPPS) is mounted
on the clutch master cylinder push rod (Fig. 20). The
wiring harness connector is inside of the vehicle
under the left side of the instrument panel.
NOTE: Switch is serviced with clutch master cylin-
der.
OPERATION
The clutch pedal position switch is used to prevent
starter motor engagement unless the clutch pedal is
depressed. An input from this switch is also used to
either shut down/prevent operation of the speed con-
trol system when pedal is depressed. The position
switch is an integral part of the clutch master cylin-
der push rod.
DIAGNOSIS AND TESTING
(1) Disconnect switch 2-wire connector attached to
pedal support bracket, under instrument panel to left
of clutch pedal (Fig. 21).(2) Check switch continuity with an ohmmeter
while operating clutch pedal.
²Pedal Depressed - Continuity
²Pedal Released - No Continuity
(3) If continuity is not present or always present,
replace clutch master cylinder. Switch is not serviced
separately.
Fig. 20 LOCATION, CLUTCH PEDAL
POSITION SWITCH
1 - CLUTCH MASTER CYLINDER
2 - CLUTCH PEDAL POSITION SWITCH
Fig. 21 CLUTCH SWITCH TEST POINT
1 - PEDAL SUPPORT BRACKET
2 - ELECTRICAL CONNECTOR
DRCLUTCH 6 - 13
LINKAGE (Continued)